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Anton Blanchard found that large POWER systems would occasionally crash in the exception exit path when profiling with perf_events. The symptom was that an interrupt would occur late in the exit path when the MSR[RI] (recoverable interrupt) bit was clear. Interrupts should be hard-disabled at this point but they were enabled. Because the interrupt was not recoverable the system panicked. The reason is that the exception exit path was calling perf_event_do_pending after hard-disabling interrupts, and perf_event_do_pending will re-enable interrupts. The simplest and cleanest fix for this is to use the same mechanism that 32-bit powerpc does, namely to cause a self-IPI by setting the decrementer to 1. This means we can remove the tests in the exception exit path and raw_local_irq_restore. This also makes sure that the call to perf_event_do_pending from timer_interrupt() happens within irq_enter/irq_exit. (Note that calling perf_event_do_pending from timer_interrupt does not mean that there is a possible 1/HZ latency; setting the decrementer to 1 ensures that the timer interrupt will happen immediately, i.e. within one timebase tick, which is a few nanoseconds or 10s of nanoseconds.) Signed-off-by: Paul Mackerras <paulus@samba.org> Cc: stable@kernel.org Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
135 lines
3.1 KiB
C
135 lines
3.1 KiB
C
/*
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* Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
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*/
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#ifndef _ASM_POWERPC_HW_IRQ_H
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#define _ASM_POWERPC_HW_IRQ_H
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#ifdef __KERNEL__
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#include <linux/errno.h>
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#include <linux/compiler.h>
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#include <asm/ptrace.h>
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#include <asm/processor.h>
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extern void timer_interrupt(struct pt_regs *);
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#ifdef CONFIG_PPC64
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#include <asm/paca.h>
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static inline unsigned long local_get_flags(void)
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{
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unsigned long flags;
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__asm__ __volatile__("lbz %0,%1(13)"
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: "=r" (flags)
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: "i" (offsetof(struct paca_struct, soft_enabled)));
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return flags;
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}
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static inline unsigned long raw_local_irq_disable(void)
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{
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unsigned long flags, zero;
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__asm__ __volatile__("li %1,0; lbz %0,%2(13); stb %1,%2(13)"
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: "=r" (flags), "=&r" (zero)
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: "i" (offsetof(struct paca_struct, soft_enabled))
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: "memory");
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return flags;
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}
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extern void raw_local_irq_restore(unsigned long);
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extern void iseries_handle_interrupts(void);
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#define raw_local_irq_enable() raw_local_irq_restore(1)
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#define raw_local_save_flags(flags) ((flags) = local_get_flags())
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#define raw_local_irq_save(flags) ((flags) = raw_local_irq_disable())
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#define raw_irqs_disabled() (local_get_flags() == 0)
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#define raw_irqs_disabled_flags(flags) ((flags) == 0)
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#ifdef CONFIG_PPC_BOOK3E
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#define __hard_irq_enable() __asm__ __volatile__("wrteei 1": : :"memory");
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#define __hard_irq_disable() __asm__ __volatile__("wrteei 0": : :"memory");
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#else
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#define __hard_irq_enable() __mtmsrd(mfmsr() | MSR_EE, 1)
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#define __hard_irq_disable() __mtmsrd(mfmsr() & ~MSR_EE, 1)
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#endif
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#define hard_irq_disable() \
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do { \
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__hard_irq_disable(); \
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get_paca()->soft_enabled = 0; \
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get_paca()->hard_enabled = 0; \
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} while(0)
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#else
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#if defined(CONFIG_BOOKE)
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#define SET_MSR_EE(x) mtmsr(x)
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#define raw_local_irq_restore(flags) __asm__ __volatile__("wrtee %0" : : "r" (flags) : "memory")
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#else
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#define SET_MSR_EE(x) mtmsr(x)
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#define raw_local_irq_restore(flags) mtmsr(flags)
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#endif
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static inline void raw_local_irq_disable(void)
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{
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#ifdef CONFIG_BOOKE
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__asm__ __volatile__("wrteei 0": : :"memory");
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#else
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unsigned long msr;
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msr = mfmsr();
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SET_MSR_EE(msr & ~MSR_EE);
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#endif
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}
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static inline void raw_local_irq_enable(void)
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{
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#ifdef CONFIG_BOOKE
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__asm__ __volatile__("wrteei 1": : :"memory");
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#else
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unsigned long msr;
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msr = mfmsr();
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SET_MSR_EE(msr | MSR_EE);
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#endif
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}
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static inline void raw_local_irq_save_ptr(unsigned long *flags)
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{
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unsigned long msr;
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msr = mfmsr();
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*flags = msr;
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#ifdef CONFIG_BOOKE
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__asm__ __volatile__("wrteei 0": : :"memory");
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#else
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SET_MSR_EE(msr & ~MSR_EE);
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#endif
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}
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#define raw_local_save_flags(flags) ((flags) = mfmsr())
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#define raw_local_irq_save(flags) raw_local_irq_save_ptr(&flags)
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#define raw_irqs_disabled() ((mfmsr() & MSR_EE) == 0)
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#define raw_irqs_disabled_flags(flags) (((flags) & MSR_EE) == 0)
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#define hard_irq_disable() raw_local_irq_disable()
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static inline int irqs_disabled_flags(unsigned long flags)
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{
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return (flags & MSR_EE) == 0;
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}
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#endif /* CONFIG_PPC64 */
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/*
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* interrupt-retrigger: should we handle this via lost interrupts and IPIs
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* or should we not care like we do now ? --BenH.
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*/
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struct irq_chip;
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_HW_IRQ_H */
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