From ccc3c3192ae78dd56dcdf5353fd1a9ef5f9a3e2b Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 27 May 2009 21:56:54 +0200 Subject: [PATCH] x86, mce: implement bootstrapping for machine check wakeups Machine checks support waking up the mcelog daemon quickly. The original wake up code for this was pretty ugly, relying on a idle notifier and a special process flag. The reason it did it this way is that the machine check handler is not subject to normal interrupt locking rules so it's not safe to call wake_up(). Instead it set a process flag and then either did the wakeup in the syscall return or in the idle notifier. This patch adds a new "bootstraping" method as replacement. The idea is that the handler checks if it's in a state where it is unsafe to call wake_up(). If it's safe it calls it directly. When it's not safe -- that is it interrupted in a critical section with interrupts disables -- it uses a new "self IPI" to trigger an IPI to its own CPU. This can be done safely because IPI triggers are atomic with some care. The IPI is raised once the interrupts are reenabled and can then safely call wake_up(). When APICs are disabled the event is just queued and will be picked up eventually by the next polling timer. I think that's a reasonable compromise, since it should only happen quite rarely. Contains fixes from Ying Huang. [ solve conflict on irqinit, make it work on 32bit (entry_arch.h) - HS ] Signed-off-by: Andi Kleen Signed-off-by: Hidetoshi Seto Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/entry_arch.h | 4 +++ arch/x86/include/asm/hw_irq.h | 1 + arch/x86/include/asm/irq_vectors.h | 5 ++++ arch/x86/kernel/cpu/mcheck/mce.c | 54 ++++++++++++++++++++++++++++++++++++++ arch/x86/kernel/entry_64.S | 5 ++++ arch/x86/kernel/irqinit.c | 3 +++ 6 files changed, 72 insertions(+) diff --git a/arch/x86/include/asm/entry_arch.h b/arch/x86/include/asm/entry_arch.h index b2eb9c06684..4cdcf5a3c96 100644 --- a/arch/x86/include/asm/entry_arch.h +++ b/arch/x86/include/asm/entry_arch.h @@ -60,4 +60,8 @@ BUILD_INTERRUPT(thermal_interrupt,THERMAL_APIC_VECTOR) BUILD_INTERRUPT(threshold_interrupt,THRESHOLD_APIC_VECTOR) #endif +#ifdef CONFIG_X86_NEW_MCE +BUILD_INTERRUPT(mce_self_interrupt,MCE_SELF_VECTOR) +#endif + #endif diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h index a7d14bbae11..4e59197e29b 100644 --- a/arch/x86/include/asm/hw_irq.h +++ b/arch/x86/include/asm/hw_irq.h @@ -32,6 +32,7 @@ extern void error_interrupt(void); extern void spurious_interrupt(void); extern void thermal_interrupt(void); extern void reschedule_interrupt(void); +extern void mce_self_interrupt(void); extern void invalidate_interrupt(void); extern void invalidate_interrupt0(void); diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h index 8c46b851296..68f7cf84a33 100644 --- a/arch/x86/include/asm/irq_vectors.h +++ b/arch/x86/include/asm/irq_vectors.h @@ -118,6 +118,11 @@ #define GENERIC_INTERRUPT_VECTOR 0xed /* + * Self IPI vector for machine checks + */ +#define MCE_SELF_VECTOR 0xeb + +/* * First APIC vector available to drivers: (vectors 0x30-0xee) we * start at 0x31(0x41) to spread out vectors evenly between priority * levels. (0x80 is the syscall vector) diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index 5031814ac94..12178162785 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -32,7 +33,10 @@ #include #include +#include +#include #include +#include #include #include @@ -287,6 +291,54 @@ static inline void mce_get_rip(struct mce *m, struct pt_regs *regs) } } +#ifdef CONFIG_X86_LOCAL_APIC +/* + * Called after interrupts have been reenabled again + * when a MCE happened during an interrupts off region + * in the kernel. + */ +asmlinkage void smp_mce_self_interrupt(struct pt_regs *regs) +{ + ack_APIC_irq(); + exit_idle(); + irq_enter(); + mce_notify_user(); + irq_exit(); +} +#endif + +static void mce_report_event(struct pt_regs *regs) +{ + if (regs->flags & (X86_VM_MASK|X86_EFLAGS_IF)) { + mce_notify_user(); + return; + } + +#ifdef CONFIG_X86_LOCAL_APIC + /* + * Without APIC do not notify. The event will be picked + * up eventually. + */ + if (!cpu_has_apic) + return; + + /* + * When interrupts are disabled we cannot use + * kernel services safely. Trigger an self interrupt + * through the APIC to instead do the notification + * after interrupts are reenabled again. + */ + apic->send_IPI_self(MCE_SELF_VECTOR); + + /* + * Wait for idle afterwards again so that we don't leave the + * APIC in a non idle state because the normal APIC writes + * cannot exclude us. + */ + apic_wait_icr_idle(); +#endif +} + DEFINE_PER_CPU(unsigned, mce_poll_count); /* @@ -530,6 +582,8 @@ void do_machine_check(struct pt_regs *regs, long error_code) /* notify userspace ASAP */ set_thread_flag(TIF_MCE_NOTIFY); + mce_report_event(regs); + /* the last thing we do is clear state */ for (i = 0; i < banks; i++) { if (test_bit(i, toclear)) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index a31a7f29cff..711c130a841 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -1011,6 +1011,11 @@ apicinterrupt THRESHOLD_APIC_VECTOR \ apicinterrupt THERMAL_APIC_VECTOR \ thermal_interrupt smp_thermal_interrupt +#ifdef CONFIG_X86_MCE +apicinterrupt MCE_SELF_VECTOR \ + mce_self_interrupt smp_mce_self_interrupt +#endif + #ifdef CONFIG_SMP apicinterrupt CALL_FUNCTION_SINGLE_VECTOR \ call_function_single_interrupt smp_call_function_single_interrupt diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c index aab3d277766..441f6ec6e9d 100644 --- a/arch/x86/kernel/irqinit.c +++ b/arch/x86/kernel/irqinit.c @@ -187,6 +187,9 @@ static void __init apic_intr_init(void) #ifdef CONFIG_X86_THRESHOLD alloc_intr_gate(THRESHOLD_APIC_VECTOR, threshold_interrupt); #endif +#if defined(CONFIG_X86_NEW_MCE) && defined(CONFIG_X86_LOCAL_APIC) + alloc_intr_gate(MCE_SELF_VECTOR, mce_self_interrupt); +#endif #if defined(CONFIG_X86_64) || defined(CONFIG_X86_LOCAL_APIC) /* self generated IPI for local APIC timer */ -- 2.11.4.GIT