ftrace: Keep address offset in ftrace_lookup_symbols

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.

Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Fixes: bad172f04f5f ("ftrace: Add ftrace_lookup_symbols function")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20220615112118.497303-3-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index e750fe141a6063547c0dda2432dc6cfceec9879a..601ccf1b2f091199355b61fc646cd7b33b2ab93e 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -8029,15 +8029,23 @@ 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;
 }
 
@@ -8062,6 +8070,7 @@ int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, unsigned long *a
        struct kallsyms_data args;
        int err;
 
+       memset(addrs, 0, sizeof(*addrs) * cnt);
        args.addrs = addrs;
        args.syms = sorted_syms;
        args.cnt = cnt;