[PATCH v7 6/8] modpost: Add modname to mod_device_table alias

Alexey Gladkov
2025-08-18T16:58:15Z

At this point, if a symbol is compiled as part of the kernel,
information about which module the symbol belongs to is lost.

To save this it is possible to add the module name to the alias name.
It's not very pretty, but it's possible for now.

Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: rust-for-linux@vger.kernel.org
Signed-off-by: Alexey Gladkov <legion@kernel.org>
Acked-by: Danilo Krummrich <dakr@kernel.org>
---
include/linux/module.h | 14 +++++++++++++-
rust/kernel/device_id.rs | 8 ++++----
scripts/mod/file2alias.c | 18 ++++++++++++++----
3 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/include/linux/module.h b/include/linux/module.h
index 3319a5269d286..e31ee29fac6b7 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -244,10 +244,22 @@ struct module_kobject *lookup_or_create_module_kobject(const char *name);
/* What your module does. */
#define MODULE_DESCRIPTION(_description) MODULE_INFO(description, _description)

+/*
+ * Format: __mod_device_table__kmod_<modname>__<type>__<name>
+ * Parts of the string `__kmod_` and `__` are used as delimiters when parsing
+ * a symbol in file2alias.c
+ */
+#define __mod_device_table(type, name) \
+ __PASTE(__mod_device_table__, \
+ __PASTE(__KBUILD_MODNAME, \
+ __PASTE(__, \
+ __PASTE(type, \
+ __PASTE(__, name)))))
+
#ifdef MODULE
/* Creates an alias so file2alias.c can find device table. */
#define MODULE_DEVICE_TABLE(type, name) \
-static typeof(name) __mod_device_table__##type##__##name \
+static typeof(name) __mod_device_table(type, name) \
__attribute__ ((used, alias(__stringify(name))))
#else /* !MODULE */
#define MODULE_DEVICE_TABLE(type, name)
diff --git a/rust/kernel/device_id.rs b/rust/kernel/device_id.rs
index 70d57814ff79b..62c42da12e9de 100644
--- a/rust/kernel/device_id.rs
+++ b/rust/kernel/device_id.rs
@@ -195,10 +195,10 @@ macro_rules! module_device_table {
($table_type: literal, $module_table_name:ident, $table_name:ident) => {
#[rustfmt::skip]
#[export_name =
- concat!("__mod_device_table__", $table_type,
- "__", module_path!(),
- "_", line!(),
- "_", stringify!($table_name))
+ concat!("__mod_device_table__", line!(),
+ "__kmod_", module_path!(),
+ "__", $table_type,
+ "__", stringify!($table_name))
]
static $module_table_name: [::core::mem::MaybeUninit<u8>; $table_name.raw_ids().size()] =
unsafe { ::core::mem::transmute_copy($table_name.raw_ids()) };
diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index 00586119a25b7..13021266a18f8 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -1476,8 +1476,8 @@ void handle_moddevtable(struct module *mod, struct elf_info *info,
{
void *symval;
char *zeros = NULL;
- const char *type, *name;
- size_t typelen;
+ const char *type, *name, *modname;
+ size_t typelen, modnamelen;
static const char *prefix = "__mod_device_table__";

/* We're looking for a section relative symbol */
@@ -1488,10 +1488,20 @@ void handle_moddevtable(struct module *mod, struct elf_info *info,
if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT)
return;

- /* All our symbols are of form __mod_device_table__<type>__<name>. */
+ /* All our symbols are of form __mod_device_table__kmod_<modname>__<type>__<name>. */
if (!strstarts(symname, prefix))
return;
- type = symname + strlen(prefix);
+
+ modname = strstr(symname, "__kmod_");
+ if (!modname)
+ return;
+ modname += strlen("__kmod_");
+
+ type = strstr(modname, "__");
+ if (!type)
+ return;
+ modnamelen = type - modname;
+ type += strlen("__");

name = strstr(type, "__");
if (!name)
--
2.50.1