tracing/kprobes: Fix symbol counting logic by looking at modules as well

Recent changes to count number of matching symbols when creating
a kprobe event failed to take into account kernel modules. As such, it
breaks kprobes on kernel module symbols, by assuming there is no match.

Fix this my calling module_kallsyms_on_each_symbol() in addition to
kallsyms_on_each_match_symbol() to perform a proper counting.

Link: https://lore.kernel.org/all/[email protected]/

Cc: Francis Laniel <[email protected]>
Cc: [email protected]
Cc: Masami Hiramatsu <[email protected]>
Cc: Steven Rostedt <[email protected]>
Fixes: b022f0c7e404 ("tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols")
Signed-off-by: Andrii Nakryiko <[email protected]>
Acked-by: Song Liu <[email protected]>
Signed-off-by: Masami Hiramatsu (Google) <[email protected]>

1 files changed, 20 insertions, 4 deletions

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 95c5b0668cb7..e834f149695b 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -714,14 +714,30 @@ static int count_symbols(void *data, unsigned long unused)
 	return 0;
 }
 
+struct sym_count_ctx {
+	unsigned int count;
+	const char *name;
+};
+
+static int count_mod_symbols(void *data, const char *name, unsigned long unused)
+{
+	struct sym_count_ctx *ctx = data;
+
+	if (strcmp(name, ctx->name) == 0)
+		ctx->count++;
+
+	return 0;
+}
+
 static unsigned int number_of_same_symbols(char *func_name)
 {
-	unsigned int count;
+	struct sym_count_ctx ctx = { .count = 0, .name = func_name };
+
+	kallsyms_on_each_match_symbol(count_symbols, func_name, &ctx.count);
 
-	count = 0;
-	kallsyms_on_each_match_symbol(count_symbols, func_name, &count);
+	module_kallsyms_on_each_symbol(NULL, count_mod_symbols, &ctx);
 
-	return count;
+	return ctx.count;
 }
 
 static int __trace_kprobe_create(int argc, const char *argv[])