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author | Paul Mackerras <paulus@samba.org> | 2010-04-13 20:46:04 +0000 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-05-26 14:29:16 -0700 |
commit | 73ef533de7533fcf514403125a0d4747d3390317 (patch) | |
tree | 83865693cb3792ac3b358733cf8203b6a820eeee | |
parent | fa157eec79e78a875790df6faf53b3501c33a462 (diff) | |
download | linux-stable-73ef533de7533fcf514403125a0d4747d3390317.tar.gz linux-stable-73ef533de7533fcf514403125a0d4747d3390317.tar.bz2 linux-stable-73ef533de7533fcf514403125a0d4747d3390317.zip |
powerpc/perf_event: Fix oops due to perf_event_do_pending call
commit 0fe1ac48bef018bed896307cd12f6ca9b5e704ab upstream.
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>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r-- | arch/powerpc/include/asm/hw_irq.h | 38 | ||||
-rw-r--r-- | arch/powerpc/kernel/asm-offsets.c | 1 | ||||
-rw-r--r-- | arch/powerpc/kernel/entry_64.S | 9 | ||||
-rw-r--r-- | arch/powerpc/kernel/irq.c | 6 | ||||
-rw-r--r-- | arch/powerpc/kernel/time.c | 60 |
5 files changed, 48 insertions, 66 deletions
diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/asm/hw_irq.h index abbc2aaaced5..c1de3c9a1d65 100644 --- a/arch/powerpc/include/asm/hw_irq.h +++ b/arch/powerpc/include/asm/hw_irq.h @@ -135,43 +135,5 @@ static inline int irqs_disabled_flags(unsigned long flags) */ struct irq_chip; -#ifdef CONFIG_PERF_EVENTS - -#ifdef CONFIG_PPC64 -static inline unsigned long test_perf_event_pending(void) -{ - unsigned long x; - - asm volatile("lbz %0,%1(13)" - : "=r" (x) - : "i" (offsetof(struct paca_struct, perf_event_pending))); - return x; -} - -static inline void set_perf_event_pending(void) -{ - asm volatile("stb %0,%1(13)" : : - "r" (1), - "i" (offsetof(struct paca_struct, perf_event_pending))); -} - -static inline void clear_perf_event_pending(void) -{ - asm volatile("stb %0,%1(13)" : : - "r" (0), - "i" (offsetof(struct paca_struct, perf_event_pending))); -} -#endif /* CONFIG_PPC64 */ - -#else /* CONFIG_PERF_EVENTS */ - -static inline unsigned long test_perf_event_pending(void) -{ - return 0; -} - -static inline void clear_perf_event_pending(void) {} -#endif /* CONFIG_PERF_EVENTS */ - #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_HW_IRQ_H */ diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 0812b0f414bb..692c056566c7 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -133,7 +133,6 @@ int main(void) DEFINE(PACAKMSR, offsetof(struct paca_struct, kernel_msr)); DEFINE(PACASOFTIRQEN, offsetof(struct paca_struct, soft_enabled)); DEFINE(PACAHARDIRQEN, offsetof(struct paca_struct, hard_enabled)); - DEFINE(PACAPERFPEND, offsetof(struct paca_struct, perf_event_pending)); DEFINE(PACACONTEXTID, offsetof(struct paca_struct, context.id)); #ifdef CONFIG_PPC_MM_SLICES DEFINE(PACALOWSLICESPSIZE, offsetof(struct paca_struct, diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 9763267e38b4..917cebc2f262 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -556,15 +556,6 @@ ALT_FW_FTR_SECTION_END_IFCLR(FW_FEATURE_ISERIES) 2: TRACE_AND_RESTORE_IRQ(r5); -#ifdef CONFIG_PERF_EVENTS - /* check paca->perf_event_pending if we're enabling ints */ - lbz r3,PACAPERFPEND(r13) - and. r3,r3,r5 - beq 27f - bl .perf_event_do_pending -27: -#endif /* CONFIG_PERF_EVENTS */ - /* extract EE bit and use it to restore paca->hard_enabled */ ld r3,_MSR(r1) rldicl r4,r3,49,63 /* r0 = (r3 >> 15) & 1 */ diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c index e5d121177984..8564a412e7a6 100644 --- a/arch/powerpc/kernel/irq.c +++ b/arch/powerpc/kernel/irq.c @@ -53,7 +53,6 @@ #include <linux/bootmem.h> #include <linux/pci.h> #include <linux/debugfs.h> -#include <linux/perf_event.h> #include <asm/uaccess.h> #include <asm/system.h> @@ -138,11 +137,6 @@ notrace void raw_local_irq_restore(unsigned long en) } #endif /* CONFIG_PPC_STD_MMU_64 */ - if (test_perf_event_pending()) { - clear_perf_event_pending(); - perf_event_do_pending(); - } - /* * if (get_paca()->hard_enabled) return; * But again we need to take care that gcc gets hard_enabled directly diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index a136a11c490d..02aab7f90295 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -530,25 +530,60 @@ void __init iSeries_time_init_early(void) } #endif /* CONFIG_PPC_ISERIES */ -#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_PPC32) -DEFINE_PER_CPU(u8, perf_event_pending); +#ifdef CONFIG_PERF_EVENTS -void set_perf_event_pending(void) +/* + * 64-bit uses a byte in the PACA, 32-bit uses a per-cpu variable... + */ +#ifdef CONFIG_PPC64 +static inline unsigned long test_perf_event_pending(void) { - get_cpu_var(perf_event_pending) = 1; - set_dec(1); - put_cpu_var(perf_event_pending); + unsigned long x; + + asm volatile("lbz %0,%1(13)" + : "=r" (x) + : "i" (offsetof(struct paca_struct, perf_event_pending))); + return x; } +static inline void set_perf_event_pending_flag(void) +{ + asm volatile("stb %0,%1(13)" : : + "r" (1), + "i" (offsetof(struct paca_struct, perf_event_pending))); +} + +static inline void clear_perf_event_pending(void) +{ + asm volatile("stb %0,%1(13)" : : + "r" (0), + "i" (offsetof(struct paca_struct, perf_event_pending))); +} + +#else /* 32-bit */ + +DEFINE_PER_CPU(u8, perf_event_pending); + +#define set_perf_event_pending_flag() __get_cpu_var(perf_event_pending) = 1 #define test_perf_event_pending() __get_cpu_var(perf_event_pending) #define clear_perf_event_pending() __get_cpu_var(perf_event_pending) = 0 -#else /* CONFIG_PERF_EVENTS && CONFIG_PPC32 */ +#endif /* 32 vs 64 bit */ + +void set_perf_event_pending(void) +{ + preempt_disable(); + set_perf_event_pending_flag(); + set_dec(1); + preempt_enable(); +} + +#else /* CONFIG_PERF_EVENTS */ #define test_perf_event_pending() 0 #define clear_perf_event_pending() -#endif /* CONFIG_PERF_EVENTS && CONFIG_PPC32 */ +#endif /* CONFIG_PERF_EVENTS */ /* * For iSeries shared processors, we have to let the hypervisor @@ -576,10 +611,6 @@ void timer_interrupt(struct pt_regs * regs) set_dec(DECREMENTER_MAX); #ifdef CONFIG_PPC32 - if (test_perf_event_pending()) { - clear_perf_event_pending(); - perf_event_do_pending(); - } if (atomic_read(&ppc_n_lost_interrupts) != 0) do_IRQ(regs); #endif @@ -597,6 +628,11 @@ void timer_interrupt(struct pt_regs * regs) calculate_steal_time(); + if (test_perf_event_pending()) { + clear_perf_event_pending(); + perf_event_do_pending(); + } + #ifdef CONFIG_PPC_ISERIES if (firmware_has_feature(FW_FEATURE_ISERIES)) get_lppaca()->int_dword.fields.decr_int = 0; |