* [PATCH v13 1/5] modules: Support extended MODVERSIONS info
2025-01-03 17:37 [PATCH v13 0/5] Extended MODVERSIONS Support Matthew Maurer
@ 2025-01-03 17:37 ` Matthew Maurer
2025-01-03 17:37 ` [PATCH v13 2/5] modpost: Produce extended MODVERSIONS information Matthew Maurer
` (4 subsequent siblings)
5 siblings, 0 replies; 12+ messages in thread
From: Matthew Maurer @ 2025-01-03 17:37 UTC (permalink / raw)
To: Michael Ellerman, Nicholas Piggin, Christophe Leroy, Naveen N Rao,
Madhavan Srinivasan, Luis Chamberlain, Petr Pavlu, Sami Tolvanen,
Daniel Gomez, Masahiro Yamada, Nathan Chancellor, Nicolas Schier,
Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Jonathan Corbet
Cc: linuxppc-dev, linux-kernel, linux-modules, linux-kbuild,
rust-for-linux, linux-doc, Matthew Maurer
Adds a new format for MODVERSIONS which stores each field in a separate
ELF section. This initially adds support for variable length names, but
could later be used to add additional fields to MODVERSIONS in a
backwards compatible way if needed. Any new fields will be ignored by
old user tooling, unlike the current format where user tooling cannot
tolerate adjustments to the format (for example making the name field
longer).
Since PPC munges its version records to strip leading dots, we reproduce
the munging for the new format. Other architectures do not appear to
have architecture-specific usage of this information.
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Matthew Maurer <mmaurer@google.com>
---
arch/powerpc/kernel/module_64.c | 24 ++++++++++-
kernel/module/internal.h | 11 +++++
kernel/module/main.c | 92 +++++++++++++++++++++++++++++++++++++----
kernel/module/version.c | 45 ++++++++++++++++++++
4 files changed, 162 insertions(+), 10 deletions(-)
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index 45dac7b46aa3cdcb2058a2320b88c0d67e5586b3..34a5aec4908fba3b91a02e914264cb525918942a 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -369,6 +369,24 @@ static void dedotify_versions(struct modversion_info *vers,
}
}
+/* Same as normal versions, remove a leading dot if present. */
+static void dedotify_ext_version_names(char *str_seq, unsigned long size)
+{
+ unsigned long out = 0;
+ unsigned long in;
+ char last = '\0';
+
+ for (in = 0; in < size; in++) {
+ /* Skip one leading dot */
+ if (last == '\0' && str_seq[in] == '.')
+ in++;
+ last = str_seq[in];
+ str_seq[out++] = last;
+ }
+ /* Zero the trailing portion of the names table for robustness */
+ memset(&str_seq[out], 0, size - out);
+}
+
/*
* Undefined symbols which refer to .funcname, hack to funcname. Make .TOC.
* seem to be defined (value set later).
@@ -438,10 +456,12 @@ int module_frob_arch_sections(Elf64_Ehdr *hdr,
me->arch.toc_section = i;
if (sechdrs[i].sh_addralign < 8)
sechdrs[i].sh_addralign = 8;
- }
- else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
+ } else if (strcmp(secstrings + sechdrs[i].sh_name, "__versions") == 0)
dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
sechdrs[i].sh_size);
+ else if (strcmp(secstrings + sechdrs[i].sh_name, "__version_ext_names") == 0)
+ dedotify_ext_version_names((void *)hdr + sechdrs[i].sh_offset,
+ sechdrs[i].sh_size);
if (sechdrs[i].sh_type == SHT_SYMTAB)
dedotify((void *)hdr + sechdrs[i].sh_offset,
diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index f10dc3ea7ff883b1c91e036b427cdb90502933b8..887838589020d95f8ca5e9751e66e1c73af34db2 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -86,6 +86,8 @@ struct load_info {
unsigned int vers;
unsigned int info;
unsigned int pcpu;
+ unsigned int vers_ext_crc;
+ unsigned int vers_ext_name;
} index;
};
@@ -389,6 +391,15 @@ void module_layout(struct module *mod, struct modversion_info *ver, struct kerne
struct kernel_symbol *ks, struct tracepoint * const *tp);
int check_modstruct_version(const struct load_info *info, struct module *mod);
int same_magic(const char *amagic, const char *bmagic, bool has_crcs);
+struct modversion_info_ext {
+ size_t remaining;
+ const u32 *crc;
+ const char *name;
+};
+void modversion_ext_start(const struct load_info *info, struct modversion_info_ext *ver);
+void modversion_ext_advance(struct modversion_info_ext *ver);
+#define for_each_modversion_info_ext(ver, info) \
+ for (modversion_ext_start(info, &ver); ver.remaining > 0; modversion_ext_advance(&ver))
#else /* !CONFIG_MODVERSIONS */
static inline int check_version(const struct load_info *info,
const char *symname,
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 59ea20102b400b5acd68347f61eef48a677c77ce..6333af32ee652011f6623739f3db95f25a26c305 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2073,6 +2073,82 @@ static int elf_validity_cache_index_str(struct load_info *info)
return 0;
}
+/**
+ * elf_validity_cache_index_versions() - Validate and cache version indices
+ * @info: Load info to cache version indices in.
+ * Must have &load_info->sechdrs and &load_info->secstrings populated.
+ * @flags: Load flags, relevant to suppress version loading, see
+ * uapi/linux/module.h
+ *
+ * If we're ignoring modversions based on @flags, zero all version indices
+ * and return validity. Othewrise check:
+ *
+ * * If "__version_ext_crcs" is present, "__version_ext_names" is present
+ * * There is a name present for every crc
+ *
+ * Then populate:
+ *
+ * * &load_info->index.vers
+ * * &load_info->index.vers_ext_crc
+ * * &load_info->index.vers_ext_names
+ *
+ * if present.
+ *
+ * Return: %0 if valid, %-ENOEXEC on failure.
+ */
+static int elf_validity_cache_index_versions(struct load_info *info, int flags)
+{
+ unsigned int vers_ext_crc;
+ unsigned int vers_ext_name;
+ size_t crc_count;
+ size_t remaining_len;
+ size_t name_size;
+ char *name;
+
+ /* If modversions were suppressed, pretend we didn't find any */
+ if (flags & MODULE_INIT_IGNORE_MODVERSIONS) {
+ info->index.vers = 0;
+ info->index.vers_ext_crc = 0;
+ info->index.vers_ext_name = 0;
+ return 0;
+ }
+
+ vers_ext_crc = find_sec(info, "__version_ext_crcs");
+ vers_ext_name = find_sec(info, "__version_ext_names");
+
+ /* If we have one field, we must have the other */
+ if (!!vers_ext_crc != !!vers_ext_name) {
+ pr_err("extended version crc+name presence does not match");
+ return -ENOEXEC;
+ }
+
+ /*
+ * If we have extended version information, we should have the same
+ * number of entries in every section.
+ */
+ if (vers_ext_crc) {
+ crc_count = info->sechdrs[vers_ext_crc].sh_size / sizeof(u32);
+ name = (void *)info->hdr +
+ info->sechdrs[vers_ext_name].sh_offset;
+ remaining_len = info->sechdrs[vers_ext_name].sh_size;
+
+ while (crc_count--) {
+ name_size = strnlen(name, remaining_len) + 1;
+ if (name_size > remaining_len) {
+ pr_err("more extended version crcs than names");
+ return -ENOEXEC;
+ }
+ remaining_len -= name_size;
+ name += name_size;
+ }
+ }
+
+ info->index.vers = find_sec(info, "__versions");
+ info->index.vers_ext_crc = vers_ext_crc;
+ info->index.vers_ext_name = vers_ext_name;
+ return 0;
+}
+
/**
* elf_validity_cache_index() - Resolve, validate, cache section indices
* @info: Load info to read from and update.
