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

Changelog:  This V2 integrated reviews from  Petr Pavlu
<[email protected]> and  Nathan Chancellor <[email protected]> to
use a more direct fix.

Thanks,

Rong

On Wed, Jun 17, 2026 at 3:46 PM <[email protected]> wrote:
>
> From: Rong Xu <[email protected]>
>
> 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 <[email protected]>
> Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
> Signed-off-by: Rong Xu <[email protected]>
> ---
>  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
>