diff options
| author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2008-04-02 15:58:40 +1100 |
|---|---|---|
| committer | Paul Mackerras <paulus@samba.org> | 2008-04-03 22:10:34 +1100 |
| commit | ff3da2e0938bae36d10d69c22bce0177b067a9e2 (patch) | |
| tree | 4df635b6bc9298fbf455ab2be23aaec04324c3f0 /arch/powerpc/kernel/head_64.S | |
| 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/kernel/head_64.S')
| -rw-r--r-- | arch/powerpc/kernel/head_64.S | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S index 11b4f6d9ffc..d3aee08e681 100644 --- a/arch/powerpc/kernel/head_64.S +++ b/arch/powerpc/kernel/head_64.S @@ -1387,12 +1387,14 @@ __secondary_start: #ifdef CONFIG_PPC_ISERIES BEGIN_FW_FTR_SECTION ori r4,r4,MSR_EE + li r8,1 + stb r8,PACAHARDIRQEN(r13) END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES) #endif BEGIN_FW_FTR_SECTION - stb r7,PACASOFTIRQEN(r13) stb r7,PACAHARDIRQEN(r13) END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES) + stb r7,PACASOFTIRQEN(r13) mtspr SPRN_SRR0,r3 mtspr SPRN_SRR1,r4 @@ -1520,15 +1522,14 @@ _INIT_GLOBAL(start_here_common) #ifdef CONFIG_PPC_ISERIES BEGIN_FW_FTR_SECTION mfmsr r5 - ori r5,r5,MSR_EE /* Hard Enabled */ + ori r5,r5,MSR_EE /* Hard Enabled on iSeries*/ mtmsrd r5 + li r5,1 END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES) #endif -BEGIN_FW_FTR_SECTION - stb r5,PACAHARDIRQEN(r13) -END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES) + stb r5,PACAHARDIRQEN(r13) /* Hard Disabled on others */ - bl .start_kernel + bl .start_kernel /* Not reached */ BUG_OPCODE |