@@ -2087,9 +2163,7 @@ static int elf_validity_cache_index_str(struct load_info *info)
* * elf_validity_cache_index_mod()
* * elf_validity_cache_index_sym()
* * elf_validity_cache_index_str()
- *
- * If versioning is not suppressed via flags, load the version index from
- * a section called "__versions" with no validation.
+ * * elf_validity_cache_index_versions()
*
* If CONFIG_SMP is enabled, load the percpu section by name with no
* validation.
@@ -2112,11 +2186,9 @@ static int elf_validity_cache_index(struct load_info *info, int flags)
err = elf_validity_cache_index_str(info);
if (err < 0)
return err;
-
- if (flags & MODULE_INIT_IGNORE_MODVERSIONS)
- info->index.vers = 0; /* Pretend no __versions section! */
- else
- info->index.vers = find_sec(info, "__versions");
+ err = elf_validity_cache_index_versions(info, flags);
+ if (err < 0)
+ return err;
info->index.pcpu = find_pcpusec(info);
@@ -2327,6 +2399,10 @@ static int rewrite_section_headers(struct load_info *info, int flags)
/* Track but don't keep modinfo and version sections. */
info->sechdrs[info->index.vers].sh_flags &= ~(unsigned long)SHF_ALLOC;
+ info->sechdrs[info->index.vers_ext_crc].sh_flags &=
+ ~(unsigned long)SHF_ALLOC;
+ info->sechdrs[info->index.vers_ext_name].sh_flags &=
+ ~(unsigned long)SHF_ALLOC;
info->sechdrs[info->index.info].sh_flags &= ~(unsigned long)SHF_ALLOC;
return 0;
diff --git a/kernel/module/version.c b/kernel/module/version.c
index 4e5731d403af20251cb2e3d6dbff8bc59109732b..3718a886832198504ebfd9b72e77005efd3d3d21 100644
--- a/kernel/module/version.c
+++ b/kernel/module/version.c
@@ -19,11 +19,28 @@ int check_version(const struct load_info *info,
unsigned int versindex = info->index.vers;
unsigned int i, num_versions;
struct modversion_info *versions;
+ struct modversion_info_ext version_ext;
/* Exporting module didn't supply crcs? OK, we're already tainted. */
if (!crc)
return 1;
+ /* If we have extended version info, rely on it */
+ if (info->index.vers_ext_crc) {
+ for_each_modversion_info_ext(version_ext, info) {
+ if (strcmp(version_ext.name, symname) != 0)
+ continue;
+ if (*version_ext.crc == *crc)
+ return 1;
+ pr_debug("Found checksum %X vs module %X\n",
+ *crc, *version_ext.crc);
+ goto bad_version;
+ }
+ pr_warn_once("%s: no extended symbol version for %s\n",
+ info->name, symname);
+ return 1;
+ }
+
/* No versions at all? modprobe --force does this. */
if (versindex == 0)
return try_to_force_load(mod, symname) == 0;
@@ -87,6 +104,34 @@ int same_magic(const char *amagic, const char *bmagic,
return strcmp(amagic, bmagic) == 0;
}
+void modversion_ext_start(const struct load_info *info,
+ struct modversion_info_ext *start)
+{
+ unsigned int crc_idx = info->index.vers_ext_crc;
+ unsigned int name_idx = info->index.vers_ext_name;
+ Elf_Shdr *sechdrs = info->sechdrs;
+
+ /*
+ * Both of these fields are needed for this to be useful
+ * Any future fields should be initialized to NULL if absent.
+ */
+ if (crc_idx == 0 || name_idx == 0) {
+ start->remaining = 0;
+ return;
+ }
+
+ start->crc = (const u32 *)sechdrs[crc_idx].sh_addr;
+ start->name = (const char *)sechdrs[name_idx].sh_addr;
+ start->remaining = sechdrs[crc_idx].sh_size / sizeof(*start->crc);
+}
+
+void modversion_ext_advance(struct modversion_info_ext *vers)
+{
+ vers->remaining--;
+ vers->crc++;
+ vers->name += strlen(vers->name) + 1;
+}
+
/*
* Generate the signature for all relevant module structures here.
* If these change, we don't want to try to parse the module.
--
2.47.1.613.gc27f4b7a9f-goog
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v13 2/5] modpost: Produce extended MODVERSIONS information
2025-01-03 17:37 [PATCH v13 0/5] Extended MODVERSIONS Support Matthew Maurer
2025-01-03 17:37 ` [PATCH v13 1/5] modules: Support extended MODVERSIONS info Matthew Maurer
@ 2025-01-03 17:37 ` Matthew Maurer
2025-01-03 17:37 ` [PATCH v13 3/5] modules: Allow extended modversions without basic MODVERSIONS Matthew Maurer
` (3 subsequent siblings)
5 siblings, 0 replies; 12+ messages in thread
From: Matthew Maurer @ 2025-01-03 17:37 UTC (permalink / raw)
To: Michael Ellerman, Nicholas Piggin, Christophe Leroy, Naveen N Rao,
Madhavan Srinivasan, Luis Chamberlain, Petr Pavlu, Sami Tolvanen,
Daniel Gomez, Masahiro Yamada, Nathan Chancellor, Nicolas Schier,
Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Jonathan Corbet
Cc: linuxppc-dev, linux-kernel, linux-modules, linux-kbuild,
rust-for-linux, linux-doc, Matthew Maurer
Generate both the existing modversions format and the new extended one
when running modpost. Presence of this metadata in the final .ko is
guarded by CONFIG_EXTENDED_MODVERSIONS.
We no longer generate an error on long symbols in modpost if
CONFIG_EXTENDED_MODVERSIONS is set, as they can now be appropriately
encoded in the extended section. These symbols will be skipped in the
previous encoding. An error will still be generated if
CONFIG_EXTENDED_MODVERSIONS is not set.
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Matthew Maurer <mmaurer@google.com>
---
kernel/module/Kconfig | 10 ++++++++
scripts/Makefile.modpost | 1 +
scripts/mod/modpost.c | 62 ++++++++++++++++++++++++++++++++++++++++++++----
3 files changed, 69 insertions(+), 4 deletions(-)
diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
index d443fc504ffca0d1001f880ec496ab1f21fe979e..9568b629a03ce8289d3f3597eefc66fc96445720 100644
--- a/kernel/module/Kconfig
+++ b/kernel/module/Kconfig
@@ -207,6 +207,16 @@ config ASM_MODVERSIONS
assembly. This can be enabled only when the target architecture
supports it.
+config EXTENDED_MODVERSIONS
+ bool "Extended Module Versioning Support"
+ depends on MODVERSIONS
+ help
+ This enables extended MODVERSIONs support, allowing long symbol
+ names to be versioned.
+
+ The most likely reason you would enable this is to enable Rust
+ support. If unsure, say N.
