https://github.com/torvalds/linux
Revision 0fe1ac48bef018bed896307cd12f6ca9b5e704ab authored by Paul Mackerras on 13 April 2010, 20:46:04 UTC, committed by Benjamin Herrenschmidt on 12 May 2010, 04:34:00 UTC
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>
1 parent cea0d76
Tip revision: 0fe1ac48bef018bed896307cd12f6ca9b5e704ab authored by Paul Mackerras on 13 April 2010, 20:46:04 UTC
powerpc/perf_event: Fix oops due to perf_event_do_pending call
powerpc/perf_event: Fix oops due to perf_event_do_pending call
Tip revision: 0fe1ac4
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crypto | ||
drivers | ||
firmware | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
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net | ||
samples | ||
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sound | ||
tools | ||
usr | ||
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.gitignore | -rw-r--r-- | 930 bytes |
.mailmap | -rw-r--r-- | 3.9 KB |
COPYING | -rw-r--r-- | 18.3 KB |
CREDITS | -rw-r--r-- | 91.8 KB |
Kbuild | -rw-r--r-- | 2.4 KB |
MAINTAINERS | -rw-r--r-- | 166.4 KB |
Makefile | -rw-r--r-- | 51.9 KB |
README | -rw-r--r-- | 17.0 KB |
REPORTING-BUGS | -rw-r--r-- | 3.3 KB |
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