diff options
author | Paul Mackerras <paulus@samba.org> | 2010-04-13 20:46:04 +0000 |
---|---|---|
committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2010-05-12 14:34:00 +1000 |
commit | 0fe1ac48bef018bed896307cd12f6ca9b5e704ab (patch) | |
tree | 6f5e68619798312ee808f23c1a0cc5799a131545 /arch/powerpc/include/asm/hw_irq.h | |
parent | cea0d767c29669bf89f86e4aee46ef462d2ebae8 (diff) |
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/include/asm/hw_irq.h')
-rw-r--r-- | arch/powerpc/include/asm/hw_irq.h | 38 |
1 files changed, 0 insertions, 38 deletions
diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/asm/hw_irq.h index 9f4c9d4f580..bd100fcf40d 100644 --- a/arch/powerpc/include/asm/hw_irq.h +++ b/arch/powerpc/include/asm/hw_irq.h @@ -130,43 +130,5 @@ static inline int irqs_disabled_flags(unsigned long flags) */ struct irq_chip; -#ifdef CONFIG_PERF_EVENTS - -#ifdef CONFIG_PPC64 -static inline unsigned long test_perf_event_pending(void) -{ - unsigned long x; - - asm volatile("lbz %0,%1(13)" - : "=r" (x) - : "i" (offsetof(struct paca_struct, perf_event_pending))); - return x; -} - -static inline void set_perf_event_pending(void) -{ - asm volatile("stb %0,%1(13)" : : - "r" (1), - "i" (offsetof(struct paca_struct, perf_event_pending))); -} - -static inline void clear_perf_event_pending(void) -{ - asm volatile("stb %0,%1(13)" : : - "r" (0), - "i" (offsetof(struct paca_struct, perf_event_pending))); -} -#endif /* CONFIG_PPC64 */ - -#else /* CONFIG_PERF_EVENTS */ - -static inline unsigned long test_perf_event_pending(void) -{ - return 0; -} - -static inline void clear_perf_event_pending(void) {} -#endif /* CONFIG_PERF_EVENTS */ - #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_HW_IRQ_H */ |