+
config MODULE_SRCVERSION_ALL
bool "Source checksum for all modules"
help
diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index ab0e94ea62496e11dbaa3ffc289ce546862795ca..40426fc6350985780c0092beb49c6cc29b9eff62 100644
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -43,6 +43,7 @@ MODPOST = $(objtree)/scripts/mod/modpost
modpost-args = \
$(if $(CONFIG_MODULES),-M) \
$(if $(CONFIG_MODVERSIONS),-m) \
+ $(if $(CONFIG_EXTENDED_MODVERSIONS),-x) \
$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a) \
$(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
$(if $(KBUILD_MODPOST_WARN),-w) \
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index e489983bb8b2850c0f95bcbdfd82f684d4e7f0c3..6324b30f6b97ac24dc517b9229f227c6c369f7d5 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -33,6 +33,8 @@ static bool module_enabled;
static bool modversions;
/* Is CONFIG_MODULE_SRCVERSION_ALL set? */
static bool all_versions;
+/* Is CONFIG_EXTENDED_MODVERSIONS set? */
+static bool extended_modversions;
/* If we are modposting external module set to 1 */
static bool external_module;
/* Only warn about unresolved symbols */
@@ -1804,6 +1806,49 @@ static void add_exported_symbols(struct buffer *buf, struct module *mod)
}
}
+/**
+ * Record CRCs for unresolved symbols, supporting long names
+ */
+static void add_extended_versions(struct buffer *b, struct module *mod)
+{
+ struct symbol *s;
+
+ if (!extended_modversions)
+ return;
+
+ buf_printf(b, "\n");
+ buf_printf(b, "static const u32 ____version_ext_crcs[]\n");
+ buf_printf(b, "__used __section(\"__version_ext_crcs\") = {\n");
+ list_for_each_entry(s, &mod->unresolved_symbols, list) {
+ if (!s->module)
+ continue;
+ if (!s->crc_valid) {
+ warn("\"%s\" [%s.ko] has no CRC!\n",
+ s->name, mod->name);
+ continue;
+ }
+ buf_printf(b, "\t0x%08x,\n", s->crc);
+ }
+ buf_printf(b, "};\n");
+
+ buf_printf(b, "static const char ____version_ext_names[]\n");
+ buf_printf(b, "__used __section(\"__version_ext_names\") =\n");
+ list_for_each_entry(s, &mod->unresolved_symbols, list) {
+ if (!s->module)
+ continue;
+ if (!s->crc_valid)
+ /*
+ * We already warned on this when producing the crc
+ * table.
+ * We need to skip its name too, as the indexes in
+ * both tables need to align.
+ */
+ continue;
+ buf_printf(b, "\t\"%s\\0\"\n", s->name);
+ }
+ buf_printf(b, ";\n");
+}
+
/**
* Record CRCs for unresolved symbols
**/
@@ -1827,9 +1872,14 @@ static void add_versions(struct buffer *b, struct module *mod)
continue;
}
if (strlen(s->name) >= MODULE_NAME_LEN) {
- error("too long symbol \"%s\" [%s.ko]\n",
- s->name, mod->name);
- break;
+ if (extended_modversions) {
+ /* this symbol will only be in the extended info */
+ continue;
+ } else {
+ error("too long symbol \"%s\" [%s.ko]\n",
+ s->name, mod->name);
+ break;
+ }
}
buf_printf(b, "\t{ 0x%08x, \"%s\" },\n",
s->crc, s->name);
@@ -1960,6 +2010,7 @@ static void write_mod_c_file(struct module *mod)
add_header(&buf, mod);
add_exported_symbols(&buf, mod);
add_versions(&buf, mod);
+ add_extended_versions(&buf, mod);
add_depends(&buf, mod);
buf_printf(&buf, "\n");
@@ -2125,7 +2176,7 @@ int main(int argc, char **argv)
LIST_HEAD(dump_lists);
struct dump_list *dl, *dl2;
- while ((opt = getopt(argc, argv, "ei:MmnT:to:au:WwENd:")) != -1) {
+ while ((opt = getopt(argc, argv, "ei:MmnT:to:au:WwENd:x")) != -1) {
switch (opt) {
case 'e':
external_module = true;
@@ -2174,6 +2225,9 @@ int main(int argc, char **argv)
case 'd':
missing_namespace_deps = optarg;
break;
+ case 'x':
+ extended_modversions = true;
+ break;
default:
exit(1);
}
--
2.47.1.613.gc27f4b7a9f-goog
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v13 3/5] modules: Allow extended modversions without basic MODVERSIONS
2025-01-03 17:37 [PATCH v13 0/5] Extended MODVERSIONS Support Matthew Maurer
2025-01-03 17:37 ` [PATCH v13 1/5] modules: Support extended MODVERSIONS info Matthew Maurer
2025-01-03 17:37 ` [PATCH v13 2/5] modpost: Produce extended MODVERSIONS information Matthew Maurer
@ 2025-01-03 17:37 ` Matthew Maurer
2025-01-03 17:37 ` [PATCH v13 4/5] Documentation/kbuild: Document storage of symbol information Matthew Maurer
` (2 subsequent siblings)
5 siblings, 0 replies; 12+ messages in thread
From: Matthew Maurer @ 2025-01-03 17:37 UTC (permalink / raw)
To: Michael Ellerman, Nicholas Piggin, Christophe Leroy, Naveen N Rao,
Madhavan Srinivasan, Luis Chamberlain, Petr Pavlu, Sami Tolvanen,
Daniel Gomez, Masahiro Yamada, Nathan Chancellor, Nicolas Schier,
Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Jonathan Corbet
Cc: linuxppc-dev, linux-kernel, linux-modules, linux-kbuild,
rust-for-linux, linux-doc, Matthew Maurer
If you know that your kernel modules will only ever be loaded by a newer
kernel, you can disable BASIC_MODVERSIONS to save space. This also
allows easy creation of test modules to see how tooling will respond to
modules that only have the new format.
Signed-off-by: Matthew Maurer <mmaurer@google.com>
---
kernel/module/Kconfig | 15 +++++++++++++++
scripts/Makefile.modpost | 1 +
scripts/mod/modpost.c | 9 +++++++--
3 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
index 9568b629a03ce8289d3f3597eefc66fc96445720..4538f3af63e1ca531d0f74ef45a6f5268e505aec 100644
--- a/kernel/module/Kconfig
+++ b/kernel/module/Kconfig
@@ -217,6 +217,21 @@ config EXTENDED_MODVERSIONS
The most likely reason you would enable this is to enable Rust
support. If unsure, say N.
+config BASIC_MODVERSIONS
+ bool "Basic Module Versioning Support"
+ depends on MODVERSIONS
+ default y
+ help
+ This enables basic MODVERSIONS support, allowing older tools or
+ kernels to potentially load modules.
+
+ Disabling this may cause older `modprobe` or `kmod` to be unable
+ to read MODVERSIONS information from built modules. With this
+ disabled, older kernels may treat this module as unversioned.
+
+ This is enabled by default when MODVERSIONS are enabled.
+ If unsure, say Y.
+
config MODULE_SRCVERSION_ALL
bool "Source checksum for all modules"
help
diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index 40426fc6350985780c0092beb49c6cc29b9eff62..d7d45067d08b94a82451d66a64eae29b6826e139 100644
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -43,6 +43,7 @@ MODPOST = $(objtree)/scripts/mod/modpost
modpost-args = \
$(if $(CONFIG_MODULES),-M) \
$(if $(CONFIG_MODVERSIONS),-m) \
+ $(if $(CONFIG_BASIC_MODVERSIONS),-b) \
$(if $(CONFIG_EXTENDED_MODVERSIONS),-x) \
$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a) \
$(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 6324b30f6b97ac24dc517b9229f227c6c369f7d5..3784f1e08104dc2ca1da10d45ed92bb8adf4826a 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -33,6 +33,8 @@ static bool module_enabled;
static bool modversions;
/* Is CONFIG_MODULE_SRCVERSION_ALL set? */
static bool all_versions;
+/* Is CONFIG_BASIC_MODVERSIONS set? */
+static bool basic_modversions;
/* Is CONFIG_EXTENDED_MODVERSIONS set? */
static bool extended_modversions;
/* If we are modposting external module set to 1 */
@@ -1856,7 +1858,7 @@ static void add_versions(struct buffer *b, struct module *mod)
{
struct symbol *s;
- if (!modversions)
+ if (!basic_modversions)
return;
buf_printf(b, "\n");
@@ -2176,7 +2178,7 @@ int main(int argc, char **argv)
LIST_HEAD(dump_lists);
struct dump_list *dl, *dl2;
- while ((opt = getopt(argc, argv, "ei:MmnT:to:au:WwENd:x")) != -1) {
+ while ((opt = getopt(argc, argv, "ei:MmnT:to:au:WwENd:xb")) != -1) {
switch (opt) {
case 'e':
external_module = true;
@@ -2225,6 +2227,9 @@ int main(int argc, char **argv)
case 'd':
missing_namespace_deps = optarg;
break;
+ case 'b':
+ basic_modversions = true;
+ break;
case 'x':
extended_modversions = true;
break;
--
2.47.1.613.gc27f4b7a9f-goog
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v13 4/5] Documentation/kbuild: Document storage of symbol information
2025-01-03 17:37 [PATCH v13 0/5] Extended MODVERSIONS Support Matthew Maurer
` (2 preceding siblings ...)
