[PATCH 3/3] tracing/kprobes: Use APIs that matches symbols with .llvm. suffix

Song Liu
2024-07-30T00:55:06Z

Use the new kallsyms APIs that matches symbols name with .llvm.<hash>
suffix. This allows userspace tools to get kprobes on the expected
function name, while the actual symbol has a .llvm.<hash> suffix.

This only effects kernel compared with CONFIG_LTO_CLANG.

Signed-off-by: Song Liu <song@kernel.org>
---
kernel/trace/trace_kprobe.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 61a6da808203..c319382c1a09 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -202,7 +202,8 @@ unsigned long trace_kprobe_address(struct trace_kprobe *tk)

if (tk->symbol) {
addr = (unsigned long)
- kallsyms_lookup_name(trace_kprobe_symbol(tk));
+ kallsyms_lookup_name_or_prefix(trace_kprobe_symbol(tk));
+
if (addr)
addr += tk->rp.kp.offset;
} else {
@@ -766,8 +767,13 @@ static unsigned int number_of_same_symbols(const char *mod, const char *func_nam
{
struct sym_count_ctx ctx = { .count = 0, .name = func_name };

- if (!mod)
+ if (!mod) {
kallsyms_on_each_match_symbol(count_symbols, func_name, &ctx.count);
+ if (IS_ENABLED(CONFIG_LTO_CLANG) && !ctx.count) {
+ kallsyms_on_each_match_symbol_or_prefix(
+ count_symbols, func_name, &ctx.count);
+ }
+ }

module_kallsyms_on_each_symbol(mod, count_mod_symbols, &ctx);

--
2.43.0