[PATCH 1/1] objtool/klp: Fix is_uncorrelated_static_local() for Clang naming

[PATCH 1/1] objtool/klp: Fix is_uncorrelated_static_local() for Clang naming

[Joe Lawrence]

For naming function-local static locals, GCC uses "<var>.<id>":
  e.g. __already_done.15

while Clang uses "<func>.<var>" with optional ".<id>"
  e.g. create_worker.__already_done.111

The existing is_uncorrelated_static_local() check only matches the GCC
convention where the variable name is a prefix.  Handle both cases by
checking for a prefix match (GCC) and by checking after the first dot
separator (Clang).

Fixes: dd590d4d57eb ("objtool/klp: Introduce klp diff subcommand for diffing object files")
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
 tools/objtool/klp-diff.c | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
index 85281b3b021f..382ca1d8d391 100644
--- a/tools/objtool/klp-diff.c
+++ b/tools/objtool/klp-diff.c
@@ -241,16 +241,17 @@ static struct symbol *next_file_symbol(struct elf *elf, struct symbol *sym)
 static bool is_uncorrelated_static_local(struct symbol *sym)
 {
 	static const char * const vars[] = {
-		"__already_done.",
-		"__func__.",
-		"__key.",
-		"__warned.",
-		"_entry.",
-		"_entry_ptr.",
-		"_rs.",
-		"descriptor.",
-		"CSWTCH.",
+		"__already_done",
+		"__func__",
+		"__key",
+		"__warned",
+		"_entry",
+		"_entry_ptr",
+		"_rs",
+		"descriptor",
+		"CSWTCH",
 	};
+	const char *dot;
 
 	if (!is_object_sym(sym) || !is_local_sym(sym))
 		return false;
@@ -258,8 +259,18 @@ static bool is_uncorrelated_static_local(struct symbol *sym)
 	if (!strcmp(sym->sec->name, ".data.once"))
 		return true;
 
+	dot = strchr(sym->name, '.');
 	for (int i = 0; i < ARRAY_SIZE(vars); i++) {
-		if (strstarts(sym->name, vars[i]))
+		size_t len = strlen(vars[i]);
+
+		/* GCC: "<var>.<id>" e.g. "__already_done.15" */
+		if (strstarts(sym->name, vars[i]) &&
+		    (sym->name[len] == '.' || sym->name[len] == '\0'))
+			return true;
+
+		/* Clang: "<func>.<var>[.<id>]" e.g. "create_worker.__already_done.111" */
+		if (dot && strstarts(dot + 1, vars[i]) &&
+		    (dot[1 + len] == '.' || dot[1 + len] == '\0'))
 			return true;
 	}
 
-- 
2.53.0

Re: [PATCH 1/1] objtool/klp: Fix is_uncorrelated_static_local() for Clang naming

[Song Liu]

On Wed, Apr 8, 2026 at 7:49 AM Joe Lawrence <joe.lawrence@redhat.com> wrote:
>
> For naming function-local static locals, GCC uses "<var>.<id>":
>   e.g. __already_done.15
>
> while Clang uses "<func>.<var>" with optional ".<id>"
>   e.g. create_worker.__already_done.111
>
> The existing is_uncorrelated_static_local() check only matches the GCC
> convention where the variable name is a prefix.  Handle both cases by
> checking for a prefix match (GCC) and by checking after the first dot
> separator (Clang).
>
> Fixes: dd590d4d57eb ("objtool/klp: Introduce klp diff subcommand for diffing object files")
> Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>

LGTM.

Acked-by: Song Liu <song@kernel.org>