From ff3da2e0938bae36d10d69c22bce0177b067a9e2 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Wed, 2 Apr 2008 15:58:40 +1100 Subject: [PATCH] [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 Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/head_64.S | 13 +++++++------ arch/powerpc/kernel/irq.c | 1 - 2 files changed, 7 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S index 11b4f6d..d3aee08 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 b0e5deb..292163f 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; } /* -- 2.7.4