* [PATCH v5 01/19] scripts: move genksyms crc32 implementation to a common include
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-11-12 4:05 ` Masahiro Yamada
2024-10-30 17:01 ` [PATCH v5 02/19] tools: Add gendwarfksyms Sami Tolvanen
` (18 subsequent siblings)
19 siblings, 1 reply; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
To avoid duplication between host programs, move the crc32 code to a
shared header file.
Suggested-by: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
---
scripts/genksyms/genksyms.c | 77 +-----------------------------
scripts/include/crc32.h | 93 +++++++++++++++++++++++++++++++++++++
2 files changed, 94 insertions(+), 76 deletions(-)
create mode 100644 scripts/include/crc32.h
diff --git a/scripts/genksyms/genksyms.c b/scripts/genksyms/genksyms.c
index f3901c55df23..2885bbcb9eec 100644
--- a/scripts/genksyms/genksyms.c
+++ b/scripts/genksyms/genksyms.c
@@ -18,6 +18,7 @@
#include <stdarg.h>
#include <getopt.h>
+#include <crc32.h>
#include "genksyms.h"
/*----------------------------------------------------------------------*/
@@ -58,82 +59,6 @@ static struct string_list *mk_node(const char *string);
static void print_location(void);
static void print_type_name(enum symbol_type type, const char *name);
-/*----------------------------------------------------------------------*/
-
-static const unsigned int crctab32[] = {
- 0x00000000U, 0x77073096U, 0xee0e612cU, 0x990951baU, 0x076dc419U,
- 0x706af48fU, 0xe963a535U, 0x9e6495a3U, 0x0edb8832U, 0x79dcb8a4U,
- 0xe0d5e91eU, 0x97d2d988U, 0x09b64c2bU, 0x7eb17cbdU, 0xe7b82d07U,
- 0x90bf1d91U, 0x1db71064U, 0x6ab020f2U, 0xf3b97148U, 0x84be41deU,
- 0x1adad47dU, 0x6ddde4ebU, 0xf4d4b551U, 0x83d385c7U, 0x136c9856U,
- 0x646ba8c0U, 0xfd62f97aU, 0x8a65c9ecU, 0x14015c4fU, 0x63066cd9U,
- 0xfa0f3d63U, 0x8d080df5U, 0x3b6e20c8U, 0x4c69105eU, 0xd56041e4U,
- 0xa2677172U, 0x3c03e4d1U, 0x4b04d447U, 0xd20d85fdU, 0xa50ab56bU,
- 0x35b5a8faU, 0x42b2986cU, 0xdbbbc9d6U, 0xacbcf940U, 0x32d86ce3U,
- 0x45df5c75U, 0xdcd60dcfU, 0xabd13d59U, 0x26d930acU, 0x51de003aU,
- 0xc8d75180U, 0xbfd06116U, 0x21b4f4b5U, 0x56b3c423U, 0xcfba9599U,
- 0xb8bda50fU, 0x2802b89eU, 0x5f058808U, 0xc60cd9b2U, 0xb10be924U,
- 0x2f6f7c87U, 0x58684c11U, 0xc1611dabU, 0xb6662d3dU, 0x76dc4190U,
- 0x01db7106U, 0x98d220bcU, 0xefd5102aU, 0x71b18589U, 0x06b6b51fU,
- 0x9fbfe4a5U, 0xe8b8d433U, 0x7807c9a2U, 0x0f00f934U, 0x9609a88eU,
- 0xe10e9818U, 0x7f6a0dbbU, 0x086d3d2dU, 0x91646c97U, 0xe6635c01U,
- 0x6b6b51f4U, 0x1c6c6162U, 0x856530d8U, 0xf262004eU, 0x6c0695edU,
- 0x1b01a57bU, 0x8208f4c1U, 0xf50fc457U, 0x65b0d9c6U, 0x12b7e950U,
- 0x8bbeb8eaU, 0xfcb9887cU, 0x62dd1ddfU, 0x15da2d49U, 0x8cd37cf3U,
- 0xfbd44c65U, 0x4db26158U, 0x3ab551ceU, 0xa3bc0074U, 0xd4bb30e2U,
- 0x4adfa541U, 0x3dd895d7U, 0xa4d1c46dU, 0xd3d6f4fbU, 0x4369e96aU,
- 0x346ed9fcU, 0xad678846U, 0xda60b8d0U, 0x44042d73U, 0x33031de5U,
- 0xaa0a4c5fU, 0xdd0d7cc9U, 0x5005713cU, 0x270241aaU, 0xbe0b1010U,
- 0xc90c2086U, 0x5768b525U, 0x206f85b3U, 0xb966d409U, 0xce61e49fU,
- 0x5edef90eU, 0x29d9c998U, 0xb0d09822U, 0xc7d7a8b4U, 0x59b33d17U,
- 0x2eb40d81U, 0xb7bd5c3bU, 0xc0ba6cadU, 0xedb88320U, 0x9abfb3b6U,
- 0x03b6e20cU, 0x74b1d29aU, 0xead54739U, 0x9dd277afU, 0x04db2615U,
- 0x73dc1683U, 0xe3630b12U, 0x94643b84U, 0x0d6d6a3eU, 0x7a6a5aa8U,
- 0xe40ecf0bU, 0x9309ff9dU, 0x0a00ae27U, 0x7d079eb1U, 0xf00f9344U,
- 0x8708a3d2U, 0x1e01f268U, 0x6906c2feU, 0xf762575dU, 0x806567cbU,
- 0x196c3671U, 0x6e6b06e7U, 0xfed41b76U, 0x89d32be0U, 0x10da7a5aU,
- 0x67dd4accU, 0xf9b9df6fU, 0x8ebeeff9U, 0x17b7be43U, 0x60b08ed5U,
- 0xd6d6a3e8U, 0xa1d1937eU, 0x38d8c2c4U, 0x4fdff252U, 0xd1bb67f1U,
- 0xa6bc5767U, 0x3fb506ddU, 0x48b2364bU, 0xd80d2bdaU, 0xaf0a1b4cU,
- 0x36034af6U, 0x41047a60U, 0xdf60efc3U, 0xa867df55U, 0x316e8eefU,
- 0x4669be79U, 0xcb61b38cU, 0xbc66831aU, 0x256fd2a0U, 0x5268e236U,
- 0xcc0c7795U, 0xbb0b4703U, 0x220216b9U, 0x5505262fU, 0xc5ba3bbeU,
- 0xb2bd0b28U, 0x2bb45a92U, 0x5cb36a04U, 0xc2d7ffa7U, 0xb5d0cf31U,
- 0x2cd99e8bU, 0x5bdeae1dU, 0x9b64c2b0U, 0xec63f226U, 0x756aa39cU,
- 0x026d930aU, 0x9c0906a9U, 0xeb0e363fU, 0x72076785U, 0x05005713U,
- 0x95bf4a82U, 0xe2b87a14U, 0x7bb12baeU, 0x0cb61b38U, 0x92d28e9bU,
- 0xe5d5be0dU, 0x7cdcefb7U, 0x0bdbdf21U, 0x86d3d2d4U, 0xf1d4e242U,
- 0x68ddb3f8U, 0x1fda836eU, 0x81be16cdU, 0xf6b9265bU, 0x6fb077e1U,
- 0x18b74777U, 0x88085ae6U, 0xff0f6a70U, 0x66063bcaU, 0x11010b5cU,
- 0x8f659effU, 0xf862ae69U, 0x616bffd3U, 0x166ccf45U, 0xa00ae278U,
- 0xd70dd2eeU, 0x4e048354U, 0x3903b3c2U, 0xa7672661U, 0xd06016f7U,
- 0x4969474dU, 0x3e6e77dbU, 0xaed16a4aU, 0xd9d65adcU, 0x40df0b66U,
- 0x37d83bf0U, 0xa9bcae53U, 0xdebb9ec5U, 0x47b2cf7fU, 0x30b5ffe9U,
- 0xbdbdf21cU, 0xcabac28aU, 0x53b39330U, 0x24b4a3a6U, 0xbad03605U,
- 0xcdd70693U, 0x54de5729U, 0x23d967bfU, 0xb3667a2eU, 0xc4614ab8U,
- 0x5d681b02U, 0x2a6f2b94U, 0xb40bbe37U, 0xc30c8ea1U, 0x5a05df1bU,
- 0x2d02ef8dU
-};
-
-static unsigned long partial_crc32_one(unsigned char c, unsigned long crc)
-{
- return crctab32[(crc ^ c) & 0xff] ^ (crc >> 8);
-}
-
-static unsigned long partial_crc32(const char *s, unsigned long crc)
-{
- while (*s)
- crc = partial_crc32_one(*s++, crc);
- return crc;
-}
-
-static unsigned long crc32(const char *s)
-{
- return partial_crc32(s, 0xffffffff) ^ 0xffffffff;
-}
-
-/*----------------------------------------------------------------------*/
-
static enum symbol_type map_to_ns(enum symbol_type t)
{
switch (t) {
diff --git a/scripts/include/crc32.h b/scripts/include/crc32.h
new file mode 100644
index 000000000000..06eedd273717
--- /dev/null
+++ b/scripts/include/crc32.h
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * CRC32 implementation.
+ *
+ * Moved from scripts/genksyms/genksyms.c, which has the following
+ * notice:
+ *
+ * Generate kernel symbol version hashes.
+ * Copyright 1996, 1997 Linux International.
+ *
+ * New implementation contributed by Richard Henderson <rth@tamu.edu>
+ * Based on original work by Bjorn Ekwall <bj0rn@blox.se>
+ *
+ * This file was part of the Linux modutils 2.4.22: moved back into the
+ * kernel sources by Rusty Russell/Kai Germaschewski.
+ */
+
+#ifndef __CRC32_H
+#define __CRC32_H
+
+static const unsigned int crctab32[] = {
+ 0x00000000U, 0x77073096U, 0xee0e612cU, 0x990951baU, 0x076dc419U,
+ 0x706af48fU, 0xe963a535U, 0x9e6495a3U, 0x0edb8832U, 0x79dcb8a4U,
+ 0xe0d5e91eU, 0x97d2d988U, 0x09b64c2bU, 0x7eb17cbdU, 0xe7b82d07U,
+ 0x90bf1d91U, 0x1db71064U, 0x6ab020f2U, 0xf3b97148U, 0x84be41deU,
+ 0x1adad47dU, 0x6ddde4ebU, 0xf4d4b551U, 0x83d385c7U, 0x136c9856U,
+ 0x646ba8c0U, 0xfd62f97aU, 0x8a65c9ecU, 0x14015c4fU, 0x63066cd9U,
+ 0xfa0f3d63U, 0x8d080df5U, 0x3b6e20c8U, 0x4c69105eU, 0xd56041e4U,
+ 0xa2677172U, 0x3c03e4d1U, 0x4b04d447U, 0xd20d85fdU, 0xa50ab56bU,
+ 0x35b5a8faU, 0x42b2986cU, 0xdbbbc9d6U, 0xacbcf940U, 0x32d86ce3U,
+ 0x45df5c75U, 0xdcd60dcfU, 0xabd13d59U, 0x26d930acU, 0x51de003aU,
+ 0xc8d75180U, 0xbfd06116U, 0x21b4f4b5U, 0x56b3c423U, 0xcfba9599U,
+ 0xb8bda50fU, 0x2802b89eU, 0x5f058808U, 0xc60cd9b2U, 0xb10be924U,
+ 0x2f6f7c87U, 0x58684c11U, 0xc1611dabU, 0xb6662d3dU, 0x76dc4190U,
+ 0x01db7106U, 0x98d220bcU, 0xefd5102aU, 0x71b18589U, 0x06b6b51fU,
+ 0x9fbfe4a5U, 0xe8b8d433U, 0x7807c9a2U, 0x0f00f934U, 0x9609a88eU,
+ 0xe10e9818U, 0x7f6a0dbbU, 0x086d3d2dU, 0x91646c97U, 0xe6635c01U,
+ 0x6b6b51f4U, 0x1c6c6162U, 0x856530d8U, 0xf262004eU, 0x6c0695edU,
+ 0x1b01a57bU, 0x8208f4c1U, 0xf50fc457U, 0x65b0d9c6U, 0x12b7e950U,
+ 0x8bbeb8eaU, 0xfcb9887cU, 0x62dd1ddfU, 0x15da2d49U, 0x8cd37cf3U,
+ 0xfbd44c65U, 0x4db26158U, 0x3ab551ceU, 0xa3bc0074U, 0xd4bb30e2U,
+ 0x4adfa541U, 0x3dd895d7U, 0xa4d1c46dU, 0xd3d6f4fbU, 0x4369e96aU,
+ 0x346ed9fcU, 0xad678846U, 0xda60b8d0U, 0x44042d73U, 0x33031de5U,
+ 0xaa0a4c5fU, 0xdd0d7cc9U, 0x5005713cU, 0x270241aaU, 0xbe0b1010U,
+ 0xc90c2086U, 0x5768b525U, 0x206f85b3U, 0xb966d409U, 0xce61e49fU,
+ 0x5edef90eU, 0x29d9c998U, 0xb0d09822U, 0xc7d7a8b4U, 0x59b33d17U,
+ 0x2eb40d81U, 0xb7bd5c3bU, 0xc0ba6cadU, 0xedb88320U, 0x9abfb3b6U,
+ 0x03b6e20cU, 0x74b1d29aU, 0xead54739U, 0x9dd277afU, 0x04db2615U,
+ 0x73dc1683U, 0xe3630b12U, 0x94643b84U, 0x0d6d6a3eU, 0x7a6a5aa8U,
+ 0xe40ecf0bU, 0x9309ff9dU, 0x0a00ae27U, 0x7d079eb1U, 0xf00f9344U,
+ 0x8708a3d2U, 0x1e01f268U, 0x6906c2feU, 0xf762575dU, 0x806567cbU,
+ 0x196c3671U, 0x6e6b06e7U, 0xfed41b76U, 0x89d32be0U, 0x10da7a5aU,
+ 0x67dd4accU, 0xf9b9df6fU, 0x8ebeeff9U, 0x17b7be43U, 0x60b08ed5U,
+ 0xd6d6a3e8U, 0xa1d1937eU, 0x38d8c2c4U, 0x4fdff252U, 0xd1bb67f1U,
+ 0xa6bc5767U, 0x3fb506ddU, 0x48b2364bU, 0xd80d2bdaU, 0xaf0a1b4cU,
+ 0x36034af6U, 0x41047a60U, 0xdf60efc3U, 0xa867df55U, 0x316e8eefU,
+ 0x4669be79U, 0xcb61b38cU, 0xbc66831aU, 0x256fd2a0U, 0x5268e236U,
+ 0xcc0c7795U, 0xbb0b4703U, 0x220216b9U, 0x5505262fU, 0xc5ba3bbeU,
+ 0xb2bd0b28U, 0x2bb45a92U, 0x5cb36a04U, 0xc2d7ffa7U, 0xb5d0cf31U,
+ 0x2cd99e8bU, 0x5bdeae1dU, 0x9b64c2b0U, 0xec63f226U, 0x756aa39cU,
+ 0x026d930aU, 0x9c0906a9U, 0xeb0e363fU, 0x72076785U, 0x05005713U,
+ 0x95bf4a82U, 0xe2b87a14U, 0x7bb12baeU, 0x0cb61b38U, 0x92d28e9bU,
+ 0xe5d5be0dU, 0x7cdcefb7U, 0x0bdbdf21U, 0x86d3d2d4U, 0xf1d4e242U,
+ 0x68ddb3f8U, 0x1fda836eU, 0x81be16cdU, 0xf6b9265bU, 0x6fb077e1U,
+ 0x18b74777U, 0x88085ae6U, 0xff0f6a70U, 0x66063bcaU, 0x11010b5cU,
+ 0x8f659effU, 0xf862ae69U, 0x616bffd3U, 0x166ccf45U, 0xa00ae278U,
+ 0xd70dd2eeU, 0x4e048354U, 0x3903b3c2U, 0xa7672661U, 0xd06016f7U,
+ 0x4969474dU, 0x3e6e77dbU, 0xaed16a4aU, 0xd9d65adcU, 0x40df0b66U,
+ 0x37d83bf0U, 0xa9bcae53U, 0xdebb9ec5U, 0x47b2cf7fU, 0x30b5ffe9U,
+ 0xbdbdf21cU, 0xcabac28aU, 0x53b39330U, 0x24b4a3a6U, 0xbad03605U,
+ 0xcdd70693U, 0x54de5729U, 0x23d967bfU, 0xb3667a2eU, 0xc4614ab8U,
+ 0x5d681b02U, 0x2a6f2b94U, 0xb40bbe37U, 0xc30c8ea1U, 0x5a05df1bU,
+ 0x2d02ef8dU
+};
+
+static inline unsigned long partial_crc32_one(unsigned char c, unsigned long crc)
+{
+ return crctab32[(crc ^ c) & 0xff] ^ (crc >> 8);
+}
+
+static inline unsigned long partial_crc32(const char *s, unsigned long crc)
+{
+ while (*s)
+ crc = partial_crc32_one(*s++, crc);
+ return crc;
+}
+
+static inline unsigned long crc32(const char *s)
+{
+ return partial_crc32(s, 0xffffffff) ^ 0xffffffff;
+}
+
+#endif /* __CRC32_H */
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* Re: [PATCH v5 01/19] scripts: move genksyms crc32 implementation to a common include
2024-10-30 17:01 ` [PATCH v5 01/19] scripts: move genksyms crc32 implementation to a common include Sami Tolvanen
@ 2024-11-12 4:05 ` Masahiro Yamada
2024-11-13 14:04 ` Neal Gompa
2024-11-13 17:53 ` Sami Tolvanen
0 siblings, 2 replies; 36+ messages in thread
From: Masahiro Yamada @ 2024-11-12 4:05 UTC (permalink / raw)
To: Sami Tolvanen
Cc: Luis Chamberlain, Miguel Ojeda, Greg Kroah-Hartman,
Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux
On Thu, Oct 31, 2024 at 2:01 AM Sami Tolvanen <samitolvanen@google.com> wrote:
>
> To avoid duplication between host programs, move the crc32 code to a
> shared header file.
Only the motivation to use this long table is to keep compatibility
between genksyms and gendwarfksyms.
I do not think this should be exposed to other programs.
If you avoid the code duplication, you can do
// scripts/gendwarfksyms/crc.c
#include "../genksyms/crc.c"
>
> Suggested-by: Petr Pavlu <petr.pavlu@suse.com>
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> Acked-by: Neal Gompa <neal@gompa.dev>
Does this Ack add any value?
Acked-by is meaningful only when it is given by someone who
maintains the relevant area or has established a reputation.
$ git grep "Neal Gompa"
$ git shortlog -n -s | grep "Neal Gompa"
2 Neal Gompa
His Ack feels more like "I like it" rather than a qualified endorsement.
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 36+ messages in thread* Re: [PATCH v5 01/19] scripts: move genksyms crc32 implementation to a common include
2024-11-12 4:05 ` Masahiro Yamada
@ 2024-11-13 14:04 ` Neal Gompa
2024-11-13 19:35 ` Luis Chamberlain
2024-11-13 17:53 ` Sami Tolvanen
1 sibling, 1 reply; 36+ messages in thread
From: Neal Gompa @ 2024-11-13 14:04 UTC (permalink / raw)
To: Masahiro Yamada
Cc: Sami Tolvanen, Luis Chamberlain, Miguel Ojeda, Greg Kroah-Hartman,
Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Hector Martin, Janne Grunau, Miroslav Benes, Asahi Linux,
Sedat Dilek, linux-kbuild, linux-kernel, linux-modules,
rust-for-linux
On Mon, Nov 11, 2024 at 11:06 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> On Thu, Oct 31, 2024 at 2:01 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> >
> > Suggested-by: Petr Pavlu <petr.pavlu@suse.com>
> > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > Acked-by: Neal Gompa <neal@gompa.dev>
>
> Does this Ack add any value?
>
> Acked-by is meaningful only when it is given by someone who
> maintains the relevant area or has established a reputation.
>
> $ git grep "Neal Gompa"
> $ git shortlog -n -s | grep "Neal Gompa"
> 2 Neal Gompa
>
> His Ack feels more like "I like it" rather than a qualified endorsement.
>
I am going to be one of the primary consumers of this code as the
Fedora Asahi kernel maintainer and have been driving Rust enablement
in the Fedora Linux kernel (and eventually the RHEL kernel). I have
tested and looked over the patches from that lens.
While I might not be well-known here, I am known by the Rust for
Linux folks, as well as the filesystem folks (since those are the main
places I tend to frequent). I am also a member of the Asahi Linux team.
I've been engaging with the Linux kernel community directly in some
fashion for nearly a decade. Unfortunately, most of that isn't in the
form of commits directly to the Linux kernel, though.
--
真実はいつも一つ！/ Always, there's only one truth!
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [PATCH v5 01/19] scripts: move genksyms crc32 implementation to a common include
2024-11-13 14:04 ` Neal Gompa
@ 2024-11-13 19:35 ` Luis Chamberlain
2024-11-14 1:08 ` Neal Gompa
0 siblings, 1 reply; 36+ messages in thread
From: Luis Chamberlain @ 2024-11-13 19:35 UTC (permalink / raw)
To: Neal Gompa
Cc: Masahiro Yamada, Sami Tolvanen, Miguel Ojeda, Greg Kroah-Hartman,
Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Hector Martin, Janne Grunau, Miroslav Benes, Asahi Linux,
Sedat Dilek, linux-kbuild, linux-kernel, linux-modules,
rust-for-linux
On Wed, Nov 13, 2024 at 09:04:51AM -0500, Neal Gompa wrote:
> On Mon, Nov 11, 2024 at 11:06 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> >
> > On Thu, Oct 31, 2024 at 2:01 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> > >
> > > Suggested-by: Petr Pavlu <petr.pavlu@suse.com>
> > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > > Acked-by: Neal Gompa <neal@gompa.dev>
> >
> > Does this Ack add any value?
> >
> > Acked-by is meaningful only when it is given by someone who
> > maintains the relevant area or has established a reputation.
> >
> > $ git grep "Neal Gompa"
> > $ git shortlog -n -s | grep "Neal Gompa"
> > 2 Neal Gompa
> >
> > His Ack feels more like "I like it" rather than a qualified endorsement.
> >
>
> I have tested and looked over the patches from that lens.
The tests you did, what exaclty was tested?
If it was to just ensure no regressions, then that information is
useful too, and with that you can just provide: Tested-by.
But actual details of what you test are useful. We now also have
automation of tests for modules, and expanding test coverage on that is
always welcomed too [0] [1] [2], so far we have 0 Rust coverage.
[0] https://github.com/linux-kdevops/kdevops
[1] https://github.com/linux-kdevops/kdevops-ci
[2] https://github.com/linux-kdevops/linux-modules-kpd/actions
Luis
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [PATCH v5 01/19] scripts: move genksyms crc32 implementation to a common include
2024-11-13 19:35 ` Luis Chamberlain
@ 2024-11-14 1:08 ` Neal Gompa
0 siblings, 0 replies; 36+ messages in thread
From: Neal Gompa @ 2024-11-14 1:08 UTC (permalink / raw)
To: Luis Chamberlain
Cc: Masahiro Yamada, Sami Tolvanen, Miguel Ojeda, Greg Kroah-Hartman,
Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Hector Martin, Janne Grunau, Miroslav Benes, Asahi Linux,
Sedat Dilek, linux-kbuild, linux-kernel, linux-modules,
rust-for-linux
On Wed, Nov 13, 2024 at 2:35 PM Luis Chamberlain <mcgrof@kernel.org> wrote:
>
> On Wed, Nov 13, 2024 at 09:04:51AM -0500, Neal Gompa wrote:
> > On Mon, Nov 11, 2024 at 11:06 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> > >
> > > On Thu, Oct 31, 2024 at 2:01 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> > > >
> > > > Suggested-by: Petr Pavlu <petr.pavlu@suse.com>
> > > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > > > Acked-by: Neal Gompa <neal@gompa.dev>
> > >
> > > Does this Ack add any value?
> > >
> > > Acked-by is meaningful only when it is given by someone who
> > > maintains the relevant area or has established a reputation.
> > >
> > > $ git grep "Neal Gompa"
> > > $ git shortlog -n -s | grep "Neal Gompa"
> > > 2 Neal Gompa
> > >
> > > His Ack feels more like "I like it" rather than a qualified endorsement.
> > >
> >
> > I have tested and looked over the patches from that lens.
>
> The tests you did, what exaclty was tested?
>
> If it was to just ensure no regressions, then that information is
> useful too, and with that you can just provide: Tested-by.
>
> But actual details of what you test are useful. We now also have
> automation of tests for modules, and expanding test coverage on that is
> always welcomed too [0] [1] [2], so far we have 0 Rust coverage.
>
I tested that I could turn on MODVERSIONS with the relevant patch
series, and get symbol expressions out of it. I didn't go very far
into it, because I didn't want to invest in reworking the kernel
symbol dependency generator for RPM packaged kernels to leverage this
until after it is finally merged. But it worked as described, even if
none of our kernel packaging infrastructure is adapted for it yet.
To be honest, I considered sending both Acked-by and Tested-by, but I
figured Acked-by would be sufficient given that I have also looked
over the code as well and thought it was reasonable.
Strictly speaking, we don't really use MODVERSIONS in Fedora, it's a
CentOS/RHEL thing. But, pushing this forward helps make Rust
enablement for Fedora easier because the Fedora kernel is managed
through the ARK project, which is mostly oriented around the needs of
the RHEL kernel team. And CentOS Hyperscale (which I am also part of
and maintain a kernel for) does have MODVERSIONS on and I would like
to be able to start enabling Rust stuff there (particularly Asahi
code, as that's currently the main interesting thing in Rust to use).
--
真実はいつも一つ！/ Always, there's only one truth!
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [PATCH v5 01/19] scripts: move genksyms crc32 implementation to a common include
2024-11-12 4:05 ` Masahiro Yamada
2024-11-13 14:04 ` Neal Gompa
@ 2024-11-13 17:53 ` Sami Tolvanen
2024-11-16 9:08 ` Masahiro Yamada
1 sibling, 1 reply; 36+ messages in thread
From: Sami Tolvanen @ 2024-11-13 17:53 UTC (permalink / raw)
To: Masahiro Yamada
Cc: Luis Chamberlain, Miguel Ojeda, Greg Kroah-Hartman,
Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux
Hi,
On Mon, Nov 11, 2024 at 8:06 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> On Thu, Oct 31, 2024 at 2:01 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> >
> > To avoid duplication between host programs, move the crc32 code to a
> > shared header file.
>
>
> Only the motivation to use this long table is to keep compatibility
> between genksyms and gendwarfksyms.
> I do not think this should be exposed to other programs.
>
>
> If you avoid the code duplication, you can do
>
> // scripts/gendwarfksyms/crc.c
> #include "../genksyms/crc.c"
Sure, that sounds reasonable. I'll change this in the next version.
> > Suggested-by: Petr Pavlu <petr.pavlu@suse.com>
> > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > Acked-by: Neal Gompa <neal@gompa.dev>
>
> Does this Ack add any value?
>
> Acked-by is meaningful only when it is given by someone who
> maintains the relevant area or has established a reputation.
>
> $ git grep "Neal Gompa"
> $ git shortlog -n -s | grep "Neal Gompa"
> 2 Neal Gompa
>
> His Ack feels more like "I like it" rather than a qualified endorsement.
Like Neal explained, an Ack from a potential user of this feature
seemed relevant, but if you don't think it's meaningful, I can
certainly drop it.
Sami
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [PATCH v5 01/19] scripts: move genksyms crc32 implementation to a common include
2024-11-13 17:53 ` Sami Tolvanen
@ 2024-11-16 9:08 ` Masahiro Yamada
2024-11-18 21:58 ` Sami Tolvanen
0 siblings, 1 reply; 36+ messages in thread
From: Masahiro Yamada @ 2024-11-16 9:08 UTC (permalink / raw)
To: Sami Tolvanen
Cc: Luis Chamberlain, Miguel Ojeda, Greg Kroah-Hartman,
Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux
On Thu, Nov 14, 2024 at 2:54 AM Sami Tolvanen <samitolvanen@google.com> wrote:
>
> Hi,
>
> On Mon, Nov 11, 2024 at 8:06 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> >
> > On Thu, Oct 31, 2024 at 2:01 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> > >
> > > To avoid duplication between host programs, move the crc32 code to a
> > > shared header file.
> >
> >
> > Only the motivation to use this long table is to keep compatibility
> > between genksyms and gendwarfksyms.
> > I do not think this should be exposed to other programs.
> >
> >
> > If you avoid the code duplication, you can do
> >
> > // scripts/gendwarfksyms/crc.c
> > #include "../genksyms/crc.c"
>
> Sure, that sounds reasonable. I'll change this in the next version.
BTW, is it necessary to share the same crc function
between genksyms and gendwarfksyms?
If CONFIG_GENKSYMS and CONFIG_GENDWARFKSYMS
were able to produce the same CRC, it would be a good motivation
to share the same function.
However, as far as I tested, gendwarfksyms generates different CRC values.
When a distro migrates to CONFIG_GENDWARFKSYMS,
the new kernel cannot load old modules built with CONFIG_GENKSYMS.
So, there is no need to share the old code.
Another solution might be to use crc32() provided by zlib, for example.
It requires another external library, but this already depends on
libdw and libelf.
>
> > > Suggested-by: Petr Pavlu <petr.pavlu@suse.com>
> > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > > Acked-by: Neal Gompa <neal@gompa.dev>
> >
> > Does this Ack add any value?
> >
> > Acked-by is meaningful only when it is given by someone who
> > maintains the relevant area or has established a reputation.
> >
> > $ git grep "Neal Gompa"
> > $ git shortlog -n -s | grep "Neal Gompa"
> > 2 Neal Gompa
> >
> > His Ack feels more like "I like it" rather than a qualified endorsement.
>
> Like Neal explained, an Ack from a potential user of this feature
> seemed relevant, but if you don't think it's meaningful, I can
> certainly drop it.
Tested-by is more suitable if he wants to leave something.
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [PATCH v5 01/19] scripts: move genksyms crc32 implementation to a common include
2024-11-16 9:08 ` Masahiro Yamada
@ 2024-11-18 21:58 ` Sami Tolvanen
2024-11-19 20:48 ` Darrick J. Wong
0 siblings, 1 reply; 36+ messages in thread
From: Sami Tolvanen @ 2024-11-18 21:58 UTC (permalink / raw)
To: Masahiro Yamada
Cc: Luis Chamberlain, Miguel Ojeda, Greg Kroah-Hartman,
Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux
Hi,
On Sat, Nov 16, 2024 at 9:09 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> On Thu, Nov 14, 2024 at 2:54 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> >
> > Hi,
> >
> > On Mon, Nov 11, 2024 at 8:06 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> > >
> > > On Thu, Oct 31, 2024 at 2:01 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> > > >
> > > > To avoid duplication between host programs, move the crc32 code to a
> > > > shared header file.
> > >
> > >
> > > Only the motivation to use this long table is to keep compatibility
> > > between genksyms and gendwarfksyms.
> > > I do not think this should be exposed to other programs.
> > >
> > >
> > > If you avoid the code duplication, you can do
> > >
> > > // scripts/gendwarfksyms/crc.c
> > > #include "../genksyms/crc.c"
> >
> > Sure, that sounds reasonable. I'll change this in the next version.
>
>
> BTW, is it necessary to share the same crc function
> between genksyms and gendwarfksyms?
>
> If CONFIG_GENKSYMS and CONFIG_GENDWARFKSYMS
> were able to produce the same CRC, it would be a good motivation
> to share the same function.
> However, as far as I tested, gendwarfksyms generates different CRC values.
>
> When a distro migrates to CONFIG_GENDWARFKSYMS,
> the new kernel cannot load old modules built with CONFIG_GENKSYMS.
No, it's not necessary to use the exact same function, this was just
to avoid adding more external dependencies.
> So, there is no need to share the old code.
> Another solution might be to use crc32() provided by zlib, for example.
> It requires another external library, but this already depends on
> libdw and libelf.
Makes sense. I'll switch to the zlib implementation in v6.
> > > > Suggested-by: Petr Pavlu <petr.pavlu@suse.com>
> > > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > > > Acked-by: Neal Gompa <neal@gompa.dev>
> > >
> > > Does this Ack add any value?
> > >
> > > Acked-by is meaningful only when it is given by someone who
> > > maintains the relevant area or has established a reputation.
> > >
> > > $ git grep "Neal Gompa"
> > > $ git shortlog -n -s | grep "Neal Gompa"
> > > 2 Neal Gompa
> > >
> > > His Ack feels more like "I like it" rather than a qualified endorsement.
> >
> > Like Neal explained, an Ack from a potential user of this feature
> > seemed relevant, but if you don't think it's meaningful, I can
> > certainly drop it.
>
> Tested-by is more suitable if he wants to leave something.
Ack. Neal, I'll drop the acks from v6, but if you end up testing that
series, please feel free to add your Tested-by.