2025-01-03 17:37 ` [PATCH v13 3/5] modules: Allow extended modversions without basic MODVERSIONS Matthew Maurer
@ 2025-01-03 17:37 ` Matthew Maurer
2025-01-03 17:37 ` [PATCH v13 5/5] rust: Use gendwarfksyms + extended modversions for CONFIG_MODVERSIONS Matthew Maurer
2025-01-10 17:38 ` [PATCH v13 0/5] Extended MODVERSIONS Support Masahiro Yamada
5 siblings, 0 replies; 12+ messages in thread
From: Matthew Maurer @ 2025-01-03 17:37 UTC (permalink / raw)
To: Michael Ellerman, Nicholas Piggin, Christophe Leroy, Naveen N Rao,
Madhavan Srinivasan, Luis Chamberlain, Petr Pavlu, Sami Tolvanen,
Daniel Gomez, Masahiro Yamada, Nathan Chancellor, Nicolas Schier,
Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Jonathan Corbet
Cc: linuxppc-dev, linux-kernel, linux-modules, linux-kbuild,
rust-for-linux, linux-doc, Matthew Maurer
Document where exported and imported symbols are kept, format options,
and limitations.
Signed-off-by: Matthew Maurer <mmaurer@google.com>
---
Documentation/kbuild/modules.rst | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/Documentation/kbuild/modules.rst b/Documentation/kbuild/modules.rst
index 101de236cd0c9abe1f5684d80063ff3f9a7fc673..a42f00d8cb90ff6ee44677c1278287ef25a84c89 100644
--- a/Documentation/kbuild/modules.rst
+++ b/Documentation/kbuild/modules.rst
@@ -423,6 +423,26 @@ Symbols From the Kernel (vmlinux + modules)
1) It lists all exported symbols from vmlinux and all modules.
2) It lists the CRC if CONFIG_MODVERSIONS is enabled.
+Version Information Formats
+---------------------------
+
+ Exported symbols have information stored in __ksymtab or __ksymtab_gpl
+ sections. Symbol names and namespaces are stored in __ksymtab_strings,
+ using a format similar to the string table used for ELF. If
+ CONFIG_MODVERSIONS is enabled, the CRCs corresponding to exported
+ symbols will be added to the __kcrctab or __kcrctab_gpl.
+
+ If CONFIG_BASIC_MODVERSIONS is enabled (default with
+ CONFIG_MODVERSIONS), imported symbols will have their symbol name and
+ CRC stored in the __versions section of the importing module. This
+ mode only supports symbols of length up to 64 bytes.
+
+ If CONFIG_EXTENDED_MODVERSIONS is enabled (required to enable both
+ CONFIG_MODVERSIONS and CONFIG_RUST at the same time), imported symbols
+ will have their symbol name recorded in the __version_ext_names
+ section as a series of concatenated, null-terminated strings. CRCs for
+ these symbols will be recorded in the __version_ext_crcs section.
+
Symbols and External Modules
----------------------------
--
2.47.1.613.gc27f4b7a9f-goog
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v13 5/5] rust: Use gendwarfksyms + extended modversions for CONFIG_MODVERSIONS
2025-01-03 17:37 [PATCH v13 0/5] Extended MODVERSIONS Support Matthew Maurer
` (3 preceding siblings ...)
2025-01-03 17:37 ` [PATCH v13 4/5] Documentation/kbuild: Document storage of symbol information Matthew Maurer
@ 2025-01-03 17:37 ` Matthew Maurer
2025-01-11 2:25 ` Masahiro Yamada
2025-01-10 17:38 ` [PATCH v13 0/5] Extended MODVERSIONS Support Masahiro Yamada
5 siblings, 1 reply; 12+ messages in thread
From: Matthew Maurer @ 2025-01-03 17:37 UTC (permalink / raw)
To: Michael Ellerman, Nicholas Piggin, Christophe Leroy, Naveen N Rao,
Madhavan Srinivasan, Luis Chamberlain, Petr Pavlu, Sami Tolvanen,
Daniel Gomez, Masahiro Yamada, Nathan Chancellor, Nicolas Schier,
Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Jonathan Corbet
Cc: linuxppc-dev, linux-kernel, linux-modules, linux-kbuild,
rust-for-linux, linux-doc, Matthew Maurer
From: Sami Tolvanen <samitolvanen@google.com>
Previously, two things stopped Rust from using MODVERSIONS:
1. Rust symbols are occasionally too long to be represented in the
original versions table
2. Rust types cannot be properly hashed by the existing genksyms
approach because:
* Looking up type definitions in Rust is more complex than C
* Type layout is potentially dependent on the compiler in Rust,
not just the source type declaration.
CONFIG_EXTENDED_MODVERSIONS addresses the first point, and
CONFIG_GENDWARFKSYMS the second. If Rust wants to use MODVERSIONS, allow
it to do so by selecting both features.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Co-developed-by: Matthew Maurer <mmaurer@google.com>
Signed-off-by: Matthew Maurer <mmaurer@google.com>
---
init/Kconfig | 3 ++-
rust/Makefile | 34 ++++++++++++++++++++++++++++++++--
2 files changed, 34 insertions(+), 3 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig
index c1f9eb3d5f2e892e977ba1425599502dc830f552..b60acfd9431e0ac2bf401ecb6523b5104ad31150 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1959,7 +1959,8 @@ config RUST
bool "Rust support"
depends on HAVE_RUST
depends on RUST_IS_AVAILABLE
- depends on !MODVERSIONS
+ select EXTENDED_MODVERSIONS if MODVERSIONS
+ depends on !MODVERSIONS || GENDWARFKSYMS
depends on !GCC_PLUGIN_RANDSTRUCT
depends on !RANDSTRUCT
depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
diff --git a/rust/Makefile b/rust/Makefile
index a40a3936126d603836e0ec9b42a1285916b60e45..80f970ad81f7989afe5ff2b5f633f50feb7f6006 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -329,10 +329,11 @@ $(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_extra = ;
$(obj)/bindings/bindings_helpers_generated.rs: $(src)/helpers/helpers.c FORCE
$(call if_changed_dep,bindgen)
+rust_exports = $(NM) -p --defined-only $(1) | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ { printf $(2),$(3) }'
+
quiet_cmd_exports = EXPORTS $@
cmd_exports = \
- $(NM) -p --defined-only $< \
- | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ {printf "EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3}' > $@
+ $(call rust_exports,$<,"EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3) > $@
$(obj)/exports_core_generated.h: $(obj)/core.o FORCE
$(call if_changed,exports)
@@ -401,11 +402,36 @@ ifneq ($(or $(CONFIG_ARM64),$(and $(CONFIG_RISCV),$(CONFIG_64BIT))),)
__ashlti3 __lshrti3
endif
+ifdef CONFIG_MODVERSIONS
+cmd_gendwarfksyms = $(if $(skip_gendwarfksyms),, \
+ $(call rust_exports,$@,"%s\n",$$3) | \
+ scripts/gendwarfksyms/gendwarfksyms \
+ $(if $(KBUILD_GENDWARFKSYMS_STABLE), --stable) \
+ $(if $(KBUILD_SYMTYPES), --symtypes $(@:.o=.symtypes),) \
+ $@ >> $(dot-target).cmd)
+endif
+
define rule_rustc_library
$(call cmd_and_fixdep,rustc_library)
$(call cmd,gen_objtooldep)
+ $(call cmd,gendwarfksyms)
endef
+define rule_rust_cc_library
+ $(call if_changed_rule,cc_o_c)
+ $(call cmd,force_checksrc)
+ $(call cmd,gendwarfksyms)
+endef
+
+# helpers.o uses the same export mechanism as Rust libraries, so ensure symbol
+# versions are calculated for the helpers too.
