[PATCH v2] modpost: Ignore Clang LTO suffixes in symbol matching

[PATCH v2] modpost: Ignore Clang LTO suffixes in symbol matching

[xur]

From: Rong Xu <xur@google.com>

When building the kernel with Clang ThinLTO enabled, the compiler
can mangle static variable names by appending suffixes such as
".llvm.<hash>" to prevent naming collisions across translation units.

This name mangling breaks the section mismatch whitelisting in modpost.
modpost relies on glob patterns (e.g., "*_ops" or "*_probe") to identify
safe references between permanent data and initialization code. Because
the LTO suffix modifies the end of the symbol name, legitimately
whitelisted structures fail the match, resulting in false positive
warnings.

For example, a static pernet_operations struct triggers the following:

  WARNING: modpost: vmlinux: section mismatch in reference: \
  ping_v4_net_ops.llvm.5641696707737373282 (section: .data) -> \
  ping_v4_proc_init_net (section: .init.text)

Fix this by ignoring "*_ops.llvm.*" in "from" symbol names (the same
as "*_ops").

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202606111233.kM8oo8Df-lkp@intel.com/
Signed-off-by: Rong Xu <xur@google.com>
---
 scripts/mod/modpost.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index d592548cbd60..a7b72a81d248 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -969,7 +969,7 @@ static int secref_whitelist(const char *fromsec, const char *fromsym,
 	/* symbols in data sections that may refer to any init/exit sections */
 	if (match(fromsec, PATTERNS(DATA_SECTIONS)) &&
 	    match(tosec, PATTERNS(ALL_INIT_SECTIONS, ALL_EXIT_SECTIONS)) &&
-	    match(fromsym, PATTERNS("*_ops", "*_console")))
+	    match(fromsym, PATTERNS("*_ops", "*_ops.llvm.*", "*_console")))
 		return 0;
 
 	/* Check for pattern 3 */

base-commit: e771677c937da5808f7b6c1f0e4a97ec1a84f8a8
-- 
2.55.0.rc0.738.g0c8ab3ebcc-goog

Re: [PATCH v2] modpost: Ignore Clang LTO suffixes in symbol matching

[Rong Xu]

Changelog:  This V2 integrated reviews from  Petr Pavlu
<petr.pavlu@suse.com> and  Nathan Chancellor <nathan@kernel.org> to
use a more direct fix.

Thanks,

Rong

On Wed, Jun 17, 2026 at 3:46 PM <xur@google.com> wrote:
>
> From: Rong Xu <xur@google.com>
>
> When building the kernel with Clang ThinLTO enabled, the compiler
> can mangle static variable names by appending suffixes such as
> ".llvm.<hash>" to prevent naming collisions across translation units.
>
> This name mangling breaks the section mismatch whitelisting in modpost.
> modpost relies on glob patterns (e.g., "*_ops" or "*_probe") to identify
> safe references between permanent data and initialization code. Because
> the LTO suffix modifies the end of the symbol name, legitimately
> whitelisted structures fail the match, resulting in false positive
> warnings.
>
> For example, a static pernet_operations struct triggers the following:
>
>   WARNING: modpost: vmlinux: section mismatch in reference: \
>   ping_v4_net_ops.llvm.5641696707737373282 (section: .data) -> \
>   ping_v4_proc_init_net (section: .init.text)
>
> Fix this by ignoring "*_ops.llvm.*" in "from" symbol names (the same
> as "*_ops").
>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202606111233.kM8oo8Df-lkp@intel.com/
> Signed-off-by: Rong Xu <xur@google.com>
> ---
>  scripts/mod/modpost.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index d592548cbd60..a7b72a81d248 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -969,7 +969,7 @@ static int secref_whitelist(const char *fromsec, const char *fromsym,
>         /* symbols in data sections that may refer to any init/exit sections */
>         if (match(fromsec, PATTERNS(DATA_SECTIONS)) &&
>             match(tosec, PATTERNS(ALL_INIT_SECTIONS, ALL_EXIT_SECTIONS)) &&
> -           match(fromsym, PATTERNS("*_ops", "*_console")))
> +           match(fromsym, PATTERNS("*_ops", "*_ops.llvm.*", "*_console")))
>                 return 0;
>
>         /* Check for pattern 3 */
>
> base-commit: e771677c937da5808f7b6c1f0e4a97ec1a84f8a8
> --
> 2.55.0.rc0.738.g0c8ab3ebcc-goog
>

Re: [PATCH v2] modpost: Ignore Clang LTO suffixes in symbol matching

[Nathan Chancellor]

On Wed, 17 Jun 2026 15:46:23 -0700, xur@google.com wrote:
> modpost: Ignore Clang LTO suffixes in symbol matching

Sashiko notes that the console variables may need the same fix but I
have tried building several configurations with distributed ThinLTO and
I do not see any modpost warnings so we can just wait to address that
until later if necessary.

Applied to

  https://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux.git kbuild-next-unstable

Thanks!

[1/1] modpost: Ignore Clang LTO suffixes in symbol matching
      https://git.kernel.org/kbuild/c/9a289cc425bf4

Please look out for regression or issue reports or other follow up
comments, as they may result in the patch/series getting dropped or
reverted. Patches applied to an "unstable" branch are accepted pending
wider testing in -next and any post-commit review; they will generally
be moved to the main branch in a week if no issues are found.

Best regards,
-- 
Cheers,
Nathan