diff options
| author | Paul Mackerras <paulus@samba.org> | 2010-04-14 00:46:04 +0400 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2010-05-12 08:34:00 +0400 |
| commit | 0fe1ac48bef018bed896307cd12f6ca9b5e704ab (patch) | |
| tree | 6f5e68619798312ee808f23c1a0cc5799a131545 /arch/powerpc/kernel/entry_64.S | |
| parent | cea0d767c29669bf89f86e4aee46ef462d2ebae8 (diff) | |
| download | linux-0fe1ac48bef018bed896307cd12f6ca9b5e704ab.tar.xz | |
powerpc/perf_event: Fix oops due to perf_event_do_pending call
Anton Blanchard found that large POWER systems would occasionally
crash in the exception exit path when profiling with perf_events.
The symptom was that an interrupt would occur late in the exit path
when the MSR[RI] (recoverable interrupt) bit was clear. Interrupts
should be hard-disabled at this point but they were enabled. Because
the interrupt was not recoverable the system panicked.
The reason is that the exception exit path was calling
perf_event_do_pending after hard-disabling interrupts, and
perf_event_do_pending will re-enable interrupts.
The simplest and cleanest fix for this is to use the same mechanism
that 32-bit powerpc does, namely to cause a self-IPI by setting the
decrementer to 1. This means we can remove the tests in the exception
exit path and raw_local_irq_restore.
This also makes sure that the call to perf_event_do_pending from
timer_interrupt() happens within irq_enter/irq_exit. (Note that
calling perf_event_do_pending from timer_interrupt does not mean that
there is a possible 1/HZ latency; setting the decrementer to 1 ensures
that the timer interrupt will happen immediately, i.e. within one
timebase tick, which is a few nanoseconds or 10s of nanoseconds.)
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: stable@kernel.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/entry_64.S')
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 9 |
1 files changed, 0 insertions, 9 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 07109d843787..42e9d908914a 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -556,15 +556,6 @@ ALT_FW_FTR_SECTION_END_IFCLR(FW_FEATURE_ISERIES) 2: TRACE_AND_RESTORE_IRQ(r5); -#ifdef CONFIG_PERF_EVENTS - /* check paca->perf_event_pending if we're enabling ints */ - lbz r3,PACAPERFPEND(r13) - and. r3,r3,r5 - beq 27f - bl .perf_event_do_pending -27: -#endif /* CONFIG_PERF_EVENTS */ - /* extract EE bit and use it to restore paca->hard_enabled */ ld r3,_MSR(r1) rldicl r4,r3,49,63 /* r0 = (r3 >> 15) & 1 */ |