| Message ID | 20240916102741.GA13899@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | arm64: stacktrace: WARN_ON(state->common.pc == orig_pc) in kunwind_recover_return_address() | expand |
Oleg Nesterov <oleg@redhat.com> writes: > I don't know the details but people report that > kunwind_recover_return_address() hits this warning. > > I know absolutely nothing about arm64 or kernel/trace/fgraph.c, but at > first glance this code looks broken: > > kunwind_recover_return_address: > > ... > > orig_pc = ftrace_graph_ret_addr(state->task, NULL, > state->common.pc, > (void *)state->common.fp); > if (WARN_ON_ONCE(state->common.pc == orig_pc)) > > ftrace_graph_ret_addr: > > ... > > if (!idx) > return ret; > > > given that kunwind_recover_return_address() passes idx == NULL to > ftrace_graph_ret_addr(), it should always return ret == state->common.pc ? > > > Perhaps this connects to 29c1c24a27 ("function_graph: Fix up ftrace_graph_ret_addr()") > and I have no idea if something like the patch below makes any sense. > Your finding is accurate. It has been fixed in upstream by c060f93253ca ("arm64: stacktrace: fix the usage of ftrace_graph_ret_addr()") See: https://elixir.bootlin.com/linux/v6.11/source/arch/arm64/kernel/stacktrace.c#L111 Thanks, Puranjay
Ah, sorry for the noise, I looked into the wrong tree, missed the recent
c060f93253ca ("arm64: stacktrace: fix the usage of ftrace_graph_ret_addr()")
On 09/16, Oleg Nesterov wrote:
>
> I don't know the details but people report that
> kunwind_recover_return_address() hits this warning.
>
> I know absolutely nothing about arm64 or kernel/trace/fgraph.c, but at
> first glance this code looks broken:
>
> kunwind_recover_return_address:
>
> ...
>
> orig_pc = ftrace_graph_ret_addr(state->task, NULL,
> state->common.pc,
> (void *)state->common.fp);
> if (WARN_ON_ONCE(state->common.pc == orig_pc))
>
> ftrace_graph_ret_addr:
>
> ...
>
> if (!idx)
> return ret;
>
>
> given that kunwind_recover_return_address() passes idx == NULL to
> ftrace_graph_ret_addr(), it should always return ret == state->common.pc ?
>
>
> Perhaps this connects to 29c1c24a27 ("function_graph: Fix up ftrace_graph_ret_addr()")
> and I have no idea if something like the patch below makes any sense.
>
> Oleg.
>
> --- a/arch/arm64/kernel/stacktrace.c
> +++ b/arch/arm64/kernel/stacktrace.c
> @@ -106,7 +106,8 @@ kunwind_recover_return_address(struct kunwind_state *state)
> if (state->task->ret_stack &&
> (state->common.pc == (unsigned long)return_to_handler)) {
> unsigned long orig_pc;
> - orig_pc = ftrace_graph_ret_addr(state->task, NULL,
> + orig_pc = ftrace_graph_ret_addr(state->task,
> + &state->task->curr_ret_stack,
> state->common.pc,
> (void *)state->common.fp);
> if (WARN_ON_ONCE(state->common.pc == orig_pc))
On 09/16, Puranjay Mohan wrote: > > Oleg Nesterov <oleg@redhat.com> writes: > > > given that kunwind_recover_return_address() passes idx == NULL to > > ftrace_graph_ret_addr(), it should always return ret == state->common.pc ? > > > > > > Perhaps this connects to 29c1c24a27 ("function_graph: Fix up ftrace_graph_ret_addr()") > > and I have no idea if something like the patch below makes any sense. > > > > Your finding is accurate. > > It has been fixed in upstream by c060f93253ca ("arm64: stacktrace: fix > the usage of ftrace_graph_ret_addr()") Yes, I have already found that commit, see my next email ;) Nevertheless, thanks a lot Puranjay for the confirmation! Oleg.
--- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -106,7 +106,8 @@ kunwind_recover_return_address(struct kunwind_state *state) if (state->task->ret_stack && (state->common.pc == (unsigned long)return_to_handler)) { unsigned long orig_pc; - orig_pc = ftrace_graph_ret_addr(state->task, NULL, + orig_pc = ftrace_graph_ret_addr(state->task, + &state->task->curr_ret_stack, state->common.pc, (void *)state->common.fp); if (WARN_ON_ONCE(state->common.pc == orig_pc))
I don't know the details but people report that kunwind_recover_return_address() hits this warning. I know absolutely nothing about arm64 or kernel/trace/fgraph.c, but at first glance this code looks broken: kunwind_recover_return_address: ... orig_pc = ftrace_graph_ret_addr(state->task, NULL, state->common.pc, (void *)state->common.fp); if (WARN_ON_ONCE(state->common.pc == orig_pc)) ftrace_graph_ret_addr: ... if (!idx) return ret; given that kunwind_recover_return_address() passes idx == NULL to ftrace_graph_ret_addr(), it should always return ret == state->common.pc ? Perhaps this connects to 29c1c24a27 ("function_graph: Fix up ftrace_graph_ret_addr()") and I have no idea if something like the patch below makes any sense. Oleg.