[PATCH v4 3/3] module/kallsyms: Ignore local labels and mapping symbols during module load

[Tiezhu Yang <yangtiezhu@loongson.cn>]

The compiler toolchains may generate local labels and mapping symbols on
certain architectures like LoongArch for optimizations and relocations.

While these local labels and mapping symbols are already ignored during
runtime lookups via find_kallsyms_symbol(), they still leak into kallsyms
for loaded modules because layout_symtab() and add_kallsyms() don't ignore
them during load time.

Consequently, tracing tools like bpftrace (which do not perform internal
filtering, unlike perf) resolve identical addresses into confusing local
labels instead of actual clear C function names.

Fix this by integrating the is_ignored_kernel_symbol() check directly into
is_core_symbol(). This ensures these unneeded symbols are stripped during
module load time, keeping /proc/kallsyms clean and resulting in accurate
call stacks.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
---
 kernel/module/kallsyms.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index d75c9f60d360..1ff8ce857d92 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -89,6 +89,9 @@ static bool is_core_symbol(struct module *mod, const struct load_info *info,
 	    !src->st_name)
 		return false;
 
+	if (is_ignored_kernel_symbol(&info->strtab[src->st_name]))
+		return false;
+
 #ifdef CONFIG_KALLSYMS_ALL
 	if (src->st_shndx == info->index.pcpu)
 		return true;
-- 
2.42.0