+$(obj)/helpers/helpers.o: $(src)/helpers/helpers.c $(recordmcount_source) FORCE
+ +$(call if_changed_rule,rust_cc_library)
+
+# Disable symbol versioning for exports.o to avoid conflicts with the actual
+# symbol versions generated from Rust objects.
+$(obj)/exports.o: private skip_gendwarfksyms = 1
+
$(obj)/core.o: private skip_clippy = 1
$(obj)/core.o: private skip_flags = -Wunreachable_pub
$(obj)/core.o: private rustc_objcopy = $(foreach sym,$(redirect-intrinsics),--redefine-sym $(sym)=__rust$(sym))
@@ -417,13 +443,16 @@ ifneq ($(or $(CONFIG_X86_64),$(CONFIG_X86_32)),)
$(obj)/core.o: scripts/target.json
endif
+$(obj)/compiler_builtins.o: private skip_gendwarfksyms = 1
$(obj)/compiler_builtins.o: private rustc_objcopy = -w -W '__*'
$(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE
+$(call if_changed_rule,rustc_library)
+$(obj)/build_error.o: private skip_gendwarfksyms = 1
$(obj)/build_error.o: $(src)/build_error.rs $(obj)/compiler_builtins.o FORCE
+$(call if_changed_rule,rustc_library)
+$(obj)/ffi.o: private skip_gendwarfksyms = 1
$(obj)/ffi.o: $(src)/ffi.rs $(obj)/compiler_builtins.o FORCE
+$(call if_changed_rule,rustc_library)
@@ -435,6 +464,7 @@ $(obj)/bindings.o: $(src)/bindings/lib.rs \
+$(call if_changed_rule,rustc_library)
$(obj)/uapi.o: private rustc_target_flags = --extern ffi
+$(obj)/uapi.o: private skip_gendwarfksyms = 1
$(obj)/uapi.o: $(src)/uapi/lib.rs \
$(obj)/ffi.o \
$(obj)/uapi/uapi_generated.rs FORCE
--
2.47.1.613.gc27f4b7a9f-goog
^ permalink raw reply related [flat|nested] 12+ messages in thread* Re: [PATCH v13 5/5] rust: Use gendwarfksyms + extended modversions for CONFIG_MODVERSIONS
2025-01-03 17:37 ` [PATCH v13 5/5] rust: Use gendwarfksyms + extended modversions for CONFIG_MODVERSIONS Matthew Maurer
@ 2025-01-11 2:25 ` Masahiro Yamada
2025-01-13 20:03 ` Sami Tolvanen
0 siblings, 1 reply; 12+ messages in thread
From: Masahiro Yamada @ 2025-01-11 2:25 UTC (permalink / raw)
To: Matthew Maurer
Cc: Michael Ellerman, Nicholas Piggin, Christophe Leroy, Naveen N Rao,
Madhavan Srinivasan, Luis Chamberlain, Petr Pavlu, Sami Tolvanen,
Daniel Gomez, Nathan Chancellor, Nicolas Schier, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
Jonathan Corbet, linuxppc-dev, linux-kernel, linux-modules,
linux-kbuild, rust-for-linux, linux-doc
On Sat, Jan 4, 2025 at 2:37 AM Matthew Maurer <mmaurer@google.com> wrote:
>
> From: Sami Tolvanen <samitolvanen@google.com>
>
> Previously, two things stopped Rust from using MODVERSIONS:
> 1. Rust symbols are occasionally too long to be represented in the
> original versions table
> 2. Rust types cannot be properly hashed by the existing genksyms
> approach because:
> * Looking up type definitions in Rust is more complex than C
> * Type layout is potentially dependent on the compiler in Rust,
> not just the source type declaration.
>
> CONFIG_EXTENDED_MODVERSIONS addresses the first point, and
> CONFIG_GENDWARFKSYMS the second. If Rust wants to use MODVERSIONS, allow
> it to do so by selecting both features.
>
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> Co-developed-by: Matthew Maurer <mmaurer@google.com>
> Signed-off-by: Matthew Maurer <mmaurer@google.com>
> ---
> init/Kconfig | 3 ++-
> rust/Makefile | 34 ++++++++++++++++++++++++++++++++--
> 2 files changed, 34 insertions(+), 3 deletions(-)
>
> diff --git a/init/Kconfig b/init/Kconfig
> index c1f9eb3d5f2e892e977ba1425599502dc830f552..b60acfd9431e0ac2bf401ecb6523b5104ad31150 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1959,7 +1959,8 @@ config RUST
> bool "Rust support"
> depends on HAVE_RUST
> depends on RUST_IS_AVAILABLE
> - depends on !MODVERSIONS
> + select EXTENDED_MODVERSIONS if MODVERSIONS
> + depends on !MODVERSIONS || GENDWARFKSYMS
> depends on !GCC_PLUGIN_RANDSTRUCT
> depends on !RANDSTRUCT
> depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
> diff --git a/rust/Makefile b/rust/Makefile
> index a40a3936126d603836e0ec9b42a1285916b60e45..80f970ad81f7989afe5ff2b5f633f50feb7f6006 100644
> --- a/rust/Makefile
> +++ b/rust/Makefile
> @@ -329,10 +329,11 @@ $(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_extra = ;
> $(obj)/bindings/bindings_helpers_generated.rs: $(src)/helpers/helpers.c FORCE
> $(call if_changed_dep,bindgen)
>
> +rust_exports = $(NM) -p --defined-only $(1) | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ { printf $(2),$(3) }'
> +
> quiet_cmd_exports = EXPORTS $@
> cmd_exports = \
> - $(NM) -p --defined-only $< \
> - | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ {printf "EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3}' > $@
> + $(call rust_exports,$<,"EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3) > $@
I noticed a nit:
Both of the two callsites of rust_exports pass
'$$3' to the last parameter instead of hardcoding it.
Is it a flexibility for future extensions?
I cannot think of any other use except for printing
the third column, i.e. symbol name.
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH v13 5/5] rust: Use gendwarfksyms + extended modversions for CONFIG_MODVERSIONS
2025-01-11 2:25 ` Masahiro Yamada
@ 2025-01-13 20:03 ` Sami Tolvanen
2025-01-14 1:22 ` Masahiro Yamada
0 siblings, 1 reply; 12+ messages in thread
From: Sami Tolvanen @ 2025-01-13 20:03 UTC (permalink / raw)
To: Masahiro Yamada
Cc: Matthew Maurer, Michael Ellerman, Nicholas Piggin,
Christophe Leroy, Naveen N Rao, Madhavan Srinivasan,
Luis Chamberlain, Petr Pavlu, Daniel Gomez, Nathan Chancellor,
Nicolas Schier, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Jonathan Corbet, linuxppc-dev, linux-kernel,
linux-modules, linux-kbuild, rust-for-linux, linux-doc
Hi Masahiro,
On Fri, Jan 10, 2025 at 6:26 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> On Sat, Jan 4, 2025 at 2:37 AM Matthew Maurer <mmaurer@google.com> wrote:
> >
> > From: Sami Tolvanen <samitolvanen@google.com>
> >
> > Previously, two things stopped Rust from using MODVERSIONS:
> > 1. Rust symbols are occasionally too long to be represented in the
> > original versions table
> > 2. Rust types cannot be properly hashed by the existing genksyms
> > approach because:
> > * Looking up type definitions in Rust is more complex than C
> > * Type layout is potentially dependent on the compiler in Rust,
> > not just the source type declaration.
