linux-kernel - [PATCH v1 4/7] modpost: Make mod_device

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Message-ID: <ffea56aecdd48eb37b7420f91abfd2dfff75c3b7.1745591072.git.legion@kernel.org>
Date: Sat, 26 Apr 2025 18:16:35 +0200
From: Alexey Gladkov <legion@...nel.org>
To: Luis Chamberlain <mcgrof@...nel.org>,
	Petr Pavlu <petr.pavlu@...e.com>,
	Sami Tolvanen <samitolvanen@...gle.com>,
	Daniel Gomez <da.gomez@...sung.com>,
	Masahiro Yamada <masahiroy@...nel.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Nicolas Schier <nicolas.schier@...ux.dev>
Cc: linux-kernel@...r.kernel.org,
	linux-modules@...r.kernel.org,
	linux-kbuild@...r.kernel.org,
	Alexey Gladkov <legion@...nel.org>
Subject: [PATCH v1 4/7] modpost: Make mod_device_table aliases more unique

In order to avoid symbol conflicts if they appear in the same binary, a
more unique alias identifier can be generated.

Signed-off-by: Alexey Gladkov <legion@...nel.org>
---
 include/linux/module.h   | 14 ++++++++++++--
 scripts/mod/file2alias.c | 18 ++++++++++++++----
 2 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/include/linux/module.h b/include/linux/module.h
index e987fd62c734..7250b4a527ec 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -247,10 +247,20 @@ extern void cleanup_module(void);
 /* What your module does. */
 #define MODULE_DESCRIPTION(_description) MODULE_INFO(description, _description)
 
+/* Format: __mod_device_table__<counter>__kmod_<modname>__<type>__<name> */
+#define __mod_device_table(type, name)	\
+	__PASTE(__mod_device_table__,	\
+	__PASTE(__COUNTER__,		\
+	__PASTE(__,			\
+	__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)					\
-extern typeof(name) __mod_device_table__##type##__##name		\
+#define MODULE_DEVICE_TABLE(type, name)			\
+extern typeof(name) __mod_device_table(type, name)	\
   __attribute__ ((unused, alias(__stringify(name))))
 #else  /* !MODULE */
 #define MODULE_DEVICE_TABLE(type, name)
diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index 00586119a25b..dff1799a4c79 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__<counter>__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)
-- 
2.49.0