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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2008-04-02 15:58:40 +1100
committerPaul Mackerras <paulus@samba.org>2008-04-03 22:10:34 +1100
commitff3da2e0938bae36d10d69c22bce0177b067a9e2 (patch)
tree4df635b6bc9298fbf455ab2be23aaec04324c3f0
parent025306f30948836a743eb68a7cbaf4ab0bfb5f47 (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>
-rw-r--r--arch/powerpc/kernel/head_64.S13
-rw-r--r--arch/powerpc/kernel/irq.c1
2 files changed, 7 insertions, 7 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
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index b0e5deb4274..292163f5b39 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -143,7 +143,6 @@ void local_irq_restore(unsigned long en)
*/
if (local_paca->lppaca_ptr->int_dword.any_int)
iseries_handle_interrupts();
- return;
}
/*