> >
> > CONFIG_EXTENDED_MODVERSIONS addresses the first point, and
> > CONFIG_GENDWARFKSYMS the second. If Rust wants to use MODVERSIONS, allow
> > it to do so by selecting both features.
> >
> > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > Co-developed-by: Matthew Maurer <mmaurer@google.com>
> > Signed-off-by: Matthew Maurer <mmaurer@google.com>
> > ---
> > init/Kconfig | 3 ++-
> > rust/Makefile | 34 ++++++++++++++++++++++++++++++++--
> > 2 files changed, 34 insertions(+), 3 deletions(-)
> >
> > diff --git a/init/Kconfig b/init/Kconfig
> > index c1f9eb3d5f2e892e977ba1425599502dc830f552..b60acfd9431e0ac2bf401ecb6523b5104ad31150 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -1959,7 +1959,8 @@ config RUST
> > bool "Rust support"
> > depends on HAVE_RUST
> > depends on RUST_IS_AVAILABLE
> > - depends on !MODVERSIONS
> > + select EXTENDED_MODVERSIONS if MODVERSIONS
> > + depends on !MODVERSIONS || GENDWARFKSYMS
> > depends on !GCC_PLUGIN_RANDSTRUCT
> > depends on !RANDSTRUCT
> > depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
> > diff --git a/rust/Makefile b/rust/Makefile
> > index a40a3936126d603836e0ec9b42a1285916b60e45..80f970ad81f7989afe5ff2b5f633f50feb7f6006 100644
> > --- a/rust/Makefile
> > +++ b/rust/Makefile
> > @@ -329,10 +329,11 @@ $(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_extra = ;
> > $(obj)/bindings/bindings_helpers_generated.rs: $(src)/helpers/helpers.c FORCE
> > $(call if_changed_dep,bindgen)
> >
> > +rust_exports = $(NM) -p --defined-only $(1) | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ { printf $(2),$(3) }'
> > +
> > quiet_cmd_exports = EXPORTS $@
> > cmd_exports = \
> > - $(NM) -p --defined-only $< \
> > - | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ {printf "EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3}' > $@
> > + $(call rust_exports,$<,"EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3) > $@
>
> I noticed a nit:
>
> Both of the two callsites of rust_exports pass
> '$$3' to the last parameter instead of hardcoding it.
>
> Is it a flexibility for future extensions?
>
> I cannot think of any other use except for printing
> the third column, i.e. symbol name.
Good catch, the last parameter isn't necessary anymore. It was used in
early versions of the series to also pass symbol addresses to
gendwarfksyms, but that's not needed since we read the symbol table
directly now.
Sami
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH v13 5/5] rust: Use gendwarfksyms + extended modversions for CONFIG_MODVERSIONS
2025-01-13 20:03 ` Sami Tolvanen
@ 2025-01-14 1:22 ` Masahiro Yamada
2025-01-14 18:58 ` Sami Tolvanen
0 siblings, 1 reply; 12+ messages in thread
From: Masahiro Yamada @ 2025-01-14 1:22 UTC (permalink / raw)
To: Sami Tolvanen
Cc: Matthew Maurer, Michael Ellerman, Nicholas Piggin,
Christophe Leroy, Naveen N Rao, Madhavan Srinivasan,
Luis Chamberlain, Petr Pavlu, Daniel Gomez, Nathan Chancellor,
Nicolas Schier, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Jonathan Corbet, linuxppc-dev, linux-kernel,
linux-modules, linux-kbuild, rust-for-linux, linux-doc
On Tue, Jan 14, 2025 at 5:04 AM Sami Tolvanen <samitolvanen@google.com> wrote:
>
> Hi Masahiro,
>
> On Fri, Jan 10, 2025 at 6:26 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> >
> > On Sat, Jan 4, 2025 at 2:37 AM Matthew Maurer <mmaurer@google.com> wrote:
> > >
> > > From: Sami Tolvanen <samitolvanen@google.com>
> > >
> > > Previously, two things stopped Rust from using MODVERSIONS:
> > > 1. Rust symbols are occasionally too long to be represented in the
> > > original versions table
> > > 2. Rust types cannot be properly hashed by the existing genksyms
> > > approach because:
> > > * Looking up type definitions in Rust is more complex than C
> > > * Type layout is potentially dependent on the compiler in Rust,
> > > not just the source type declaration.
> > >
> > > CONFIG_EXTENDED_MODVERSIONS addresses the first point, and
> > > CONFIG_GENDWARFKSYMS the second. If Rust wants to use MODVERSIONS, allow
> > > it to do so by selecting both features.
> > >
> > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > > Co-developed-by: Matthew Maurer <mmaurer@google.com>
> > > Signed-off-by: Matthew Maurer <mmaurer@google.com>
> > > ---
> > > init/Kconfig | 3 ++-
> > > rust/Makefile | 34 ++++++++++++++++++++++++++++++++--
> > > 2 files changed, 34 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/init/Kconfig b/init/Kconfig
> > > index c1f9eb3d5f2e892e977ba1425599502dc830f552..b60acfd9431e0ac2bf401ecb6523b5104ad31150 100644
> > > --- a/init/Kconfig
> > > +++ b/init/Kconfig
> > > @@ -1959,7 +1959,8 @@ config RUST
> > > bool "Rust support"
> > > depends on HAVE_RUST
> > > depends on RUST_IS_AVAILABLE
> > > - depends on !MODVERSIONS
> > > + select EXTENDED_MODVERSIONS if MODVERSIONS
> > > + depends on !MODVERSIONS || GENDWARFKSYMS
> > > depends on !GCC_PLUGIN_RANDSTRUCT
> > > depends on !RANDSTRUCT
> > > depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
> > > diff --git a/rust/Makefile b/rust/Makefile
> > > index a40a3936126d603836e0ec9b42a1285916b60e45..80f970ad81f7989afe5ff2b5f633f50feb7f6006 100644
> > > --- a/rust/Makefile
> > > +++ b/rust/Makefile
> > > @@ -329,10 +329,11 @@ $(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_extra = ;
> > > $(obj)/bindings/bindings_helpers_generated.rs: $(src)/helpers/helpers.c FORCE
> > > $(call if_changed_dep,bindgen)
> > >
> > > +rust_exports = $(NM) -p --defined-only $(1) | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ { printf $(2),$(3) }'
> > > +
> > > quiet_cmd_exports = EXPORTS $@
> > > cmd_exports = \
> > > - $(NM) -p --defined-only $< \
> > > - | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ {printf "EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3}' > $@
> > > + $(call rust_exports,$<,"EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3) > $@
> >
> > I noticed a nit:
> >
> > Both of the two callsites of rust_exports pass
> > '$$3' to the last parameter instead of hardcoding it.
> >
> > Is it a flexibility for future extensions?
> >
> > I cannot think of any other use except for printing
> > the third column, i.e. symbol name.
