[PATCH v2 3/3] tracing/kprobes: Use APIs that matches symbols without .XXX suffix

[Song Liu]

Use the new kallsyms APIs that matches symbols name with .XXX
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 compile with CONFIG_LTO_CLANG.

Signed-off-by: Song Liu <song@xxxxxxxxxx>
---
 kernel/kprobes.c            |  6 +++++-
 kernel/trace/trace_kprobe.c | 11 ++++++++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index e85de37d9e1e..99102283b076 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -70,7 +70,11 @@ static DEFINE_PER_CPU(struct kprobe *, kprobe_instance);
 kprobe_opcode_t * __weak kprobe_lookup_name(const char *name,
 					unsigned int __unused)
 {
-	return ((kprobe_opcode_t *)(kallsyms_lookup_name(name)));
+	unsigned long addr = kallsyms_lookup_name(name);
+
+	if (IS_ENABLED(CONFIG_LTO_CLANG) && !addr)
+		addr = kallsyms_lookup_name_without_suffix(name);
+	return ((kprobe_opcode_t *)(addr));
 }
 
 /*
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 61a6da808203..d2ad0c561c83 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -203,6 +203,10 @@ unsigned long trace_kprobe_address(struct trace_kprobe *tk)
 	if (tk->symbol) {
 		addr = (unsigned long)
 			kallsyms_lookup_name(trace_kprobe_symbol(tk));
+
+		if (IS_ENABLED(CONFIG_LTO_CLANG) && !addr)
+			addr = kallsyms_lookup_name_without_suffix(trace_kprobe_symbol(tk));
+
 		if (addr)
 			addr += tk->rp.kp.offset;
 	} else {
@@ -766,8 +770,13 @@ 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_without_suffix(
+				count_symbols, func_name, &ctx.count);
+		}
+	}
 
 	module_kallsyms_on_each_symbol(mod, count_mod_symbols, &ctx);
 
-- 
2.43.0