[PATCH v3 3/3] module/kallsyms: Filter out local and mapping symbols during module load

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

While the symbols are already filtered out during runtime lookups via
find_kallsyms_symbol(), they still leak into /proc/kallsyms for loaded
modules because layout_symtab() and add_kallsyms() do not filter 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_local_mapping_symbol() check directly into
the newly introduced is_kept_symbol() helper. 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>
---
 kernel/module/kallsyms.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index ff8d904afe56..cc2a68956e43 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c

@@ -89,6 +89,9 @@ static bool is_kept_symbol(struct module *mod, const struct load_info *info,
 	    !src->st_name)
 		return false;
 
+	if (is_local_mapping_symbol(&info->strtab[src->st_name]))
+		return false;
+
 #ifdef CONFIG_KALLSYMS_ALL
 	if (src->st_shndx == info->index.pcpu)
 		return true;

-- 
2.42.0