Re: [PATCH 2/3] static_call: Fix static_call_text_reserved() vs __init

Masami Hiramatsu
2021-06-28T14:34:41Z

On Mon, 28 Jun 2021 13:24:11 +0200
Peter Zijlstra <peterz@infradead.org> wrote:

> It turns out that static_call_text_reserved() was reporting __init
> text as being reserved past the time when the __init text was freed
> and re-used.
>
> This is mostly harmless and will at worst result in refusing a kprobe.
>
> Fixes: 6333e8f73b83 ("static_call: Avoid kprobes on inline static_call()s")
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

This looks good to me.

Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>

Thank you,

> ---
> kernel/static_call.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
> --- a/kernel/static_call.c
> +++ b/kernel/static_call.c
> @@ -292,13 +292,15 @@ static int addr_conflict(struct static_c
>
> static int __static_call_text_reserved(struct static_call_site *iter_start,
> struct static_call_site *iter_stop,
> - void *start, void *end)
> + void *start, void *end, bool init)
> {
> struct static_call_site *iter = iter_start;
>
> while (iter < iter_stop) {
> - if (addr_conflict(iter, start, end))
> - return 1;
> + if (init || !static_call_is_init(iter)) {
> + if (addr_conflict(iter, start, end))
> + return 1;
> + }
> iter++;
> }
>
> @@ -324,7 +326,7 @@ static int __static_call_mod_text_reserv
>
> ret = __static_call_text_reserved(mod->static_call_sites,
> mod->static_call_sites + mod->num_static_call_sites,
> - start, end);
> + start, end, mod->state == MODULE_STATE_COMING);
>
> module_put(mod);
>
> @@ -459,8 +461,9 @@ static inline int __static_call_mod_text
>
> int static_call_text_reserved(void *start, void *end)
> {
> + bool init = system_state < SYSTEM_RUNNING;
> int ret = __static_call_text_reserved(__start_static_call_sites,
> - __stop_static_call_sites, start, end);
> + __stop_static_call_sites, start, end, init);
>
> if (ret)
> return ret;
>
>

--
Masami Hiramatsu <mhiramat@kernel.org>