Re: [PATCH -tip v4 10/12] x86/kprobes: Push a fake return address at kretprobe_trampoline

Masami Hiramatsu
2021-03-25T03:25:24Z

On Wed, 24 Mar 2021 20:26:13 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Thu, 25 Mar 2021 08:47:41 +0900
> Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
> > > I think the REGS and REGS_PARTIAL cases can also be affected by function
> > > graph tracing. So should they use the generic unwind_recover_ret_addr()
> > > instead of unwind_recover_kretprobe()?
> >
> > Yes, but I'm not sure this parameter can be applied.
> > For example, it passed "state->sp - sizeof(unsigned long)" as where the
> > return address stored address. Is that same on ftrace graph too?
>
> Stack traces on the return side of function graph tracer has never
> worked. It's on my todo list, because that's one of the requirements to
> get right if we every manage to combine kretprobe and function graph
> tracers together.

OK, then at this point let's just fix the kretprobe side.

Thanks,

>
> -- Steve

--
Masami Hiramatsu <mhiramat@kernel.org>