Sami
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [PATCH v5 01/19] scripts: move genksyms crc32 implementation to a common include
2024-11-18 21:58 ` Sami Tolvanen
@ 2024-11-19 20:48 ` Darrick J. Wong
2024-11-19 21:37 ` Sami Tolvanen
0 siblings, 1 reply; 36+ messages in thread
From: Darrick J. Wong @ 2024-11-19 20:48 UTC (permalink / raw)
To: Sami Tolvanen
Cc: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman, Matthew Maurer, Alex Gaynor, Gary Guo,
Petr Pavlu, Daniel Gomez, Neal Gompa, Hector Martin, Janne Grunau,
Miroslav Benes, Asahi Linux, Sedat Dilek, linux-kbuild,
linux-kernel, linux-modules, rust-for-linux
On Mon, Nov 18, 2024 at 09:58:09PM +0000, Sami Tolvanen wrote:
> Hi,
>
> On Sat, Nov 16, 2024 at 9:09 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
> >
> > On Thu, Nov 14, 2024 at 2:54 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> > >
> > > Hi,
> > >
> > > On Mon, Nov 11, 2024 at 8:06 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> > > >
> > > > On Thu, Oct 31, 2024 at 2:01 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> > > > >
> > > > > To avoid duplication between host programs, move the crc32 code to a
> > > > > shared header file.
> > > >
> > > >
> > > > Only the motivation to use this long table is to keep compatibility
> > > > between genksyms and gendwarfksyms.
> > > > I do not think this should be exposed to other programs.
> > > >
> > > >
> > > > If you avoid the code duplication, you can do
> > > >
> > > > // scripts/gendwarfksyms/crc.c
> > > > #include "../genksyms/crc.c"
> > >
> > > Sure, that sounds reasonable. I'll change this in the next version.
> >
> >
> > BTW, is it necessary to share the same crc function
> > between genksyms and gendwarfksyms?
> >
> > If CONFIG_GENKSYMS and CONFIG_GENDWARFKSYMS
> > were able to produce the same CRC, it would be a good motivation
> > to share the same function.
> > However, as far as I tested, gendwarfksyms generates different CRC values.
crc32() is operating on different data, right? CONFIG_GENDWARFKSYMS
computes a crc of the DWARF data, whereas CONFIG_GENKSYMS computes a crc
of a magic string from ... the source code, right? Hence the crcs will
never match?
> > When a distro migrates to CONFIG_GENDWARFKSYMS,
> > the new kernel cannot load old modules built with CONFIG_GENKSYMS.
>
> No, it's not necessary to use the exact same function, this was just
> to avoid adding more external dependencies.
>
> > So, there is no need to share the old code.
> > Another solution might be to use crc32() provided by zlib, for example.
> > It requires another external library, but this already depends on
> > libdw and libelf.
>
> Makes sense. I'll switch to the zlib implementation in v6.
>
> > > > > Suggested-by: Petr Pavlu <petr.pavlu@suse.com>
> > > > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > > > > Acked-by: Neal Gompa <neal@gompa.dev>
> > > >
> > > > Does this Ack add any value?
> > > >
> > > > Acked-by is meaningful only when it is given by someone who
> > > > maintains the relevant area or has established a reputation.
> > > >
> > > > $ git grep "Neal Gompa"
> > > > $ git shortlog -n -s | grep "Neal Gompa"
> > > > 2 Neal Gompa
> > > >
> > > > His Ack feels more like "I like it" rather than a qualified endorsement.
> > >
> > > Like Neal explained, an Ack from a potential user of this feature
> > > seemed relevant, but if you don't think it's meaningful, I can
> > > certainly drop it.
> >
> > Tested-by is more suitable if he wants to leave something.
>
> Ack. Neal, I'll drop the acks from v6, but if you end up testing that
> series, please feel free to add your Tested-by.
Just my 2 cents, but it seems rude to me to *remove* an Ack from an
existing patchset on the grounds that person doesn't appear often in the
kernel log. "We won't hire you for this entry level job because you
don't have experience" etc.
Also, wouldn't Neal be one of the people shepherding this change into
distro kernels? He seems to show up somewhat frequently in the Fedora
and SUSE ecosystems.
Is the problem here that you all think "Acked-by" isn't appropriate from
someone who isn't a subsystem maintainer, but the kernel doesn't seem to
have a tag for "downstream consumer of this change says they're willing
to put their name on the line for this"?
Maybe should we go full Parks and Rec:
Not-Against-You-On-This-One: Neal Gompa <neal@gompa.dev>
--D
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [PATCH v5 01/19] scripts: move genksyms crc32 implementation to a common include
2024-11-19 20:48 ` Darrick J. Wong
@ 2024-11-19 21:37 ` Sami Tolvanen
0 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-11-19 21:37 UTC (permalink / raw)
To: Darrick J. Wong, Greg Kroah-Hartman
Cc: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda, Matthew Maurer,
Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez, Neal Gompa,
Hector Martin, Janne Grunau, Miroslav Benes, Asahi Linux,
Sedat Dilek, linux-kbuild, linux-kernel, linux-modules,
rust-for-linux
Hi Darrick,
On Tue, Nov 19, 2024 at 12:48 PM Darrick J. Wong <djwong@kernel.org> wrote:
>
> On Mon, Nov 18, 2024 at 09:58:09PM +0000, Sami Tolvanen wrote:
> > Hi,
> >
> > On Sat, Nov 16, 2024 at 9:09 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
> > >
> > > On Thu, Nov 14, 2024 at 2:54 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> > > >
> > > > Hi,
> > > >
> > > > On Mon, Nov 11, 2024 at 8:06 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> > > > >
> > > > > On Thu, Oct 31, 2024 at 2:01 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> > > > > >
> > > > > > To avoid duplication between host programs, move the crc32 code to a
> > > > > > shared header file.
> > > > >
> > > > >
> > > > > Only the motivation to use this long table is to keep compatibility
> > > > > between genksyms and gendwarfksyms.
> > > > > I do not think this should be exposed to other programs.
> > > > >
> > > > >
> > > > > If you avoid the code duplication, you can do
> > > > >
> > > > > // scripts/gendwarfksyms/crc.c
> > > > > #include "../genksyms/crc.c"
> > > >
> > > > Sure, that sounds reasonable. I'll change this in the next version.
> > >
> > >
> > > BTW, is it necessary to share the same crc function
> > > between genksyms and gendwarfksyms?
> > >
> > > If CONFIG_GENKSYMS and CONFIG_GENDWARFKSYMS
> > > were able to produce the same CRC, it would be a good motivation
> > > to share the same function.
> > > However, as far as I tested, gendwarfksyms generates different CRC values.
>
> crc32() is operating on different data, right? CONFIG_GENDWARFKSYMS
> computes a crc of the DWARF data, whereas CONFIG_GENKSYMS computes a crc
> of a magic string from ... the source code, right? Hence the crcs will
> never match?
Correct, they will never match.
> > > > > > Suggested-by: Petr Pavlu <petr.pavlu@suse.com>
> > > > > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > > > > > Acked-by: Neal Gompa <neal@gompa.dev>
> > > > >
> > > > > Does this Ack add any value?
> > > > >
> > > > > Acked-by is meaningful only when it is given by someone who
> > > > > maintains the relevant area or has established a reputation.
> > > > >
> > > > > $ git grep "Neal Gompa"
> > > > > $ git shortlog -n -s | grep "Neal Gompa"
> > > > > 2 Neal Gompa
> > > > >
> > > > > His Ack feels more like "I like it" rather than a qualified endorsement.
> > > >
> > > > Like Neal explained, an Ack from a potential user of this feature
> > > > seemed relevant, but if you don't think it's meaningful, I can
> > > > certainly drop it.
> > >
> > > Tested-by is more suitable if he wants to leave something.
> >
> > Ack. Neal, I'll drop the acks from v6, but if you end up testing that
> > series, please feel free to add your Tested-by.
>
> Just my 2 cents, but it seems rude to me to *remove* an Ack from an
> existing patchset on the grounds that person doesn't appear often in the
> kernel log. "We won't hire you for this entry level job because you
> don't have experience" etc.
>
> Also, wouldn't Neal be one of the people shepherding this change into
> distro kernels? He seems to show up somewhat frequently in the Fedora
> and SUSE ecosystems.
>
> Is the problem here that you all think "Acked-by" isn't appropriate from
> someone who isn't a subsystem maintainer, but the kernel doesn't seem to
> have a tag for "downstream consumer of this change says they're willing
> to put their name on the line for this"?
I certainly appreciate Neal's input, but I don't have a strong opinion
about which tag is appropriate. The documentation seems to suggest
that Acked-by is _often_ used by maintainers and focuses on that use
case, but doesn't explicitly rule out other folks acking patches
either:
https://docs.kernel.org/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by
Perhaps Greg, or someone else with more experience with the nuances of
acking, can clarify the policy in this situation?
Sami
^ permalink raw reply [flat|nested] 36+ messages in thread
* [PATCH v5 02/19] tools: Add gendwarfksyms
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 01/19] scripts: move genksyms crc32 implementation to a common include Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 03/19] gendwarfksyms: Add address matching Sami Tolvanen
` (17 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
Add a basic DWARF parser, which uses libdw to traverse the debugging
information in an object file and looks for functions and variables.
In follow-up patches, this will be expanded to produce symbol versions
for CONFIG_MODVERSIONS from DWARF.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
---
kernel/module/Kconfig | 8 ++
scripts/Makefile | 1 +
scripts/gendwarfksyms/.gitignore | 2 +
scripts/gendwarfksyms/Makefile | 8 ++
scripts/gendwarfksyms/dwarf.c | 166 ++++++++++++++++++++++++++
scripts/gendwarfksyms/gendwarfksyms.c | 126 +++++++++++++++++++
scripts/gendwarfksyms/gendwarfksyms.h | 98 +++++++++++++++
scripts/gendwarfksyms/symbols.c | 96 +++++++++++++++
8 files changed, 505 insertions(+)
create mode 100644 scripts/gendwarfksyms/.gitignore
create mode 100644 scripts/gendwarfksyms/Makefile
create mode 100644 scripts/gendwarfksyms/dwarf.c
create mode 100644 scripts/gendwarfksyms/gendwarfksyms.c
create mode 100644 scripts/gendwarfksyms/gendwarfksyms.h
create mode 100644 scripts/gendwarfksyms/symbols.c
diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
index 7c6588148d42..f9e5f82fa88b 100644
--- a/kernel/module/Kconfig
+++ b/kernel/module/Kconfig
@@ -169,6 +169,14 @@ config MODVERSIONS
make them incompatible with the kernel you are running. If
unsure, say N.
+config GENDWARFKSYMS
+ bool
+ depends on DEBUG_INFO
+ # Requires full debugging information, split DWARF not supported.
+ depends on !DEBUG_INFO_REDUCED && !DEBUG_INFO_SPLIT
+ # Requires ELF object files.
+ depends on !LTO
+
config ASM_MODVERSIONS
bool
default HAVE_ASM_MODVERSIONS && MODVERSIONS
diff --git a/scripts/Makefile b/scripts/Makefile
index 6bcda4b9d054..d7fec46d38c0 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -54,6 +54,7 @@ targets += module.lds
subdir-$(CONFIG_GCC_PLUGINS) += gcc-plugins
subdir-$(CONFIG_MODVERSIONS) += genksyms
+subdir-$(CONFIG_GENDWARFKSYMS) += gendwarfksyms
subdir-$(CONFIG_SECURITY_SELINUX) += selinux
subdir-$(CONFIG_SECURITY_IPE) += ipe
diff --git a/scripts/gendwarfksyms/.gitignore b/scripts/gendwarfksyms/.gitignore
new file mode 100644
index 000000000000..0927f8d3cd96
--- /dev/null
+++ b/scripts/gendwarfksyms/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0
+/gendwarfksyms
diff --git a/scripts/gendwarfksyms/Makefile b/scripts/gendwarfksyms/Makefile
new file mode 100644
index 000000000000..9f8fec4fd39b
--- /dev/null
+++ b/scripts/gendwarfksyms/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0
+hostprogs-always-y += gendwarfksyms
+
+gendwarfksyms-objs += gendwarfksyms.o
+gendwarfksyms-objs += dwarf.o
+gendwarfksyms-objs += symbols.o
+
+HOSTLDLIBS_gendwarfksyms := -ldw -lelf
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
new file mode 100644
index 000000000000..81df3e2ad3ae
--- /dev/null
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Google LLC
+ */
+
+#include "gendwarfksyms.h"
+
+static bool get_ref_die_attr(Dwarf_Die *die, unsigned int id, Dwarf_Die *value)
+{
+ Dwarf_Attribute da;
+
+ /* dwarf_formref_die returns a pointer instead of an error value. */
+ return dwarf_attr(die, id, &da) && dwarf_formref_die(&da, value);
+}
+
+#define DEFINE_GET_STRING_ATTR(attr) \
+ static const char *get_##attr##_attr(Dwarf_Die *die) \
+ { \
+ Dwarf_Attribute da; \
+ if (dwarf_attr(die, DW_AT_##attr, &da)) \
+ return dwarf_formstring(&da); \
+ return NULL; \
+ }
+
+DEFINE_GET_STRING_ATTR(name)
+DEFINE_GET_STRING_ATTR(linkage_name)
+
+static const char *get_symbol_name(Dwarf_Die *die)
+{
+ const char *name;
+
+ /* rustc uses DW_AT_linkage_name for exported symbols */
+ name = get_linkage_name_attr(die);
+ if (!name)
+ name = get_name_attr(die);
+
+ return name;
+}
+
+static bool match_export_symbol(struct state *state, Dwarf_Die *die)
+{
+ Dwarf_Die *source = die;
+ Dwarf_Die origin;
+
+ /* If the DIE has an abstract origin, use it for type information. */
+ if (get_ref_die_attr(die, DW_AT_abstract_origin, &origin))
+ source = &origin;
+
+ state->sym = symbol_get(get_symbol_name(die));
+
+ /* Look up using the origin name if there are no matches. */
+ if (!state->sym && source != die)
+ state->sym = symbol_get(get_symbol_name(source));
+
+ state->die = *source;
+ return !!state->sym;
+}
+
+/*
+ * Type string processing
+ */
+static void process(const char *s)
+{
+ s = s ?: "<null>";
+
+ if (dump_dies)
+ fputs(s, stderr);
+}
+
+bool match_all(Dwarf_Die *die)
+{
+ return true;
+}
+
+int process_die_container(struct state *state, Dwarf_Die *die,
+ die_callback_t func, die_match_callback_t match)
+{
+ Dwarf_Die current;
+ int res;
+
+ res = checkp(dwarf_child(die, ¤t));
+ while (!res) {
+ if (match(¤t)) {
+ /* <0 = error, 0 = continue, >0 = stop */
+ res = checkp(func(state, ¤t));
+ if (res)
+ return res;
+ }
+
+ res = checkp(dwarf_siblingof(¤t, ¤t));
+ }
+
+ return 0;
+}
+
+/*
+ * Exported symbol processing
+ */
+static void process_symbol(struct state *state, Dwarf_Die *die,
+ die_callback_t process_func)
+{
+ debug("%s", state->sym->name);
+ check(process_func(state, die));
+ if (dump_dies)
+ fputs("\n", stderr);
+}
+
+static int __process_subprogram(struct state *state, Dwarf_Die *die)
+{
+ process("subprogram");
+ return 0;
+}
+
+static void process_subprogram(struct state *state, Dwarf_Die *die)
+{
+ process_symbol(state, die, __process_subprogram);
+}
+
+static int __process_variable(struct state *state, Dwarf_Die *die)
+{
+ process("variable ");
+ return 0;
+}
+
+static void process_variable(struct state *state, Dwarf_Die *die)
+{
+ process_symbol(state, die, __process_variable);
+}
+
+static int process_exported_symbols(struct state *unused, Dwarf_Die *die)
+{
+ int tag = dwarf_tag(die);
+
+ switch (tag) {
+ /* Possible containers of exported symbols */
+ case DW_TAG_namespace:
+ case DW_TAG_class_type:
+ case DW_TAG_structure_type:
+ return check(process_die_container(
+ NULL, die, process_exported_symbols, match_all));
+
+ /* Possible exported symbols */
+ case DW_TAG_subprogram:
+ case DW_TAG_variable: {
+ struct state state;
+
+ if (!match_export_symbol(&state, die))
+ return 0;
+
+ if (tag == DW_TAG_subprogram)
+ process_subprogram(&state, &state.die);
+ else
+ process_variable(&state, &state.die);
+
+ return 0;
+ }
+ default:
+ return 0;
+ }
+}
+
+void process_cu(Dwarf_Die *cudie)
+{
+ check(process_die_container(NULL, cudie, process_exported_symbols,
+ match_all));
+}
diff --git a/scripts/gendwarfksyms/gendwarfksyms.c b/scripts/gendwarfksyms/gendwarfksyms.c
new file mode 100644
index 000000000000..f84fa98fcbdb
--- /dev/null
+++ b/scripts/gendwarfksyms/gendwarfksyms.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Google LLC
+ */
+
+#include <fcntl.h>
+#include <getopt.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <string.h>
+#include <unistd.h>
+#include "gendwarfksyms.h"
+
+/*
+ * Options
+ */
+
+/* Print debugging information to stderr */
+int debug;
+/* Dump DIE contents */
+int dump_dies;
+
+static void usage(void)
+{
+ fputs("Usage: gendwarfksyms [options] elf-object-file ... < symbol-list\n\n"
+ "Options:\n"
+ " -d, --debug Print debugging information\n"
+ " --dump-dies Dump DWARF DIE contents\n"
+ " -h, --help Print this message\n"
+ "\n",
+ stderr);
+}
+
+static int process_module(Dwfl_Module *mod, void **userdata, const char *name,
+ Dwarf_Addr base, void *arg)
+{
+ Dwarf_Addr dwbias;
+ Dwarf_Die cudie;
+ Dwarf_CU *cu = NULL;
+ Dwarf *dbg;
+ int res;
+
+ debug("%s", name);
+ dbg = dwfl_module_getdwarf(mod, &dwbias);
+
+ do {
+ res = dwarf_get_units(dbg, cu, &cu, NULL, NULL, &cudie, NULL);
+ if (res < 0)
+ error("dwarf_get_units failed: no debugging information?");
+ if (res == 1)
+ break; /* No more units */
+
+ process_cu(&cudie);
+ } while (cu);
+
+ return DWARF_CB_OK;
+}
+
+static const Dwfl_Callbacks callbacks = {
+ .section_address = dwfl_offline_section_address,
+ .find_debuginfo = dwfl_standard_find_debuginfo,
+};
+
+int main(int argc, char **argv)
+{
+ unsigned int n;
+ int opt;
+
+ struct option opts[] = { { "debug", 0, NULL, 'd' },
+ { "dump-dies", 0, &dump_dies, 1 },
+ { "help", 0, NULL, 'h' },
+ { 0, 0, NULL, 0 } };
+
+ while ((opt = getopt_long(argc, argv, "dh", opts, NULL)) != EOF) {
+ switch (opt) {
+ case 0:
+ break;
+ case 'd':
+ debug = 1;
+ break;
+ case 'h':
+ usage();
+ return 0;
+ default:
+ usage();
+ return 1;
+ }
+ }
+
+ if (optind >= argc) {
+ usage();
+ error("no input files?");
+ }
+
+ symbol_read_exports(stdin);
+
+ for (n = optind; n < argc; n++) {
+ Dwfl *dwfl;
+ int fd;
+
+ fd = open(argv[n], O_RDONLY);
+ if (fd == -1)
+ error("open failed for '%s': %s", argv[n],
+ strerror(errno));
+
+ dwfl = dwfl_begin(&callbacks);
+ if (!dwfl)
+ error("dwfl_begin failed for '%s': %s", argv[n],
+ dwarf_errmsg(-1));
+
+ if (!dwfl_report_offline(dwfl, argv[n], argv[n], fd))
+ error("dwfl_report_offline failed for '%s': %s",
+ argv[n], dwarf_errmsg(-1));
+
+ dwfl_report_end(dwfl, NULL, NULL);
+
+ if (dwfl_getmodules(dwfl, &process_module, NULL, 0))
+ error("dwfl_getmodules failed for '%s'", argv[n]);
+
+ dwfl_end(dwfl);
+ }
+
+ symbol_free();
+
+ return 0;
+}
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
new file mode 100644
index 000000000000..c5437ee31321
--- /dev/null
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2024 Google LLC
+ */
+
+#include <dwarf.h>
+#include <elfutils/libdw.h>
+#include <elfutils/libdwfl.h>
+#include <inttypes.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <hash.h>
+#include <hashtable.h>
+#include <list.h>
+#include <xalloc.h>
+
+#ifndef __GENDWARFKSYMS_H
+#define __GENDWARFKSYMS_H
+
+/*
+ * Options -- in gendwarfksyms.c
+ */
+extern int debug;
+extern int dump_dies;
+
+/*
+ * Output helpers
+ */
+#define __PREFIX "gendwarfksyms: "
+#define __println(prefix, format, ...) \
+ fprintf(stderr, prefix __PREFIX "%s: " format "\n", __func__, \
+ ##__VA_ARGS__)
+
+#define debug(format, ...) \
+ do { \
+ if (debug) \
+ __println("", format, ##__VA_ARGS__); \
+ } while (0)
+
+#define warn(format, ...) __println("warning: ", format, ##__VA_ARGS__)
+#define error(format, ...) \
+ do { \
+ __println("error: ", format, ##__VA_ARGS__); \
+ exit(1); \
+ } while (0)
+
+/*
+ * Error handling helpers
+ */
+#define __check(expr, test) \
+ ({ \
+ int __res = expr; \
+ if (test) \
+ error("`%s` failed: %d", #expr, __res); \
+ __res; \
+ })
+
+/* Error == non-zero values */
+#define check(expr) __check(expr, __res)
+/* Error == negative values */
+#define checkp(expr) __check(expr, __res < 0)
+
+/*
+ * symbols.c
+ */
+
+struct symbol {
+ const char *name;
+ struct hlist_node name_hash;
+};
+
+typedef void (*symbol_callback_t)(struct symbol *, void *arg);
+
+void symbol_read_exports(FILE *file);
+struct symbol *symbol_get(const char *name);
+void symbol_free(void);
+
+/*
+ * dwarf.c
+ */
+
+struct state {
+ struct symbol *sym;
+ Dwarf_Die die;
+};
+
+typedef int (*die_callback_t)(struct state *state, Dwarf_Die *die);
+typedef bool (*die_match_callback_t)(Dwarf_Die *die);
+bool match_all(Dwarf_Die *die);
+
+int process_die_container(struct state *state, Dwarf_Die *die,
+ die_callback_t func, die_match_callback_t match);
+
+void process_cu(Dwarf_Die *cudie);
+
+#endif /* __GENDWARFKSYMS_H */
diff --git a/scripts/gendwarfksyms/symbols.c b/scripts/gendwarfksyms/symbols.c
new file mode 100644
index 000000000000..2c901670224b
--- /dev/null
+++ b/scripts/gendwarfksyms/symbols.c
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Google LLC
+ */
+
+#include "gendwarfksyms.h"
+
+#define SYMBOL_HASH_BITS 15
+static HASHTABLE_DEFINE(symbol_names, 1 << SYMBOL_HASH_BITS);
+
+static unsigned int for_each(const char *name, symbol_callback_t func,
+ void *data)
+{
+ struct hlist_node *tmp;
+ struct symbol *match;
+
+ if (!name || !*name)
+ return 0;
+
+ hash_for_each_possible_safe(symbol_names, match, tmp, name_hash,
+ hash_str(name)) {
+ if (strcmp(match->name, name))
+ continue;
+
+ if (func)
+ func(match, data);
+
+ return 1;
+ }
+
+ return 0;
+}
+
+static bool is_exported(const char *name)
+{
+ return for_each(name, NULL, NULL) > 0;
+}
+
+void symbol_read_exports(FILE *file)
+{
+ struct symbol *sym;
+ char *line = NULL;
+ char *name = NULL;
+ size_t size = 0;
+ int nsym = 0;
+
+ while (getline(&line, &size, file) > 0) {
+ if (sscanf(line, "%ms\n", &name) != 1)
+ error("malformed input line: %s", line);
+
+ if (is_exported(name)) {
+ /* Ignore duplicates */
+ free(name);
+ continue;
+ }
+
+ sym = xcalloc(1, sizeof(struct symbol));
+ sym->name = name;
+
+ hash_add(symbol_names, &sym->name_hash, hash_str(sym->name));
+ ++nsym;
+
+ debug("%s", sym->name);
+ }
+
+ free(line);
+ debug("%d exported symbols", nsym);
+}
+
+static void get_symbol(struct symbol *sym, void *arg)
+{
+ struct symbol **res = arg;
+
+ *res = sym;
+}
+
+struct symbol *symbol_get(const char *name)
+{
+ struct symbol *sym = NULL;
+
+ for_each(name, get_symbol, &sym);
+ return sym;
+}
+
+void symbol_free(void)
+{
+ struct hlist_node *tmp;
+ struct symbol *sym;
+
+ hash_for_each_safe(symbol_names, sym, tmp, name_hash) {
+ free((void *)sym->name);
+ free(sym);
+ }
+
+ hash_init(symbol_names);
+}
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 03/19] gendwarfksyms: Add address matching
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 01/19] scripts: move genksyms crc32 implementation to a common include Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 02/19] tools: Add gendwarfksyms Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 04/19] gendwarfksyms: Expand base_type Sami Tolvanen
` (16 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
The compiler may choose not to emit type information in DWARF for all
aliases, but it's possible for each alias to be exported separately.
To ensure we find type information for the aliases as well, read
{section, address} tuples from the symbol table and match symbols also
by address.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
---
scripts/gendwarfksyms/gendwarfksyms.c | 2 +
scripts/gendwarfksyms/gendwarfksyms.h | 13 +++
scripts/gendwarfksyms/symbols.c | 161 ++++++++++++++++++++++++++
3 files changed, 176 insertions(+)
diff --git a/scripts/gendwarfksyms/gendwarfksyms.c b/scripts/gendwarfksyms/gendwarfksyms.c
index f84fa98fcbdb..1763234b6329 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.c
+++ b/scripts/gendwarfksyms/gendwarfksyms.c
@@ -103,6 +103,8 @@ int main(int argc, char **argv)
error("open failed for '%s': %s", argv[n],
strerror(errno));
+ symbol_read_symtab(fd);
+
dwfl = dwfl_begin(&callbacks);
if (!dwfl)
error("dwfl_begin failed for '%s': %s", argv[n],
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
index c5437ee31321..f75d8ca33b45 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.h
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -66,14 +66,27 @@ extern int dump_dies;
* symbols.c
*/
+static inline unsigned int addr_hash(uintptr_t addr)
+{
+ return hash_ptr((const void *)addr);
+}
+
+struct symbol_addr {
+ uint32_t section;
+ Elf64_Addr address;
+};
+
struct symbol {
const char *name;
+ struct symbol_addr addr;
+ struct hlist_node addr_hash;
struct hlist_node name_hash;
};
typedef void (*symbol_callback_t)(struct symbol *, void *arg);
void symbol_read_exports(FILE *file);
+void symbol_read_symtab(int fd);
struct symbol *symbol_get(const char *name);
void symbol_free(void);
diff --git a/scripts/gendwarfksyms/symbols.c b/scripts/gendwarfksyms/symbols.c
index 2c901670224b..e7343394248b 100644
--- a/scripts/gendwarfksyms/symbols.c
+++ b/scripts/gendwarfksyms/symbols.c
@@ -6,8 +6,39 @@
#include "gendwarfksyms.h"
#define SYMBOL_HASH_BITS 15
+
+/* struct symbol_addr -> struct symbol */
+static HASHTABLE_DEFINE(symbol_addrs, 1 << SYMBOL_HASH_BITS);
+/* name -> struct symbol */
static HASHTABLE_DEFINE(symbol_names, 1 << SYMBOL_HASH_BITS);
+static inline unsigned int symbol_addr_hash(const struct symbol_addr *addr)
+{
+ return hash_32(addr->section ^ addr_hash(addr->address));
+}
+
+static unsigned int __for_each_addr(struct symbol *sym, symbol_callback_t func,
+ void *data)
+{
+ struct hlist_node *tmp;
+ struct symbol *match = NULL;
+ unsigned int processed = 0;
+
+ hash_for_each_possible_safe(symbol_addrs, match, tmp, addr_hash,
+ symbol_addr_hash(&sym->addr)) {
+ if (match == sym)
+ continue; /* Already processed */
+
+ if (match->addr.section == sym->addr.section &&
+ match->addr.address == sym->addr.address) {
+ func(match, data);
+ ++processed;
+ }
+ }
+
+ return processed;
+}
+
static unsigned int for_each(const char *name, symbol_callback_t func,
void *data)
{
@@ -22,9 +53,13 @@ static unsigned int for_each(const char *name, symbol_callback_t func,
if (strcmp(match->name, name))
continue;
+ /* Call func for the match, and all address matches */
if (func)
func(match, data);
+ if (match->addr.section != SHN_UNDEF)
+ return __for_each_addr(match, func, data) + 1;
+
return 1;
}
@@ -56,6 +91,7 @@ void symbol_read_exports(FILE *file)
sym = xcalloc(1, sizeof(struct symbol));
sym->name = name;
+ sym->addr.section = SHN_UNDEF;
hash_add(symbol_names, &sym->name_hash, hash_str(sym->name));
++nsym;
@@ -82,6 +118,130 @@ struct symbol *symbol_get(const char *name)
return sym;
}
+typedef void (*elf_symbol_callback_t)(const char *name, GElf_Sym *sym,
+ Elf32_Word xndx, void *arg);
+
+static void elf_for_each_global(int fd, elf_symbol_callback_t func, void *arg)
+{
+ size_t sym_size;
+ GElf_Shdr shdr_mem;
+ GElf_Shdr *shdr;
+ Elf_Data *xndx_data = NULL;
+ Elf_Scn *scn;
+ Elf *elf;
+
+ if (elf_version(EV_CURRENT) != EV_CURRENT)
+ error("elf_version failed: %s", elf_errmsg(-1));
+
+ elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+ if (!elf)
+ error("elf_begin failed: %s", elf_errmsg(-1));
+
+ scn = elf_nextscn(elf, NULL);
+
+ while (scn) {
+ shdr = gelf_getshdr(scn, &shdr_mem);
+ if (!shdr)
+ error("gelf_getshdr failed: %s", elf_errmsg(-1));
+
+ if (shdr->sh_type == SHT_SYMTAB_SHNDX) {
+ xndx_data = elf_getdata(scn, NULL);
+ if (!xndx_data)
+ error("elf_getdata failed: %s", elf_errmsg(-1));
+ break;
+ }
+
+ scn = elf_nextscn(elf, scn);
+ }
+
+ sym_size = gelf_fsize(elf, ELF_T_SYM, 1, EV_CURRENT);
+ scn = elf_nextscn(elf, NULL);
+
+ while (scn) {
+ shdr = gelf_getshdr(scn, &shdr_mem);
+ if (!shdr)
+ error("gelf_getshdr failed: %s", elf_errmsg(-1));
+
+ if (shdr->sh_type == SHT_SYMTAB) {
+ unsigned int nsyms;
+ unsigned int n;
+ Elf_Data *data = elf_getdata(scn, NULL);
+
+ if (!data)
+ error("elf_getdata failed: %s", elf_errmsg(-1));
+
+ if (shdr->sh_entsize != sym_size)
+ error("expected sh_entsize (%lu) to be %zu",
+ shdr->sh_entsize, sym_size);
+
+ nsyms = shdr->sh_size / shdr->sh_entsize;
+
+ for (n = 1; n < nsyms; ++n) {
+ const char *name = NULL;
+ Elf32_Word xndx = 0;
+ GElf_Sym sym_mem;
+ GElf_Sym *sym;
+
+ sym = gelf_getsymshndx(data, xndx_data, n,
+ &sym_mem, &xndx);
+
+ if (!sym ||
+ GELF_ST_BIND(sym->st_info) == STB_LOCAL)
+ continue;
+
+ if (sym->st_shndx != SHN_XINDEX)
+ xndx = sym->st_shndx;
+
+ name = elf_strptr(elf, shdr->sh_link,
+ sym->st_name);
+ if (!name)
+ error("elf_strptr failed: %s",
+ elf_errmsg(-1));
+
+ /* Skip empty symbol names */
+ if (*name)
+ func(name, sym, xndx, arg);
+ }
+ }
+
+ scn = elf_nextscn(elf, scn);
+ }
+
+ check(elf_end(elf));
+}
+
+static void set_symbol_addr(struct symbol *sym, void *arg)
+{
+ struct symbol_addr *addr = arg;
+
+ if (sym->addr.section == SHN_UNDEF) {
+ sym->addr = *addr;
+ hash_add(symbol_addrs, &sym->addr_hash,
+ symbol_addr_hash(&sym->addr));
+
+ debug("%s -> { %u, %lx }", sym->name, sym->addr.section,
+ sym->addr.address);
+ } else if (sym->addr.section != addr->section ||
+ sym->addr.address != addr->address) {
+ warn("multiple addresses for symbol %s?", sym->name);
+ }
+}
+
+static void elf_set_symbol_addr(const char *name, GElf_Sym *sym,
+ Elf32_Word xndx, void *arg)
+{
+ struct symbol_addr addr = { .section = xndx, .address = sym->st_value };
+
+ /* Set addresses for exported symbols */
+ if (addr.section != SHN_UNDEF)
+ for_each(name, set_symbol_addr, &addr);
+}
+
+void symbol_read_symtab(int fd)
+{
+ elf_for_each_global(fd, elf_set_symbol_addr, NULL);
+}
+
void symbol_free(void)
{
struct hlist_node *tmp;
@@ -92,5 +252,6 @@ void symbol_free(void)
free(sym);
}
+ hash_init(symbol_addrs);
hash_init(symbol_names);
}
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 04/19] gendwarfksyms: Expand base_type
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (2 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 03/19] gendwarfksyms: Add address matching Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 05/19] gendwarfksyms: Add a cache for processed DIEs Sami Tolvanen
` (15 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
Start making gendwarfksyms more useful by adding support for
expanding DW_TAG_base_type types and basic DWARF attributes.
