[PATCH bpf-next 2/3] ftrace: Keep address offset in ftrace_lookup_symbols

[Jiri Olsa <jolsa@kernel.org>]

We want to store the resolved address on the same index as
the symbol string, because that's the user (bpf kprobe link)
code assumption.

Also making sure we don't store duplicates that might be
present in kallsyms.

Fixes: bed0d9a50dac ("ftrace: Add ftrace_lookup_symbols function")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/trace/ftrace.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 674add0aafb3..00d0ba6397ed 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -7984,15 +7984,23 @@ static int kallsyms_callback(void *data, const char *name,
 			     struct module *mod, unsigned long addr)
 {
 	struct kallsyms_data *args = data;
+	const char **sym;
+	int idx;
 
-	if (!bsearch(&name, args->syms, args->cnt, sizeof(*args->syms), symbols_cmp))
+	sym = bsearch(&name, args->syms, args->cnt, sizeof(*args->syms), symbols_cmp);
+	if (!sym)
+		return 0;
+
+	idx = sym - args->syms;
+	if (args->addrs[idx])
 		return 0;
 
 	addr = ftrace_location(addr);
 	if (!addr)
 		return 0;
 
-	args->addrs[args->found++] = addr;
+	args->addrs[idx] = addr;
+	args->found++;
 	return args->found == args->cnt ? 1 : 0;
 }
 
@@ -8017,6 +8025,7 @@ int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, unsigned long *a
 	struct kallsyms_data args;
 	int err;
 
+	memset(addrs, 0x0, sizeof(*addrs) * cnt);
 	args.addrs = addrs;
 	args.syms = sorted_syms;
 	args.cnt = cnt;
-- 
2.35.3