[PATCH 03/15] gendwarfksyms: Add CRC calculation

Sami Tolvanen
2024-06-17T17:58:31Z

Add a basic CRC32 implementation adapted from genksyms, and produce
matching output from type strings.

Example usage:

$ nm -p --defined-only rust/alloc.o | \
awk '/ (T|R|D) / {printf "%s %s\n",$1, $3}' | \
tools/gendwarfksyms/gendwarfksyms rust/alloc.o

Output:

#SYMVER _RNvNvMs_NtCscg2doA4GLaz_5alloc3vecINtB6_3VecppE11swap_remove13assert_failed 0x985f94dd
#SYMVER _RNvXs1_NtCscg2doA4GLaz_5alloc11collectionsNtB5_15TryReserveErrorNtNtCs5QSdWC790r4_4core3fmt7Display3fmt 0x985f94dd
#SYMVER _RNvNvMs_NtCscg2doA4GLaz_5alloc3vecINtB6_3VecppE6remove13assert_failed 0x985f94dd
...

Note that type strings are not yet expanded, so the CRCs can only
distinguish between functions and variables for now.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
tools/gendwarfksyms/Build | 1 +
tools/gendwarfksyms/crc32.c | 69 ++++++++++++++++++++++++++++
tools/gendwarfksyms/crc32.h | 34 ++++++++++++++
tools/gendwarfksyms/gendwarfksyms.c | 1 +
tools/gendwarfksyms/gendwarfksyms.h | 6 +++
tools/gendwarfksyms/symbols.c | 71 +++++++++++++++++++++++++++--
tools/gendwarfksyms/types.c | 19 ++++++--
7 files changed, 194 insertions(+), 7 deletions(-)
create mode 100644 tools/gendwarfksyms/crc32.c
create mode 100644 tools/gendwarfksyms/crc32.h

diff --git a/tools/gendwarfksyms/Build b/tools/gendwarfksyms/Build
index a83c59bfef8b..518642c9b9de 100644
--- a/tools/gendwarfksyms/Build
+++ b/tools/gendwarfksyms/Build
@@ -1,3 +1,4 @@
gendwarfksyms-y += gendwarfksyms.o
+gendwarfksyms-y += crc32.o
gendwarfksyms-y += symbols.o
gendwarfksyms-y += types.o
diff --git a/tools/gendwarfksyms/crc32.c b/tools/gendwarfksyms/crc32.c
new file mode 100644
index 000000000000..23b328cd74f2
--- /dev/null
+++ b/tools/gendwarfksyms/crc32.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Based on 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.
+ */
+
+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
+};
diff --git a/tools/gendwarfksyms/crc32.h b/tools/gendwarfksyms/crc32.h
new file mode 100644
index 000000000000..89e4454b2a70
--- /dev/null
+++ b/tools/gendwarfksyms/crc32.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Based on 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
+
+extern const unsigned int crctab32[];
+
+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;
+}
+
+#endif /* __CRC32_H */
diff --git a/tools/gendwarfksyms/gendwarfksyms.c b/tools/gendwarfksyms/gendwarfksyms.c
index 4a1bd9239182..7938b7440674 100644
--- a/tools/gendwarfksyms/gendwarfksyms.c
+++ b/tools/gendwarfksyms/gendwarfksyms.c
@@ -125,6 +125,7 @@ int main(int argc, const char **argv)
}

dwfl_end(dwfl);
+ symbol_print_versions();

return 0;
}
diff --git a/tools/gendwarfksyms/gendwarfksyms.h b/tools/gendwarfksyms/gendwarfksyms.h
index b77855cc94a7..7440f1c73500 100644
--- a/tools/gendwarfksyms/gendwarfksyms.h
+++ b/tools/gendwarfksyms/gendwarfksyms.h
@@ -52,17 +52,22 @@ extern bool debug;
/*
* symbols.c
*/
+enum symbol_state { UNPROCESSED, PROCESSED_ADDR, PROCESSED_NAME };

/* Exported symbol -- matching either the name or the address */
struct symbol {
const char *name;
uintptr_t addr;
+ enum symbol_state state;
+ unsigned long crc;
struct hlist_node addr_hash;
struct hlist_node name_hash;
};

+extern int symbol_set_crc(struct symbol *sym, unsigned long crc);
extern int symbol_read_list(FILE *file);
extern struct symbol *symbol_get(uintptr_t addr, const char *name);
+extern void symbol_print_versions(void);

/*
* types.c
@@ -73,6 +78,7 @@ struct state {
Dwarf *dbg;
struct symbol *sym;
Dwarf_Die origin;
+ unsigned long crc;
};

typedef int (*die_callback_t)(struct state *state, Dwarf_Die *die);
diff --git a/tools/gendwarfksyms/symbols.c b/tools/gendwarfksyms/symbols.c
index 2cae61bcede7..71029635fc83 100644
--- a/tools/gendwarfksyms/symbols.c
+++ b/tools/gendwarfksyms/symbols.c
@@ -18,7 +18,8 @@ static u32 name_hash(const char *name)
}