Example:
$ echo loops_per_jiffy | \
scripts/gendwarfksyms/gendwarfksyms \
--debug --dump-dies vmlinux.o
...
gendwarfksyms: process_symbol: loops_per_jiffy
variable base_type unsigned long byte_size(8) encoding(7)
...
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
---
scripts/gendwarfksyms/dwarf.c | 159 ++++++++++++++++++++++++++++++++++
1 file changed, 159 insertions(+)
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index 81df3e2ad3ae..35fd1dfeeadc 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -3,8 +3,20 @@
* Copyright (C) 2024 Google LLC
*/
+#include <stdarg.h>
#include "gendwarfksyms.h"
+#define DEFINE_GET_ATTR(attr, type) \
+ static bool get_##attr##_attr(Dwarf_Die *die, unsigned int id, \
+ type *value) \
+ { \
+ Dwarf_Attribute da; \
+ return dwarf_attr(die, id, &da) && \
+ !dwarf_form##attr(&da, value); \
+ }
+
+DEFINE_GET_ATTR(udata, Dwarf_Word)
+
static bool get_ref_die_attr(Dwarf_Die *die, unsigned int id, Dwarf_Die *value)
{
Dwarf_Attribute da;
@@ -67,6 +79,109 @@ static void process(const char *s)
fputs(s, stderr);
}
+#define MAX_FMT_BUFFER_SIZE 128
+
+static void process_fmt(const char *fmt, ...)
+{
+ char buf[MAX_FMT_BUFFER_SIZE];
+ va_list args;
+
+ va_start(args, fmt);
+
+ if (checkp(vsnprintf(buf, sizeof(buf), fmt, args)) >= sizeof(buf))
+ error("vsnprintf overflow: increase MAX_FMT_BUFFER_SIZE");
+
+ process(buf);
+ va_end(args);
+}
+
+#define MAX_FQN_SIZE 64
+
+/* Get a fully qualified name from DWARF scopes */
+static char *get_fqn(Dwarf_Die *die)
+{
+ const char *list[MAX_FQN_SIZE];
+ Dwarf_Die *scopes = NULL;
+ bool has_name = false;
+ char *fqn = NULL;
+ char *p;
+ int count = 0;
+ int len = 0;
+ int res;
+ int i;
+
+ res = checkp(dwarf_getscopes_die(die, &scopes));
+ if (!res) {
+ list[count] = get_name_attr(die);
+
+ if (!list[count])
+ return NULL;
+
+ len += strlen(list[count]);
+ count++;
+
+ goto done;
+ }
+
+ for (i = res - 1; i >= 0 && count < MAX_FQN_SIZE; i--) {
+ if (dwarf_tag(&scopes[i]) == DW_TAG_compile_unit)
+ continue;
+
+ list[count] = get_name_attr(&scopes[i]);
+
+ if (list[count]) {
+ has_name = true;
+ } else {
+ list[count] = "<anonymous>";
+ has_name = false;
+ }
+
+ len += strlen(list[count]);
+ count++;
+
+ if (i > 0) {
+ list[count++] = "::";
+ len += 2;
+ }
+ }
+
+ free(scopes);
+
+ if (count == MAX_FQN_SIZE)
+ warn("increase MAX_FQN_SIZE: reached the maximum");
+
+ /* Consider the DIE unnamed if the last scope doesn't have a name */
+ if (!has_name)
+ return NULL;
+done:
+ fqn = xmalloc(len + 1);
+ *fqn = '\0';
+
+ p = fqn;
+ for (i = 0; i < count; i++)
+ p = stpcpy(p, list[i]);
+
+ return fqn;
+}
+
+static void process_fqn(Dwarf_Die *die)
+{
+ process(" ");
+ process(get_fqn(die) ?: "");
+}
+
+#define DEFINE_PROCESS_UDATA_ATTRIBUTE(attribute) \
+ static void process_##attribute##_attr(Dwarf_Die *die) \
+ { \
+ Dwarf_Word value; \
+ if (get_udata_attr(die, DW_AT_##attribute, &value)) \
+ process_fmt(" " #attribute "(%" PRIu64 ")", value); \
+ }
+
+DEFINE_PROCESS_UDATA_ATTRIBUTE(alignment)
+DEFINE_PROCESS_UDATA_ATTRIBUTE(byte_size)
+DEFINE_PROCESS_UDATA_ATTRIBUTE(encoding)
+
bool match_all(Dwarf_Die *die)
{
return true;
@@ -93,6 +208,49 @@ int process_die_container(struct state *state, Dwarf_Die *die,
return 0;
}
+static int process_type(struct state *state, Dwarf_Die *die);
+
+static void process_type_attr(struct state *state, Dwarf_Die *die)
+{
+ Dwarf_Die type;
+
+ if (get_ref_die_attr(die, DW_AT_type, &type)) {
+ check(process_type(state, &type));
+ return;
+ }
+
+ /* Compilers can omit DW_AT_type -- print out 'void' to clarify */
+ process("base_type void");
+}
+
+static void process_base_type(struct state *state, Dwarf_Die *die)
+{
+ process("base_type");
+ process_fqn(die);
+ process_byte_size_attr(die);
+ process_encoding_attr(die);
+ process_alignment_attr(die);
+}
+
+#define PROCESS_TYPE(type) \
+ case DW_TAG_##type##_type: \
+ process_##type##_type(state, die); \
+ break;
+
+static int process_type(struct state *state, Dwarf_Die *die)
+{
+ int tag = dwarf_tag(die);
+
+ switch (tag) {
+ PROCESS_TYPE(base)
+ default:
+ debug("unimplemented type: %x", tag);
+ break;
+ }
+
+ return 0;
+}
+
/*
* Exported symbol processing
*/
@@ -119,6 +277,7 @@ static void process_subprogram(struct state *state, Dwarf_Die *die)
static int __process_variable(struct state *state, Dwarf_Die *die)
{
process("variable ");
+ process_type_attr(state, die);
return 0;
}
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 05/19] gendwarfksyms: Add a cache for processed DIEs
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (3 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 04/19] gendwarfksyms: Expand base_type Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 06/19] gendwarfksyms: Expand type modifiers and typedefs Sami Tolvanen
` (14 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
Basic types in DWARF repeat frequently and traversing the DIEs using
libdw is relatively slow. Add a simple hashtable based cache for the
processed DIEs.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
---
scripts/gendwarfksyms/Makefile | 1 +
scripts/gendwarfksyms/die.c | 143 ++++++++++++++++++++++++++
scripts/gendwarfksyms/dwarf.c | 136 +++++++++++++++++-------
scripts/gendwarfksyms/gendwarfksyms.c | 6 ++
scripts/gendwarfksyms/gendwarfksyms.h | 63 +++++++++++-
5 files changed, 308 insertions(+), 41 deletions(-)
create mode 100644 scripts/gendwarfksyms/die.c
diff --git a/scripts/gendwarfksyms/Makefile b/scripts/gendwarfksyms/Makefile
index 9f8fec4fd39b..c0d4ce50fc27 100644
--- a/scripts/gendwarfksyms/Makefile
+++ b/scripts/gendwarfksyms/Makefile
@@ -2,6 +2,7 @@
hostprogs-always-y += gendwarfksyms
gendwarfksyms-objs += gendwarfksyms.o
+gendwarfksyms-objs += die.o
gendwarfksyms-objs += dwarf.o
gendwarfksyms-objs += symbols.o
diff --git a/scripts/gendwarfksyms/die.c b/scripts/gendwarfksyms/die.c
new file mode 100644
index 000000000000..28d89fce89fc
--- /dev/null
+++ b/scripts/gendwarfksyms/die.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Google LLC
+ */
+
+#include <string.h>
+#include "gendwarfksyms.h"
+
+#define DIE_HASH_BITS 20
+
+/* {die->addr, state} -> struct die * */
+static HASHTABLE_DEFINE(die_map, 1 << DIE_HASH_BITS);
+
+static unsigned int map_hits;
+static unsigned int map_misses;
+
+static inline unsigned int die_hash(uintptr_t addr, enum die_state state)
+{
+ return hash_32(addr_hash(addr) ^ (unsigned int)state);
+}
+
+static void init_die(struct die *cd)
+{
+ cd->state = DIE_INCOMPLETE;
+ cd->fqn = NULL;
+ cd->tag = -1;
+ cd->addr = 0;
+ INIT_LIST_HEAD(&cd->fragments);
+}
+
+static struct die *create_die(Dwarf_Die *die, enum die_state state)
+{
+ struct die *cd;
+
+ cd = xmalloc(sizeof(struct die));
+ init_die(cd);
+ cd->addr = (uintptr_t)die->addr;
+
+ hash_add(die_map, &cd->hash, die_hash(cd->addr, state));
+ return cd;
+}
+
+int __die_map_get(uintptr_t addr, enum die_state state, struct die **res)
+{
+ struct die *cd;
+
+ hash_for_each_possible(die_map, cd, hash, die_hash(addr, state)) {
+ if (cd->addr == addr && cd->state == state) {
+ *res = cd;
+ return 0;
+ }
+ }
+
+ return -1;
+}
+
+struct die *die_map_get(Dwarf_Die *die, enum die_state state)
+{
+ struct die *cd;
+
+ if (__die_map_get((uintptr_t)die->addr, state, &cd) == 0) {
+ map_hits++;
+ return cd;
+ }
+
+ map_misses++;
+ return create_die(die, state);
+}
+
+static void reset_die(struct die *cd)
+{
+ struct die_fragment *tmp;
+ struct die_fragment *df;
+
+ list_for_each_entry_safe(df, tmp, &cd->fragments, list) {
+ if (df->type == FRAGMENT_STRING)
+ free(df->data.str);
+ free(df);
+ }
+
+ if (cd->fqn && *cd->fqn)
+ free(cd->fqn);
+ init_die(cd);
+}
+
+void die_map_free(void)
+{
+ struct hlist_node *tmp;
+ unsigned int stats[DIE_LAST + 1];
+ struct die *cd;
+ int i;
+
+ memset(stats, 0, sizeof(stats));
+
+ hash_for_each_safe(die_map, cd, tmp, hash) {
+ stats[cd->state]++;
+ reset_die(cd);
+ free(cd);
+ }
+ hash_init(die_map);
+
+ if (map_hits + map_misses > 0)
+ debug("hits %u, misses %u (hit rate %.02f%%)", map_hits,
+ map_misses,
+ (100.0f * map_hits) / (map_hits + map_misses));
+
+ for (i = 0; i <= DIE_LAST; i++)
+ debug("%s: %u entries", die_state_name(i), stats[i]);
+}
+
+static struct die_fragment *append_item(struct die *cd)
+{
+ struct die_fragment *df;
+
+ df = xmalloc(sizeof(struct die_fragment));
+ df->type = FRAGMENT_EMPTY;
+ list_add_tail(&df->list, &cd->fragments);
+ return df;
+}
+
+void die_map_add_string(struct die *cd, const char *str)
+{
+ struct die_fragment *df;
+
+ if (!cd)
+ return;
+
+ df = append_item(cd);
+ df->data.str = xstrdup(str);
+ df->type = FRAGMENT_STRING;
+}
+
+void die_map_add_die(struct die *cd, struct die *child)
+{
+ struct die_fragment *df;
+
+ if (!cd)
+ return;
+
+ df = append_item(cd);
+ df->data.addr = child->addr;
+ df->type = FRAGMENT_DIE;
+}
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index 35fd1dfeeadc..c2cd4743515e 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -71,17 +71,19 @@ static bool match_export_symbol(struct state *state, Dwarf_Die *die)
/*
* Type string processing
*/
-static void process(const char *s)
+static void process(struct die *cache, const char *s)
{
s = s ?: "<null>";
if (dump_dies)
fputs(s, stderr);
+
+ die_map_add_string(cache, s);
}
#define MAX_FMT_BUFFER_SIZE 128
-static void process_fmt(const char *fmt, ...)
+static void process_fmt(struct die *cache, const char *fmt, ...)
{
char buf[MAX_FMT_BUFFER_SIZE];
va_list args;
@@ -91,7 +93,7 @@ static void process_fmt(const char *fmt, ...)
if (checkp(vsnprintf(buf, sizeof(buf), fmt, args)) >= sizeof(buf))
error("vsnprintf overflow: increase MAX_FMT_BUFFER_SIZE");
- process(buf);
+ process(cache, buf);
va_end(args);
}
@@ -164,18 +166,28 @@ static char *get_fqn(Dwarf_Die *die)
return fqn;
}
-static void process_fqn(Dwarf_Die *die)
+static void update_fqn(struct die *cache, Dwarf_Die *die)
+{
+ if (!cache->fqn)
+ cache->fqn = get_fqn(die) ?: "";
+}
+
+static void process_fqn(struct die *cache, Dwarf_Die *die)
{
- process(" ");
- process(get_fqn(die) ?: "");
+ update_fqn(cache, die);
+ if (*cache->fqn)
+ process(cache, " ");
+ process(cache, cache->fqn);
}
-#define DEFINE_PROCESS_UDATA_ATTRIBUTE(attribute) \
- static void process_##attribute##_attr(Dwarf_Die *die) \
- { \
- Dwarf_Word value; \
- if (get_udata_attr(die, DW_AT_##attribute, &value)) \
- process_fmt(" " #attribute "(%" PRIu64 ")", value); \
+#define DEFINE_PROCESS_UDATA_ATTRIBUTE(attribute) \
+ static void process_##attribute##_attr(struct die *cache, \
+ Dwarf_Die *die) \
+ { \
+ Dwarf_Word value; \
+ if (get_udata_attr(die, DW_AT_##attribute, &value)) \
+ process_fmt(cache, " " #attribute "(%" PRIu64 ")", \
+ value); \
}
DEFINE_PROCESS_UDATA_ATTRIBUTE(alignment)
@@ -187,8 +199,9 @@ bool match_all(Dwarf_Die *die)
return true;
}
-int process_die_container(struct state *state, Dwarf_Die *die,
- die_callback_t func, die_match_callback_t match)
+int process_die_container(struct state *state, struct die *cache,
+ Dwarf_Die *die, die_callback_t func,
+ die_match_callback_t match)
{
Dwarf_Die current;
int res;
@@ -197,7 +210,7 @@ int process_die_container(struct state *state, Dwarf_Die *die,
while (!res) {
if (match(¤t)) {
/* <0 = error, 0 = continue, >0 = stop */
- res = checkp(func(state, ¤t));
+ res = checkp(func(state, cache, ¤t));
if (res)
return res;
}
@@ -208,39 +221,78 @@ int process_die_container(struct state *state, Dwarf_Die *die,
return 0;
}
-static int process_type(struct state *state, Dwarf_Die *die);
+static int process_type(struct state *state, struct die *parent,
+ Dwarf_Die *die);
-static void process_type_attr(struct state *state, Dwarf_Die *die)
+static void process_type_attr(struct state *state, struct die *cache,
+ Dwarf_Die *die)
{
Dwarf_Die type;
if (get_ref_die_attr(die, DW_AT_type, &type)) {
- check(process_type(state, &type));
+ check(process_type(state, cache, &type));
return;
}
/* Compilers can omit DW_AT_type -- print out 'void' to clarify */
- process("base_type void");
+ process(cache, "base_type void");
+}
+
+static void process_base_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ process(cache, "base_type");
+ process_fqn(cache, die);
+ process_byte_size_attr(cache, die);
+ process_encoding_attr(cache, die);
+ process_alignment_attr(cache, die);
}
-static void process_base_type(struct state *state, Dwarf_Die *die)
+static void process_cached(struct state *state, struct die *cache,
+ Dwarf_Die *die)
{
- process("base_type");
- process_fqn(die);
- process_byte_size_attr(die);
- process_encoding_attr(die);
- process_alignment_attr(die);
+ struct die_fragment *df;
+ Dwarf_Die child;
+
+ list_for_each_entry(df, &cache->fragments, list) {
+ switch (df->type) {
+ case FRAGMENT_STRING:
+ process(NULL, df->data.str);
+ break;
+ case FRAGMENT_DIE:
+ if (!dwarf_die_addr_die(dwarf_cu_getdwarf(die->cu),
+ (void *)df->data.addr, &child))
+ error("dwarf_die_addr_die failed");
+ check(process_type(state, NULL, &child));
+ break;
+ default:
+ error("empty die_fragment");
+ }
+ }
}
-#define PROCESS_TYPE(type) \
- case DW_TAG_##type##_type: \
- process_##type##_type(state, die); \
+#define PROCESS_TYPE(type) \
+ case DW_TAG_##type##_type: \
+ process_##type##_type(state, cache, die); \
break;
-static int process_type(struct state *state, Dwarf_Die *die)
+static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
{
+ struct die *cache;
int tag = dwarf_tag(die);
+ /*
+ * If we have the DIE already cached, use it instead of walking
+ * through DWARF.
+ */
+ cache = die_map_get(die, DIE_COMPLETE);
+
+ if (cache->state == DIE_COMPLETE) {
+ process_cached(state, cache, die);
+ die_map_add_die(parent, cache);
+ return 0;
+ }
+
switch (tag) {
PROCESS_TYPE(base)
default:
@@ -248,6 +300,11 @@ static int process_type(struct state *state, Dwarf_Die *die)
break;
}
+ /* Update cache state and append to the parent (if any) */
+ cache->tag = tag;
+ cache->state = DIE_COMPLETE;
+ die_map_add_die(parent, cache);
+
return 0;
}
@@ -258,14 +315,15 @@ static void process_symbol(struct state *state, Dwarf_Die *die,
die_callback_t process_func)
{
debug("%s", state->sym->name);
- check(process_func(state, die));
+ check(process_func(state, NULL, die));
if (dump_dies)
fputs("\n", stderr);
}
-static int __process_subprogram(struct state *state, Dwarf_Die *die)
+static int __process_subprogram(struct state *state, struct die *cache,
+ Dwarf_Die *die)
{
- process("subprogram");
+ process(cache, "subprogram");
return 0;
}
@@ -274,10 +332,11 @@ static void process_subprogram(struct state *state, Dwarf_Die *die)
process_symbol(state, die, __process_subprogram);
}
-static int __process_variable(struct state *state, Dwarf_Die *die)
+static int __process_variable(struct state *state, struct die *cache,
+ Dwarf_Die *die)
{
- process("variable ");
- process_type_attr(state, die);
+ process(cache, "variable ");
+ process_type_attr(state, cache, die);
return 0;
}
@@ -286,7 +345,8 @@ static void process_variable(struct state *state, Dwarf_Die *die)
process_symbol(state, die, __process_variable);
}
-static int process_exported_symbols(struct state *unused, Dwarf_Die *die)
+static int process_exported_symbols(struct state *unused, struct die *cache,
+ Dwarf_Die *die)
{
int tag = dwarf_tag(die);
@@ -296,7 +356,7 @@ static int process_exported_symbols(struct state *unused, Dwarf_Die *die)
case DW_TAG_class_type:
case DW_TAG_structure_type:
return check(process_die_container(
- NULL, die, process_exported_symbols, match_all));
+ NULL, cache, die, process_exported_symbols, match_all));
/* Possible exported symbols */
case DW_TAG_subprogram:
@@ -320,6 +380,6 @@ static int process_exported_symbols(struct state *unused, Dwarf_Die *die)
void process_cu(Dwarf_Die *cudie)
{
- check(process_die_container(NULL, cudie, process_exported_symbols,
+ check(process_die_container(NULL, NULL, cudie, process_exported_symbols,
match_all));
}
diff --git a/scripts/gendwarfksyms/gendwarfksyms.c b/scripts/gendwarfksyms/gendwarfksyms.c
index 1763234b6329..7552fde495ef 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.c
+++ b/scripts/gendwarfksyms/gendwarfksyms.c
@@ -43,6 +43,10 @@ static int process_module(Dwfl_Module *mod, void **userdata, const char *name,
debug("%s", name);
dbg = dwfl_module_getdwarf(mod, &dwbias);
+ /*
+ * Look for exported symbols in each CU, follow the DIE tree, and add
+ * the entries to die_map.
+ */
do {
res = dwarf_get_units(dbg, cu, &cu, NULL, NULL, &cudie, NULL);
if (res < 0)
@@ -53,6 +57,8 @@ static int process_module(Dwfl_Module *mod, void **userdata, const char *name,
process_cu(&cudie);
} while (cu);
+ die_map_free();
+
return DWARF_CB_OK;
}
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
index f75d8ca33b45..b2aded992d42 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.h
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -90,6 +90,61 @@ void symbol_read_symtab(int fd);
struct symbol *symbol_get(const char *name);
void symbol_free(void);
+/*
+ * die.c
+ */
+
+enum die_state {
+ DIE_INCOMPLETE,
+ DIE_COMPLETE,
+ DIE_LAST = DIE_COMPLETE
+};
+
+enum die_fragment_type {
+ FRAGMENT_EMPTY,
+ FRAGMENT_STRING,
+ FRAGMENT_DIE
+};
+
+struct die_fragment {
+ enum die_fragment_type type;
+ union {
+ char *str;
+ uintptr_t addr;
+ } data;
+ struct list_head list;
+};
+
+#define CASE_CONST_TO_STR(name) \
+ case name: \
+ return #name;
+
+static inline const char *die_state_name(enum die_state state)
+{
+ switch (state) {
+ CASE_CONST_TO_STR(DIE_INCOMPLETE)
+ CASE_CONST_TO_STR(DIE_COMPLETE)
+ }
+
+ error("unexpected die_state: %d", state);
+}
+
+struct die {
+ enum die_state state;
+ char *fqn;
+ int tag;
+ uintptr_t addr;
+ struct list_head fragments;
+ struct hlist_node hash;
+};
+
+int __die_map_get(uintptr_t addr, enum die_state state, struct die **res);
+struct die *die_map_get(Dwarf_Die *die, enum die_state state);
+void die_map_add_string(struct die *pd, const char *str);
+void die_map_add_linebreak(struct die *pd, int linebreak);
+void die_map_add_die(struct die *pd, struct die *child);
+void die_map_free(void);
+
/*
* dwarf.c
*/
@@ -99,12 +154,14 @@ struct state {
Dwarf_Die die;
};
-typedef int (*die_callback_t)(struct state *state, Dwarf_Die *die);
+typedef int (*die_callback_t)(struct state *state, struct die *cache,
+ Dwarf_Die *die);
typedef bool (*die_match_callback_t)(Dwarf_Die *die);
bool match_all(Dwarf_Die *die);
-int process_die_container(struct state *state, Dwarf_Die *die,
- die_callback_t func, die_match_callback_t match);
+int process_die_container(struct state *state, struct die *cache,
+ Dwarf_Die *die, die_callback_t func,
+ die_match_callback_t match);
void process_cu(Dwarf_Die *cudie);
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 06/19] gendwarfksyms: Expand type modifiers and typedefs
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (4 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 05/19] gendwarfksyms: Add a cache for processed DIEs Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 07/19] gendwarfksyms: Expand subroutine_type Sami Tolvanen
` (13 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
Add support for expanding DWARF type modifiers, such as pointers,
const values etc., and typedefs. These types all have DW_AT_type
attribute pointing to the underlying type, and thus produce similar
output.
Also add linebreaks and indentation to debugging output to make it
more readable.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
---
scripts/gendwarfksyms/die.c | 12 +++++
scripts/gendwarfksyms/dwarf.c | 67 +++++++++++++++++++++++++++
scripts/gendwarfksyms/gendwarfksyms.h | 5 ++
3 files changed, 84 insertions(+)
diff --git a/scripts/gendwarfksyms/die.c b/scripts/gendwarfksyms/die.c
index 28d89fce89fc..2829387fd815 100644
--- a/scripts/gendwarfksyms/die.c
+++ b/scripts/gendwarfksyms/die.c
@@ -130,6 +130,18 @@ void die_map_add_string(struct die *cd, const char *str)
df->type = FRAGMENT_STRING;
}
+void die_map_add_linebreak(struct die *cd, int linebreak)
+{
+ struct die_fragment *df;
+
+ if (!cd)
+ return;
+
+ df = append_item(cd);
+ df->data.linebreak = linebreak;
+ df->type = FRAGMENT_LINEBREAK;
+}
+
void die_map_add_die(struct die *cd, struct die *child)
{
struct die_fragment *df;
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index c2cd4743515e..1d67ee18a388 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -6,6 +6,17 @@
#include <stdarg.h>
#include "gendwarfksyms.h"
+static bool do_linebreak;
+static int indentation_level;
+
+/* Line breaks and indentation for pretty-printing */
+static void process_linebreak(struct die *cache, int n)
+{
+ indentation_level += n;
+ do_linebreak = true;
+ die_map_add_linebreak(cache, n);
+}
+
#define DEFINE_GET_ATTR(attr, type) \
static bool get_##attr##_attr(Dwarf_Die *die, unsigned int id, \
type *value) \
@@ -75,6 +86,12 @@ static void process(struct die *cache, const char *s)
{
s = s ?: "<null>";
+ if (dump_dies && do_linebreak) {
+ fputs("\n", stderr);
+ for (int i = 0; i < indentation_level; i++)
+ fputs(" ", stderr);
+ do_linebreak = false;
+ }
if (dump_dies)
fputs(s, stderr);
@@ -238,6 +255,40 @@ static void process_type_attr(struct state *state, struct die *cache,
process(cache, "base_type void");
}
+/* Container types with DW_AT_type */
+static void __process_type(struct state *state, struct die *cache,
+ Dwarf_Die *die, const char *type)
+{
+ process(cache, type);
+ process_fqn(cache, die);
+ process(cache, " {");
+ process_linebreak(cache, 1);
+ process_type_attr(state, cache, die);
+ process_linebreak(cache, -1);
+ process(cache, "}");
+ process_byte_size_attr(cache, die);
+ process_alignment_attr(cache, die);
+}
+
+#define DEFINE_PROCESS_TYPE(type) \
+ static void process_##type##_type(struct state *state, \
+ struct die *cache, Dwarf_Die *die) \
+ { \
+ __process_type(state, cache, die, #type "_type"); \
+ }
+
+DEFINE_PROCESS_TYPE(atomic)
+DEFINE_PROCESS_TYPE(const)
+DEFINE_PROCESS_TYPE(immutable)
+DEFINE_PROCESS_TYPE(packed)
+DEFINE_PROCESS_TYPE(pointer)
+DEFINE_PROCESS_TYPE(reference)
+DEFINE_PROCESS_TYPE(restrict)
+DEFINE_PROCESS_TYPE(rvalue_reference)
+DEFINE_PROCESS_TYPE(shared)
+DEFINE_PROCESS_TYPE(volatile)
+DEFINE_PROCESS_TYPE(typedef)
+
static void process_base_type(struct state *state, struct die *cache,
Dwarf_Die *die)
{
@@ -259,6 +310,9 @@ static void process_cached(struct state *state, struct die *cache,
case FRAGMENT_STRING:
process(NULL, df->data.str);
break;
+ case FRAGMENT_LINEBREAK:
+ process_linebreak(NULL, df->data.linebreak);
+ break;
case FRAGMENT_DIE:
if (!dwarf_die_addr_die(dwarf_cu_getdwarf(die->cu),
(void *)df->data.addr, &child))
@@ -294,7 +348,20 @@ static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
}
switch (tag) {
+ /* Type modifiers */
+ PROCESS_TYPE(atomic)
+ PROCESS_TYPE(const)
+ PROCESS_TYPE(immutable)
+ PROCESS_TYPE(packed)
+ PROCESS_TYPE(pointer)
+ PROCESS_TYPE(reference)
+ PROCESS_TYPE(restrict)
+ PROCESS_TYPE(rvalue_reference)
+ PROCESS_TYPE(shared)
+ PROCESS_TYPE(volatile)
+ /* Other types */
PROCESS_TYPE(base)
+ PROCESS_TYPE(typedef)
default:
debug("unimplemented type: %x", tag);
break;
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
index b2aded992d42..206ba8e3f1a8 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.h
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -62,6 +62,9 @@ extern int dump_dies;
/* Error == negative values */
#define checkp(expr) __check(expr, __res < 0)
+/* Consistent aliases (DW_TAG_<type>_type) for DWARF tags */
+#define DW_TAG_typedef_type DW_TAG_typedef
+
/*
* symbols.c
*/
@@ -103,6 +106,7 @@ enum die_state {
enum die_fragment_type {
FRAGMENT_EMPTY,
FRAGMENT_STRING,
+ FRAGMENT_LINEBREAK,
FRAGMENT_DIE
};
@@ -110,6 +114,7 @@ struct die_fragment {
enum die_fragment_type type;
union {
char *str;
+ int linebreak;
uintptr_t addr;
} data;
struct list_head list;
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 07/19] gendwarfksyms: Expand subroutine_type
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (5 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 06/19] gendwarfksyms: Expand type modifiers and typedefs Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 08/19] gendwarfksyms: Expand array_type Sami Tolvanen
` (12 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
Add support for expanding DW_TAG_subroutine_type and the parameters
in DW_TAG_formal_parameter. Use this to also expand subprograms.
