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author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2008-04-02 15:58:40 +1100 |
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committer | Paul Mackerras <paulus@samba.org> | 2008-04-03 22:10:34 +1100 |
commit | ff3da2e0938bae36d10d69c22bce0177b067a9e2 (patch) | |
tree | 4df635b6bc9298fbf455ab2be23aaec04324c3f0 /arch/powerpc/mm/mmu_context_32.c | |
parent | 025306f30948836a743eb68a7cbaf4ab0bfb5f47 (diff) |
[POWERPC] Fix iSeries hard irq enabling regression
A subtle bug sneaked into iSeries recently. On this platform, we must
not normally clear MSR:EE (the hardware external interrupt enable)
except for short periods of time. Taking an interrupt while
soft-disabled doesn't cause us to clear it for example.
The iSeries kernel expects to mostly run with MSR:EE enabled at all
times except in a few exception entry/exit code paths. Thus
local_irq_enable() doesn't check if it needs to hard-enable as it
expects this to be unnecessary on iSeries.
However, hard_irq_disable() _does_ cause MSR:EE to be cleared,
including on iSeries. A call to it was recently added to the
context switch code, thus causing interrupts to become disabled
for a long periods of time, causing the iSeries watchdog to kick
in under some circumstances and other nasty things.
This patch fixes it by making local_irq_enable() properly re-enable
MSR:EE on iSeries. It basically removes a return statement here
to make iSeries use the same code path as everybody else. That does
mean that we might occasionally get spurious decrementer interrupts
but I don't think that matters.
Another option would have been to make hard_irq_disable() a nop
on iSeries but I didn't like it much, in case we have good reasons
to hard-disable.
Part of the patch is fixes to make sure the hard_enabled PACA field
is properly set on iSeries as it used not to be before, since it
was mostly unused.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/mm/mmu_context_32.c')
0 files changed, 0 insertions, 0 deletions