From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id BCE7CB6FB7 for ; Fri, 11 May 2012 12:13:07 +1000 (EST) Message-ID: <1336702358.3881.77.camel@pasglop> Subject: [PATCH] powerpc/irq: Fix another case of lazy IRQ state getting out of sync From: Benjamin Herrenschmidt To: Sukadev Bhattiprolu , Wang Sheng-Hui Date: Fri, 11 May 2012 12:12:38 +1000 In-Reply-To: <1336696621.3881.72.camel@pasglop> References: <20120511002354.GA8895@us.ibm.com> <1336696621.3881.72.camel@pasglop> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Cc: Paul Mackerras , linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 --- Please test ASAP as I need to send that to Linus today diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index f8a7a1a..293e283 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 5ec1b23..fe8cf8e 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); /*