Example output with --dump-dies:
subprogram (
formal_parameter pointer_type {
const_type {
base_type char byte_size(1) encoding(6)
}
}
)
-> base_type unsigned long byte_size(8) encoding(7)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
---
scripts/gendwarfksyms/dwarf.c | 84 ++++++++++++++++++++++++++-
scripts/gendwarfksyms/gendwarfksyms.h | 4 ++
2 files changed, 85 insertions(+), 3 deletions(-)
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index 1d67ee18a388..7e6b477d7c12 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -211,6 +211,15 @@ DEFINE_PROCESS_UDATA_ATTRIBUTE(alignment)
DEFINE_PROCESS_UDATA_ATTRIBUTE(byte_size)
DEFINE_PROCESS_UDATA_ATTRIBUTE(encoding)
+/* Match functions -- die_match_callback_t */
+#define DEFINE_MATCH(type) \
+ static bool match_##type##_type(Dwarf_Die *die) \
+ { \
+ return dwarf_tag(die) == DW_TAG_##type##_type; \
+ }
+
+DEFINE_MATCH(formal_parameter)
+
bool match_all(Dwarf_Die *die)
{
return true;
@@ -223,19 +232,28 @@ int process_die_container(struct state *state, struct die *cache,
Dwarf_Die current;
int res;
+ /* Track the first item in lists. */
+ if (state)
+ state->first_list_item = true;
+
res = checkp(dwarf_child(die, ¤t));
while (!res) {
if (match(¤t)) {
/* <0 = error, 0 = continue, >0 = stop */
res = checkp(func(state, cache, ¤t));
if (res)
- return res;
+ goto out;
}
res = checkp(dwarf_siblingof(¤t, ¤t));
}
- return 0;
+ res = 0;
+out:
+ if (state)
+ state->first_list_item = false;
+
+ return res;
}
static int process_type(struct state *state, struct die *parent,
@@ -255,6 +273,40 @@ static void process_type_attr(struct state *state, struct die *cache,
process(cache, "base_type void");
}
+static void process_list_comma(struct state *state, struct die *cache)
+{
+ if (state->first_list_item) {
+ state->first_list_item = false;
+ } else {
+ process(cache, " ,");
+ process_linebreak(cache, 0);
+ }
+}
+
+/* Comma-separated with DW_AT_type */
+static void __process_list_type(struct state *state, struct die *cache,
+ Dwarf_Die *die, const char *type)
+{
+ const char *name = get_name_attr(die);
+
+ process_list_comma(state, cache);
+ process(cache, type);
+ process_type_attr(state, cache, die);
+ if (name) {
+ process(cache, " ");
+ process(cache, name);
+ }
+}
+
+#define DEFINE_PROCESS_LIST_TYPE(type) \
+ static void process_##type##_type(struct state *state, \
+ struct die *cache, Dwarf_Die *die) \
+ { \
+ __process_list_type(state, cache, die, #type " "); \
+ }
+
+DEFINE_PROCESS_LIST_TYPE(formal_parameter)
+
/* Container types with DW_AT_type */
static void __process_type(struct state *state, struct die *cache,
Dwarf_Die *die, const char *type)
@@ -289,6 +341,29 @@ DEFINE_PROCESS_TYPE(shared)
DEFINE_PROCESS_TYPE(volatile)
DEFINE_PROCESS_TYPE(typedef)
+static void __process_subroutine_type(struct state *state, struct die *cache,
+ Dwarf_Die *die, const char *type)
+{
+ process(cache, type);
+ process(cache, " (");
+ process_linebreak(cache, 1);
+ /* Parameters */
+ check(process_die_container(state, cache, die, process_type,
+ match_formal_parameter_type));
+ process_linebreak(cache, -1);
+ process(cache, ")");
+ process_linebreak(cache, 0);
+ /* Return type */
+ process(cache, "-> ");
+ process_type_attr(state, cache, die);
+}
+
+static void process_subroutine_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ __process_subroutine_type(state, cache, die, "subroutine_type");
+}
+
static void process_base_type(struct state *state, struct die *cache,
Dwarf_Die *die)
{
@@ -359,8 +434,11 @@ static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
PROCESS_TYPE(rvalue_reference)
PROCESS_TYPE(shared)
PROCESS_TYPE(volatile)
+ /* Subtypes */
+ PROCESS_TYPE(formal_parameter)
/* Other types */
PROCESS_TYPE(base)
+ PROCESS_TYPE(subroutine)
PROCESS_TYPE(typedef)
default:
debug("unimplemented type: %x", tag);
@@ -390,7 +468,7 @@ static void process_symbol(struct state *state, Dwarf_Die *die,
static int __process_subprogram(struct state *state, struct die *cache,
Dwarf_Die *die)
{
- process(cache, "subprogram");
+ __process_subroutine_type(state, cache, die, "subprogram");
return 0;
}
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
index 206ba8e3f1a8..d01fc1488f76 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.h
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -63,6 +63,7 @@ extern int dump_dies;
#define checkp(expr) __check(expr, __res < 0)
/* Consistent aliases (DW_TAG_<type>_type) for DWARF tags */
+#define DW_TAG_formal_parameter_type DW_TAG_formal_parameter
#define DW_TAG_typedef_type DW_TAG_typedef
/*
@@ -157,6 +158,9 @@ void die_map_free(void);
struct state {
struct symbol *sym;
Dwarf_Die die;
+
+ /* List expansion */
+ bool first_list_item;
};
typedef int (*die_callback_t)(struct state *state, struct die *cache,
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 08/19] gendwarfksyms: Expand array_type
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (6 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 07/19] gendwarfksyms: Expand subroutine_type Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 09/19] gendwarfksyms: Expand structure types Sami Tolvanen
` (11 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
Add support for expanding DW_TAG_array_type, and the subrange type
indicating array size.
Example source code:
const char *s[34];
Output with --dump-dies:
variable array_type[34] {
pointer_type {
const_type {
base_type char byte_size(1) encoding(6)
}
} byte_size(8)
}
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
---
scripts/gendwarfksyms/dwarf.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index 7e6b477d7c12..ade9b3b7b119 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -219,6 +219,7 @@ DEFINE_PROCESS_UDATA_ATTRIBUTE(encoding)
}
DEFINE_MATCH(formal_parameter)
+DEFINE_MATCH(subrange)
bool match_all(Dwarf_Die *die)
{
@@ -341,6 +342,33 @@ DEFINE_PROCESS_TYPE(shared)
DEFINE_PROCESS_TYPE(volatile)
DEFINE_PROCESS_TYPE(typedef)
+static void process_subrange_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ Dwarf_Word count = 0;
+
+ if (get_udata_attr(die, DW_AT_count, &count))
+ process_fmt(cache, "[%" PRIu64 "]", count);
+ else if (get_udata_attr(die, DW_AT_upper_bound, &count))
+ process_fmt(cache, "[%" PRIu64 "]", count + 1);
+ else
+ process(cache, "[]");
+}
+
+static void process_array_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ process(cache, "array_type");
+ /* Array size */
+ check(process_die_container(state, cache, die, process_type,
+ match_subrange_type));
+ process(cache, " {");
+ process_linebreak(cache, 1);
+ process_type_attr(state, cache, die);
+ process_linebreak(cache, -1);
+ process(cache, "}");
+}
+
static void __process_subroutine_type(struct state *state, struct die *cache,
Dwarf_Die *die, const char *type)
{
@@ -436,7 +464,9 @@ static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
PROCESS_TYPE(volatile)
/* Subtypes */
PROCESS_TYPE(formal_parameter)
+ PROCESS_TYPE(subrange)
/* Other types */
+ PROCESS_TYPE(array)
PROCESS_TYPE(base)
PROCESS_TYPE(subroutine)
PROCESS_TYPE(typedef)
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 09/19] gendwarfksyms: Expand structure types
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (7 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 08/19] gendwarfksyms: Expand array_type Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 10/19] gendwarfksyms: Limit structure expansion Sami Tolvanen
` (10 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
Recursively expand DWARF structure types, i.e. structs, unions, and
enums. Also include relevant DWARF attributes in type strings to
encode structure layout, for example.
Example output with --dump-dies:
subprogram (
formal_parameter structure_type &str {
member pointer_type {
base_type u8 byte_size(1) encoding(7)
} data_ptr data_member_location(0) ,
member base_type usize byte_size(8) encoding(7) length data_member_location(8)
} byte_size(16) alignment(8) msg
)
-> base_type void
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
---
scripts/gendwarfksyms/dwarf.c | 138 +++++++++++++++++++++++++-
scripts/gendwarfksyms/gendwarfksyms.h | 5 +
2 files changed, 141 insertions(+), 2 deletions(-)
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index ade9b3b7b119..98191ca7cef0 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -207,9 +207,14 @@ static void process_fqn(struct die *cache, Dwarf_Die *die)
value); \
}
+DEFINE_PROCESS_UDATA_ATTRIBUTE(accessibility)
DEFINE_PROCESS_UDATA_ATTRIBUTE(alignment)
+DEFINE_PROCESS_UDATA_ATTRIBUTE(bit_size)
DEFINE_PROCESS_UDATA_ATTRIBUTE(byte_size)
DEFINE_PROCESS_UDATA_ATTRIBUTE(encoding)
+DEFINE_PROCESS_UDATA_ATTRIBUTE(data_bit_offset)
+DEFINE_PROCESS_UDATA_ATTRIBUTE(data_member_location)
+DEFINE_PROCESS_UDATA_ATTRIBUTE(discr_value)
/* Match functions -- die_match_callback_t */
#define DEFINE_MATCH(type) \
@@ -218,7 +223,9 @@ DEFINE_PROCESS_UDATA_ATTRIBUTE(encoding)
return dwarf_tag(die) == DW_TAG_##type##_type; \
}
+DEFINE_MATCH(enumerator)
DEFINE_MATCH(formal_parameter)
+DEFINE_MATCH(member)
DEFINE_MATCH(subrange)
bool match_all(Dwarf_Die *die)
@@ -297,6 +304,10 @@ static void __process_list_type(struct state *state, struct die *cache,
process(cache, " ");
process(cache, name);
}
+ process_accessibility_attr(cache, die);
+ process_bit_size_attr(cache, die);
+ process_data_bit_offset_attr(cache, die);
+ process_data_member_location_attr(cache, die);
}
#define DEFINE_PROCESS_LIST_TYPE(type) \
@@ -307,6 +318,7 @@ static void __process_list_type(struct state *state, struct die *cache,
}
DEFINE_PROCESS_LIST_TYPE(formal_parameter)
+DEFINE_PROCESS_LIST_TYPE(member)
/* Container types with DW_AT_type */
static void __process_type(struct state *state, struct die *cache,
@@ -339,6 +351,7 @@ DEFINE_PROCESS_TYPE(reference)
DEFINE_PROCESS_TYPE(restrict)
DEFINE_PROCESS_TYPE(rvalue_reference)
DEFINE_PROCESS_TYPE(shared)
+DEFINE_PROCESS_TYPE(template_type_parameter)
DEFINE_PROCESS_TYPE(volatile)
DEFINE_PROCESS_TYPE(typedef)
@@ -392,6 +405,107 @@ static void process_subroutine_type(struct state *state, struct die *cache,
__process_subroutine_type(state, cache, die, "subroutine_type");
}
+static void process_variant_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ process_list_comma(state, cache);
+ process(cache, "variant {");
+ process_linebreak(cache, 1);
+ check(process_die_container(state, cache, die, process_type,
+ match_member_type));
+ process_linebreak(cache, -1);
+ process(cache, "}");
+ process_discr_value_attr(cache, die);
+}
+
+static void process_variant_part_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ process_list_comma(state, cache);
+ process(cache, "variant_part {");
+ process_linebreak(cache, 1);
+ check(process_die_container(state, cache, die, process_type,
+ match_all));
+ process_linebreak(cache, -1);
+ process(cache, "}");
+}
+
+static int ___process_structure_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ switch (dwarf_tag(die)) {
+ case DW_TAG_member:
+ case DW_TAG_variant_part:
+ return check(process_type(state, cache, die));
+ case DW_TAG_class_type:
+ case DW_TAG_enumeration_type:
+ case DW_TAG_structure_type:
+ case DW_TAG_template_type_parameter:
+ case DW_TAG_union_type:
+ case DW_TAG_subprogram:
+ /* Skip non-member types, including member functions */
+ return 0;
+ default:
+ error("unexpected structure_type child: %x", dwarf_tag(die));
+ }
+}
+
+static void __process_structure_type(struct state *state, struct die *cache,
+ Dwarf_Die *die, const char *type,
+ die_callback_t process_func,
+ die_match_callback_t match_func)
+{
+ process(cache, type);
+ process_fqn(cache, die);
+ process(cache, " {");
+ process_linebreak(cache, 1);
+
+ check(process_die_container(state, cache, die, process_func,
+ match_func));
+
+ process_linebreak(cache, -1);
+ process(cache, "}");
+
+ process_byte_size_attr(cache, die);
+ process_alignment_attr(cache, die);
+}
+
+#define DEFINE_PROCESS_STRUCTURE_TYPE(structure) \
+ static void process_##structure##_type( \
+ struct state *state, struct die *cache, Dwarf_Die *die) \
+ { \
+ __process_structure_type(state, cache, die, \
+ #structure "_type", \
+ ___process_structure_type, \
+ match_all); \
+ }
+
+DEFINE_PROCESS_STRUCTURE_TYPE(class)
+DEFINE_PROCESS_STRUCTURE_TYPE(structure)
+DEFINE_PROCESS_STRUCTURE_TYPE(union)
+
+static void process_enumerator_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ Dwarf_Word value;
+
+ process_list_comma(state, cache);
+ process(cache, "enumerator");
+ process_fqn(cache, die);
+
+ if (get_udata_attr(die, DW_AT_const_value, &value)) {
+ process(cache, " = ");
+ process_fmt(cache, "%" PRIu64, value);
+ }
+}
+
+static void process_enumeration_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ __process_structure_type(state, cache, die, "enumeration_type",
+ process_type, match_enumerator_type);
+}
+
static void process_base_type(struct state *state, struct die *cache,
Dwarf_Die *die)
{
@@ -402,6 +516,16 @@ static void process_base_type(struct state *state, struct die *cache,
process_alignment_attr(cache, die);
}
+static void process_unspecified_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ /*
+ * These can be emitted for stand-alone assembly code, which means we
+ * might run into them in vmlinux.o.
+ */
+ process(cache, "unspecified_type");
+}
+
static void process_cached(struct state *state, struct die *cache,
Dwarf_Die *die)
{
@@ -462,17 +586,27 @@ static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
PROCESS_TYPE(rvalue_reference)
PROCESS_TYPE(shared)
PROCESS_TYPE(volatile)
+ /* Container types */
+ PROCESS_TYPE(class)
+ PROCESS_TYPE(structure)
+ PROCESS_TYPE(union)
+ PROCESS_TYPE(enumeration)
/* Subtypes */
+ PROCESS_TYPE(enumerator)
PROCESS_TYPE(formal_parameter)
+ PROCESS_TYPE(member)
PROCESS_TYPE(subrange)
+ PROCESS_TYPE(template_type_parameter)
+ PROCESS_TYPE(variant)
+ PROCESS_TYPE(variant_part)
/* Other types */
PROCESS_TYPE(array)
PROCESS_TYPE(base)
PROCESS_TYPE(subroutine)
PROCESS_TYPE(typedef)
+ PROCESS_TYPE(unspecified)
default:
- debug("unimplemented type: %x", tag);
- break;
+ error("unexpected type: %x", tag);
}
/* Update cache state and append to the parent (if any) */
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
index d01fc1488f76..8e087a5d58e2 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.h
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -63,8 +63,13 @@ extern int dump_dies;
#define checkp(expr) __check(expr, __res < 0)
/* Consistent aliases (DW_TAG_<type>_type) for DWARF tags */
+#define DW_TAG_enumerator_type DW_TAG_enumerator
#define DW_TAG_formal_parameter_type DW_TAG_formal_parameter
+#define DW_TAG_member_type DW_TAG_member
+#define DW_TAG_template_type_parameter_type DW_TAG_template_type_parameter
#define DW_TAG_typedef_type DW_TAG_typedef
+#define DW_TAG_variant_part_type DW_TAG_variant_part
+#define DW_TAG_variant_type DW_TAG_variant
/*
* symbols.c
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 10/19] gendwarfksyms: Limit structure expansion
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (8 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 09/19] gendwarfksyms: Expand structure types Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-11-20 21:54 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 11/19] gendwarfksyms: Add die_map debugging Sami Tolvanen
` (9 subsequent siblings)
19 siblings, 1 reply; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
Expand each structure type only once per exported symbol. This
is necessary to support self-referential structures, which would
otherwise result in infinite recursion, but is still sufficient for
catching ABI changes.
For pointers, limit structure expansion after the first pointer
in the symbol type. This should be plenty for detecting ABI
differences, but it stops us from pulling in half the kernel for
types that contain pointers to large kernel data structures, like
task_struct, for example.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
---
scripts/gendwarfksyms/Makefile | 1 +
scripts/gendwarfksyms/cache.c | 44 +++++++++++
scripts/gendwarfksyms/dwarf.c | 109 ++++++++++++++++++++++++--
scripts/gendwarfksyms/gendwarfksyms.h | 37 +++++++++
4 files changed, 183 insertions(+), 8 deletions(-)
create mode 100644 scripts/gendwarfksyms/cache.c
diff --git a/scripts/gendwarfksyms/Makefile b/scripts/gendwarfksyms/Makefile
index c0d4ce50fc27..c06145d84df8 100644
--- a/scripts/gendwarfksyms/Makefile
+++ b/scripts/gendwarfksyms/Makefile
@@ -2,6 +2,7 @@
hostprogs-always-y += gendwarfksyms
gendwarfksyms-objs += gendwarfksyms.o
+gendwarfksyms-objs += cache.o
gendwarfksyms-objs += die.o
gendwarfksyms-objs += dwarf.o
gendwarfksyms-objs += symbols.o
diff --git a/scripts/gendwarfksyms/cache.c b/scripts/gendwarfksyms/cache.c
new file mode 100644
index 000000000000..2f1517133a20
--- /dev/null
+++ b/scripts/gendwarfksyms/cache.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Google LLC
+ */
+
+#include "gendwarfksyms.h"
+
+struct expanded {
+ uintptr_t addr;
+ struct hlist_node hash;
+};
+
+void __cache_mark_expanded(struct expansion_cache *ec, uintptr_t addr)
+{
+ struct expanded *es;
+
+ es = xmalloc(sizeof(struct expanded));
+ es->addr = addr;
+ hash_add(ec->cache, &es->hash, addr_hash(addr));
+}
+
+bool __cache_was_expanded(struct expansion_cache *ec, uintptr_t addr)
+{
+ struct expanded *es;
+
+ hash_for_each_possible(ec->cache, es, hash, addr_hash(addr)) {
+ if (es->addr == addr)
+ return true;
+ }
+
+ return false;
+}
+
+void cache_clear_expanded(struct expansion_cache *ec)
+{
+ struct hlist_node *tmp;
+ struct expanded *es;
+
+ hash_for_each_safe(ec->cache, es, tmp, hash) {
+ free(es);
+ }
+
+ hash_init(ec->cache);
+}
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index 98191ca7cef0..cf929d6808be 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -26,6 +26,7 @@ static void process_linebreak(struct die *cache, int n)
!dwarf_form##attr(&da, value); \
}
+DEFINE_GET_ATTR(flag, bool)
DEFINE_GET_ATTR(udata, Dwarf_Word)
static bool get_ref_die_attr(Dwarf_Die *die, unsigned int id, Dwarf_Die *value)
@@ -79,6 +80,13 @@ static bool match_export_symbol(struct state *state, Dwarf_Die *die)
return !!state->sym;
}
+static bool is_declaration(Dwarf_Die *die)
+{
+ bool value;
+
+ return get_flag_attr(die, DW_AT_declaration, &value) && value;
+}
+
/*
* Type string processing
*/
@@ -455,19 +463,27 @@ static void __process_structure_type(struct state *state, struct die *cache,
die_callback_t process_func,
die_match_callback_t match_func)
{
+ bool is_decl;
+
process(cache, type);
process_fqn(cache, die);
process(cache, " {");
process_linebreak(cache, 1);
- check(process_die_container(state, cache, die, process_func,
- match_func));
+ is_decl = is_declaration(die);
+
+ if (!is_decl && state->expand.expand) {
+ check(process_die_container(state, cache, die, process_func,
+ match_func));
+ }
process_linebreak(cache, -1);
process(cache, "}");
- process_byte_size_attr(cache, die);
- process_alignment_attr(cache, die);
+ if (!is_decl && state->expand.expand) {
+ process_byte_size_attr(cache, die);
+ process_alignment_attr(cache, die);
+ }
}
#define DEFINE_PROCESS_STRUCTURE_TYPE(structure) \
@@ -552,6 +568,42 @@ static void process_cached(struct state *state, struct die *cache,
}
}
+static void state_init(struct state *state)
+{
+ state->expand.expand = true;
+ state->expand.ptr_depth = 0;
+ state->expand.ptr_expansion_depth = 0;
+ hash_init(state->expansion_cache.cache);
+}
+
+static void expansion_state_restore(struct expansion_state *state,
+ struct expansion_state *saved)
+{
+ state->expand = saved->expand;
+ state->ptr_depth = saved->ptr_depth;
+ state->ptr_expansion_depth = saved->ptr_expansion_depth;
+}
+
+static void expansion_state_save(struct expansion_state *state,
+ struct expansion_state *saved)
+{
+ expansion_state_restore(saved, state);
+}
+
+static bool is_pointer_type(int tag)
+{
+ return tag == DW_TAG_pointer_type || tag == DW_TAG_reference_type;
+}
+
+static bool is_expanded_type(int tag)
+{
+ return tag == DW_TAG_class_type || tag == DW_TAG_structure_type ||
+ tag == DW_TAG_union_type || tag == DW_TAG_enumeration_type;
+}
+
+/* The maximum depth for expanding structures in pointers */
+#define MAX_POINTER_EXPANSION_DEPTH 2
+
#define PROCESS_TYPE(type) \
case DW_TAG_##type##_type: \
process_##type##_type(state, cache, die); \
@@ -559,18 +611,55 @@ static void process_cached(struct state *state, struct die *cache,
static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
{
+ enum die_state want_state = DIE_COMPLETE;
struct die *cache;
+ struct expansion_state saved;
int tag = dwarf_tag(die);
+ expansion_state_save(&state->expand, &saved);
+
/*
- * If we have the DIE already cached, use it instead of walking
+ * Structures and enumeration types are expanded only once per
+ * exported symbol. This is sufficient for detecting ABI changes
+ * within the structure.
+ *
+ * We fully expand the first pointer reference in the exported
+ * symbol, but limit the expansion of further pointer references
+ * to at most MAX_POINTER_EXPANSION_DEPTH levels.
+ */
+ if (is_pointer_type(tag))
+ state->expand.ptr_depth++;
+
+ if (is_expanded_type(tag)) {
+ if (cache_was_expanded(&state->expansion_cache, die->addr))
+ state->expand.expand = false;
+
+ if (state->expand.ptr_depth > 0) {
+ if (state->expand.ptr_expansion_depth >=
+ MAX_POINTER_EXPANSION_DEPTH)
+ state->expand.expand = false;
+
+ if (state->expand.expand)
+ state->expand.ptr_expansion_depth++;
+ }
+
+ if (state->expand.expand)
+ cache_mark_expanded(&state->expansion_cache, die->addr);
+ else
+ want_state = DIE_UNEXPANDED;
+ }
+
+ /*
+ * If we have want_state already cached, use it instead of walking
* through DWARF.
*/
- cache = die_map_get(die, DIE_COMPLETE);
+ cache = die_map_get(die, want_state);
- if (cache->state == DIE_COMPLETE) {
+ if (cache->state == want_state) {
process_cached(state, cache, die);
die_map_add_die(parent, cache);
+
+ expansion_state_restore(&state->expand, &saved);
return 0;
}
@@ -611,9 +700,10 @@ static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
/* Update cache state and append to the parent (if any) */
cache->tag = tag;
- cache->state = DIE_COMPLETE;
+ cache->state = want_state;
die_map_add_die(parent, cache);
+ expansion_state_restore(&state->expand, &saved);
return 0;
}
@@ -675,11 +765,14 @@ static int process_exported_symbols(struct state *unused, struct die *cache,
if (!match_export_symbol(&state, die))
return 0;
+ state_init(&state);
+
if (tag == DW_TAG_subprogram)
process_subprogram(&state, &state.die);
else
process_variable(&state, &state.die);
+ cache_clear_expanded(&state.expansion_cache);
return 0;
}
default:
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
index 8e087a5d58e2..da28a35d19b2 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.h
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -105,6 +105,7 @@ void symbol_free(void);
enum die_state {
DIE_INCOMPLETE,
+ DIE_UNEXPANDED,
DIE_COMPLETE,
DIE_LAST = DIE_COMPLETE
};
@@ -134,6 +135,7 @@ static inline const char *die_state_name(enum die_state state)
{
switch (state) {
CASE_CONST_TO_STR(DIE_INCOMPLETE)
+ CASE_CONST_TO_STR(DIE_UNEXPANDED)
CASE_CONST_TO_STR(DIE_COMPLETE)
}
@@ -156,9 +158,40 @@ void die_map_add_linebreak(struct die *pd, int linebreak);
void die_map_add_die(struct die *pd, struct die *child);
void die_map_free(void);
+/*
+ * cache.c
+ */
+
+#define EXPANSION_CACHE_HASH_BITS 11
+
+/* A cache for addresses we've already seen. */
+struct expansion_cache {
+ HASHTABLE_DECLARE(cache, 1 << EXPANSION_CACHE_HASH_BITS);
+};
+
+void __cache_mark_expanded(struct expansion_cache *ec, uintptr_t addr);
+bool __cache_was_expanded(struct expansion_cache *ec, uintptr_t addr);
+
+static inline void cache_mark_expanded(struct expansion_cache *ec, void *addr)
+{
+ __cache_mark_expanded(ec, (uintptr_t)addr);
+}
+
+static inline bool cache_was_expanded(struct expansion_cache *ec, void *addr)
+{
+ return __cache_was_expanded(ec, (uintptr_t)addr);
+}
+
+void cache_clear_expanded(struct expansion_cache *ec);
+
/*
* dwarf.c
*/
+struct expansion_state {
+ bool expand;
+ unsigned int ptr_depth;
+ unsigned int ptr_expansion_depth;
+};
struct state {
struct symbol *sym;
@@ -166,6 +199,10 @@ struct state {
/* List expansion */
bool first_list_item;
+
+ /* Structure expansion */
+ struct expansion_state expand;
+ struct expansion_cache expansion_cache;
};
typedef int (*die_callback_t)(struct state *state, struct die *cache,
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* Re: [PATCH v5 10/19] gendwarfksyms: Limit structure expansion
2024-10-30 17:01 ` [PATCH v5 10/19] gendwarfksyms: Limit structure expansion Sami Tolvanen
@ 2024-11-20 21:54 ` Sami Tolvanen
0 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-11-20 21:54 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux
On Wed, Oct 30, 2024 at 05:01:17PM +0000, Sami Tolvanen wrote:
>
> For pointers, limit structure expansion after the first pointer
> in the symbol type. This should be plenty for detecting ABI
> differences, but it stops us from pulling in half the kernel for
> types that contain pointers to large kernel data structures, like
> task_struct, for example.
We spent some time backtesting gendwarfksyms with android15-6.6
releases to validate the kABI stability options that are currently
implemented [1]. While we discovered a few missing knobs that are
needed, we also realized that pointer expansion limits don't work
when symbols are removed (which is possible without breaking the
existing ABI when TRIM_UNUSED_KSYMS is used), as the processing
cut-off can change. Petr also had some concerns about this earlier,
so instead of coming up with an alternative solution, I'm going to
drop the pointer expansion limit in v6.
I still think that it would be great to come up with a better way to
limit how deep into internal data structures we go when calculating
versions, but I suspect that's going to be challenging unless C
grows an annotation for public / private struct members.
While looking into another version stability issue compared to
genksyms, we also came to the conclusion that private structure
definitions in .c files should be excluded from processing as they
are opaque outside the CU and cannot change the ABI. I'll include
this in v6 as well.
[1] https://github.com/samitolvanen/linux/commits/android15-6.6-2024-11-gendwarfksyms/
Sami
^ permalink raw reply [flat|nested] 36+ messages in thread
* [PATCH v5 11/19] gendwarfksyms: Add die_map debugging
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (9 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 10/19] gendwarfksyms: Limit structure expansion Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 12/19] gendwarfksyms: Add symtypes output Sami Tolvanen
` (8 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
Debugging the DWARF processing can be somewhat challenging, so add
more detailed debugging output for die_map operations. Add the
--dump-die-map flag, which adds color coded tags to the output for
die_map changes.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
---
scripts/gendwarfksyms/dwarf.c | 15 +++++++++++++++
scripts/gendwarfksyms/gendwarfksyms.c | 7 +++++++
scripts/gendwarfksyms/gendwarfksyms.h | 13 +++++++++++++
3 files changed, 35 insertions(+)
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index cf929d6808be..513f37d1798a 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -103,6 +103,8 @@ static void process(struct die *cache, const char *s)
if (dump_dies)
fputs(s, stderr);
+ if (cache)
+ die_debug_r("cache %p string '%s'", cache, s);
die_map_add_string(cache, s);
}
@@ -551,6 +553,8 @@ static void process_cached(struct state *state, struct die *cache,
list_for_each_entry(df, &cache->fragments, list) {
switch (df->type) {
case FRAGMENT_STRING:
+ die_debug_b("cache %p STRING '%s'", cache,
+ df->data.str);
process(NULL, df->data.str);
break;
case FRAGMENT_LINEBREAK:
@@ -560,6 +564,8 @@ static void process_cached(struct state *state, struct die *cache,
if (!dwarf_die_addr_die(dwarf_cu_getdwarf(die->cu),
(void *)df->data.addr, &child))
error("dwarf_die_addr_die failed");
+ die_debug_b("cache %p DIE addr %" PRIxPTR " tag %x",
+ cache, df->data.addr, dwarf_tag(&child));
check(process_type(state, NULL, &child));
break;
default:
@@ -656,6 +662,9 @@ static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
cache = die_map_get(die, want_state);
if (cache->state == want_state) {
+ die_debug_g("cached addr %p tag %x -- %s", die->addr, tag,
+ die_state_name(cache->state));
+
process_cached(state, cache, die);
die_map_add_die(parent, cache);
@@ -663,6 +672,9 @@ static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
return 0;
}
+ die_debug_g("addr %p tag %x -- %s -> %s", die->addr, tag,
+ die_state_name(cache->state), die_state_name(want_state));
+
switch (tag) {
/* Type modifiers */
PROCESS_TYPE(atomic)
@@ -698,6 +710,9 @@ static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
error("unexpected type: %x", tag);
}
+ die_debug_r("parent %p cache %p die addr %p tag %x", parent, cache,
+ die->addr, tag);
+
/* Update cache state and append to the parent (if any) */
cache->tag = tag;
cache->state = want_state;
diff --git a/scripts/gendwarfksyms/gendwarfksyms.c b/scripts/gendwarfksyms/gendwarfksyms.c
index 7552fde495ef..ed6d8c585268 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.c
+++ b/scripts/gendwarfksyms/gendwarfksyms.c
@@ -19,6 +19,8 @@
int debug;
/* Dump DIE contents */
int dump_dies;
+/* Print debugging information about die_map changes */
+int dump_die_map;
static void usage(void)
{
@@ -26,6 +28,7 @@ static void usage(void)
"Options:\n"
" -d, --debug Print debugging information\n"
" --dump-dies Dump DWARF DIE contents\n"
+ " --dump-die-map Print debugging information about die_map changes\n"
" -h, --help Print this message\n"
"\n",
stderr);
@@ -74,6 +77,7 @@ int main(int argc, char **argv)
struct option opts[] = { { "debug", 0, NULL, 'd' },
{ "dump-dies", 0, &dump_dies, 1 },
+ { "dump-die-map", 0, &dump_die_map, 1 },
{ "help", 0, NULL, 'h' },
{ 0, 0, NULL, 0 } };
@@ -93,6 +97,9 @@ int main(int argc, char **argv)
}
}
+ if (dump_die_map)
+ dump_dies = 1;
+
if (optind >= argc) {
usage();
error("no input files?");
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
index da28a35d19b2..72912c6b6e64 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.h
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -24,6 +24,7 @@
*/
extern int debug;
extern int dump_dies;
+extern int dump_die_map;
/*
* Output helpers
@@ -46,6 +47,18 @@ extern int dump_dies;
exit(1); \
} while (0)
+#define __die_debug(color, format, ...) \
+ do { \
+ if (dump_dies && dump_die_map) \
+ fprintf(stderr, \
+ "\033[" #color "m<" format ">\033[39m", \
+ __VA_ARGS__); \
+ } while (0)
+
+#define die_debug_r(format, ...) __die_debug(91, format, __VA_ARGS__)
+#define die_debug_g(format, ...) __die_debug(92, format, __VA_ARGS__)
+#define die_debug_b(format, ...) __die_debug(94, format, __VA_ARGS__)
+
/*
* Error handling helpers
*/
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 12/19] gendwarfksyms: Add symtypes output
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (10 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 11/19] gendwarfksyms: Add die_map debugging Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 13/19] gendwarfksyms: Add symbol versioning Sami Tolvanen
` (7 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
Add support for producing genksyms-style symtypes files. Process
die_map to find the longest expansions for each type, and use symtypes
references in type definitions. The basic file format is similar to
genksyms, with two notable exceptions:
1. Type names with spaces (common with Rust) in references are
wrapped in single quotes. E.g.:
s#'core::result::Result<u8, core::num::error::ParseIntError>'
2. The actual type definition is the simple parsed DWARF format we
output with --dump-dies, not the preprocessed C-style format
genksyms produces.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
---
scripts/gendwarfksyms/Makefile | 1 +
scripts/gendwarfksyms/die.c | 11 +
scripts/gendwarfksyms/dwarf.c | 1 +
scripts/gendwarfksyms/gendwarfksyms.c | 33 ++-
scripts/gendwarfksyms/gendwarfksyms.h | 19 ++
scripts/gendwarfksyms/symbols.c | 4 +-
scripts/gendwarfksyms/types.c | 359 ++++++++++++++++++++++++++
7 files changed, 425 insertions(+), 3 deletions(-)
create mode 100644 scripts/gendwarfksyms/types.c
diff --git a/scripts/gendwarfksyms/Makefile b/scripts/gendwarfksyms/Makefile
index c06145d84df8..6540282dc746 100644
--- a/scripts/gendwarfksyms/Makefile
+++ b/scripts/gendwarfksyms/Makefile
@@ -6,5 +6,6 @@ gendwarfksyms-objs += cache.o
gendwarfksyms-objs += die.o
gendwarfksyms-objs += dwarf.o
gendwarfksyms-objs += symbols.o
+gendwarfksyms-objs += types.o
HOSTLDLIBS_gendwarfksyms := -ldw -lelf
diff --git a/scripts/gendwarfksyms/die.c b/scripts/gendwarfksyms/die.c
index 2829387fd815..df1ca3a032bb 100644
--- a/scripts/gendwarfksyms/die.c
+++ b/scripts/gendwarfksyms/die.c
@@ -22,6 +22,7 @@ static inline unsigned int die_hash(uintptr_t addr, enum die_state state)
static void init_die(struct die *cd)
{
cd->state = DIE_INCOMPLETE;
+ cd->mapped = false;
cd->fqn = NULL;
cd->tag = -1;
cd->addr = 0;
@@ -83,6 +84,16 @@ static void reset_die(struct die *cd)
init_die(cd);
}
+void die_map_for_each(die_map_callback_t func, void *arg)
+{
+ struct hlist_node *tmp;
+ struct die *cd;
+
+ hash_for_each_safe(die_map, cd, tmp, hash) {
+ func(cd, arg);
+ }
+}
+
void die_map_free(void)
{
struct hlist_node *tmp;
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index 513f37d1798a..3d2c1aa24960 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -730,6 +730,7 @@ static void process_symbol(struct state *state, Dwarf_Die *die,
{
debug("%s", state->sym->name);
check(process_func(state, NULL, die));
+ state->sym->state = SYMBOL_MAPPED;
if (dump_dies)
fputs("\n", stderr);
}
diff --git a/scripts/gendwarfksyms/gendwarfksyms.c b/scripts/gendwarfksyms/gendwarfksyms.c
index ed6d8c585268..76a38b733ad2 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.c
+++ b/scripts/gendwarfksyms/gendwarfksyms.c
@@ -21,6 +21,11 @@ int debug;
int dump_dies;
/* Print debugging information about die_map changes */
int dump_die_map;
+/* Print out type strings (i.e. type_map) */
+int dump_types;
+/* Write a symtypes file */
+int symtypes;
+static const char *symtypes_file;
static void usage(void)
{
@@ -29,6 +34,8 @@ static void usage(void)
" -d, --debug Print debugging information\n"
" --dump-dies Dump DWARF DIE contents\n"
" --dump-die-map Print debugging information about die_map changes\n"
+ " --dump-types Dump type strings\n"
+ " -T, --symtypes file Write a symtypes file\n"
" -h, --help Print this message\n"
"\n",
stderr);
@@ -41,6 +48,7 @@ static int process_module(Dwfl_Module *mod, void **userdata, const char *name,
Dwarf_Die cudie;
Dwarf_CU *cu = NULL;
Dwarf *dbg;
+ FILE *symfile = arg;
int res;
debug("%s", name);
@@ -60,6 +68,10 @@ static int process_module(Dwfl_Module *mod, void **userdata, const char *name,
process_cu(&cudie);
} while (cu);
+ /*
+ * Use die_map to expand type strings and write them to `symfile`.