>
> Good catch, the last parameter isn't necessary anymore. It was used in
> early versions of the series to also pass symbol addresses to
> gendwarfksyms, but that's not needed since we read the symbol table
> directly now.
If you submit a diff, I will squash it to 5/5.
(You do not need to input commit description body)
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH v13 5/5] rust: Use gendwarfksyms + extended modversions for CONFIG_MODVERSIONS
2025-01-14 1:22 ` Masahiro Yamada
@ 2025-01-14 18:58 ` Sami Tolvanen
2025-01-17 23:53 ` Masahiro Yamada
0 siblings, 1 reply; 12+ messages in thread
From: Sami Tolvanen @ 2025-01-14 18:58 UTC (permalink / raw)
To: Masahiro Yamada
Cc: Matthew Maurer, Michael Ellerman, Nicholas Piggin,
Christophe Leroy, Naveen N Rao, Madhavan Srinivasan,
Luis Chamberlain, Petr Pavlu, Daniel Gomez, Nathan Chancellor,
Nicolas Schier, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Jonathan Corbet, linuxppc-dev, linux-kernel,
linux-modules, linux-kbuild, rust-for-linux, linux-doc
On Tue, Jan 14, 2025 at 10:22:15AM +0900, Masahiro Yamada wrote:
> On Tue, Jan 14, 2025 at 5:04 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> >
> > Hi Masahiro,
> >
> > On Fri, Jan 10, 2025 at 6:26 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> > >
> > > On Sat, Jan 4, 2025 at 2:37 AM Matthew Maurer <mmaurer@google.com> wrote:
> > > >
> > > > From: Sami Tolvanen <samitolvanen@google.com>
> > > >
> > > > Previously, two things stopped Rust from using MODVERSIONS:
> > > > 1. Rust symbols are occasionally too long to be represented in the
> > > > original versions table
> > > > 2. Rust types cannot be properly hashed by the existing genksyms
> > > > approach because:
> > > > * Looking up type definitions in Rust is more complex than C
> > > > * Type layout is potentially dependent on the compiler in Rust,
> > > > not just the source type declaration.
> > > >
> > > > CONFIG_EXTENDED_MODVERSIONS addresses the first point, and
> > > > CONFIG_GENDWARFKSYMS the second. If Rust wants to use MODVERSIONS, allow
> > > > it to do so by selecting both features.
> > > >
> > > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > > > Co-developed-by: Matthew Maurer <mmaurer@google.com>
> > > > Signed-off-by: Matthew Maurer <mmaurer@google.com>
> > > > ---
> > > > init/Kconfig | 3 ++-
> > > > rust/Makefile | 34 ++++++++++++++++++++++++++++++++--
> > > > 2 files changed, 34 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/init/Kconfig b/init/Kconfig
> > > > index c1f9eb3d5f2e892e977ba1425599502dc830f552..b60acfd9431e0ac2bf401ecb6523b5104ad31150 100644
> > > > --- a/init/Kconfig
> > > > +++ b/init/Kconfig
> > > > @@ -1959,7 +1959,8 @@ config RUST
> > > > bool "Rust support"
> > > > depends on HAVE_RUST
> > > > depends on RUST_IS_AVAILABLE
> > > > - depends on !MODVERSIONS
> > > > + select EXTENDED_MODVERSIONS if MODVERSIONS
> > > > + depends on !MODVERSIONS || GENDWARFKSYMS
> > > > depends on !GCC_PLUGIN_RANDSTRUCT
> > > > depends on !RANDSTRUCT
> > > > depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
> > > > diff --git a/rust/Makefile b/rust/Makefile
> > > > index a40a3936126d603836e0ec9b42a1285916b60e45..80f970ad81f7989afe5ff2b5f633f50feb7f6006 100644
> > > > --- a/rust/Makefile
> > > > +++ b/rust/Makefile
> > > > @@ -329,10 +329,11 @@ $(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_extra = ;
> > > > $(obj)/bindings/bindings_helpers_generated.rs: $(src)/helpers/helpers.c FORCE
> > > > $(call if_changed_dep,bindgen)
> > > >
> > > > +rust_exports = $(NM) -p --defined-only $(1) | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ { printf $(2),$(3) }'
> > > > +
> > > > quiet_cmd_exports = EXPORTS $@
> > > > cmd_exports = \
> > > > - $(NM) -p --defined-only $< \
> > > > - | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ {printf "EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3}' > $@
> > > > + $(call rust_exports,$<,"EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3) > $@
> > >
> > > I noticed a nit:
> > >
> > > Both of the two callsites of rust_exports pass
> > > '$$3' to the last parameter instead of hardcoding it.
> > >
> > > Is it a flexibility for future extensions?
> > >
> > > I cannot think of any other use except for printing
> > > the third column, i.e. symbol name.
> >
> > Good catch, the last parameter isn't necessary anymore. It was used in
> > early versions of the series to also pass symbol addresses to
> > gendwarfksyms, but that's not needed since we read the symbol table
> > directly now.
>
> If you submit a diff, I will squash it to 5/5.
> (You do not need to input commit description body)
Thanks, here's a diff that drops the last parameter.
Sami
diff --git a/rust/Makefile b/rust/Makefile
index 80f970ad81f7..ab300bfb46f6 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -329,11 +329,11 @@ $(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_extra = ;
$(obj)/bindings/bindings_helpers_generated.rs: $(src)/helpers/helpers.c FORCE
$(call if_changed_dep,bindgen)
-rust_exports = $(NM) -p --defined-only $(1) | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ { printf $(2),$(3) }'
+rust_exports = $(NM) -p --defined-only $(1) | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ { printf $(2),$$3 }'
quiet_cmd_exports = EXPORTS $@
cmd_exports = \
- $(call rust_exports,$<,"EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3) > $@
+ $(call rust_exports,$<,"EXPORT_SYMBOL_RUST_GPL(%s);\n") > $@
$(obj)/exports_core_generated.h: $(obj)/core.o FORCE
$(call if_changed,exports)
@@ -404,7 +404,7 @@ endif
ifdef CONFIG_MODVERSIONS
cmd_gendwarfksyms = $(if $(skip_gendwarfksyms),, \
- $(call rust_exports,$@,"%s\n",$$3) | \
+ $(call rust_exports,$@,"%s\n") | \
scripts/gendwarfksyms/gendwarfksyms \
$(if $(KBUILD_GENDWARFKSYMS_STABLE), --stable) \
$(if $(KBUILD_SYMTYPES), --symtypes $(@:.o=.symtypes),) \
^ permalink raw reply related [flat|nested] 12+ messages in thread* Re: [PATCH v13 5/5] rust: Use gendwarfksyms + extended modversions for CONFIG_MODVERSIONS
2025-01-14 18:58 ` Sami Tolvanen
@ 2025-01-17 23:53 ` Masahiro Yamada
0 siblings, 0 replies; 12+ messages in thread
From: Masahiro Yamada @ 2025-01-17 23:53 UTC (permalink / raw)
To: Sami Tolvanen
Cc: Matthew Maurer, Michael Ellerman, Nicholas Piggin,
Christophe Leroy, Naveen N Rao, Madhavan Srinivasan,
Luis Chamberlain, Petr Pavlu, Daniel Gomez, Nathan Chancellor,
Nicolas Schier, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Jonathan Corbet, linuxppc-dev, linux-kernel,
linux-modules, linux-kbuild, rust-for-linux, linux-doc
On Wed, Jan 15, 2025 at 3:58 AM Sami Tolvanen <samitolvanen@google.com> wrote:
>
> On Tue, Jan 14, 2025 at 10:22:15AM +0900, Masahiro Yamada wrote:
> > On Tue, Jan 14, 2025 at 5:04 AM Sami Tolvanen <samitolvanen@google.com> wrote:
> > >
> > > Hi Masahiro,
> > >
> > > On Fri, Jan 10, 2025 at 6:26 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> > > >
> > > > On Sat, Jan 4, 2025 at 2:37 AM Matthew Maurer <mmaurer@google.com> wrote:
> > > > >
> > > > > From: Sami Tolvanen <samitolvanen@google.com>
> > > > >
> > > > > Previously, two things stopped Rust from using MODVERSIONS:
> > > > > 1. Rust symbols are occasionally too long to be represented in the
> > > > > original versions table
> > > > > 2. Rust types cannot be properly hashed by the existing genksyms
> > > > > approach because:
> > > > > * Looking up type definitions in Rust is more complex than C
> > > > > * Type layout is potentially dependent on the compiler in Rust,
> > > > > not just the source type declaration.