/* symbol_for_each callback -- return true to stop, false to continue */
-typedef bool (*symbol_callback_t)(struct symbol *, void *arg);
+typedef bool (*symbol_callback_t)(struct symbol *, enum symbol_state type,
+ void *arg);

static bool for_each_addr(uintptr_t addr, symbol_callback_t func, void *data)
{
@@ -30,7 +31,7 @@ static bool for_each_addr(uintptr_t addr, symbol_callback_t func, void *data)

hash_for_each_possible(symbol_addrs, sym, addr_hash, addr) {
if (sym->addr == addr) {
- if (func(sym, data))
+ if (func(sym, PROCESSED_ADDR, data))
return true;
found = true;
}
@@ -49,7 +50,7 @@ static bool for_each_name(const char *name, symbol_callback_t func, void *data)

hash_for_each_possible(symbol_names, sym, name_hash, name_hash(name)) {
if (!strcmp(sym->name, name)) {
- if (func(sym, data))
+ if (func(sym, PROCESSED_NAME, data))
return true;
found = true;
}
@@ -71,6 +72,45 @@ static bool for_each(uintptr_t addr, const char *name, symbol_callback_t func,
return found;
}

+static bool set_crc(struct symbol *sym, enum symbol_state type, void *data)
+{
+ unsigned long *crc = data;
+
+ /* Prefer an address match if found, otherwise match by name. */
+ if (type == PROCESSED_ADDR) {
+ if (sym->state == PROCESSED_ADDR) {
+ warn("symbol %s (@ %lx) already matched by address (crc %lx vs. %lx)",
+ sym->name, sym->addr, sym->crc, *crc);
+ return false;
+ }
+ if (sym->state == PROCESSED_NAME && sym->crc != *crc)
+ debug("symbol %s (@ %lx) overriding name match (crc %lx vs. %lx)",
+ sym->name, sym->addr, sym->crc, *crc);
+ } else if (type == PROCESSED_NAME) {
+ if (sym->state == PROCESSED_ADDR) {
+ if (sym->crc != *crc)
+ debug("symbol %s (@ %lx) ignoring name match (crc %lx vs. %lx)",
+ sym->name, sym->addr, sym->crc, *crc);
+ return false;
+ }
+ if (sym->state == PROCESSED_NAME) {
+ warn("symbol %s (@ %lx) already matched by name (crc %lx vs. %lx)",
+ sym->name, sym->addr, sym->crc, *crc);
+ return false;
+ }
+ }
+
+ sym->state = type;
+ sym->crc = *crc;
+
+ return false; /* Continue */
+}
+
+int symbol_set_crc(struct symbol *sym, unsigned long crc)
+{
+ return for_each(sym->addr, sym->name, set_crc, &crc) ? 0 : -1;
+}
+
int symbol_read_list(FILE *file)
{
struct symbol *sym;
@@ -99,6 +139,8 @@ int symbol_read_list(FILE *file)

sym->addr = (uintptr_t)addr;
sym->name = name;
+ sym->state = UNPROCESSED;
+ sym->crc = 0;
name = NULL;

hash_add(symbol_addrs, &sym->addr_hash, sym->addr);
@@ -111,7 +153,7 @@ int symbol_read_list(FILE *file)
return 0;
}

-static bool return_symbol(struct symbol *sym, void *arg)
+static bool return_symbol(struct symbol *sym, enum symbol_state type, void *arg)
{
struct symbol **res = (struct symbol **)arg;

@@ -128,3 +170,24 @@ struct symbol *symbol_get(uintptr_t addr, const char *name)

return NULL;
}
+
+void symbol_print_versions(void)
+{
+ struct hlist_node *tmp;
+ struct symbol *sym;
+ int i;
+
+ hash_for_each_safe(symbol_addrs, i, tmp, sym, addr_hash) {
+ if (sym->state == UNPROCESSED)
+ warn("no information for symbol %s (@ %lx)", sym->name,
+ sym->addr);
+
+ printf("#SYMVER %s 0x%08lx\n", sym->name, sym->crc);
+
+ free((void *)sym->name);
+ free(sym);
+ }
+
+ hash_init(symbol_addrs);
+ hash_init(symbol_names);
+}
diff --git a/tools/gendwarfksyms/types.c b/tools/gendwarfksyms/types.c
index f1ce7bfcf510..47ae967d42ee 100644
--- a/tools/gendwarfksyms/types.c
+++ b/tools/gendwarfksyms/types.c
@@ -4,6 +4,7 @@
*/

#include "gendwarfksyms.h"
+#include "crc32.h"

#define DEFINE_GET_ATTR(attr, type) \
static bool get_##attr##_attr(Dwarf_Die *die, unsigned int id, \
@@ -68,7 +69,7 @@ static Dwarf_Die *get_exported(struct state *state, Dwarf_Die *die)
}

/*
- * Type string processing
+ * Type string and CRC processing
*/
static int process(struct state *state, const char *s)
{
@@ -77,6 +78,7 @@ static int process(struct state *state, const char *s)
if (debug)
fputs(s, stderr);

+ state->crc = partial_crc32(s, state->crc);
return 0;
}

@@ -101,6 +103,11 @@ int process_die_container(struct state *state, Dwarf_Die *die,
return 0;
}

+static void state_init(struct state *state)
+{
+ state->crc = 0xffffffff;
+}
+
/*
* Exported symbol processing
*/
@@ -130,17 +137,23 @@ static int process_exported_symbols(struct state *state, Dwarf_Die *die)
case DW_TAG_subprogram:
case DW_TAG_variable:
die = get_exported(state, die);
- if (!die || !state->sym)
+ if (!die || !state->sym || state->sym->state != UNPROCESSED)
return 0;

+ /*
+ * For each exported symbol, compute a CRC of the expanded type
+ * description.
+ */
debug("%s (@ %lx)", state->sym->name, state->sym->addr);
+ state_init(state);

if (tag == DW_TAG_subprogram)
check(process_subprogram(state, die));
else
check(process_variable(state, die));

- return 0;
+ return check(
+ symbol_set_crc(state->sym, state->crc ^ 0xffffffff));
default:
return 0;
}
--
2.45.2.627.g7a2c4fd464-goog