+ */
+ generate_symtypes(symfile);
die_map_free();
return DWARF_CB_OK;
@@ -72,22 +84,29 @@ static const Dwfl_Callbacks callbacks = {
int main(int argc, char **argv)
{
+ FILE *symfile = NULL;
unsigned int n;
int opt;
struct option opts[] = { { "debug", 0, NULL, 'd' },
{ "dump-dies", 0, &dump_dies, 1 },
{ "dump-die-map", 0, &dump_die_map, 1 },
+ { "dump-types", 0, &dump_types, 1 },
+ { "symtypes", 1, NULL, 'T' },
{ "help", 0, NULL, 'h' },
{ 0, 0, NULL, 0 } };
- while ((opt = getopt_long(argc, argv, "dh", opts, NULL)) != EOF) {
+ while ((opt = getopt_long(argc, argv, "dT:h", opts, NULL)) != EOF) {
switch (opt) {
case 0:
break;
case 'd':
debug = 1;
break;
+ case 'T':
+ symtypes = 1;
+ symtypes_file = optarg;
+ break;
case 'h':
usage();
return 0;
@@ -107,6 +126,13 @@ int main(int argc, char **argv)
symbol_read_exports(stdin);
+ if (symtypes_file) {
+ symfile = fopen(symtypes_file, "w");
+ if (!symfile)
+ error("fopen failed for '%s': %s", symtypes_file,
+ strerror(errno));
+ }
+
for (n = optind; n < argc; n++) {
Dwfl *dwfl;
int fd;
@@ -129,12 +155,15 @@ int main(int argc, char **argv)
dwfl_report_end(dwfl, NULL, NULL);
- if (dwfl_getmodules(dwfl, &process_module, NULL, 0))
+ if (dwfl_getmodules(dwfl, &process_module, symfile, 0))
error("dwfl_getmodules failed for '%s'", argv[n]);
dwfl_end(dwfl);
}
+ if (symfile)
+ check(fclose(symfile));
+
symbol_free();
return 0;
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
index 72912c6b6e64..835ebcea6e97 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.h
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -25,6 +25,8 @@
extern int debug;
extern int dump_dies;
extern int dump_die_map;
+extern int dump_types;
+extern int symtypes;
/*
* Output helpers
@@ -93,6 +95,11 @@ static inline unsigned int addr_hash(uintptr_t addr)
return hash_ptr((const void *)addr);
}
+enum symbol_state {
+ SYMBOL_UNPROCESSED,
+ SYMBOL_MAPPED,
+};
+
struct symbol_addr {
uint32_t section;
Elf64_Addr address;
@@ -103,6 +110,8 @@ struct symbol {
struct symbol_addr addr;
struct hlist_node addr_hash;
struct hlist_node name_hash;
+ enum symbol_state state;
+ uintptr_t die_addr;
};
typedef void (*symbol_callback_t)(struct symbol *, void *arg);
@@ -157,6 +166,7 @@ static inline const char *die_state_name(enum die_state state)
struct die {
enum die_state state;
+ bool mapped;
char *fqn;
int tag;
uintptr_t addr;
@@ -164,10 +174,13 @@ struct die {
struct hlist_node hash;
};
+typedef void (*die_map_callback_t)(struct die *, void *arg);
+
int __die_map_get(uintptr_t addr, enum die_state state, struct die **res);
struct die *die_map_get(Dwarf_Die *die, enum die_state state);
void die_map_add_string(struct die *pd, const char *str);
void die_map_add_linebreak(struct die *pd, int linebreak);
+void die_map_for_each(die_map_callback_t func, void *arg);
void die_map_add_die(struct die *pd, struct die *child);
void die_map_free(void);
@@ -229,4 +242,10 @@ int process_die_container(struct state *state, struct die *cache,
void process_cu(Dwarf_Die *cudie);
+/*
+ * types.c
+ */
+
+void generate_symtypes(FILE *file);
+
#endif /* __GENDWARFKSYMS_H */
diff --git a/scripts/gendwarfksyms/symbols.c b/scripts/gendwarfksyms/symbols.c
index e7343394248b..6ed0c4769e6f 100644
--- a/scripts/gendwarfksyms/symbols.c
+++ b/scripts/gendwarfksyms/symbols.c
@@ -92,6 +92,7 @@ void symbol_read_exports(FILE *file)
sym = xcalloc(1, sizeof(struct symbol));
sym->name = name;
sym->addr.section = SHN_UNDEF;
+ sym->state = SYMBOL_UNPROCESSED;
hash_add(symbol_names, &sym->name_hash, hash_str(sym->name));
++nsym;
@@ -107,7 +108,8 @@ static void get_symbol(struct symbol *sym, void *arg)
{
struct symbol **res = arg;
- *res = sym;
+ if (sym->state == SYMBOL_UNPROCESSED)
+ *res = sym;
}
struct symbol *symbol_get(const char *name)
diff --git a/scripts/gendwarfksyms/types.c b/scripts/gendwarfksyms/types.c
new file mode 100644
index 000000000000..c05811299eba
--- /dev/null
+++ b/scripts/gendwarfksyms/types.c
@@ -0,0 +1,359 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Google LLC
+ */
+
+#include "gendwarfksyms.h"
+
+static struct expansion_cache expansion_cache;
+
+/*
+ * A simple linked list of shared or owned strings to avoid copying strings
+ * around when not necessary.
+ */
+struct type_list_entry {
+ const char *str;
+ void *owned;
+ struct list_head list;
+};
+
+static void type_list_free(struct list_head *list)
+{
+ struct type_list_entry *entry;
+ struct type_list_entry *tmp;
+
+ list_for_each_entry_safe(entry, tmp, list, list) {
+ if (entry->owned)
+ free(entry->owned);
+ free(entry);
+ }
+
+ INIT_LIST_HEAD(list);
+}
+
+static int type_list_append(struct list_head *list, const char *s, void *owned)
+{
+ struct type_list_entry *entry;
+
+ if (!s)
+ return 0;
+
+ entry = xmalloc(sizeof(struct type_list_entry));
+ entry->str = s;
+ entry->owned = owned;
+ list_add_tail(&entry->list, list);
+
+ return strlen(entry->str);
+}
+
+static void type_list_write(struct list_head *list, FILE *file)
+{
+ struct type_list_entry *entry;
+
+ list_for_each_entry(entry, list, list) {
+ if (entry->str)
+ checkp(fputs(entry->str, file));
+ }
+}
+
+/*
+ * An expanded type string in symtypes format.
+ */
+struct type_expansion {
+ char *name;
+ size_t len;
+ struct list_head expanded;
+ struct hlist_node hash;
+};
+
+static void type_expansion_init(struct type_expansion *type)
+{
+ type->name = NULL;
+ type->len = 0;
+ INIT_LIST_HEAD(&type->expanded);
+}
+
+static inline void type_expansion_free(struct type_expansion *type)
+{
+ free(type->name);
+ type->name = NULL;
+ type->len = 0;
+ type_list_free(&type->expanded);
+}
+
+static void type_expansion_append(struct type_expansion *type, const char *s,
+ void *owned)
+{
+ type->len += type_list_append(&type->expanded, s, owned);
+}
+
+/*
+ * type_map -- the longest expansions for each type.
+ *
+ * const char *name -> struct type_expansion *
+ */
+#define TYPE_HASH_BITS 16
+static HASHTABLE_DEFINE(type_map, 1 << TYPE_HASH_BITS);
+
+static int type_map_get(const char *name, struct type_expansion **res)
+{
+ struct type_expansion *e;
+
+ hash_for_each_possible(type_map, e, hash, hash_str(name)) {
+ if (!strcmp(name, e->name)) {
+ *res = e;
+ return 0;
+ }
+ }
+
+ return -1;
+}
+
+static void type_map_add(const char *name, struct type_expansion *type)
+{
+ struct type_expansion *e;
+
+ if (type_map_get(name, &e)) {
+ e = xmalloc(sizeof(struct type_expansion));
+ type_expansion_init(e);
+ e->name = xstrdup(name);
+
+ hash_add(type_map, &e->hash, hash_str(e->name));
+
+ if (dump_types)
+ debug("adding %s", e->name);
+ } else {
+ /* Use the longest available expansion */
+ if (type->len <= e->len)
+ return;
+
+ type_list_free(&e->expanded);
+
+ if (dump_types)
+ debug("replacing %s", e->name);
+ }
+
+ /* Take ownership of type->expanded */
+ list_replace_init(&type->expanded, &e->expanded);
+ e->len = type->len;
+
+ if (dump_types) {
+ checkp(fputs(e->name, stderr));
+ checkp(fputs(" ", stderr));
+ type_list_write(&e->expanded, stderr);
+ checkp(fputs("\n", stderr));
+ }
+}
+
+static void type_map_write(FILE *file)
+{
+ struct type_expansion *e;
+ struct hlist_node *tmp;
+
+ if (!file)
+ return;
+
+ hash_for_each_safe(type_map, e, tmp, hash) {
+ checkp(fputs(e->name, file));
+ checkp(fputs(" ", file));
+ type_list_write(&e->expanded, file);
+ checkp(fputs("\n", file));
+ }
+}
+
+static void type_map_free(void)
+{
+ struct type_expansion *e;
+ struct hlist_node *tmp;
+
+ hash_for_each_safe(type_map, e, tmp, hash) {
+ type_expansion_free(e);
+ free(e);
+ }
+
+ hash_init(type_map);
+}
+
+/*
+ * Type reference format: <prefix>#<name>, where prefix:
+ * s -> structure
+ * u -> union
+ * e -> enum
+ * t -> typedef
+ *
+ * Names with spaces are additionally wrapped in single quotes.
+ */
+static char get_type_prefix(int tag)
+{
+ switch (tag) {
+ case DW_TAG_class_type:
+ case DW_TAG_structure_type:
+ return 's';
+ case DW_TAG_union_type:
+ return 'u';
+ case DW_TAG_enumeration_type:
+ return 'e';
+ case DW_TAG_typedef_type:
+ return 't';
+ default:
+ return 0;
+ }
+}
+
+static char *get_type_name(struct die *cache)
+{
+ const char *quote;
+ char prefix;
+ char *name;
+
+ if (cache->state == DIE_INCOMPLETE) {
+ warn("found incomplete cache entry: %p", cache);
+ return NULL;
+ }
+ if (!cache->fqn || !*cache->fqn)
+ return NULL;
+
+ prefix = get_type_prefix(cache->tag);
+ if (!prefix)
+ return NULL;
+
+ /* Wrap names with spaces in single quotes */
+ quote = strstr(cache->fqn, " ") ? "'" : "";
+
+ /* <prefix>#<type_name>\0 */
+ if (asprintf(&name, "%c#%s%s%s", prefix, quote, cache->fqn, quote) < 0)
+ error("asprintf failed for '%s'", cache->fqn);
+
+ return name;
+}
+
+static void __type_expand(struct die *cache, struct type_expansion *type,
+ bool recursive);
+
+static void type_expand_child(struct die *cache, struct type_expansion *type,
+ bool recursive)
+{
+ struct type_expansion child;
+ char *name;
+
+ name = get_type_name(cache);
+ if (!name) {
+ __type_expand(cache, type, recursive);
+ return;
+ }
+
+ if (recursive && !__cache_was_expanded(&expansion_cache, cache->addr)) {
+ __cache_mark_expanded(&expansion_cache, cache->addr);
+ type_expansion_init(&child);
+ __type_expand(cache, &child, true);
+ type_map_add(name, &child);
+ type_expansion_free(&child);
+ }
+
+ type_expansion_append(type, name, name);
+}
+
+static void __type_expand(struct die *cache, struct type_expansion *type,
+ bool recursive)
+{
+ struct die_fragment *df;
+ struct die *child;
+
+ list_for_each_entry(df, &cache->fragments, list) {
+ switch (df->type) {
+ case FRAGMENT_STRING:
+ type_expansion_append(type, df->data.str, NULL);
+ break;
+ case FRAGMENT_DIE:
+ /* Use a complete die_map expansion if available */
+ if (__die_map_get(df->data.addr, DIE_COMPLETE,
+ &child) &&
+ __die_map_get(df->data.addr, DIE_UNEXPANDED,
+ &child))
+ error("unknown child: %" PRIxPTR,
+ df->data.addr);
+
+ type_expand_child(child, type, recursive);
+ break;
+ case FRAGMENT_LINEBREAK:
+ /*
+ * Keep whitespace in the symtypes format, but avoid
+ * repeated spaces.
+ */
+ if (list_is_last(&df->list, &cache->fragments) ||
+ list_next_entry(df, list)->type !=
+ FRAGMENT_LINEBREAK)
+ type_expansion_append(type, " ", NULL);
+ break;
+ default:
+ error("empty die_fragment in %p", cache);
+ }
+ }
+}
+
+static void type_expand(struct die *cache, struct type_expansion *type,
+ bool recursive)
+{
+ type_expansion_init(type);
+ __type_expand(cache, type, recursive);
+ cache_clear_expanded(&expansion_cache);
+}
+
+static void expand_type(struct die *cache, void *arg)
+{
+ struct type_expansion type;
+ char *name;
+
+ if (cache->mapped)
+ return;
+
+ cache->mapped = true;
+
+ /*
+ * Skip unexpanded die_map entries if there's a complete
+ * expansion available for this DIE.
+ */
+ if (cache->state == DIE_UNEXPANDED &&
+ !__die_map_get(cache->addr, DIE_COMPLETE, &cache)) {
+ if (cache->mapped)
+ return;
+
+ cache->mapped = true;
+ }
+
+ name = get_type_name(cache);
+ if (!name)
+ return;
+
+ debug("%s", name);
+ type_expand(cache, &type, true);
+ type_map_add(name, &type);
+
+ type_expansion_free(&type);
+ free(name);
+}
+
+void generate_symtypes(FILE *file)
+{
+ hash_init(expansion_cache.cache);
+
+ /*
+ * die_map processing:
+ *
+ * 1. die_map contains all types referenced in exported symbol
+ * signatures, but can contain duplicates just like the original
+ * DWARF, and some references may not be fully expanded depending
+ * on how far we processed the DIE tree for that specific symbol.
+ *
+ * For each die_map entry, find the longest available expansion,
+ * and add it to type_map.
+ */
+ die_map_for_each(expand_type, NULL);
+
+ /*
+ * 2. If a symtypes file is requested, write type_map contents to
+ * the file.
+ */
+ type_map_write(file);
+ type_map_free();
+}
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 13/19] gendwarfksyms: Add symbol versioning
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (11 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 12/19] gendwarfksyms: Add symtypes output Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 14/19] gendwarfksyms: Add support for kABI rules Sami Tolvanen
` (6 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
Calculate symbol versions from the fully expanded type strings in
type_map, and output the versions in a genksyms-compatible format.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
---
scripts/gendwarfksyms/dwarf.c | 25 +++++-
scripts/gendwarfksyms/gendwarfksyms.c | 10 ++-
scripts/gendwarfksyms/gendwarfksyms.h | 13 ++-
scripts/gendwarfksyms/symbols.c | 53 +++++++++++
scripts/gendwarfksyms/types.c | 122 +++++++++++++++++++++++++-
5 files changed, 215 insertions(+), 8 deletions(-)
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index 3d2c1aa24960..1f63f28add4b 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -725,12 +725,33 @@ static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
/*
* Exported symbol processing
*/
+static struct die *get_symbol_cache(struct state *state, Dwarf_Die *die)
+{
+ struct die *cache;
+
+ cache = die_map_get(die, DIE_SYMBOL);
+
+ if (cache->state != DIE_INCOMPLETE)
+ return NULL; /* We already processed a symbol for this DIE */
+
+ cache->tag = dwarf_tag(die);
+ return cache;
+}
+
static void process_symbol(struct state *state, Dwarf_Die *die,
die_callback_t process_func)
{
+ struct die *cache;
+
+ symbol_set_die(state->sym, die);
+
+ cache = get_symbol_cache(state, die);
+ if (!cache)
+ return;
+
debug("%s", state->sym->name);
- check(process_func(state, NULL, die));
- state->sym->state = SYMBOL_MAPPED;
+ check(process_func(state, cache, die));
+ cache->state = DIE_SYMBOL;
if (dump_dies)
fputs("\n", stderr);
}
diff --git a/scripts/gendwarfksyms/gendwarfksyms.c b/scripts/gendwarfksyms/gendwarfksyms.c
index 76a38b733ad2..fd2429ea198f 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.c
+++ b/scripts/gendwarfksyms/gendwarfksyms.c
@@ -23,6 +23,8 @@ int dump_dies;
int dump_die_map;
/* Print out type strings (i.e. type_map) */
int dump_types;
+/* Print out expanded type strings used for symbol versions */
+int dump_versions;
/* Write a symtypes file */
int symtypes;
static const char *symtypes_file;
@@ -35,6 +37,7 @@ static void usage(void)
" --dump-dies Dump DWARF DIE contents\n"
" --dump-die-map Print debugging information about die_map changes\n"
" --dump-types Dump type strings\n"
+ " --dump-versions Dump expanded type strings used for symbol versions\n"
" -T, --symtypes file Write a symtypes file\n"
" -h, --help Print this message\n"
"\n",
@@ -69,9 +72,10 @@ static int process_module(Dwfl_Module *mod, void **userdata, const char *name,
} while (cu);
/*
- * Use die_map to expand type strings and write them to `symfile`.
+ * Use die_map to expand type strings, write them to `symfile`, and
+ * calculate symbol versions.
*/
- generate_symtypes(symfile);
+ generate_symtypes_and_versions(symfile);
die_map_free();
return DWARF_CB_OK;
@@ -92,6 +96,7 @@ int main(int argc, char **argv)
{ "dump-dies", 0, &dump_dies, 1 },
{ "dump-die-map", 0, &dump_die_map, 1 },
{ "dump-types", 0, &dump_types, 1 },
+ { "dump-versions", 0, &dump_versions, 1 },
{ "symtypes", 1, NULL, 'T' },
{ "help", 0, NULL, 'h' },
{ 0, 0, NULL, 0 } };
@@ -164,6 +169,7 @@ int main(int argc, char **argv)
if (symfile)
check(fclose(symfile));
+ symbol_print_versions();
symbol_free();
return 0;
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
index 835ebcea6e97..88a9c1c5db20 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.h
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -26,6 +26,7 @@ extern int debug;
extern int dump_dies;
extern int dump_die_map;
extern int dump_types;
+extern int dump_versions;
extern int symtypes;
/*
@@ -98,6 +99,7 @@ static inline unsigned int addr_hash(uintptr_t addr)
enum symbol_state {
SYMBOL_UNPROCESSED,
SYMBOL_MAPPED,
+ SYMBOL_PROCESSED
};
struct symbol_addr {
@@ -112,6 +114,7 @@ struct symbol {
struct hlist_node name_hash;
enum symbol_state state;
uintptr_t die_addr;
+ unsigned long crc;
};
typedef void (*symbol_callback_t)(struct symbol *, void *arg);
@@ -119,6 +122,10 @@ typedef void (*symbol_callback_t)(struct symbol *, void *arg);
void symbol_read_exports(FILE *file);
void symbol_read_symtab(int fd);
struct symbol *symbol_get(const char *name);
+void symbol_set_die(struct symbol *sym, Dwarf_Die *die);
+void symbol_set_crc(struct symbol *sym, unsigned long crc);
+void symbol_for_each(symbol_callback_t func, void *arg);
+void symbol_print_versions(void);
void symbol_free(void);
/*
@@ -129,7 +136,8 @@ enum die_state {
DIE_INCOMPLETE,
DIE_UNEXPANDED,
DIE_COMPLETE,
- DIE_LAST = DIE_COMPLETE
+ DIE_SYMBOL,
+ DIE_LAST = DIE_SYMBOL
};
enum die_fragment_type {
@@ -159,6 +167,7 @@ static inline const char *die_state_name(enum die_state state)
CASE_CONST_TO_STR(DIE_INCOMPLETE)
CASE_CONST_TO_STR(DIE_UNEXPANDED)
CASE_CONST_TO_STR(DIE_COMPLETE)
+ CASE_CONST_TO_STR(DIE_SYMBOL)
}
error("unexpected die_state: %d", state);
@@ -246,6 +255,6 @@ void process_cu(Dwarf_Die *cudie);
* types.c
*/
-void generate_symtypes(FILE *file);
+void generate_symtypes_and_versions(FILE *file);
#endif /* __GENDWARFKSYMS_H */
diff --git a/scripts/gendwarfksyms/symbols.c b/scripts/gendwarfksyms/symbols.c
index 6ed0c4769e6f..e0c9007f7250 100644
--- a/scripts/gendwarfksyms/symbols.c
+++ b/scripts/gendwarfksyms/symbols.c
@@ -66,6 +66,36 @@ static unsigned int for_each(const char *name, symbol_callback_t func,
return 0;
}
+static void set_crc(struct symbol *sym, void *data)
+{
+ unsigned long *crc = data;
+
+ if (sym->state == SYMBOL_PROCESSED && sym->crc != *crc)
+ warn("overriding version for symbol %s (crc %lx vs. %lx)",
+ sym->name, sym->crc, *crc);
+
+ sym->state = SYMBOL_PROCESSED;
+ sym->crc = *crc;
+}
+
+void symbol_set_crc(struct symbol *sym, unsigned long crc)
+{
+ if (for_each(sym->name, set_crc, &crc) == 0)
+ error("no matching symbols: '%s'", sym->name);
+}
+
+static void set_die(struct symbol *sym, void *data)
+{
+ sym->die_addr = (uintptr_t)((Dwarf_Die *)data)->addr;
+ sym->state = SYMBOL_MAPPED;
+}
+
+void symbol_set_die(struct symbol *sym, Dwarf_Die *die)
+{
+ if (for_each(sym->name, set_die, die) == 0)
+ error("no matching symbols: '%s'", sym->name);
+}
+
static bool is_exported(const char *name)
{
return for_each(name, NULL, NULL) > 0;
@@ -120,6 +150,16 @@ struct symbol *symbol_get(const char *name)
return sym;
}
+void symbol_for_each(symbol_callback_t func, void *arg)
+{
+ struct hlist_node *tmp;
+ struct symbol *sym;
+
+ hash_for_each_safe(symbol_names, sym, tmp, name_hash) {
+ func(sym, arg);
+ }
+}
+
typedef void (*elf_symbol_callback_t)(const char *name, GElf_Sym *sym,
Elf32_Word xndx, void *arg);
@@ -244,6 +284,19 @@ void symbol_read_symtab(int fd)
elf_for_each_global(fd, elf_set_symbol_addr, NULL);
}
+void symbol_print_versions(void)
+{
+ struct hlist_node *tmp;
+ struct symbol *sym;
+
+ hash_for_each_safe(symbol_names, sym, tmp, name_hash) {
+ if (sym->state != SYMBOL_PROCESSED)
+ warn("no information for symbol %s", sym->name);
+
+ printf("#SYMVER %s 0x%08lx\n", sym->name, sym->crc);
+ }
+}
+
void symbol_free(void)
{
struct hlist_node *tmp;
diff --git a/scripts/gendwarfksyms/types.c b/scripts/gendwarfksyms/types.c
index c05811299eba..08886063363c 100644
--- a/scripts/gendwarfksyms/types.c
+++ b/scripts/gendwarfksyms/types.c
@@ -3,6 +3,7 @@
* Copyright (C) 2024 Google LLC
*/
+#include <crc32.h>
#include "gendwarfksyms.h"
static struct expansion_cache expansion_cache;
@@ -174,6 +175,33 @@ static void type_map_free(void)
hash_init(type_map);
}
+/*
+ * CRC for a type, with an optional fully expanded type string for
+ * debugging.
+ */
+struct version {
+ struct type_expansion type;
+ unsigned long crc;
+};
+
+static void version_init(struct version *version)
+{
+ version->crc = 0xffffffff;
+ type_expansion_init(&version->type);
+}
+
+static void version_free(struct version *version)
+{
+ type_expansion_free(&version->type);
+}
+
+static void version_add(struct version *version, const char *s)
+{
+ version->crc = partial_crc32(s, version->crc);
+ if (dump_versions)
+ type_expansion_append(&version->type, s, NULL);
+}
+
/*
* Type reference format: <prefix>#<name>, where prefix:
* s -> structure
@@ -183,6 +211,12 @@ static void type_map_free(void)
*
* Names with spaces are additionally wrapped in single quotes.
*/
+static inline bool is_type_prefix(const char *s)
+{
+ return (s[0] == 's' || s[0] == 'u' || s[0] == 'e' || s[0] == 't') &&
+ s[1] == '#';
+}
+
static char get_type_prefix(int tag)
{
switch (tag) {
@@ -210,6 +244,8 @@ static char *get_type_name(struct die *cache)
warn("found incomplete cache entry: %p", cache);
return NULL;
}
+ if (cache->state == DIE_SYMBOL)
+ return NULL;
if (!cache->fqn || !*cache->fqn)
return NULL;
@@ -227,6 +263,39 @@ static char *get_type_name(struct die *cache)
return name;
}
+static void __calculate_version(struct version *version, struct list_head *list)
+{
+ struct type_list_entry *entry;
+ struct type_expansion *e;
+
+ /* Calculate a CRC over an expanded type string */
+ list_for_each_entry(entry, list, list) {
+ if (is_type_prefix(entry->str)) {
+ check(type_map_get(entry->str, &e));
+
+ /*
+ * It's sufficient to expand each type reference just
+ * once to detect changes.
+ */
+ if (cache_was_expanded(&expansion_cache, e)) {
+ version_add(version, entry->str);
+ } else {
+ cache_mark_expanded(&expansion_cache, e);
+ __calculate_version(version, &e->expanded);
+ }
+ } else {
+ version_add(version, entry->str);
+ }
+ }
+}
+
+static void calculate_version(struct version *version, struct list_head *list)
+{
+ version_init(version);
+ __calculate_version(version, list);
+ cache_clear_expanded(&expansion_cache);
+}
+
static void __type_expand(struct die *cache, struct type_expansion *type,
bool recursive);
@@ -333,7 +402,49 @@ static void expand_type(struct die *cache, void *arg)
free(name);
}
-void generate_symtypes(FILE *file)
+static void expand_symbol(struct symbol *sym, void *arg)
+{
+ struct type_expansion type;
+ struct version version;
+ struct die *cache;
+
+ /*
+ * No need to expand again unless we want a symtypes file entry
+ * for the symbol. Note that this means `sym` has the same address
+ * as another symbol that was already processed.
+ */
+ if (!symtypes && sym->state == SYMBOL_PROCESSED)
+ return;
+
+ if (__die_map_get(sym->die_addr, DIE_SYMBOL, &cache))
+ return; /* We'll warn about missing CRCs later. */
+
+ type_expand(cache, &type, false);
+
+ /* If the symbol already has a version, don't calculate it again. */
+ if (sym->state != SYMBOL_PROCESSED) {
+ calculate_version(&version, &type.expanded);
+ symbol_set_crc(sym, version.crc);
+ debug("%s = %lx", sym->name, version.crc);
+
+ if (dump_versions) {
+ checkp(fputs(sym->name, stderr));
+ checkp(fputs(" ", stderr));
+ type_list_write(&version.type.expanded, stderr);
+ checkp(fputs("\n", stderr));
+ }
+
+ version_free(&version);
+ }
+
+ /* These aren't needed in type_map unless we want a symtypes file. */
+ if (symtypes)
+ type_map_add(sym->name, &type);
+
+ type_expansion_free(&type);
+}
+
+void generate_symtypes_and_versions(FILE *file)
{
hash_init(expansion_cache.cache);
@@ -351,7 +462,14 @@ void generate_symtypes(FILE *file)
die_map_for_each(expand_type, NULL);
/*
- * 2. If a symtypes file is requested, write type_map contents to
+ * 2. For each exported symbol, expand the die_map type, and use
+ * type_map expansions to calculate a symbol version from the
+ * fully expanded type string.
+ */
+ symbol_for_each(expand_symbol, NULL);
+
+ /*
+ * 3. If a symtypes file is requested, write type_map contents to
* the file.
*/
type_map_write(file);
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 14/19] gendwarfksyms: Add support for kABI rules
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (12 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 13/19] gendwarfksyms: Add symbol versioning Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 15/19] gendwarfksyms: Add support for reserved and ignored fields Sami Tolvanen
` (5 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
Distributions that want to maintain a stable kABI need the ability
to make ABI compatible changes to kernel without affecting symbol
versions, either because of LTS updates or backports.
With genksyms, developers would typically hide these changes from
version calculation with #ifndef __GENKSYMS__, which would result
in the symbol version not changing even though the actual type has
changed. When we process precompiled object files, this isn't an
option.
To support this use case, add a --stable command line flag that
gates kABI stability features that are not needed in mainline
kernels, but can be useful for distributions, and add support for
kABI rules, which can be used to restrict gendwarfksyms output.
The rules are specified as a set of null-terminated strings stored
in the .discard.gendwarfksyms.kabi_rules section. Each rule consists
of four strings as follows:
"version\0type\0target\0value"
The version string ensures the structure can be changed in a
backwards compatible way. The type string indicates the type of the
rule, and target and value strings contain rule-specific data.
Initially support two simple rules:
1. Declaration-only structures
A structure declaration can change into a full definition when
additional includes are pulled in to the TU, which changes the
versions of any symbol that references the struct. Add support
for defining declaration-only structs whose definition is not
expanded during versioning.
2. Ignored enum fields
It's possible to add new enum fields without changing the ABI,
but as the fields are included in symbol versioning, this would
change the versions. Add support for ignoring specific fields.
