Messages in this thread Patch in this message | | | From | Arun Sharma <> | Subject | [PATCH 1/4] perf, x86: Allow multiple stacks | Date | Fri, 20 Apr 2012 15:41:33 -0700 |
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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.
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 | 6 ------ 1 files changed, 0 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index bb8e034..9f98636 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -1785,9 +1785,6 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry) if (bytes != sizeof(frame)) break; - if (fp < compat_ptr(regs->sp)) - break; - perf_callchain_store(entry, frame.return_address); fp = compat_ptr(frame.next_frame); } @@ -1831,9 +1828,6 @@ 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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