Messages in this thread | | | Date | Thu, 19 Apr 2012 07:22:11 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH] perf, x86: Disable sanity check |
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On Wed, Apr 18, 2012 at 04:24:09PM -0700, Arun Sharma wrote: > Without this patch, applications with two different stack > regions (eg: native stack vs JIT stack) get truncated > callchains even when RBP chaining is present. GDB shows proper > stack traces and the frame pointer chaining is intact. > > This patch disables the (fp < RSP) check, hoping that other checks > in the code save the day for us. In our limited testing, this > didn't seem to break anything. > > In the long term, we could potentially have userspace advise > the kernel on the range of valid stack addresses, so we don't > spend a lot of time unwinding from bogus addresses.
So rbp is part of the JIT stack but not rsp? Do you have a practical example of that? I must confess I don't know much about JIT stack.
Thanks.
> > Signed-off-by: Arun Sharma <asharma@fb.com> > Cc: Ingo Molnar <mingo@elte.hu> > CC: Arnaldo Carvalho de Melo <acme@redhat.com> > Cc: Frederic Weisbecker <fweisbec@gmail.com> > Cc: Mike Galbraith <efault@gmx.de> > Cc: Paul Mackerras <paulus@samba.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Stephane Eranian <eranian@google.com> > Cc: Namhyung Kim <namhyung.kim@lge.com> > Cc: Tom Zanussi <tzanussi@gmail.com> > Cc: linux-kernel@vger.kernel.org > Cc: linux-perf-users@vger.kernel.org > > --- > arch/x86/kernel/cpu/perf_event.c | 3 --- > 1 files changed, 0 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c > index 07f46ba..87d9abd 100644 > --- a/arch/x86/kernel/cpu/perf_event.c > +++ b/arch/x86/kernel/cpu/perf_event.c > @@ -1596,9 +1596,6 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) > if (bytes != sizeof(frame)) > break; > > - if ((unsigned long)fp < regs->sp) > - break; > - > perf_callchain_store(entry, frame.return_address); > fp = frame.next_frame; > } > -- > 1.7.8.4 >
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