Add examples for using the rules under the examples/ directory.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
---
scripts/gendwarfksyms/Makefile | 1 +
scripts/gendwarfksyms/dwarf.c | 19 +-
scripts/gendwarfksyms/examples/kabi.h | 61 +++++
scripts/gendwarfksyms/examples/kabi_rules.c | 56 +++++
scripts/gendwarfksyms/gendwarfksyms.c | 11 +-
scripts/gendwarfksyms/gendwarfksyms.h | 12 +
scripts/gendwarfksyms/kabi.c | 263 ++++++++++++++++++++
7 files changed, 419 insertions(+), 4 deletions(-)
create mode 100644 scripts/gendwarfksyms/examples/kabi.h
create mode 100644 scripts/gendwarfksyms/examples/kabi_rules.c
create mode 100644 scripts/gendwarfksyms/kabi.c
diff --git a/scripts/gendwarfksyms/Makefile b/scripts/gendwarfksyms/Makefile
index 6540282dc746..27258c31e839 100644
--- a/scripts/gendwarfksyms/Makefile
+++ b/scripts/gendwarfksyms/Makefile
@@ -5,6 +5,7 @@ gendwarfksyms-objs += gendwarfksyms.o
gendwarfksyms-objs += cache.o
gendwarfksyms-objs += die.o
gendwarfksyms-objs += dwarf.o
+gendwarfksyms-objs += kabi.o
gendwarfksyms-objs += symbols.o
gendwarfksyms-objs += types.o
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index 1f63f28add4b..d634dd79b736 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -80,11 +80,12 @@ static bool match_export_symbol(struct state *state, Dwarf_Die *die)
return !!state->sym;
}
-static bool is_declaration(Dwarf_Die *die)
+static bool is_declaration(struct die *cache, Dwarf_Die *die)
{
bool value;
- return get_flag_attr(die, DW_AT_declaration, &value) && value;
+ return (get_flag_attr(die, DW_AT_declaration, &value) && value) ||
+ kabi_is_struct_declonly(cache->fqn);
}
/*
@@ -472,9 +473,10 @@ static void __process_structure_type(struct state *state, struct die *cache,
process(cache, " {");
process_linebreak(cache, 1);
- is_decl = is_declaration(die);
+ is_decl = is_declaration(cache, die);
if (!is_decl && state->expand.expand) {
+ state->expand.current_fqn = cache->fqn;
check(process_die_container(state, cache, die, process_func,
match_func));
}
@@ -507,6 +509,15 @@ static void process_enumerator_type(struct state *state, struct die *cache,
{
Dwarf_Word value;
+ if (stable) {
+ /* Get the fqn before we process anything */
+ update_fqn(cache, die);
+
+ if (kabi_is_enumerator_ignored(state->expand.current_fqn,
+ cache->fqn))
+ return;
+ }
+
process_list_comma(state, cache);
process(cache, "enumerator");
process_fqn(cache, die);
@@ -579,6 +590,7 @@ static void state_init(struct state *state)
state->expand.expand = true;
state->expand.ptr_depth = 0;
state->expand.ptr_expansion_depth = 0;
+ state->expand.current_fqn = NULL;
hash_init(state->expansion_cache.cache);
}
@@ -588,6 +600,7 @@ static void expansion_state_restore(struct expansion_state *state,
state->expand = saved->expand;
state->ptr_depth = saved->ptr_depth;
state->ptr_expansion_depth = saved->ptr_expansion_depth;
+ state->current_fqn = saved->current_fqn;
}
static void expansion_state_save(struct expansion_state *state,
diff --git a/scripts/gendwarfksyms/examples/kabi.h b/scripts/gendwarfksyms/examples/kabi.h
new file mode 100644
index 000000000000..95799594c934
--- /dev/null
+++ b/scripts/gendwarfksyms/examples/kabi.h
@@ -0,0 +1,61 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2024 Google LLC
+ *
+ * Example macros for maintaining kABI stability.
+ *
+ * This file is based on android_kabi.h, which has the following notice:
+ *
+ * Heavily influenced by rh_kabi.h which came from the RHEL/CENTOS kernel
+ * and was:
+ * Copyright (c) 2014 Don Zickus
+ * Copyright (c) 2015-2018 Jiri Benc
+ * Copyright (c) 2015 Sabrina Dubroca, Hannes Frederic Sowa
+ * Copyright (c) 2016-2018 Prarit Bhargava
+ * Copyright (c) 2017 Paolo Abeni, Larry Woodman
+ */
+
+#ifndef __KABI_H__
+#define __KABI_H__
+
+/* Kernel macros for userspace testing. */
+#ifndef __aligned
+#define __aligned(x) __attribute__((__aligned__(x)))
+#endif
+#ifndef __used
+#define __used __attribute__((__used__))
+#endif
+#ifndef __section
+#define __section(section) __attribute__((__section__(section)))
+#endif
+#ifndef __PASTE
+#define ___PASTE(a, b) a##b
+#define __PASTE(a, b) ___PASTE(a, b)
+#endif
+#ifndef __stringify
+#define __stringify_1(x...) #x
+#define __stringify(x...) __stringify_1(x)
+#endif
+
+#define __KABI_RULE(hint, target, value) \
+ static const char __PASTE(__gendwarfksyms_rule_, \
+ __COUNTER__)[] __used __aligned(1) \
+ __section(".discard.gendwarfksyms.kabi_rules") = \
+ "1\0" #hint "\0" #target "\0" #value
+
+/*
+ * KABI_STRUCT_DECLONLY(fqn)
+ * Treat the struct fqn as a declaration, i.e. even if a definition
+ * is available, don't expand the contents.
+ */
+#define KABI_STRUCT_DECLONLY(fqn) __KABI_RULE(struct_declonly, fqn, )
+
+/*
+ * KABI_ENUMERATOR_IGNORE(fqn, field)
+ * When expanding enum fqn, skip the provided field. This makes it
+ * possible to hide added enum fields from versioning.
+ */
+#define KABI_ENUMERATOR_IGNORE(fqn, field) \
+ __KABI_RULE(enumerator_ignore, fqn, field)
+
+#endif /* __KABI_H__ */
diff --git a/scripts/gendwarfksyms/examples/kabi_rules.c b/scripts/gendwarfksyms/examples/kabi_rules.c
new file mode 100644
index 000000000000..446818e67d80
--- /dev/null
+++ b/scripts/gendwarfksyms/examples/kabi_rules.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Google LLC
+ *
+ * Examples for kABI rules with --stable.
+ */
+
+/*
+ * The comments below each example contain the expected gendwarfksyms
+ * output which can be verified using LLVM's FileCheck tool:
+ *
+ * https://llvm.org/docs/CommandGuide/FileCheck.html
+ *
+ * RUN: gcc -g -c examples/kabi_rules.c -o examples/kabi_rules.o
+ *
+ * Verify --stable output:
+ *
+ * RUN: echo -e "ex0\nex1" | \
+ * RUN: ./gendwarfksyms --stable --dump-dies \
+ * RUN: examples/kabi_rules.o 2>&1 >/dev/null | \
+ * RUN: FileCheck examples/kabi_rules.c --check-prefix=STABLE
+ */
+
+#include "kabi.h"
+
+struct s {
+ int a;
+};
+
+KABI_STRUCT_DECLONLY(s);
+
+struct s e0;
+
+/*
+ * STABLE: variable structure_type s {
+ * STABLE-NEXT: }
+ */
+
+enum e {
+ A,
+ B,
+ C,
+ D,
+};
+
+KABI_ENUMERATOR_IGNORE(e, B);
+KABI_ENUMERATOR_IGNORE(e, C);
+
+enum e e1;
+
+/*
+ * STABLE: variable enumeration_type e {
+ * STABLE-NEXT: enumerator A = 0 ,
+ * STABLE-NEXT: enumerator D = 3
+ * STABLE-NEXT: } byte_size(4)
+ */
diff --git a/scripts/gendwarfksyms/gendwarfksyms.c b/scripts/gendwarfksyms/gendwarfksyms.c
index fd2429ea198f..25865d9eab56 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.c
+++ b/scripts/gendwarfksyms/gendwarfksyms.c
@@ -25,6 +25,8 @@ int dump_die_map;
int dump_types;
/* Print out expanded type strings used for symbol versions */
int dump_versions;
+/* Support kABI stability features */
+int stable;
/* Write a symtypes file */
int symtypes;
static const char *symtypes_file;
@@ -38,6 +40,7 @@ static void usage(void)
" --dump-die-map Print debugging information about die_map changes\n"
" --dump-types Dump type strings\n"
" --dump-versions Dump expanded type strings used for symbol versions\n"
+ " -s, --stable Support kABI stability features\n"
" -T, --symtypes file Write a symtypes file\n"
" -h, --help Print this message\n"
"\n",
@@ -97,17 +100,21 @@ int main(int argc, char **argv)
{ "dump-die-map", 0, &dump_die_map, 1 },
{ "dump-types", 0, &dump_types, 1 },
{ "dump-versions", 0, &dump_versions, 1 },
+ { "stable", 0, NULL, 's' },
{ "symtypes", 1, NULL, 'T' },
{ "help", 0, NULL, 'h' },
{ 0, 0, NULL, 0 } };
- while ((opt = getopt_long(argc, argv, "dT:h", opts, NULL)) != EOF) {
+ while ((opt = getopt_long(argc, argv, "dsT:h", opts, NULL)) != EOF) {
switch (opt) {
case 0:
break;
case 'd':
debug = 1;
break;
+ case 's':
+ stable = 1;
+ break;
case 'T':
symtypes = 1;
symtypes_file = optarg;
@@ -148,6 +155,7 @@ int main(int argc, char **argv)
strerror(errno));
symbol_read_symtab(fd);
+ kabi_read_rules(fd);
dwfl = dwfl_begin(&callbacks);
if (!dwfl)
@@ -164,6 +172,7 @@ int main(int argc, char **argv)
error("dwfl_getmodules failed for '%s'", argv[n]);
dwfl_end(dwfl);
+ kabi_free();
}
if (symfile)
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
index 88a9c1c5db20..d8aa3210b0fe 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.h
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -27,6 +27,7 @@ extern int dump_dies;
extern int dump_die_map;
extern int dump_types;
extern int dump_versions;
+extern int stable;
extern int symtypes;
/*
@@ -226,6 +227,7 @@ struct expansion_state {
bool expand;
unsigned int ptr_depth;
unsigned int ptr_expansion_depth;
+ const char *current_fqn;
};
struct state {
@@ -257,4 +259,14 @@ void process_cu(Dwarf_Die *cudie);
void generate_symtypes_and_versions(FILE *file);
+/*
+ * kabi.c
+ */
+
+bool kabi_is_enumerator_ignored(const char *fqn, const char *field);
+bool kabi_is_struct_declonly(const char *fqn);
+
+void kabi_read_rules(int fd);
+void kabi_free(void);
+
#endif /* __GENDWARFKSYMS_H */
diff --git a/scripts/gendwarfksyms/kabi.c b/scripts/gendwarfksyms/kabi.c
new file mode 100644
index 000000000000..c532f8b2fe0c
--- /dev/null
+++ b/scripts/gendwarfksyms/kabi.c
@@ -0,0 +1,263 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Google LLC
+ */
+
+#include "gendwarfksyms.h"
+
+#define KABI_RULE_SECTION ".discard.gendwarfksyms.kabi_rules"
+#define KABI_RULE_VERSION "1"
+
+/*
+ * The rule section consists of four null-terminated strings per
+ * entry:
+ *
+ * 1. version
+ * Entry format version. Must match KABI_RULE_VERSION.
+ *
+ * 2. type
+ * Type of the kABI rule. Must be one of the tags defined below.
+ *
+ * 3. target
+ * Rule-dependent target, typically the fully qualified name of
+ * the target DIE.
+ *
+ * 4. value
+ * Rule-dependent value.
+ */
+#define KABI_RULE_MIN_ENTRY_SIZE \
+ (/* version\0 */ 2 + /* type\0 */ 2 + /* target\0" */ 1 + \
+ /* value\0 */ 1)
+#define KABI_RULE_EMPTY_VALUE ""
+
+/*
+ * Rule: struct_declonly
+ * - For the struct in the target field, treat it as a declaration
+ * only even if a definition is available.
+ */
+#define KABI_RULE_TAG_STRUCT_DECLONLY "struct_declonly"
+
+/*
+ * Rule: enumerator_ignore
+ * - For the enum in the target field, ignore the named enumerator
+ * in the value field.
+ */
+#define KABI_RULE_TAG_ENUMERATOR_IGNORE "enumerator_ignore"
+
+enum kabi_rule_type {
+ KABI_RULE_TYPE_UNKNOWN,
+ KABI_RULE_TYPE_STRUCT_DECLONLY,
+ KABI_RULE_TYPE_ENUMERATOR_IGNORE,
+};
+
+#define RULE_HASH_BITS 10
+
+struct rule {
+ enum kabi_rule_type type;
+ const char *target;
+ const char *value;
+ struct hlist_node hash;
+};
+
+/* { type, target, value } -> struct rule */
+static HASHTABLE_DEFINE(rules, 1 << RULE_HASH_BITS);
+
+static inline unsigned int rule_values_hash(enum kabi_rule_type type,
+ const char *target,
+ const char *value)
+{
+ return hash_32(type) ^ hash_str(target) ^ hash_str(value);
+}
+
+static inline unsigned int rule_hash(const struct rule *rule)
+{
+ return rule_values_hash(rule->type, rule->target, rule->value);
+}
+
+static inline const char *get_rule_field(const char **pos, ssize_t *left)
+{
+ const char *start = *pos;
+ size_t len;
+
+ if (*left <= 0)
+ error("unexpected end of kABI rules");
+
+ len = strnlen(start, *left) + 1;
+ *pos += len;
+ *left -= len;
+
+ return start;
+}
+
+void kabi_read_rules(int fd)
+{
+ GElf_Shdr shdr_mem;
+ GElf_Shdr *shdr;
+ Elf_Data *rule_data = NULL;
+ Elf_Scn *scn;
+ Elf *elf;
+ size_t shstrndx;
+ const char *rule_str;
+ ssize_t left;
+ int i;
+
+ const struct {
+ enum kabi_rule_type type;
+ const char *tag;
+ } rule_types[] = {
+ {
+ .type = KABI_RULE_TYPE_STRUCT_DECLONLY,
+ .tag = KABI_RULE_TAG_STRUCT_DECLONLY,
+ },
+ {
+ .type = KABI_RULE_TYPE_ENUMERATOR_IGNORE,
+ .tag = KABI_RULE_TAG_ENUMERATOR_IGNORE,
+ },
+ };
+
+ if (!stable)
+ return;
+
+ if (elf_version(EV_CURRENT) != EV_CURRENT)
+ error("elf_version failed: %s", elf_errmsg(-1));
+
+ elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+ if (!elf)
+ error("elf_begin failed: %s", elf_errmsg(-1));
+
+ if (elf_getshdrstrndx(elf, &shstrndx) < 0)
+ error("elf_getshdrstrndx failed: %s", elf_errmsg(-1));
+
+ scn = elf_nextscn(elf, NULL);
+
+ while (scn) {
+ const char *sname;
+
+ shdr = gelf_getshdr(scn, &shdr_mem);
+ if (!shdr)
+ error("gelf_getshdr failed: %s", elf_errmsg(-1));
+
+ sname = elf_strptr(elf, shstrndx, shdr->sh_name);
+ if (!sname)
+ error("elf_strptr failed: %s", elf_errmsg(-1));
+
+ if (!strcmp(sname, KABI_RULE_SECTION)) {
+ rule_data = elf_getdata(scn, NULL);
+ if (!rule_data)
+ error("elf_getdata failed: %s", elf_errmsg(-1));
+ break;
+ }
+
+ scn = elf_nextscn(elf, scn);
+ }
+
+ if (!rule_data) {
+ debug("kABI rules not found");
+ return;
+ }
+
+ rule_str = rule_data->d_buf;
+ left = shdr->sh_size;
+
+ if (left < KABI_RULE_MIN_ENTRY_SIZE)
+ error("kABI rule section too small: %zd bytes", left);
+
+ if (rule_str[left - 1] != '\0')
+ error("kABI rules are not null-terminated");
+
+ while (left > KABI_RULE_MIN_ENTRY_SIZE) {
+ enum kabi_rule_type type = KABI_RULE_TYPE_UNKNOWN;
+ const char *field;
+ struct rule *rule;
+
+ /* version */
+ field = get_rule_field(&rule_str, &left);
+
+ if (strcmp(field, KABI_RULE_VERSION))
+ error("unsupported kABI rule version: '%s'", field);
+
+ /* type */
+ field = get_rule_field(&rule_str, &left);
+
+ for (i = 0; i < ARRAY_SIZE(rule_types); i++) {
+ if (!strcmp(field, rule_types[i].tag)) {
+ type = rule_types[i].type;
+ break;
+ }
+ }
+
+ if (type == KABI_RULE_TYPE_UNKNOWN)
+ error("unsupported kABI rule type: '%s'", field);
+
+ rule = xmalloc(sizeof(struct rule));
+
+ rule->type = type;
+ rule->target = xstrdup(get_rule_field(&rule_str, &left));
+ rule->value = xstrdup(get_rule_field(&rule_str, &left));
+
+ hash_add(rules, &rule->hash, rule_hash(rule));
+
+ debug("kABI rule: type: '%s', target: '%s', value: '%s'", field,
+ rule->target, rule->value);
+ }
+
+ if (left > 0)
+ warn("unexpected data at the end of the kABI rules section");
+
+ check(elf_end(elf));
+}
+
+bool kabi_is_struct_declonly(const char *fqn)
+{
+ struct rule *rule;
+
+ if (!stable)
+ return false;
+ if (!fqn || !*fqn)
+ return false;
+
+ hash_for_each_possible(rules, rule, hash,
+ rule_values_hash(KABI_RULE_TYPE_STRUCT_DECLONLY,
+ fqn, KABI_RULE_EMPTY_VALUE)) {
+ if (rule->type == KABI_RULE_TYPE_STRUCT_DECLONLY &&
+ !strcmp(fqn, rule->target))
+ return true;
+ }
+
+ return false;
+}
+
+bool kabi_is_enumerator_ignored(const char *fqn, const char *field)
+{
+ struct rule *rule;
+
+ if (!stable)
+ return false;
+ if (!fqn || !*fqn || !field || !*field)
+ return false;
+
+ hash_for_each_possible(
+ rules, rule, hash,
+ rule_values_hash(KABI_RULE_TYPE_ENUMERATOR_IGNORE, fqn,
+ field)) {
+ if (rule->type == KABI_RULE_TYPE_ENUMERATOR_IGNORE &&
+ !strcmp(fqn, rule->target) && !strcmp(field, rule->value))
+ return true;
+ }
+
+ return false;
+}
+
+void kabi_free(void)
+{
+ struct hlist_node *tmp;
+ struct rule *rule;
+
+ hash_for_each_safe(rules, rule, tmp, hash) {
+ free((void *)rule->target);
+ free((void *)rule->value);
+ free(rule);
+ }
+
+ hash_init(rules);
+}
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 15/19] gendwarfksyms: Add support for reserved and ignored fields
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (13 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 14/19] gendwarfksyms: Add support for kABI rules Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 16/19] gendwarfksyms: Add support for symbol type pointers Sami Tolvanen
` (4 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
Distributions that want to maintain a stable kABI need the ability
to make ABI compatible changes to kernel data structures without
affecting symbol versions, either because of LTS updates or backports.
With genksyms, developers would typically hide these changes from
version calculation with #ifndef __GENKSYMS__, which would result
in the symbol version not changing even though the actual type has
changed. When we process precompiled object files, this isn't an
option.
Change union processing to recognize field name prefixes that allow
the user to ignore the union completely during symbol versioning with
a __kabi_ignored prefix in a field name, or to replace the type of a
placeholder field using a __kabi_reserved field name prefix.
For example, assume we want to add a new field to an existing
alignment hole in a data structure, and ignore the new field when
calculating symbol versions:
struct struct1 {
int a;
/* a 4-byte alignment hole */
unsigned long b;
};
To add `int n` to the alignment hole, we can add a union that includes
a __kabi_ignored field that causes gendwarfksyms to ignore the entire
union:
struct struct1 {
int a;
union {
char __kabi_ignored_0;
int n;
};
unsigned long b;
};
With --stable, both structs produce the same symbol version.
Alternatively, when a distribution expects future modification to a
data structure, they can explicitly add reserved fields:
struct struct2 {
long a;
long __kabi_reserved_0; /* reserved for future use */
};
To take the field into use, we can again replace it with a union, with
one of the fields keeping the __kabi_reserved name prefix to indicate
the original type:
struct struct2 {
long a;
union {
long __kabi_reserved_0;
struct {
int b;
int v;
};
};
Here gendwarfksyms --stable replaces the union with the type of the
placeholder field when calculating versions.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
---
scripts/gendwarfksyms/dwarf.c | 221 +++++++++++++++++++++-
scripts/gendwarfksyms/examples/kabi.h | 80 ++++++++
scripts/gendwarfksyms/examples/kabi_ex0.c | 86 +++++++++
scripts/gendwarfksyms/examples/kabi_ex1.c | 89 +++++++++
scripts/gendwarfksyms/examples/kabi_ex2.c | 98 ++++++++++
scripts/gendwarfksyms/gendwarfksyms.h | 9 +
6 files changed, 582 insertions(+), 1 deletion(-)
create mode 100644 scripts/gendwarfksyms/examples/kabi_ex0.c
create mode 100644 scripts/gendwarfksyms/examples/kabi_ex1.c
create mode 100644 scripts/gendwarfksyms/examples/kabi_ex2.c
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index d634dd79b736..ba0f502ad20c 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -3,9 +3,30 @@
* Copyright (C) 2024 Google LLC
*/
+#include <assert.h>
#include <stdarg.h>
#include "gendwarfksyms.h"
+/* See get_union_kabi_status */
+#define KABI_PREFIX "__kabi_"
+#define KABI_PREFIX_LEN (sizeof(KABI_PREFIX) - 1)
+#define KABI_RESERVED_PREFIX "reserved"
+#define KABI_RESERVED_PREFIX_LEN (sizeof(KABI_RESERVED_PREFIX) - 1)
+#define KABI_IGNORED_PREFIX "ignored"
+#define KABI_IGNORED_PREFIX_LEN (sizeof(KABI_IGNORED_PREFIX) - 1)
+
+static inline bool is_kabi_prefix(const char *name)
+{
+ return name && !strncmp(name, KABI_PREFIX, KABI_PREFIX_LEN);
+}
+
+enum kabi_status {
+ /* >0 to stop DIE processing */
+ KABI_NORMAL = 1,
+ KABI_RESERVED,
+ KABI_IGNORED,
+};
+
static bool do_linebreak;
static int indentation_level;
@@ -308,6 +329,9 @@ static void __process_list_type(struct state *state, struct die *cache,
{
const char *name = get_name_attr(die);
+ if (stable && is_kabi_prefix(name))
+ name = NULL;
+
process_list_comma(state, cache);
process(cache, type);
process_type_attr(state, cache, die);
@@ -441,11 +465,191 @@ static void process_variant_part_type(struct state *state, struct die *cache,
process(cache, "}");
}
+static int get_kabi_status(Dwarf_Die *die)
+{
+ const char *name = get_name_attr(die);
+
+ if (is_kabi_prefix(name)) {
+ name += KABI_PREFIX_LEN;
+
+ if (!strncmp(name, KABI_RESERVED_PREFIX,
+ KABI_RESERVED_PREFIX_LEN))
+ return KABI_RESERVED;
+ if (!strncmp(name, KABI_IGNORED_PREFIX,
+ KABI_IGNORED_PREFIX_LEN))
+ return KABI_IGNORED;
+ }
+
+ return KABI_NORMAL;
+}
+
+static int check_struct_member_kabi_status(struct state *state,
+ struct die *__unused, Dwarf_Die *die)
+{
+ int res;
+
+ assert(dwarf_tag(die) == DW_TAG_member_type);
+
+ /*
+ * If the union member is a struct, expect the __kabi field to
+ * be the first member of the structure, i.e..:
+ *
+ * union {
+ * type new_member;
+ * struct {
+ * type __kabi_field;
+ * }
+ * };
+ */
+ res = get_kabi_status(die);
+
+ if (res == KABI_RESERVED &&
+ !get_ref_die_attr(die, DW_AT_type, &state->kabi.placeholder))
+ error("structure member missing a type?");
+
+ return res;
+}
+
+static int check_union_member_kabi_status(struct state *state,
+ struct die *__unused, Dwarf_Die *die)
+{
+ Dwarf_Die type;
+ int res;
+
+ assert(dwarf_tag(die) == DW_TAG_member_type);
+
+ if (!get_ref_die_attr(die, DW_AT_type, &type))
+ error("union member missing a type?");
+
+ /*
+ * We expect a union with two members. Check if either of them
+ * has a __kabi name prefix, i.e.:
+ *
+ * union {
+ * ...
+ * type memberN; // <- type, N = {0,1}
+ * ...
+ * };
+ *
+ * The member can also be a structure type, in which case we'll
+ * check the first structure member.
+ *
+ * In any case, stop processing after we've seen two members.
+ */
+ res = get_kabi_status(die);
+
+ if (res == KABI_RESERVED)
+ state->kabi.placeholder = type;
+ if (res != KABI_NORMAL)
+ return res;
+
+ if (dwarf_tag(&type) == DW_TAG_structure_type)
+ res = checkp(process_die_container(
+ state, NULL, &type, check_struct_member_kabi_status,
+ match_member_type));
+
+ if (res <= KABI_NORMAL && ++state->kabi.members < 2)
+ return 0; /* Continue */
+
+ return res;
+}
+
+static int get_union_kabi_status(Dwarf_Die *die, Dwarf_Die *placeholder)
+{
+ struct state state;
+ int res;
+
+ if (!stable)
+ return KABI_NORMAL;
+
+ /*
+ * To maintain a stable kABI, distributions may choose to reserve
+ * space in structs for later use by adding placeholder members,
+ * for example:
+ *
+ * struct s {
+ * u32 a;
+ * // an 8-byte placeholder for future use
+ * u64 __kabi_reserved_0;
+ * };
+ *
+ * When the reserved member is taken into use, the type change
+ * would normally cause the symbol version to change as well, but
+ * if the replacement uses the following convention, gendwarfksyms
+ * continues to use the placeholder type for versioning instead,
+ * thus maintaining the same symbol version:
+ *
+ * struct s {
+ * u32 a;
+ * union {
+ * // placeholder replaced with a new member `b`
+ * struct t b;
+ * struct {
+ * // the placeholder type that is still
+ * // used for versioning
+ * u64 __kabi_reserved_0;
+ * };
+ * };
+ * };
+ *
+ * I.e., as long as the replaced member is in a union, and the
+ * placeholder has a __kabi_reserved name prefix, we'll continue
+ * to use the placeholder type (here u64) for version calculation
+ * instead of the union type.
+ *
+ * It's also possible to ignore new members from versioning if
+ * they've been added to alignment holes, for example, by
+ * including them in a union with another member that uses the
+ * __kabi_ignored name prefix:
+ *
+ * struct s {
+ * u32 a;
+ * // an alignment hole is used to add `n`
+ * union {
+ * u32 n;
+ * // hide the entire union member from versioning
+ * u8 __kabi_ignored_0;
+ * };
+ * u64 b;
+ * };
+ *
+ * Note that the user of this feature is responsible for ensuring
+ * that the structure actually remains ABI compatible.
+ */
+ state.kabi.members = 0;
+
+ res = checkp(process_die_container(&state, NULL, die,
+ check_union_member_kabi_status,
+ match_member_type));
+
+ if (placeholder && res == KABI_RESERVED)
+ *placeholder = state.kabi.placeholder;
+
+ return res;
+}
+
+static bool is_kabi_ignored(Dwarf_Die *die)
+{
+ Dwarf_Die type;
+
+ if (!stable)
+ return false;
+
+ if (!get_ref_die_attr(die, DW_AT_type, &type))
+ error("member missing a type?");
+
+ return dwarf_tag(&type) == DW_TAG_union_type &&
+ checkp(get_union_kabi_status(&type, NULL)) == KABI_IGNORED;
+}
+
static int ___process_structure_type(struct state *state, struct die *cache,
Dwarf_Die *die)
{
switch (dwarf_tag(die)) {
case DW_TAG_member:
+ if (is_kabi_ignored(die))
+ return 0;
+ return check(process_type(state, cache, die));
case DW_TAG_variant_part:
return check(process_type(state, cache, die));
case DW_TAG_class_type:
@@ -502,7 +706,22 @@ static void __process_structure_type(struct state *state, struct die *cache,
DEFINE_PROCESS_STRUCTURE_TYPE(class)
DEFINE_PROCESS_STRUCTURE_TYPE(structure)
-DEFINE_PROCESS_STRUCTURE_TYPE(union)
+
+static void process_union_type(struct state *state, struct die *cache,
+ Dwarf_Die *die)
+{
+ Dwarf_Die placeholder;
+
+ int res = checkp(get_union_kabi_status(die, &placeholder));
+
+ if (res == KABI_RESERVED)
+ check(process_type(state, cache, &placeholder));
+ if (res > KABI_NORMAL)
+ return;
+
+ __process_structure_type(state, cache, die, "union_type",
+ ___process_structure_type, match_all);
+}
static void process_enumerator_type(struct state *state, struct die *cache,
Dwarf_Die *die)
diff --git a/scripts/gendwarfksyms/examples/kabi.h b/scripts/gendwarfksyms/examples/kabi.h
index 95799594c934..796ef9ae1cd6 100644
--- a/scripts/gendwarfksyms/examples/kabi.h
+++ b/scripts/gendwarfksyms/examples/kabi.h
@@ -43,6 +43,28 @@
__section(".discard.gendwarfksyms.kabi_rules") = \
"1\0" #hint "\0" #target "\0" #value
+#define __KABI_NORMAL_SIZE_ALIGN(_orig, _new) \
+ union { \
+ _Static_assert( \
+ sizeof(struct { _new; }) <= sizeof(struct { _orig; }), \
+ __FILE__ ":" __stringify(__LINE__) ": " __stringify( \
+ _new) " is larger than " __stringify(_orig)); \
+ _Static_assert( \
+ __alignof__(struct { _new; }) <= \
+ __alignof__(struct { _orig; }), \
+ __FILE__ ":" __stringify(__LINE__) ": " __stringify( \
+ _orig) " is not aligned the same as " __stringify(_new)); \
+ }
+
+#define __KABI_REPLACE(_orig, _new) \
+ union { \
+ _new; \
+ struct { \
+ _orig; \
+ }; \
+ __KABI_NORMAL_SIZE_ALIGN(_orig, _new); \
+ }
+
/*
* KABI_STRUCT_DECLONLY(fqn)
* Treat the struct fqn as a declaration, i.e. even if a definition
@@ -58,4 +80,62 @@
#define KABI_ENUMERATOR_IGNORE(fqn, field) \
__KABI_RULE(enumerator_ignore, fqn, field)
+/*
+ * KABI_RESERVE
+ * Reserve some "padding" in a structure for use by LTS backports.
+ * This is normally placed at the end of a structure.
+ * number: the "number" of the padding variable in the structure. Start with
+ * 1 and go up.
+ */
+#define KABI_RESERVE(n) unsigned long __kabi_reserved##n
+
+/*
+ * KABI_RESERVE_ARRAY
+ * Same as _BACKPORT_RESERVE but allocates an array with the specified
+ * size in bytes.
+ */
+#define KABI_RESERVE_ARRAY(n, s) \
+ unsigned char __aligned(8) __kabi_reserved##n[s]
+
+/*
+ * KABI_IGNORE
+ * Add a new field that's ignored in versioning.
+ */
+#define KABI_IGNORE(n, _new) \
+ union { \
+ _new; \
+ unsigned char __kabi_ignored##n; \
+ }
+
+/*
+ * KABI_USE(number, _new)
+ * Use a previous padding entry that was defined with KABI_RESERVE
+ * number: the previous "number" of the padding variable
+ * _new: the variable to use now instead of the padding variable
+ */
+#define KABI_USE(number, _new) __KABI_REPLACE(KABI_RESERVE(number), _new)
+
+/*
+ * KABI_USE2(number, _new1, _new2)
+ * Use a previous padding entry that was defined with KABI_RESERVE for
+ * two new variables that fit into 64 bits. This is good for when you do not
+ * want to "burn" a 64bit padding variable for a smaller variable size if not
+ * needed.
+ */
+#define KABI_USE2(number, _new1, _new2) \
+ __KABI_REPLACE( \
+ KABI_RESERVE(number), struct { \
+ _new1; \
+ _new2; \
+ })
+/*
+ * KABI_USE_ARRAY(number, bytes, _new)
+ * Use a previous padding entry that was defined with KABI_RESERVE_ARRAY
+ * number: the previous "number" of the padding variable
+ * bytes: the size in bytes reserved for the array
+ * _new: the variable to use now instead of the padding variable
+ */
+#define KABI_USE_ARRAY(number, bytes, _new) \
+ __KABI_REPLACE(KABI_RESERVE_ARRAY(number, bytes), _new)
+
#endif /* __KABI_H__ */
diff --git a/scripts/gendwarfksyms/examples/kabi_ex0.c b/scripts/gendwarfksyms/examples/kabi_ex0.c
new file mode 100644
index 000000000000..934324cba837
--- /dev/null
+++ b/scripts/gendwarfksyms/examples/kabi_ex0.c
@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * kabi_ex0.c
+ *
+ * Copyright (C) 2024 Google LLC
+ *
+ * Reserved and ignored data structure field examples with --stable.
+ */
+
+/*
+ * The comments below each example contain the expected gendwarfksyms
+ * output, which can be verified using LLVM's FileCheck tool:
+ *
+ * https://llvm.org/docs/CommandGuide/FileCheck.html
+ *
+ * $ gcc -g -c examples/kabi_ex0.c examples/kabi_ex0.o
+ *
+ * Verify --stable output:
+ *
+ * $ echo -e "ex0a\nex0b\nex0c" | \
+ * ./gendwarfksyms --stable --dump-dies \
+ * examples/kabi_ex0.o 2>&1 >/dev/null | \
+ * FileCheck examples/kabi_ex0.c --check-prefix=STABLE
+ *
+ * Verify that symbol versions match with --stable:
+ *
+ * $ echo -e "ex0a\nex0b\nex0c" | \
+ * ./gendwarfksyms --stable examples/kabi_ex0.o | \
+ * sort | \
+ * FileCheck examples/kabi_ex0.c --check-prefix=VERSION
+ */
+
+#include "kabi.h"
+
+/*
+ * Example 0: Reserved fields.