> > > > >
> > > > > CONFIG_EXTENDED_MODVERSIONS addresses the first point, and
> > > > > CONFIG_GENDWARFKSYMS the second. If Rust wants to use MODVERSIONS, allow
> > > > > it to do so by selecting both features.
> > > > >
> > > > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > > > > Co-developed-by: Matthew Maurer <mmaurer@google.com>
> > > > > Signed-off-by: Matthew Maurer <mmaurer@google.com>
> > > > > ---
> > > > > init/Kconfig | 3 ++-
> > > > > rust/Makefile | 34 ++++++++++++++++++++++++++++++++--
> > > > > 2 files changed, 34 insertions(+), 3 deletions(-)
> > > > >
> > > > > diff --git a/init/Kconfig b/init/Kconfig
> > > > > index c1f9eb3d5f2e892e977ba1425599502dc830f552..b60acfd9431e0ac2bf401ecb6523b5104ad31150 100644
> > > > > --- a/init/Kconfig
> > > > > +++ b/init/Kconfig
> > > > > @@ -1959,7 +1959,8 @@ config RUST
> > > > > bool "Rust support"
> > > > > depends on HAVE_RUST
> > > > > depends on RUST_IS_AVAILABLE
> > > > > - depends on !MODVERSIONS
> > > > > + select EXTENDED_MODVERSIONS if MODVERSIONS
> > > > > + depends on !MODVERSIONS || GENDWARFKSYMS
> > > > > depends on !GCC_PLUGIN_RANDSTRUCT
> > > > > depends on !RANDSTRUCT
> > > > > depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
> > > > > diff --git a/rust/Makefile b/rust/Makefile
> > > > > index a40a3936126d603836e0ec9b42a1285916b60e45..80f970ad81f7989afe5ff2b5f633f50feb7f6006 100644
> > > > > --- a/rust/Makefile
> > > > > +++ b/rust/Makefile
> > > > > @@ -329,10 +329,11 @@ $(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_extra = ;
> > > > > $(obj)/bindings/bindings_helpers_generated.rs: $(src)/helpers/helpers.c FORCE
> > > > > $(call if_changed_dep,bindgen)
> > > > >
> > > > > +rust_exports = $(NM) -p --defined-only $(1) | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ { printf $(2),$(3) }'
> > > > > +
> > > > > quiet_cmd_exports = EXPORTS $@
> > > > > cmd_exports = \
> > > > > - $(NM) -p --defined-only $< \
> > > > > - | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ {printf "EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3}' > $@
> > > > > + $(call rust_exports,$<,"EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3) > $@
> > > >
> > > > I noticed a nit:
> > > >
> > > > Both of the two callsites of rust_exports pass
> > > > '$$3' to the last parameter instead of hardcoding it.
> > > >
> > > > Is it a flexibility for future extensions?
> > > >
> > > > I cannot think of any other use except for printing
> > > > the third column, i.e. symbol name.
> > >
> > > Good catch, the last parameter isn't necessary anymore. It was used in
> > > early versions of the series to also pass symbol addresses to
> > > gendwarfksyms, but that's not needed since we read the symbol table
> > > directly now.
> >
> > If you submit a diff, I will squash it to 5/5.
> > (You do not need to input commit description body)
>
> Thanks, here's a diff that drops the last parameter.
Squashed.
Thanks!
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH v13 0/5] Extended MODVERSIONS Support
2025-01-03 17:37 [PATCH v13 0/5] Extended MODVERSIONS Support Matthew Maurer
` (4 preceding siblings ...)
2025-01-03 17:37 ` [PATCH v13 5/5] rust: Use gendwarfksyms + extended modversions for CONFIG_MODVERSIONS Matthew Maurer
@ 2025-01-10 17:38 ` Masahiro Yamada
5 siblings, 0 replies; 12+ messages in thread
From: Masahiro Yamada @ 2025-01-10 17:38 UTC (permalink / raw)
To: Matthew Maurer
Cc: Michael Ellerman, Nicholas Piggin, Christophe Leroy, Naveen N Rao,
Madhavan Srinivasan, Luis Chamberlain, Petr Pavlu, Sami Tolvanen,
Daniel Gomez, Nathan Chancellor, Nicolas Schier, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
Jonathan Corbet, linuxppc-dev, linux-kernel, linux-modules,
linux-kbuild, rust-for-linux, linux-doc
On Sat, Jan 4, 2025 at 2:37 AM Matthew Maurer <mmaurer@google.com> wrote:
>
> This patch series is intended for use alongside the Implement DWARF
> modversions series [1] to enable RUST and MODVERSIONS at the same
> time.
>
> Elsewhere, we've seen a desire for long symbol name support for LTO
> symbol names [2], and the previous series came up [3] as a possible
> solution rather than hashing, which some have objected [4] to.
>
> This series adds a MODVERSIONS format which uses a section per column.
> This avoids userspace tools breaking if we need to make a similar change
> to the format in the future - we would do so by adding a new section,
> rather than editing the struct definition. In the new format, the name
> section is formatted as a concatenated sequence of NUL-terminated
> strings, which allows for arbitrary length names.
>
> Emitting the extended format is guarded by CONFIG_EXTENDED_MODVERSIONS,
> but the kernel always knows how to validate both the original and
> extended formats.
>
> Emitting the existing format is now guarded by CONFIG_BASIC_MODVERSIONS,
> but it is enabled by default when MODVERSIONS is enabled and must be
> explicitly disabled by the user.
>
> Disabling CONFIG_BASIC_MODVERSIONS may cause some userspace tools to be
> unable to retrieve CRCs until they are patched to understand the new
> location. Even with CONFIG_BASIC_MODVERSIONS enabled, those tools will
> be unable to read the CRCs for long symbols until they are updated to
> read the new format. This is not expected to interfere with normal
> operation, as the primary use for CRCs embedded in the module is
> load-time verification by the kernel. Recording and monitoring of CRCs
> is typically done through Module.symvers.
>
> Selecting RUST and MODVERSIONS is now possible if GENDWARFKSYMS is
> selected, and will implicitly select EXTENDED_MODVERSIONS.
>
> This series depends upon DWARF-based versions [1] and Masahiro's u32
> fixup patch [5].
>
> [1] https://lore.kernel.org/lkml/20241219210736.2990838-20-samitolvanen@google.com/
> [2] https://lore.kernel.org/lkml/20240605032120.3179157-1-song@kernel.org/
> [3] https://lore.kernel.org/lkml/ZoxbEEsK40ASi1cY@bombadil.infradead.org/
> [4] https://lore.kernel.org/lkml/0b2697fd-7ab4-469f-83a6-ec9ebc701ba0@suse.com/
> [5] https://lore.kernel.org/linux-kbuild/20241228154603.2234284-1-masahiroy@kernel.org
>
> Changes in v13:
> - Fixed up missed s32 usage (Thanks Sami).
Applied to linux-kbuild.
Thanks.
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 12+ messages in thread