* Re: [PATCH] ftrace/jprobes/s390: Fix conflict between jprobes and function graph tracing
[not found] ` <20160728143933.1a2abc97@gandalf.local.home>
@ 2016-07-31 12:21 ` Jiri Olsa
2016-07-31 13:25 ` Martin Schwidefsky
0 siblings, 1 reply; 2+ messages in thread
From: Jiri Olsa @ 2016-07-31 12:21 UTC (permalink / raw)
To: Steven Rostedt
Cc: Jiri Olsa, lkml, Ingo Molnar, Michael Grundy, Martin Schwidefsky,
Masami Hiramatsu, linux-s390, Heiko Carstens
On Thu, Jul 28, 2016 at 02:39:33PM -0400, Steven Rostedt wrote:
> On Mon, 18 Jul 2016 15:26:41 +0200
> Jiri Olsa <jolsa@kernel.org> wrote:
>
> > This fixes the same issue Steven already fixed for x86
> > in following commit:
> >
> > 237d28db036e ftrace/jprobes/x86: Fix conflict between jprobes and function graph tracing
> >
> > It fixes the crash, that happens when function graph tracing
> > and jprobes are used simultaneously. Please refer to above
> > commit for details.
>
> I'm guessing that this should go in via the s390 tree.
oops, I forgot to CC s390 mailing list.. CC-ing now
I can repost if needed
thanks,
jirka
>
> Acked-by: Steven Rostedt <rostedt@goodmis.org>
>
> -- Steve
>
> >
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> > arch/s390/kernel/kprobes.c | 12 ++++++++++++
> > 1 file changed, 12 insertions(+)
> >
> > diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
> > index 250f5972536a..dd6306c51bd6 100644
> > --- a/arch/s390/kernel/kprobes.c
> > +++ b/arch/s390/kernel/kprobes.c
> > @@ -690,6 +690,15 @@ int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
> > stack = (unsigned long) regs->gprs[15];
> >
> > memcpy(kcb->jprobes_stack, (void *) stack, MIN_STACK_SIZE(stack));
> > +
> > + /*
> > + * jprobes use jprobe_return() which skips the normal return
> > + * path of the function, and this messes up the accounting of the
> > + * function graph tracer to get messed up.
> > + *
> > + * Pause function graph tracing while performing the jprobe function.
> > + */
> > + pause_graph_tracing();
> > return 1;
> > }
> > NOKPROBE_SYMBOL(setjmp_pre_handler);
> > @@ -705,6 +714,9 @@ int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
> > struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
> > unsigned long stack;
> >
> > + /* It's OK to start function graph tracing again */
> > + unpause_graph_tracing();
> > +
> > stack = (unsigned long) kcb->jprobe_saved_regs.gprs[15];
> >
> > /* Put the regs back */
>
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