+ */
+
+struct {
+ int a;
+ KABI_RESERVE(0);
+ KABI_RESERVE(1);
+} ex0a;
+
+/*
+ * STABLE: variable structure_type {
+ * STABLE-NEXT: member base_type int byte_size(4) encoding(5) a data_member_location(0) ,
+ * STABLE-NEXT: member base_type [[ULONG:long unsigned int|unsigned long]] byte_size(8) encoding(7) data_member_location(8) ,
+ * STABLE-NEXT: member base_type [[ULONG]] byte_size(8) encoding(7) data_member_location(16)
+ * STABLE-NEXT: } byte_size(24)
+ *
+ * VERSION-DAG: #SYMVER ex0a 0x[[#%.08x,EX0:]]
+ */
+
+struct {
+ int a;
+ KABI_RESERVE(0);
+ KABI_USE2(1, int b, int c);
+} ex0b;
+
+/*
+ * STABLE: variable structure_type {
+ * STABLE-NEXT: member base_type int byte_size(4) encoding(5) a data_member_location(0) ,
+ * STABLE-NEXT: member base_type [[ULONG]] byte_size(8) encoding(7) data_member_location(8) ,
+ * STABLE-NEXT: member base_type [[ULONG]] byte_size(8) encoding(7) data_member_location(16)
+ *
+ * STABLE-NEXT: } byte_size(24)
+ *
+ * VERSION-DAG: #SYMVER ex0b 0x[[#%.08x,EX0]]
+ */
+
+struct {
+ int a;
+ KABI_USE(0, void *p);
+ KABI_USE2(1, int b, int c);
+} ex0c;
+
+/*
+ * STABLE: variable structure_type {
+ * STABLE-NEXT: member base_type int byte_size(4) encoding(5) a data_member_location(0) ,
+ * STABLE-NEXT: member base_type [[ULONG]] byte_size(8) encoding(7) data_member_location(8) ,
+ * STABLE-NEXT: member base_type [[ULONG]] byte_size(8) encoding(7) data_member_location(16)
+ * STABLE-NEXT: } byte_size(24)
+ *
+ * VERSION-DAG: #SYMVER ex0c 0x[[#%.08x,EX0]]
+ */
diff --git a/scripts/gendwarfksyms/examples/kabi_ex1.c b/scripts/gendwarfksyms/examples/kabi_ex1.c
new file mode 100644
index 000000000000..7bc34bc7dec8
--- /dev/null
+++ b/scripts/gendwarfksyms/examples/kabi_ex1.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * kabi_ex1.c
+ *
+ * Copyright (C) 2024 Google LLC
+ *
+ * Reserved and ignored data structure field examples with --stable.
+ */
+
+/*
+ * The comments below each example contain the expected gendwarfksyms
+ * output, which can be verified using LLVM's FileCheck tool:
+ *
+ * https://llvm.org/docs/CommandGuide/FileCheck.html
+ *
+ * $ gcc -g -c examples/kabi_ex1.c examples/kabi_ex1.o
+ *
+ * Verify --stable output:
+ *
+ * $ echo -e "ex1a\nex1b\nex1c" | \
+ * ./gendwarfksyms --stable --dump-dies \
+ * examples/kabi_ex1.o 2>&1 >/dev/null | \
+ * FileCheck examples/kabi_ex1.c --check-prefix=STABLE
+ *
+ * Verify that symbol versions match with --stable:
+ *
+ * $ echo -e "ex1a\nex1b\nex1c" | \
+ * ./gendwarfksyms --stable examples/kabi_ex1.o | \
+ * sort | \
+ * FileCheck examples/kabi_ex1.c --check-prefix=VERSION
+ */
+
+#include "kabi.h"
+
+/*
+ * Example 1: A reserved array.
+ */
+
+struct {
+ unsigned int a;
+ KABI_RESERVE_ARRAY(0, 64);
+} ex1a;
+
+/*
+ * STABLE: variable structure_type {
+ * STABLE-NEXT: member base_type unsigned int byte_size(4) encoding(7) a data_member_location(0) ,
+ * STABLE-NEXT: member array_type[64] {
+ * STABLE-NEXT: base_type unsigned char byte_size(1) encoding(8)
+ * STABLE-NEXT: } data_member_location(8)
+ * STABLE-NEXT: } byte_size(72)
+ *
+ * VERSION-DAG: #SYMVER ex1a 0x[[#%.08x,EX1:]]
+ */
+
+struct {
+ unsigned int a;
+ KABI_USE_ARRAY(
+ 0, 64, struct {
+ void *p;
+ KABI_RESERVE_ARRAY(1, 56);
+ });
+} ex1b;
+
+/*
+ * STABLE: variable structure_type {
+ * STABLE-NEXT: member base_type unsigned int byte_size(4) encoding(7) a data_member_location(0) ,
+ * STABLE-NEXT: member array_type[64] {
+ * STABLE-NEXT: base_type unsigned char byte_size(1) encoding(8)
+ * STABLE-NEXT: } data_member_location(8)
+ * STABLE-NEXT: } byte_size(72)
+ *
+ * VERSION-DAG: #SYMVER ex1b 0x[[#%.08x,EX1]]
+ */
+
+struct {
+ unsigned int a;
+ KABI_USE_ARRAY(0, 64, void *p[8]);
+} ex1c;
+
+/*
+ * STABLE: variable structure_type {
+ * STABLE-NEXT: member base_type unsigned int byte_size(4) encoding(7) a data_member_location(0) ,
+ * STABLE-NEXT: member array_type[64] {
+ * STABLE-NEXT: base_type unsigned char byte_size(1) encoding(8)
+ * STABLE-NEXT: } data_member_location(8)
+ * STABLE-NEXT: } byte_size(72)
+ *
+ * VERSION-DAG: #SYMVER ex1c 0x[[#%.08x,EX1]]
+ */
diff --git a/scripts/gendwarfksyms/examples/kabi_ex2.c b/scripts/gendwarfksyms/examples/kabi_ex2.c
new file mode 100644
index 000000000000..947ea5675b4f
--- /dev/null
+++ b/scripts/gendwarfksyms/examples/kabi_ex2.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * kabi_ex2.c
+ *
+ * Copyright (C) 2024 Google LLC
+ *
+ * Reserved and ignored data structure field examples with --stable.
+ */
+
+/*
+ * The comments below each example contain the expected gendwarfksyms
+ * output, which can be verified using LLVM's FileCheck tool:
+ *
+ * https://llvm.org/docs/CommandGuide/FileCheck.html
+ *
+ * $ gcc -g -c examples/kabi_ex2.c examples/kabi_ex2.o
+ *
+ * Verify --stable output:
+ *
+ * $ echo -e "ex2a\nex2b\nex2c" | \
+ * ./gendwarfksyms --stable --dump-dies \
+ * examples/kabi_ex2.o 2>&1 >/dev/null | \
+ * FileCheck examples/kabi_ex2.c --check-prefix=STABLE
+ *
+ * Verify that symbol versions match with --stable:
+ *
+ * $ echo -e "ex2a\nex2b\nex2c" | \
+ * ./gendwarfksyms --stable examples/kabi_ex2.o | \
+ * sort | \
+ * FileCheck examples/kabi_ex2.c --check-prefix=VERSION
+ */
+
+#include "kabi.h"
+
+/*
+ * Example 2: An ignored field added to an alignment hole.
+ */
+
+struct {
+ int a;
+ unsigned long b;
+ int c;
+ unsigned long d;
+} ex2a;
+
+/*
+ * STABLE: variable structure_type {
+ * STABLE-NEXT: member base_type int byte_size(4) encoding(5) a data_member_location(0) ,
+ * STABLE-NEXT: member base_type [[ULONG:long unsigned int|unsigned long]] byte_size(8) encoding(7) b data_member_location(8)
+ * STABLE-NEXT: member base_type int byte_size(4) encoding(5) c data_member_location(16) ,
+ * STABLE-NEXT: member base_type [[ULONG]] byte_size(8) encoding(7) d data_member_location(24)
+ * STABLE-NEXT: } byte_size(32)
+ *
+ * VERSION-DAG: #SYMVER ex2a 0x[[#%.08x,EX2:]]
+ */
+
+struct {
+ int a;
+ KABI_IGNORE(0, unsigned int n);
+ unsigned long b;
+ int c;
+ unsigned long d;
+} ex2b;
+
+_Static_assert(sizeof(ex2a) == sizeof(ex2b), "ex2a size doesn't match ex2b");
+
+/*
+ * STABLE: variable structure_type {
+ * STABLE-NEXT: member base_type int byte_size(4) encoding(5) a data_member_location(0) ,
+ * STABLE-NEXT: member base_type [[ULONG]] byte_size(8) encoding(7) b data_member_location(8)
+ * STABLE-NEXT: member base_type int byte_size(4) encoding(5) c data_member_location(16) ,
+ * STABLE-NEXT: member base_type [[ULONG]] byte_size(8) encoding(7) d data_member_location(24)
+ * STABLE-NEXT: } byte_size(32)
+ *
+ * VERSION-DAG: #SYMVER ex2b 0x[[#%.08x,EX2]]
+ */
+
+struct {
+ int a;
+ KABI_IGNORE(0, unsigned int n);
+ unsigned long b;
+ int c;
+ KABI_IGNORE(1, unsigned int m);
+ unsigned long d;
+} ex2c;
+
+_Static_assert(sizeof(ex2a) == sizeof(ex2c), "ex2a size doesn't match ex2c");
+
+/*
+ * STABLE: variable structure_type {
+ * STABLE-NEXT: member base_type int byte_size(4) encoding(5) a data_member_location(0) ,
+ * STABLE-NEXT: member base_type [[ULONG]] byte_size(8) encoding(7) b data_member_location(8)
+ * STABLE-NEXT: member base_type int byte_size(4) encoding(5) c data_member_location(16) ,
+ * STABLE-NEXT: member base_type [[ULONG]] byte_size(8) encoding(7) d data_member_location(24)
+ * STABLE-NEXT: } byte_size(32)
+ *
+ * VERSION-DAG: #SYMVER ex2c 0x[[#%.08x,EX2]]
+ */
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
index d8aa3210b0fe..962c36326ccc 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.h
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -223,6 +223,7 @@ void cache_clear_expanded(struct expansion_cache *ec);
/*
* dwarf.c
*/
+
struct expansion_state {
bool expand;
unsigned int ptr_depth;
@@ -230,6 +231,11 @@ struct expansion_state {
const char *current_fqn;
};
+struct kabi_state {
+ int members;
+ Dwarf_Die placeholder;
+};
+
struct state {
struct symbol *sym;
Dwarf_Die die;
@@ -240,6 +246,9 @@ struct state {
/* Structure expansion */
struct expansion_state expand;
struct expansion_cache expansion_cache;
+
+ /* Reserved or ignored members */
+ struct kabi_state kabi;
};
typedef int (*die_callback_t)(struct state *state, struct die *cache,
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 16/19] gendwarfksyms: Add support for symbol type pointers
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (14 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 15/19] gendwarfksyms: Add support for reserved and ignored fields Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 17/19] export: Add __gendwarfksyms_ptr_ references to exported symbols Sami Tolvanen
` (3 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
The compiler may choose not to emit type information in DWARF for
external symbols. Clang, for example, does this for symbols not
defined in the current TU.
To provide a way to work around this issue, add support for
__gendwarfksyms_ptr_<symbol> pointers that force the compiler to emit
the necessary type information in DWARF also for the missing symbols.
Example usage:
#define GENDWARFKSYMS_PTR(sym) \
static typeof(sym) *__gendwarfksyms_ptr_##sym __used \
__section(".discard.gendwarfksyms") = &sym;
extern int external_symbol(void);
GENDWARFKSYMS_PTR(external_symbol);
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
---
scripts/gendwarfksyms/dwarf.c | 55 +++++++++++++++++++++-
scripts/gendwarfksyms/examples/symbolptr.c | 33 +++++++++++++
scripts/gendwarfksyms/gendwarfksyms.h | 7 +++
scripts/gendwarfksyms/symbols.c | 27 +++++++++++
4 files changed, 121 insertions(+), 1 deletion(-)
create mode 100644 scripts/gendwarfksyms/examples/symbolptr.c
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index ba0f502ad20c..10224756f2af 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -1013,6 +1013,31 @@ static void process_variable(struct state *state, Dwarf_Die *die)
process_symbol(state, die, __process_variable);
}
+static void save_symbol_ptr(struct state *state)
+{
+ Dwarf_Die ptr_type;
+ Dwarf_Die type;
+
+ if (!get_ref_die_attr(&state->die, DW_AT_type, &ptr_type) ||
+ dwarf_tag(&ptr_type) != DW_TAG_pointer_type)
+ error("%s must be a pointer type!",
+ get_symbol_name(&state->die));
+
+ if (!get_ref_die_attr(&ptr_type, DW_AT_type, &type))
+ error("%s pointer missing a type attribute?",
+ get_symbol_name(&state->die));
+
+ /*
+ * Save the symbol pointer DIE in case the actual symbol is
+ * missing from the DWARF. Clang, for example, intentionally
+ * omits external symbols from the debugging information.
+ */
+ if (dwarf_tag(&type) == DW_TAG_subroutine_type)
+ symbol_set_ptr(state->sym, &type);
+ else
+ symbol_set_ptr(state->sym, &ptr_type);
+}
+
static int process_exported_symbols(struct state *unused, struct die *cache,
Dwarf_Die *die)
{
@@ -1036,7 +1061,9 @@ static int process_exported_symbols(struct state *unused, struct die *cache,
state_init(&state);
- if (tag == DW_TAG_subprogram)
+ if (is_symbol_ptr(get_symbol_name(&state.die)))
+ save_symbol_ptr(&state);
+ else if (tag == DW_TAG_subprogram)
process_subprogram(&state, &state.die);
else
process_variable(&state, &state.die);
@@ -1049,8 +1076,34 @@ static int process_exported_symbols(struct state *unused, struct die *cache,
}
}
+static void process_symbol_ptr(struct symbol *sym, void *arg)
+{
+ struct state state;
+ Dwarf *dwarf = arg;
+
+ if (sym->state != SYMBOL_UNPROCESSED || !sym->ptr_die_addr)
+ return;
+
+ debug("%s", sym->name);
+ state_init(&state);
+ state.sym = sym;
+
+ if (!dwarf_die_addr_die(dwarf, (void *)sym->ptr_die_addr, &state.die))
+ error("dwarf_die_addr_die failed for symbol ptr: '%s'",
+ sym->name);
+
+ if (dwarf_tag(&state.die) == DW_TAG_subroutine_type)
+ process_subprogram(&state, &state.die);
+ else
+ process_variable(&state, &state.die);
+
+ cache_clear_expanded(&state.expansion_cache);
+}
+
void process_cu(Dwarf_Die *cudie)
{
check(process_die_container(NULL, NULL, cudie, process_exported_symbols,
match_all));
+
+ symbol_for_each(process_symbol_ptr, dwarf_cu_getdwarf(cudie->cu));
}
diff --git a/scripts/gendwarfksyms/examples/symbolptr.c b/scripts/gendwarfksyms/examples/symbolptr.c
new file mode 100644
index 000000000000..b7b97cd39769
--- /dev/null
+++ b/scripts/gendwarfksyms/examples/symbolptr.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Google LLC
+ *
+ * Example for symbol pointers. When compiled with Clang, gendwarfkyms
+ * uses a symbol pointer for `f`.
+ *
+ * $ clang -g -c examples/symbolptr.c examples/symbolptr.o
+ * $ echo -e "f\ng\np" | ./gendwarfksyms -d examples/symbolptr.o
+ */
+
+/* Kernel macros for userspace testing. */
+#ifndef __used
+#define __used __attribute__((__used__))
+#endif
+#ifndef __section
+#define __section(section) __attribute__((__section__(section)))
+#endif
+
+#define __GENDWARFKSYMS_EXPORT(sym) \
+ static typeof(sym) *__gendwarfksyms_ptr_##sym __used \
+ __section(".discard.gendwarfksyms") = &sym;
+
+extern void f(unsigned int arg);
+void g(int *arg);
+void g(int *arg) {}
+
+struct s;
+extern struct s *p;
+
+__GENDWARFKSYMS_EXPORT(f);
+__GENDWARFKSYMS_EXPORT(g);
+__GENDWARFKSYMS_EXPORT(p);
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
index 962c36326ccc..c9277af76d7b 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.h
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -92,6 +92,10 @@ extern int symtypes;
* symbols.c
*/
+/* See symbols.c:is_symbol_ptr */
+#define SYMBOL_PTR_PREFIX "__gendwarfksyms_ptr_"
+#define SYMBOL_PTR_PREFIX_LEN (sizeof(SYMBOL_PTR_PREFIX) - 1)
+
static inline unsigned int addr_hash(uintptr_t addr)
{
return hash_ptr((const void *)addr);
@@ -115,14 +119,17 @@ struct symbol {
struct hlist_node name_hash;
enum symbol_state state;
uintptr_t die_addr;
+ uintptr_t ptr_die_addr;
unsigned long crc;
};
typedef void (*symbol_callback_t)(struct symbol *, void *arg);
+bool is_symbol_ptr(const char *name);
void symbol_read_exports(FILE *file);
void symbol_read_symtab(int fd);
struct symbol *symbol_get(const char *name);
+void symbol_set_ptr(struct symbol *sym, Dwarf_Die *ptr);
void symbol_set_die(struct symbol *sym, Dwarf_Die *die);
void symbol_set_crc(struct symbol *sym, unsigned long crc);
void symbol_for_each(symbol_callback_t func, void *arg);
diff --git a/scripts/gendwarfksyms/symbols.c b/scripts/gendwarfksyms/symbols.c
index e0c9007f7250..e00c86fa0ba2 100644
--- a/scripts/gendwarfksyms/symbols.c
+++ b/scripts/gendwarfksyms/symbols.c
@@ -39,6 +39,20 @@ static unsigned int __for_each_addr(struct symbol *sym, symbol_callback_t func,
return processed;
}
+/*
+ * For symbols without debugging information (e.g. symbols defined in other
+ * TUs), we also match __gendwarfksyms_ptr_<symbol_name> symbols, which the
+ * kernel uses to ensure type information is present in the TU that exports
+ * the symbol. A __gendwarfksyms_ptr pointer must have the same type as the
+ * exported symbol, e.g.:
+ *
+ * typeof(symname) *__gendwarf_ptr_symname = &symname;
+ */
+bool is_symbol_ptr(const char *name)
+{
+ return name && !strncmp(name, SYMBOL_PTR_PREFIX, SYMBOL_PTR_PREFIX_LEN);
+}
+
static unsigned int for_each(const char *name, symbol_callback_t func,
void *data)
{
@@ -47,6 +61,8 @@ static unsigned int for_each(const char *name, symbol_callback_t func,
if (!name || !*name)
return 0;
+ if (is_symbol_ptr(name))
+ name += SYMBOL_PTR_PREFIX_LEN;
hash_for_each_possible_safe(symbol_names, match, tmp, name_hash,
hash_str(name)) {
@@ -84,6 +100,17 @@ void symbol_set_crc(struct symbol *sym, unsigned long crc)
error("no matching symbols: '%s'", sym->name);
}
+static void set_ptr(struct symbol *sym, void *data)
+{
+ sym->ptr_die_addr = (uintptr_t)((Dwarf_Die *)data)->addr;
+}
+
+void symbol_set_ptr(struct symbol *sym, Dwarf_Die *ptr)
+{
+ if (for_each(sym->name, set_ptr, ptr) == 0)
+ error("no matching symbols: '%s'", sym->name);
+}
+
static void set_die(struct symbol *sym, void *data)
{
sym->die_addr = (uintptr_t)((Dwarf_Die *)data)->addr;
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 17/19] export: Add __gendwarfksyms_ptr_ references to exported symbols
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (15 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 16/19] gendwarfksyms: Add support for symbol type pointers Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 17:01 ` [PATCH v5 18/19] kbuild: Add gendwarfksyms as an alternative to genksyms Sami Tolvanen
` (2 subsequent siblings)
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
With gendwarfksyms, we need each TU where the EXPORT_SYMBOL() macro
is used to also contain DWARF type information for the symbols it
exports. However, as a TU can also export external symbols and
compilers may choose not to emit debugging information for symbols not
defined in the current TU, the missing types will result in missing
symbol versions. Stand-alone assembly code also doesn't contain type
information for exported symbols, so we need to compile a temporary
object file with asm-prototypes.h instead, and similarly need to
ensure the DWARF in the temporary object file contains the necessary
types.
To always emit type information for external exports, add explicit
__gendwarfksyms_ptr_<symbol> references to them in EXPORT_SYMBOL().
gendwarfksyms will use the type information for __gendwarfksyms_ptr_*
if needed. Discard the pointers from the final binary to avoid further
bloat.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
---
include/linux/export.h | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/include/linux/export.h b/include/linux/export.h
index 0bbd02fd351d..cf71d3202e5b 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -52,9 +52,24 @@
#else
+#ifdef CONFIG_GENDWARFKSYMS
+/*
+ * With CONFIG_GENDWARFKSYMS, ensure the compiler emits debugging
+ * information for all exported symbols, including those defined in
+ * different TUs, by adding a __gendwarfksyms_ptr_<symbol> pointer
+ * that's discarded during the final link.
+ */
+#define __GENDWARFKSYMS_EXPORT(sym) \
+ static typeof(sym) *__gendwarfksyms_ptr_##sym __used \
+ __section(".discard.gendwarfksyms") = &sym;
+#else
+#define __GENDWARFKSYMS_EXPORT(sym)
+#endif
+
#define __EXPORT_SYMBOL(sym, license, ns) \
extern typeof(sym) sym; \
__ADDRESSABLE(sym) \
+ __GENDWARFKSYMS_EXPORT(sym) \
asm(__stringify(___EXPORT_SYMBOL(sym, license, ns)))
#endif
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* [PATCH v5 18/19] kbuild: Add gendwarfksyms as an alternative to genksyms
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (16 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 17/19] export: Add __gendwarfksyms_ptr_ references to exported symbols Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-11-12 4:08 ` Masahiro Yamada
2024-10-30 17:01 ` [PATCH v5 19/19] Documentation/kbuild: Add DWARF module versioning Sami Tolvanen
2024-10-30 20:59 ` [PATCH v5 00/19] Implement DWARF modversions Sedat Dilek
19 siblings, 1 reply; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
When MODVERSIONS is enabled, allow selecting gendwarfksyms as the
implementation, but default to genksyms.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
---
kernel/module/Kconfig | 25 ++++++++++++++++++++++++-
scripts/Makefile | 2 +-
scripts/Makefile.build | 41 +++++++++++++++++++++++++++++++++--------
3 files changed, 58 insertions(+), 10 deletions(-)
diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
index f9e5f82fa88b..e6b2427e5c19 100644
--- a/kernel/module/Kconfig
+++ b/kernel/module/Kconfig
@@ -169,13 +169,36 @@ config MODVERSIONS
make them incompatible with the kernel you are running. If
unsure, say N.
+choice
+ prompt "Module versioning implementation"
+ depends on MODVERSIONS
+ default GENKSYMS
+ help
+ Select the tool used to calculate symbol versions for modules.
+
+ If unsure, select GENKSYMS.
+
+config GENKSYMS
+ bool "genksyms (from source code)"
+ help
+ Calculate symbol versions from pre-processed source code using
+ genksyms.
+
+ If unsure, say Y.
+
config GENDWARFKSYMS
- bool
+ bool "gendwarfksyms (from debugging information)"
depends on DEBUG_INFO
# Requires full debugging information, split DWARF not supported.
depends on !DEBUG_INFO_REDUCED && !DEBUG_INFO_SPLIT
# Requires ELF object files.
depends on !LTO
+ help
+ Calculate symbol versions from DWARF debugging information using
+ gendwarfksyms. Requires DEBUG_INFO to be enabled.
+
+ If unsure, say N.
+endchoice
config ASM_MODVERSIONS
bool
diff --git a/scripts/Makefile b/scripts/Makefile
index d7fec46d38c0..8533f4498885 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -53,7 +53,7 @@ hostprogs += unifdef
targets += module.lds
subdir-$(CONFIG_GCC_PLUGINS) += gcc-plugins
-subdir-$(CONFIG_MODVERSIONS) += genksyms
+subdir-$(CONFIG_GENKSYMS) += genksyms
subdir-$(CONFIG_GENDWARFKSYMS) += gendwarfksyms
subdir-$(CONFIG_SECURITY_SELINUX) += selinux
subdir-$(CONFIG_SECURITY_IPE) += ipe
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 8f423a1faf50..d2a0440cdb79 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -107,18 +107,31 @@ cmd_cpp_i_c = $(CPP) $(c_flags) -o $@ $<
$(obj)/%.i: $(obj)/%.c FORCE
$(call if_changed_dep,cpp_i_c)
+getexportsymbols = $(NM) $(1) | sed -n 's/.* __export_symbol_\(.*\)/$(2)/p'
+
+gendwarfksyms = scripts/gendwarfksyms/gendwarfksyms \
+ $(if $(1), --symtypes $(2)) \
+ $(if $(KBUILD_GENDWARFKSYMS_STABLE), --stable)
+
genksyms = scripts/genksyms/genksyms \
$(if $(1), -T $(2)) \
$(if $(KBUILD_PRESERVE), -p) \
-r $(or $(wildcard $(2:.symtypes=.symref)), /dev/null)
# These mirror gensymtypes_S and co below, keep them in synch.
+ifdef CONFIG_GENDWARFKSYMS
+symtypes_dep_c = $(obj)/%.o
+cmd_gensymtypes_c = $(if $(skip_gendwarfksyms),, \
+ $(call getexportsymbols,$(2:.symtypes=.o),\1) | \
+ $(gendwarfksyms) $(2:.symtypes=.o))
+else
cmd_gensymtypes_c = $(CPP) -D__GENKSYMS__ $(c_flags) $< | $(genksyms)
+endif # CONFIG_GENDWARFKSYMS
quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
cmd_cc_symtypes_c = $(call cmd_gensymtypes_c,true,$@) >/dev/null
-$(obj)/%.symtypes : $(obj)/%.c FORCE
+$(obj)/%.symtypes : $(obj)/%.c $(symtypes_dep_c) FORCE
$(call cmd,cc_symtypes_c)
# LLVM assembly
@@ -314,19 +327,31 @@ $(obj)/%.ll: $(obj)/%.rs FORCE
# This is convoluted. The .S file must first be preprocessed to run guards and
# expand names, then the resulting exports must be constructed into plain
# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
-# to make the genksyms input.
+# to make the genksyms input or compiled into an object for gendwarfksyms.
#
# These mirror gensymtypes_c and co above, keep them in synch.
-cmd_gensymtypes_S = \
- { echo "\#include <linux/kernel.h>" ; \
- echo "\#include <asm/asm-prototypes.h>" ; \
- $(NM) $@ | sed -n 's/.* __export_symbol_\(.*\)/EXPORT_SYMBOL(\1);/p' ; } | \
- $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | $(genksyms)
+getasmexports = \
+ { echo "\#include <linux/kernel.h>" ; \
+ echo "\#include <linux/string.h>" ; \
+ echo "\#include <asm/asm-prototypes.h>" ; \
+ $(call getexportsymbols,$(2:.symtypes=.o),EXPORT_SYMBOL(\1);) ; }
+
+ifdef CONFIG_GENDWARFKSYMS
+cmd_gensymtypes_S = \
+ $(getasmexports) | \
+ $(CC) $(c_flags) -c -o $(2:.symtypes=.gendwarfksyms.o) -xc -; \
+ $(call getexportsymbols,$(2:.symtypes=.o),\1) | \
+ $(gendwarfksyms) $(2:.symtypes=.gendwarfksyms.o)
+else
+cmd_gensymtypes_S = \
+ $(getasmexports) | \
+ $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | $(genksyms)
+endif # CONFIG_GENDWARFKSYMS
quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
cmd_cc_symtypes_S = $(call cmd_gensymtypes_S,true,$@) >/dev/null
-$(obj)/%.symtypes : $(obj)/%.S FORCE
+$(obj)/%.symtypes : $(obj)/%.S $(obj)/%.o FORCE
$(call cmd,cc_symtypes_S)
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* Re: [PATCH v5 18/19] kbuild: Add gendwarfksyms as an alternative to genksyms
2024-10-30 17:01 ` [PATCH v5 18/19] kbuild: Add gendwarfksyms as an alternative to genksyms Sami Tolvanen
@ 2024-11-12 4:08 ` Masahiro Yamada
2024-11-13 17:48 ` Sami Tolvanen
0 siblings, 1 reply; 36+ messages in thread
From: Masahiro Yamada @ 2024-11-12 4:08 UTC (permalink / raw)
To: Sami Tolvanen
Cc: Luis Chamberlain, Miguel Ojeda, Greg Kroah-Hartman,
Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux
On Thu, Oct 31, 2024 at 2:01 AM Sami Tolvanen <samitolvanen@google.com> wrote:
>
> When MODVERSIONS is enabled, allow selecting gendwarfksyms as the
> implementation, but default to genksyms.
>
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> Acked-by: Neal Gompa <neal@gompa.dev>
> ---
> kernel/module/Kconfig | 25 ++++++++++++++++++++++++-
> scripts/Makefile | 2 +-
> scripts/Makefile.build | 41 +++++++++++++++++++++++++++++++++--------
> 3 files changed, 58 insertions(+), 10 deletions(-)
>
> diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
> index f9e5f82fa88b..e6b2427e5c19 100644
> --- a/kernel/module/Kconfig
> +++ b/kernel/module/Kconfig
> @@ -169,13 +169,36 @@ config MODVERSIONS
> make them incompatible with the kernel you are running. If
> unsure, say N.
>
> +choice
> + prompt "Module versioning implementation"
> + depends on MODVERSIONS
> + default GENKSYMS
> + help
> + Select the tool used to calculate symbol versions for modules.
> +
> + If unsure, select GENKSYMS.
> +
> +config GENKSYMS
> + bool "genksyms (from source code)"
> + help
> + Calculate symbol versions from pre-processed source code using
> + genksyms.
> +
> + If unsure, say Y.
> +
> config GENDWARFKSYMS
> - bool
> + bool "gendwarfksyms (from debugging information)"
> depends on DEBUG_INFO
> # Requires full debugging information, split DWARF not supported.
> depends on !DEBUG_INFO_REDUCED && !DEBUG_INFO_SPLIT
> # Requires ELF object files.
> depends on !LTO
> + help
> + Calculate symbol versions from DWARF debugging information using
> + gendwarfksyms. Requires DEBUG_INFO to be enabled.
> +
> + If unsure, say N.
> +endchoice
>
> config ASM_MODVERSIONS
> bool
> diff --git a/scripts/Makefile b/scripts/Makefile
> index d7fec46d38c0..8533f4498885 100644
> --- a/scripts/Makefile
> +++ b/scripts/Makefile
> @@ -53,7 +53,7 @@ hostprogs += unifdef
> targets += module.lds
>
> subdir-$(CONFIG_GCC_PLUGINS) += gcc-plugins
> -subdir-$(CONFIG_MODVERSIONS) += genksyms
> +subdir-$(CONFIG_GENKSYMS) += genksyms
> subdir-$(CONFIG_GENDWARFKSYMS) += gendwarfksyms
> subdir-$(CONFIG_SECURITY_SELINUX) += selinux
> subdir-$(CONFIG_SECURITY_IPE) += ipe
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 8f423a1faf50..d2a0440cdb79 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -107,18 +107,31 @@ cmd_cpp_i_c = $(CPP) $(c_flags) -o $@ $<
> $(obj)/%.i: $(obj)/%.c FORCE
> $(call if_changed_dep,cpp_i_c)
>
> +getexportsymbols = $(NM) $(1) | sed -n 's/.* __export_symbol_\(.*\)/$(2)/p'
> +
> +gendwarfksyms = scripts/gendwarfksyms/gendwarfksyms \
> + $(if $(1), --symtypes $(2)) \
> + $(if $(KBUILD_GENDWARFKSYMS_STABLE), --stable)
> +
> genksyms = scripts/genksyms/genksyms \
> $(if $(1), -T $(2)) \
> $(if $(KBUILD_PRESERVE), -p) \
> -r $(or $(wildcard $(2:.symtypes=.symref)), /dev/null)
>
> # These mirror gensymtypes_S and co below, keep them in synch.
