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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2012-05-10 16:12:38 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2012-05-12 09:40:41 +1000
commit7c0482e3d055e5de056d3c693b821e39205b99ae (patch)
treead8d3ff6965d675c6bd255c5665deab7fba5df9f /arch/powerpc
parent4e25651b70b8d6ded7229ead8181619e121b648d (diff)
downloadtalos-op-linux-7c0482e3d055e5de056d3c693b821e39205b99ae.tar.gz
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powerpc/irq: Fix another case of lazy IRQ state getting out of sync
So we have another case of paca->irq_happened getting out of sync with the HW irq state. This can happen when a perfmon interrupt occurs while soft disabled, as it will return to a soft disabled but hard enabled context while leaving a stale PACA_IRQ_HARD_DIS flag set. This patch fixes it, and also adds a test for the condition of those flags being out of sync in arch_local_irq_restore() when CONFIG_TRACE_IRQFLAGS is enabled. This helps catching those gremlins faster (and so far I can't seem see any anymore, so that's good news). Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/kernel/entry_64.S44
-rw-r--r--arch/powerpc/kernel/irq.c13
2 files changed, 44 insertions, 13 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index fc6015027a86..ef2074c3e906 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -588,23 +588,19 @@ _GLOBAL(ret_from_except_lite)
fast_exc_return_irq:
restore:
/*
- * This is the main kernel exit path, we first check if we
- * have to change our interrupt state.
+ * This is the main kernel exit path. First we check if we
+ * are about to re-enable interrupts
*/
ld r5,SOFTE(r1)
lbz r6,PACASOFTIRQEN(r13)
- cmpwi cr1,r5,0
- cmpw cr0,r5,r6
- beq cr0,4f
+ cmpwi cr0,r5,0
+ beq restore_irq_off
- /* We do, handle disable first, which is easy */
- bne cr1,3f;
- li r0,0
- stb r0,PACASOFTIRQEN(r13);
- TRACE_DISABLE_INTS
- b 4f
+ /* We are enabling, were we already enabled ? Yes, just return */
+ cmpwi cr0,r6,1
+ beq cr0,do_restore
-3: /*
+ /*
* We are about to soft-enable interrupts (we are hard disabled
* at this point). We check if there's anything that needs to
* be replayed first.
@@ -626,7 +622,7 @@ restore_no_replay:
/*
* Final return path. BookE is handled in a different file
*/
-4:
+do_restore:
#ifdef CONFIG_PPC_BOOK3E
b .exception_return_book3e
#else
@@ -700,6 +696,25 @@ fast_exception_return:
#endif /* CONFIG_PPC_BOOK3E */
/*
+ * We are returning to a context with interrupts soft disabled.
+ *
+ * However, we may also about to hard enable, so we need to
+ * make sure that in this case, we also clear PACA_IRQ_HARD_DIS
+ * or that bit can get out of sync and bad things will happen
+ */
+restore_irq_off:
+ ld r3,_MSR(r1)
+ lbz r7,PACAIRQHAPPENED(r13)
+ andi. r0,r3,MSR_EE
+ beq 1f
+ rlwinm r7,r7,0,~PACA_IRQ_HARD_DIS
+ stb r7,PACAIRQHAPPENED(r13)
+1: li r0,0
+ stb r0,PACASOFTIRQEN(r13);
+ TRACE_DISABLE_INTS
+ b do_restore
+
+ /*
* Something did happen, check if a re-emit is needed
* (this also clears paca->irq_happened)
*/
@@ -748,6 +763,9 @@ restore_check_irq_replay:
#endif /* CONFIG_PPC_BOOK3E */
1: b .ret_from_except /* What else to do here ? */
+
+
+3:
do_work:
#ifdef CONFIG_PREEMPT
andi. r0,r3,MSR_PR /* Returning to user mode? */
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index c6c6f3b7f8cd..641da9e868ce 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -229,6 +229,19 @@ notrace void arch_local_irq_restore(unsigned long en)
*/
if (unlikely(irq_happened != PACA_IRQ_HARD_DIS))
__hard_irq_disable();
+#ifdef CONFIG_TRACE_IRQFLAG
+ else {
+ /*
+ * We should already be hard disabled here. We had bugs
+ * where that wasn't the case so let's dbl check it and
+ * warn if we are wrong. Only do that when IRQ tracing
+ * is enabled as mfmsr() can be costly.
+ */
+ if (WARN_ON(mfmsr() & MSR_EE))
+ __hard_irq_disable();
+ }
+#endif /* CONFIG_TRACE_IRQFLAG */
+
set_soft_enabled(0);
/*
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