[PATCH] livepatch: match symbols exactly in klp_find_object_symbol()

[Song Liu <song@xxxxxxxxxx>]

With CONFIG_LTO_CLANG, kallsyms.c:cleanup_symbol_name() removes symbols
suffixes during comparison. This is problematic for livepatch, as
kallsyms_on_each_match_symbol may find multiple matches for the same
symbol, and fail with:

  livepatch: unresolvable ambiguity for symbol 'xxx' in object 'yyy'

Fix this by using kallsyms_on_each_symbol instead, and matching symbols
exactly.

Signed-off-by: Song Liu <song@xxxxxxxxxx>
---
 kernel/livepatch/core.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 61328328c474..507e1e2e4290 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -125,10 +125,13 @@ struct klp_find_arg {
 	unsigned long pos;
 };
 
-static int klp_match_callback(void *data, unsigned long addr)
+static int klp_find_callback(void *data, const char *name, unsigned long addr)
 {
 	struct klp_find_arg *args = data;
 
+	if (strcmp(args->name, name))
+		return 0;
+
 	args->addr = addr;
 	args->count++;
 
@@ -143,16 +146,6 @@ static int klp_match_callback(void *data, unsigned long addr)
 	return 0;
 }
 
-static int klp_find_callback(void *data, const char *name, unsigned long addr)
-{
-	struct klp_find_arg *args = data;
-
-	if (strcmp(args->name, name))
-		return 0;
-
-	return klp_match_callback(data, addr);
-}
-
 static int klp_find_object_symbol(const char *objname, const char *name,
 				  unsigned long sympos, unsigned long *addr)
 {
@@ -166,7 +159,7 @@ static int klp_find_object_symbol(const char *objname, const char *name,
 	if (objname)
 		module_kallsyms_on_each_symbol(objname, klp_find_callback, &args);
 	else
-		kallsyms_on_each_match_symbol(klp_match_callback, name, &args);
+		kallsyms_on_each_symbol(klp_find_callback, &args);
 
 	/*
 	 * Ensure an address was found. If sympos is 0, ensure symbol is unique;
-- 
2.34.1