> +ifdef CONFIG_GENDWARFKSYMS
> +symtypes_dep_c = $(obj)/%.o
> +cmd_gensymtypes_c = $(if $(skip_gendwarfksyms),, \
> + $(call getexportsymbols,$(2:.symtypes=.o),\1) | \
> + $(gendwarfksyms) $(2:.symtypes=.o))
> +else
> cmd_gensymtypes_c = $(CPP) -D__GENKSYMS__ $(c_flags) $< | $(genksyms)
> +endif # CONFIG_GENDWARFKSYMS
>
> quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
> cmd_cc_symtypes_c = $(call cmd_gensymtypes_c,true,$@) >/dev/null
>
> -$(obj)/%.symtypes : $(obj)/%.c FORCE
> +$(obj)/%.symtypes : $(obj)/%.c $(symtypes_dep_c) FORCE
> $(call cmd,cc_symtypes_c)
>
> # LLVM assembly
> @@ -314,19 +327,31 @@ $(obj)/%.ll: $(obj)/%.rs FORCE
> # This is convoluted. The .S file must first be preprocessed to run guards and
> # expand names, then the resulting exports must be constructed into plain
> # EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
> -# to make the genksyms input.
> +# to make the genksyms input or compiled into an object for gendwarfksyms.
> #
> # These mirror gensymtypes_c and co above, keep them in synch.
> -cmd_gensymtypes_S = \
> - { echo "\#include <linux/kernel.h>" ; \
> - echo "\#include <asm/asm-prototypes.h>" ; \
> - $(NM) $@ | sed -n 's/.* __export_symbol_\(.*\)/EXPORT_SYMBOL(\1);/p' ; } | \
> - $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | $(genksyms)
> +getasmexports = \
> + { echo "\#include <linux/kernel.h>" ; \
> + echo "\#include <linux/string.h>" ; \
> + echo "\#include <asm/asm-prototypes.h>" ; \
> + $(call getexportsymbols,$(2:.symtypes=.o),EXPORT_SYMBOL(\1);) ; }
> +
> +ifdef CONFIG_GENDWARFKSYMS
> +cmd_gensymtypes_S = \
> + $(getasmexports) | \
> + $(CC) $(c_flags) -c -o $(2:.symtypes=.gendwarfksyms.o) -xc -; \
> + $(call getexportsymbols,$(2:.symtypes=.o),\1) | \
> + $(gendwarfksyms) $(2:.symtypes=.gendwarfksyms.o)
I do not want to see crazy suffix replacements like this.
I decided to delete this.
https://lore.kernel.org/linux-kbuild/20241111171753.2917697-2-masahiroy@kernel.org/T/#u
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 36+ messages in thread* Re: [PATCH v5 18/19] kbuild: Add gendwarfksyms as an alternative to genksyms
2024-11-12 4:08 ` Masahiro Yamada
@ 2024-11-13 17:48 ` Sami Tolvanen
0 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-11-13 17:48 UTC (permalink / raw)
To: Masahiro Yamada
Cc: Luis Chamberlain, Miguel Ojeda, Greg Kroah-Hartman,
Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux
Hi Masahiro,
On Mon, Nov 11, 2024 at 8:09 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> On Thu, Oct 31, 2024 at 2:01 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> >
> > # These mirror gensymtypes_c and co above, keep them in synch.
> > -cmd_gensymtypes_S = \
> > - { echo "\#include <linux/kernel.h>" ; \
> > - echo "\#include <asm/asm-prototypes.h>" ; \
> > - $(NM) $@ | sed -n 's/.* __export_symbol_\(.*\)/EXPORT_SYMBOL(\1);/p' ; } | \
> > - $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | $(genksyms)
> > +getasmexports = \
> > + { echo "\#include <linux/kernel.h>" ; \
> > + echo "\#include <linux/string.h>" ; \
> > + echo "\#include <asm/asm-prototypes.h>" ; \
> > + $(call getexportsymbols,$(2:.symtypes=.o),EXPORT_SYMBOL(\1);) ; }
> > +
> > +ifdef CONFIG_GENDWARFKSYMS
> > +cmd_gensymtypes_S = \
> > + $(getasmexports) | \
> > + $(CC) $(c_flags) -c -o $(2:.symtypes=.gendwarfksyms.o) -xc -; \
> > + $(call getexportsymbols,$(2:.symtypes=.o),\1) | \
> > + $(gendwarfksyms) $(2:.symtypes=.gendwarfksyms.o)
>
>
> I do not want to see crazy suffix replacements like this.
Yeah, I agree. It does get a bit ugly.
> I decided to delete this.
> https://lore.kernel.org/linux-kbuild/20241111171753.2917697-2-masahiroy@kernel.org/T/#u
Cool, thanks! I'll rebase v6 on top of your patch.
Sami
^ permalink raw reply [flat|nested] 36+ messages in thread
* [PATCH v5 19/19] Documentation/kbuild: Add DWARF module versioning
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (17 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 18/19] kbuild: Add gendwarfksyms as an alternative to genksyms Sami Tolvanen
@ 2024-10-30 17:01 ` Sami Tolvanen
2024-10-30 20:59 ` [PATCH v5 00/19] Implement DWARF modversions Sedat Dilek
19 siblings, 0 replies; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 17:01 UTC (permalink / raw)
To: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman
Cc: Matthew Maurer, Alex Gaynor, Gary Guo, Petr Pavlu, Daniel Gomez,
Neal Gompa, Hector Martin, Janne Grunau, Miroslav Benes,
Asahi Linux, Sedat Dilek, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux, Sami Tolvanen
Add documentation for gendwarfksyms changes, and the kABI stability
features that can be useful for distributions even though they're not
used in mainline kernels.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Neal Gompa <neal@gompa.dev>
---
Documentation/kbuild/gendwarfksyms.rst | 276 +++++++++++++++++++++++++
Documentation/kbuild/index.rst | 1 +
2 files changed, 277 insertions(+)
create mode 100644 Documentation/kbuild/gendwarfksyms.rst
diff --git a/Documentation/kbuild/gendwarfksyms.rst b/Documentation/kbuild/gendwarfksyms.rst
new file mode 100644
index 000000000000..0f5000491132
--- /dev/null
+++ b/Documentation/kbuild/gendwarfksyms.rst
@@ -0,0 +1,276 @@
+=======================
+DWARF module versioning
+=======================
+
+1. Introduction
+===============
+
+When CONFIG_MODVERSIONS is enabled, symbol versions for modules
+are typically calculated from preprocessed source code using the
+**genksyms** tool. However, this is incompatible with languages such
+as Rust, where the source code has insufficient information about
+the resulting ABI. With CONFIG_GENDWARFKSYMS (and CONFIG_DEBUG_INFO)
+selected, **gendwarfksyms** is used instead to calculate symbol versions
+from the DWARF debugging information, which contains the necessary
+details about the final module ABI.
+
+1.1. Usage
+==========
+
+gendwarfksyms accepts a list of object files on the command line, and a
+list of symbol names (one per line) in standard input::
+
+ Usage: gendwarfksyms [options] elf-object-file ... < symbol-list
+
+ Options:
+ -d, --debug Print debugging information
+ --dump-dies Dump DWARF DIE contents
+ --dump-die-map Print debugging information about die_map changes
+ --dump-types Dump type strings
+ --dump-versions Dump expanded type strings used for symbol versions
+ -s, --stable Support kABI stability features
+ -T, --symtypes file Write a symtypes file
+ -h, --help Print this message
+
+
+2. Type information availability
+================================
+
+While symbols are typically exported in the same translation unit (TU)
+where they're defined, it's also perfectly fine for a TU to export
+external symbols. For example, this is done when calculating symbol
+versions for exports in stand-alone assembly code.
+
+To ensure the compiler emits the necessary DWARF type information in the
+TU where symbols are actually exported, gendwarfksyms adds a pointer
+to exported symbols in the `EXPORT_SYMBOL()` macro using the following
+macro::
+
+ #define __GENDWARFKSYMS_EXPORT(sym) \
+ static typeof(sym) *__gendwarfksyms_ptr_##sym __used \
+ __section(".discard.gendwarfksyms") = &sym;
+
+
+When a symbol pointer is found in DWARF, gendwarfksyms can use its
+type for calculating symbol versions even if the symbol is defined
+elsewhere. The name of the symbol pointer is expected to start with
+`__gendwarfksyms_ptr_`, followed by the name of the exported symbol.
+
+3. Symtypes output format
+=========================
+
+Similarly to genksyms, gendwarfksyms supports writing a symtypes
+file for each processed object that contain types for exported
+symbols and each referenced type that was used in calculating symbol
+versions. These files can be useful when trying to determine what
+exactly caused symbol versions to change between builds. To generate
+symtypes files during a kernel build, set `KBUILD_SYMTYPES=1`.
+
+Matching the existing format, the first column of each line contains
+either a type reference or a symbol name. Type references have a
+one-letter prefix followed by "#" and the name of the type. Four
+reference types are supported::
+
+ e#<type> = enum
+ s#<type> = struct
+ t#<type> = typedef
+ u#<type> = union
+
+Type names with spaces in them are wrapped in single quotes, e.g.::
+
+ s#'core::result::Result<u8, core::num::error::ParseIntError>'
+
+The rest of the line contains a type string. Unlike with genksyms that
+produces C-style type strings, gendwarfksyms uses the same simple parsed
+DWARF format produced by **--dump-dies**, but with type references
+instead of fully expanded strings.
+
+4. Maintaining a stable kABI
+============================
+
+Distribution maintainers often need the ability to make ABI compatible
+changes to kernel data structures due to LTS updates or backports. Using
+the traditional `#ifndef __GENKSYMS__` to hide these changes from symbol
+versioning won't work when processing object files. To support this
+use case, gendwarfksyms provides kABI stability features designed to
+hide changes that won't affect the ABI when calculating versions. These
+features are all gated behind the **--stable** command line flag and are
+not used in the mainline kernel. To use stable features during a kernel
+build, set `KBUILD_GENDWARFKSYMS_STABLE=1`.
+
+Examples for using these features are provided in the
+**scripts/gendwarfksyms/examples** directory, including helper macros
+for source code annotation. Note that as these features are only used to
+transform the inputs for symbol versioning, the user is responsible for
+ensuring that their changes actually won't break the ABI.
+
+4.1. kABI rules
+===============
+
+kABI rules allow distributions to fine-tune certain parts
+of gendwarfksyms output and thus control how symbol
+versions are calculated. These rules are defined in the
+`.discard.gendwarfksyms.kabi_rules` section of the object file and
+consist of simple null-terminated strings with the following structure::
+
+ version\0type\0target\0value\0
+
+This string sequence is repeated as many times as needed to express all
+the rules. The fields are as follows:
+
+- `version`: Ensures backward compatibility for future changes to the
+ structure. Currently expected to be "1".
+- `type`: Indicates the type of rule being applied.
+- `target`: Specifies the target of the rule, typically the fully
+ qualified name of the DWARF Debugging Information Entry (DIE).
+- `value`: Provides rule-specific data.
+
+The following helper macro, for example, can be used to specify rules
+in the source code::
+
+ #define __KABI_RULE(hint, target, value) \
+ static const char __PASTE(__gendwarfksyms_rule_, \
+ __COUNTER__)[] __used __aligned(1) \
+ __section(".discard.gendwarfksyms.kabi_rules") = \
+ "1\0" #hint "\0" #target "\0" #value
+
+
+Currently, only the rules discussed in this section are supported, but
+the format is extensible enough to allow further rules to be added as
+need arises.
+
+4.1.1. Managing structure visibility
+====================================
+
+A structure declaration can change into a full definition when
+additional includes are pulled into the translation unit. This changes
+the versions of any symbol that references the structure even if the ABI
+remains unchanged. As it may not be possible to drop includes without
+breaking the build, the `struct_declonly` rule can be used to specify a
+data structure as declaration-only, even if the debugging information
+contains the full definition.
+
+The rule fields are expected to be as follows:
+
+- `type`: "struct_declonly"
+- `target`: The fully qualified name of the target data structure
+ (as shown in **--dump-dies** output).
+- `value`: This field is ignored and is expected to have the value ";".
+
+Using the `__KABI_RULE` macro, this rule can be defined as::
+
+ #define KABI_STRUCT_DECLONLY(fqn) \
+ __KABI_RULE(struct_declonly, fqn, ;)
+
+Example usage::
+
+ struct s {
+ /* definition */
+ };
+
+ KABI_STRUCT_DECLONLY(s);
+
+4.1.2. Adding enumerators
+=========================
+
+For enums, all enumerators and their values are included in calculating
+symbol versions, which becomes a problem if we later need to add more
+enumerators without changing symbol versions. The `enumerator_ignore`
+rule allows us to hide named enumerators from the input.
+
+The rule fields are expected to be as follows:
+
+- `type`: "enumerator_ignore"
+- `target`: The fully qualified name of the target enum
+ (as shown in **--dump-dies** output).
+- `value`: The name of the enumerator to ignore.
+
+Using the `__KABI_RULE` macro, this rule can be defined as::
+
+ #define KABI_ENUMERATOR_IGNORE(fqn, field) \
+ __KABI_RULE(enumerator_ignore, fqn, field)
+
+Example usage::
+
+ enum e {
+ A, B, C, D,
+ };
+
+ KABI_ENUMERATOR_IGNORE(e, B);
+ KABI_ENUMERATOR_IGNORE(e, C);
+
+
+4.3. Adding structure members
+=============================
+
+Perhaps the most common ABI compatible changeis adding a member to a
+kernel data structure. When changes to a structure are anticipated,
+distribution maintainers can pre-emptively reserve space in the
+structure and take it into use later without breaking the ABI. If
+changes are needed to data structures without reserved space, existing
+alignment holes can potentially be used instead. While kABI rules could
+be added for these type of changes, using unions is typically a more
+natural method. This section describes gendwarfksyms support for using
+reserved space in data structures and hiding members that don't change
+the ABI when calculating symbol versions.
+
+4.3.1. Reserving space and replacing members
+============================================
+
+To reserve space in a struct, adding a member of any type with a name
+that starts with `__kabi_` will result in the name being left out of
+symbol versioning::
+
+ struct s {
+ long a;
+ long __kabi_reserved_0; /* reserved for future use */
+ };
+
+The space reserved by this member can be later taken into use by
+wrapping it into a union, which includes the original type and the
+replacement struct member::
+
+ struct s {
+ long a;
+ union {
+ long __kabi_reserved_0; /* original type */
+ struct b b; /* replaced field */
+ };
+ };
+
+As long as the reserved member's name in the union starts with
+`__kabi_reserved_`, the original type will be used for symbol
+versioning and rest of the union is ignored. The examples include
+`KABI_(RESERVE|USE)*` macros that help simplify the process and also
+ensure the replacement member's size won't exceed the reserved space.
+
+4.3.2. Hiding members
+=====================
+
+Predicting which structures will require changes during the support
+timeframe isn't always possible, in which case one might have to resort
+to placing new members into existing alignment holes::
+
+ struct s {
+ int a;
+ /* a 4-byte alignment hole */
+ unsigned long b;
+ };
+
+
+While this won't change the size of the data structure, one needs to
+be able to hide the added members from symbol versioning. Similarly
+to reserved fields, this can be accomplished by wrapping the added
+member to a union where one of the fields has a name starting with
+`__kabi_ignored`::
+
+ struct s {
+ int a;
+ union {
+ char __kabi_ignored_0;
+ int n;
+ };
+ unsigned long b;
+ };
+
+With **--stable**, both versions produce the same symbol version.
diff --git a/Documentation/kbuild/index.rst b/Documentation/kbuild/index.rst
index cee2f99f734b..e82af05cd652 100644
--- a/Documentation/kbuild/index.rst
+++ b/Documentation/kbuild/index.rst
@@ -21,6 +21,7 @@ Kernel Build System
reproducible-builds
gcc-plugins
llvm
+ gendwarfksyms
.. only:: subproject and html
--
2.47.0.163.g1226f6d8fa-goog
^ permalink raw reply related [flat|nested] 36+ messages in thread* Re: [PATCH v5 00/19] Implement DWARF modversions
2024-10-30 17:01 [PATCH v5 00/19] Implement DWARF modversions Sami Tolvanen
` (18 preceding siblings ...)
2024-10-30 17:01 ` [PATCH v5 19/19] Documentation/kbuild: Add DWARF module versioning Sami Tolvanen
@ 2024-10-30 20:59 ` Sedat Dilek
2024-10-30 21:14 ` Sami Tolvanen
19 siblings, 1 reply; 36+ messages in thread
From: Sedat Dilek @ 2024-10-30 20:59 UTC (permalink / raw)
To: Sami Tolvanen
Cc: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman, Matthew Maurer, Alex Gaynor, Gary Guo,
Petr Pavlu, Daniel Gomez, Neal Gompa, Hector Martin, Janne Grunau,
Miroslav Benes, Asahi Linux, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux
On Wed, Oct 30, 2024 at 6:01 PM Sami Tolvanen <samitolvanen@google.com> wrote:
>
> Hi,
>
> Here's v5 of the DWARF modversions series. The main motivation is
> modversions support for Rust, which is important for distributions
> like Android that are about to ship Rust kernel modules. Per Luis'
> request [1], v2 dropped the Rust specific bits from the series and
> instead added the feature as an option for the entire kernel to
> make it easier to evaluate the benefits of this approach, and to
> get better test coverage. Matt is addressing Rust modversion_info
> compatibility issues in a separate patch set [2] that depends on this
> series, and actually allows modversions to be enabled with Rust.
>
> Short background: Unlike C, Rust source code doesn't have sufficient
> information about the final ABI, as the compiler has considerable
> freedom in adjusting structure layout, for example, which makes
> using a source code parser like genksyms a non-starter. Based on
> earlier feedback, this series uses DWARF debugging information for
> computing versions. DWARF is an established and a relatively stable
> format, which includes all the necessary ABI details, and adding a
> CONFIG_DEBUG_INFO dependency for Rust symbol versioning seems like a
> reasonable trade-off as most distributions already enable it.
>
> The first patch moves the genksyms CRC32 implementation to a shared
> header file to avoid code duplication and the next 15 patches add
> gendwarfksyms, a tool for computing symbol versions from DWARF. When
> passed a list of exported symbols and object files, the tool
> generates an expanded type string for each symbol and computes symbol
> CRCs similarly to genksyms. gendwarfksyms is written in C and uses
> libdw to process DWARF. Patch 17 ensures that debugging information
> is present where we need it, patch 18 adds gendwarfksyms as an
> alternative to genksyms, and the last patch adds documentation.
>
> v5 is based on v6.12-rc5 and for your convenience the series is also
> available here:
>
> https://github.com/samitolvanen/linux/commits/gendwarfksyms-v5
>
> If you also want to test the series with Rust modules, this branch
> adds Matt's latest modversion_info series:
>
> https://github.com/samitolvanen/linux/commits/rustmodversions-v5
>
> Sami
>
>
> [1] https://lore.kernel.org/lkml/ZnIZEtkkQWEIGf9n@bombadil.infradead.org/
> [2] https://lore.kernel.org/lkml/20240925233854.90072-1-mmaurer@google.com/
>
> ---
>
> v5:
> - Rebased on v6.12-rc5.
>
> - Fixed an issue with limiting structure expansion, and applied
> Petr's clean-up. (Patch 10)
>
> - Dropped an unnecessary return statement in error path. (Patch
> 12)
>
> - Addressed several other smaller issues Petr brought up. (Patches
> 13, 14, and 15)
>
> - Added a KBUILD_GENDWARFKSYMS_STABLE flag to enable --stable for
> the entire kernel build. (Patch 18)
>
Hi Sami,
perfect timing: Nathan uploaded SLIM LLVM toolchain v19.1.3
KBUILD_GENDWARFKSYMS_STABLE is to be set manually?
What value is recommended?
Thanks.
-Sedat-
> - Updated documentation to include KBUILD flags. (Patch 19)
>
> - Picked up Reviewed-by tags from v4.
>
> v4: https://lore.kernel.org/lkml/20241008183823.36676-21-samitolvanen@google.com/
> - Rebased on v6.12-rc2, which now includes all the prerequisites.
>
> - Dropped unnecessary name_only parameter for symbols.c::for_each
> and cleaned up error handling. (Patch 3)
>
> - Fixed anonymous scope handling to ensure unnamed DIEs don't get
> names. (Patch 4)
>
> - Added non-variant children to variant_type output, and included
> DW_AT_discr_value attributes for variants. (Patch 9)
>
> - Added another symbol pointer test case. (Patch 16)
>
> - Picked up (Acked|Reviewed)-by tags from v3.
>
>
> v3: https://lore.kernel.org/lkml/20240923181846.549877-22-samitolvanen@google.com/
> - Updated SPX license headers.
>
> - Squashed the first two patches in v2 and tried to reduce churn as
> much as reasonable.
>
> - Dropped patch 18 from v2 ("x86/asm-prototypes: Include
> <asm/ptrace.h>") as it's addressed by a separate patch.
>
> - Changed the error handling code to immediately terminate instead
> of propagating the errors back to main, which cleaned up the code
> quite a bit.
>
> - Switched to the list and hashtable implementations in scripts and
> dropped the remaining tools/include dependencies. Added a couple
> missing list macros. (patch 1)
>
> - Moved the genksyms CRC32 implementation to scripts/include and
> dropped the duplicate code. (patches 2 and 14)
>
> - Switched from ad-hoc command line parsing to getopt_long (patch 3).
>
> - Added structure member and function parameter names to the DIE
> output to match genksyms behavior, and tweaked the symtypes format
> to be more parser-friendly in general based on Petr's suggestions.
>
> - Replaced the declaration-only struct annotations with more generic
> kABI stability rules that allow source code annotations to be used
> where #ifndef __GENKSYMS__ was previously used. Added support for
> rules that can be used to exclude enumerators from versioning.
> (patch 16)
>
> - Per Miroslav's suggestion, added an option to hide structure
> members from versioning when they're added to existing alignment
> holes, for example. (patch 16)
>
> - Per Greg's request, added documentation and example macros for the
> --stable features, and a couple of test cases. (patches 15, 16, and
> 20)
>
> - Fixed making symtypes files, which need to depend on .o files with
> gendwarfksyms. (patch 19)
>
> - Addressed several other smaller issues that Petr and Masahiro
> kindly pointed out during the v2 review.
>
>
> v2: https://lore.kernel.org/lkml/20240815173903.4172139-21-samitolvanen@google.com/
> - Per Luis' request, dropped Rust-specific patches and added
> gendwarfksyms as an alternative to genksyms for the entire
> kernel.
>
> - Added support for missing DWARF features needed to handle
> also non-Rust code.
>
> - Changed symbol address matching to use the symbol table
> information instead of relying on addresses in DWARF.
>
> - Added __gendwarfksyms_ptr patches to ensure the compiler emits
> the necessary type information in DWARF even for symbols that
> are defined in other TUs.
>
> - Refactored debugging output and moved the more verbose output
> behind --dump* flags.
>
> - Added a --symtypes flag for generating a genksyms-style
> symtypes output based on Petr's feedback, and refactored
> symbol version calculations to be based on symtypes instead
> of raw --dump-dies output.
>
> - Based on feedback from Greg and Petr, added --stable flag and
> support for reserved data structure fields and declaration-onl
> structures. Also added examples for using these features.
>
> - Added a GENDWARFKSYMS option and hooked up kbuild support
> for both C and assembly code. Note that with gendwarfksyms,
> we have to actually build a temporary .o file for calculating
> assembly modversions.
>
> v1: https://lore.kernel.org/lkml/20240617175818.58219-17-samitolvanen@google.com/
>
> ---
>
> Sami Tolvanen (19):
> scripts: move genksyms crc32 implementation to a common include
> tools: Add gendwarfksyms
> gendwarfksyms: Add address matching
> gendwarfksyms: Expand base_type
> gendwarfksyms: Add a cache for processed DIEs
> gendwarfksyms: Expand type modifiers and typedefs
> gendwarfksyms: Expand subroutine_type
> gendwarfksyms: Expand array_type
> gendwarfksyms: Expand structure types
> gendwarfksyms: Limit structure expansion
> gendwarfksyms: Add die_map debugging
> gendwarfksyms: Add symtypes output
> gendwarfksyms: Add symbol versioning
> gendwarfksyms: Add support for kABI rules
> gendwarfksyms: Add support for reserved and ignored fields
> gendwarfksyms: Add support for symbol type pointers
> export: Add __gendwarfksyms_ptr_ references to exported symbols
> kbuild: Add gendwarfksyms as an alternative to genksyms
> Documentation/kbuild: Add DWARF module versioning
>
> Documentation/kbuild/gendwarfksyms.rst | 276 +++++
> Documentation/kbuild/index.rst | 1 +
> include/linux/export.h | 15 +
> kernel/module/Kconfig | 31 +
> scripts/Makefile | 3 +-
> scripts/Makefile.build | 41 +-
> scripts/gendwarfksyms/.gitignore | 2 +
> scripts/gendwarfksyms/Makefile | 12 +
> scripts/gendwarfksyms/cache.c | 44 +
> scripts/gendwarfksyms/die.c | 166 +++
> scripts/gendwarfksyms/dwarf.c | 1109 +++++++++++++++++++
> scripts/gendwarfksyms/examples/kabi.h | 141 +++
> scripts/gendwarfksyms/examples/kabi_ex0.c | 86 ++
> scripts/gendwarfksyms/examples/kabi_ex1.c | 89 ++
> scripts/gendwarfksyms/examples/kabi_ex2.c | 98 ++
> scripts/gendwarfksyms/examples/kabi_rules.c | 56 +
> scripts/gendwarfksyms/examples/symbolptr.c | 33 +
> scripts/gendwarfksyms/gendwarfksyms.c | 185 ++++
> scripts/gendwarfksyms/gendwarfksyms.h | 288 +++++
> scripts/gendwarfksyms/kabi.c | 263 +++++
> scripts/gendwarfksyms/symbols.c | 339 ++++++
> scripts/gendwarfksyms/types.c | 477 ++++++++
> scripts/genksyms/genksyms.c | 77 +-
> scripts/include/crc32.h | 93 ++
> 24 files changed, 3840 insertions(+), 85 deletions(-)
> create mode 100644 Documentation/kbuild/gendwarfksyms.rst
> create mode 100644 scripts/gendwarfksyms/.gitignore
> create mode 100644 scripts/gendwarfksyms/Makefile
> create mode 100644 scripts/gendwarfksyms/cache.c
> create mode 100644 scripts/gendwarfksyms/die.c
> create mode 100644 scripts/gendwarfksyms/dwarf.c
> create mode 100644 scripts/gendwarfksyms/examples/kabi.h
> create mode 100644 scripts/gendwarfksyms/examples/kabi_ex0.c
> create mode 100644 scripts/gendwarfksyms/examples/kabi_ex1.c
> create mode 100644 scripts/gendwarfksyms/examples/kabi_ex2.c
> create mode 100644 scripts/gendwarfksyms/examples/kabi_rules.c
> create mode 100644 scripts/gendwarfksyms/examples/symbolptr.c
> create mode 100644 scripts/gendwarfksyms/gendwarfksyms.c
> create mode 100644 scripts/gendwarfksyms/gendwarfksyms.h
> create mode 100644 scripts/gendwarfksyms/kabi.c
> create mode 100644 scripts/gendwarfksyms/symbols.c
> create mode 100644 scripts/gendwarfksyms/types.c
> create mode 100644 scripts/include/crc32.h
>
>
> base-commit: 81983758430957d9a5cb3333fe324fd70cf63e7e
> --
> 2.47.0.163.g1226f6d8fa-goog
>
^ permalink raw reply [flat|nested] 36+ messages in thread* Re: [PATCH v5 00/19] Implement DWARF modversions
2024-10-30 20:59 ` [PATCH v5 00/19] Implement DWARF modversions Sedat Dilek
@ 2024-10-30 21:14 ` Sami Tolvanen
2024-10-31 1:56 ` Sedat Dilek
0 siblings, 1 reply; 36+ messages in thread
From: Sami Tolvanen @ 2024-10-30 21:14 UTC (permalink / raw)
To: sedat.dilek
Cc: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman, Matthew Maurer, Alex Gaynor, Gary Guo,
Petr Pavlu, Daniel Gomez, Neal Gompa, Hector Martin, Janne Grunau,
Miroslav Benes, Asahi Linux, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux
Hi Sedat,
On Wed, Oct 30, 2024 at 2:00 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>
> Hi Sami,
>
> perfect timing: Nathan uploaded SLIM LLVM toolchain v19.1.3
>
> KBUILD_GENDWARFKSYMS_STABLE is to be set manually?
> What value is recommended?
The usage is similar to KBUILD_SYMTYPES, you can just set
KBUILD_GENDWARFKSYMS_STABLE=1 to use --stable when calculating
versions. However, it's not normally necessary to set this flag at all
when building your own kernel, it's mostly for distributions.
Sami
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [PATCH v5 00/19] Implement DWARF modversions
2024-10-30 21:14 ` Sami Tolvanen
@ 2024-10-31 1:56 ` Sedat Dilek
2024-10-31 6:18 ` Sedat Dilek
0 siblings, 1 reply; 36+ messages in thread
From: Sedat Dilek @ 2024-10-31 1:56 UTC (permalink / raw)
To: Sami Tolvanen
Cc: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman, Matthew Maurer, Alex Gaynor, Gary Guo,
Petr Pavlu, Daniel Gomez, Neal Gompa, Hector Martin, Janne Grunau,
Miroslav Benes, Asahi Linux, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux
On Wed, Oct 30, 2024 at 10:14 PM Sami Tolvanen <samitolvanen@google.com> wrote:
>
> Hi Sedat,
>
> On Wed, Oct 30, 2024 at 2:00 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >
> > Hi Sami,
> >
> > perfect timing: Nathan uploaded SLIM LLVM toolchain v19.1.3
> >
> > KBUILD_GENDWARFKSYMS_STABLE is to be set manually?
> > What value is recommended?
>
> The usage is similar to KBUILD_SYMTYPES, you can just set
> KBUILD_GENDWARFKSYMS_STABLE=1 to use --stable when calculating
> versions. However, it's not normally necessary to set this flag at all
> when building your own kernel, it's mostly for distributions.
>
> Sami
OK, thanks.
# cat /proc/version
Linux version 6.12.0-rc5-1-amd64-clang19-kcfi
(sedat.dilek@gmail.com@iniza) (ClangBuiltLinux clang version 19.1.3
(https://github.com/llvm/llvm-project.git
ab51eccf88f5321e7c60591c5546b254b6afab99), ClangBuiltLinux LLD 19.1.3
(https://github.com/llvm/llvm-project.git
ab51eccf88f5321e7c60591c5546b254b6afab99)) #1~trixie+dileks SMP
PREEMPT_DYNAMIC 2024-10-30
Tested-by: Sedat Dilek <sedat,dilek@gmail.com> # LLVM/Clang v19.1.3 on x86-64
Best regards,
-Sedat-
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [PATCH v5 00/19] Implement DWARF modversions
2024-10-31 1:56 ` Sedat Dilek
@ 2024-10-31 6:18 ` Sedat Dilek
0 siblings, 0 replies; 36+ messages in thread
From: Sedat Dilek @ 2024-10-31 6:18 UTC (permalink / raw)
To: Sami Tolvanen
Cc: Masahiro Yamada, Luis Chamberlain, Miguel Ojeda,
Greg Kroah-Hartman, Matthew Maurer, Alex Gaynor, Gary Guo,
Petr Pavlu, Daniel Gomez, Neal Gompa, Hector Martin, Janne Grunau,
Miroslav Benes, Asahi Linux, linux-kbuild, linux-kernel,
linux-modules, rust-for-linux
On Thu, Oct 31, 2024 at 2:56 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>
> On Wed, Oct 30, 2024 at 10:14 PM Sami Tolvanen <samitolvanen@google.com> wrote:
> >
> > Hi Sedat,
> >
> > On Wed, Oct 30, 2024 at 2:00 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> > >
> > > Hi Sami,
> > >
> > > perfect timing: Nathan uploaded SLIM LLVM toolchain v19.1.3
> > >
> > > KBUILD_GENDWARFKSYMS_STABLE is to be set manually?
> > > What value is recommended?
> >
> > The usage is similar to KBUILD_SYMTYPES, you can just set
> > KBUILD_GENDWARFKSYMS_STABLE=1 to use --stable when calculating
> > versions. However, it's not normally necessary to set this flag at all
> > when building your own kernel, it's mostly for distributions.
> >
> > Sami
>
> OK, thanks.
>
> # cat /proc/version
> Linux version 6.12.0-rc5-1-amd64-clang19-kcfi
> (sedat.dilek@gmail.com@iniza) (ClangBuiltLinux clang version 19.1.3
> (https://github.com/llvm/llvm-project.git
> ab51eccf88f5321e7c60591c5546b254b6afab99), ClangBuiltLinux LLD 19.1.3
> (https://github.com/llvm/llvm-project.git
> ab51eccf88f5321e7c60591c5546b254b6afab99)) #1~trixie+dileks SMP
> PREEMPT_DYNAMIC 2024-10-30
>
> Tested-by: Sedat Dilek <sedat,dilek@gmail.com> # LLVM/Clang v19.1.3 on x86-64
>
Fix email-address in credit tag:
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v19.1.3 on x86-64
-sed@-
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