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

[Tiezhu Yang]

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@xxxxxxxxxxx>
---
 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