diff options
Diffstat (limited to 'arch/powerpc/perf/core-book3s.c')
| -rw-r--r-- | arch/powerpc/perf/core-book3s.c | 100 |
1 files changed, 98 insertions, 2 deletions
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c index 8d4ff93462fb..b5b42cf0a703 100644 --- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -17,6 +17,7 @@ #include <asm/firmware.h> #include <asm/ptrace.h> #include <asm/code-patching.h> +#include <asm/hw_irq.h> #include <asm/interrupt.h> #ifdef CONFIG_PPC64 @@ -775,6 +776,34 @@ static void pmao_restore_workaround(bool ebb) mtspr(SPRN_PMC6, pmcs[5]); } +/* + * If the perf subsystem wants performance monitor interrupts as soon as + * possible (e.g., to sample the instruction address and stack chain), + * this should return true. The IRQ masking code can then enable MSR[EE] + * in some places (e.g., interrupt handlers) that allows PMI interrupts + * through to improve accuracy of profiles, at the cost of some performance. + * + * The PMU counters can be enabled by other means (e.g., sysfs raw SPR + * access), but in that case there is no need for prompt PMI handling. + * + * This currently returns true if any perf counter is being used. It + * could possibly return false if only events are being counted rather than + * samples being taken, but for now this is good enough. + */ +bool power_pmu_wants_prompt_pmi(void) +{ + struct cpu_hw_events *cpuhw; + + /* + * This could simply test local_paca->pmcregs_in_use if that were not + * under ifdef KVM. + */ + if (!ppmu) + return false; + + cpuhw = this_cpu_ptr(&cpu_hw_events); + return cpuhw->n_events; +} #endif /* CONFIG_PPC64 */ static void perf_event_interrupt(struct pt_regs *regs); @@ -857,6 +886,19 @@ static void write_pmc(int idx, unsigned long val) } } +static int any_pmc_overflown(struct cpu_hw_events *cpuhw) +{ + int i, idx; + + for (i = 0; i < cpuhw->n_events; i++) { + idx = cpuhw->event[i]->hw.idx; + if ((idx) && ((int)read_pmc(idx) < 0)) + return idx; + } + + return 0; +} + /* Called from sysrq_handle_showregs() */ void perf_event_print_debug(void) { @@ -1281,11 +1323,13 @@ static void power_pmu_disable(struct pmu *pmu) /* * Set the 'freeze counters' bit, clear EBE/BHRBA/PMCC/PMAO/FC56 + * Also clear PMXE to disable PMI's getting triggered in some + * corner cases during PMU disable. */ val = mmcr0 = mfspr(SPRN_MMCR0); val |= MMCR0_FC; val &= ~(MMCR0_EBE | MMCR0_BHRBA | MMCR0_PMCC | MMCR0_PMAO | - MMCR0_FC56); + MMCR0_PMXE | MMCR0_FC56); /* Set mmcr0 PMCCEXT for p10 */ if (ppmu->flags & PPMU_ARCH_31) val |= MMCR0_PMCCEXT; @@ -1299,6 +1343,34 @@ static void power_pmu_disable(struct pmu *pmu) mb(); isync(); + /* + * Some corner cases could clear the PMU counter overflow + * while a masked PMI is pending. One such case is when + * a PMI happens during interrupt replay and perf counter + * values are cleared by PMU callbacks before replay. + * + * If any PMC corresponding to the active PMU events are + * overflown, disable the interrupt by clearing the paca + * bit for PMI since we are disabling the PMU now. + * Otherwise provide a warning if there is PMI pending, but + * no counter is found overflown. + */ + if (any_pmc_overflown(cpuhw)) { + /* + * Since power_pmu_disable runs under local_irq_save, it + * could happen that code hits a PMC overflow without PMI + * pending in paca. Hence only clear PMI pending if it was + * set. + * + * If a PMI is pending, then MSR[EE] must be disabled (because + * the masked PMI handler disabling EE). So it is safe to + * call clear_pmi_irq_pending(). + */ + if (pmi_irq_pending()) + clear_pmi_irq_pending(); + } else + WARN_ON(pmi_irq_pending()); + val = mmcra = cpuhw->mmcr.mmcra; /* @@ -1390,6 +1462,15 @@ static void power_pmu_enable(struct pmu *pmu) * (possibly updated for removal of events). */ if (!cpuhw->n_added) { + /* + * If there is any active event with an overflown PMC + * value, set back PACA_IRQ_PMI which would have been + * cleared in power_pmu_disable(). + */ + hard_irq_disable(); + if (any_pmc_overflown(cpuhw)) + set_pmi_irq_pending(); + mtspr(SPRN_MMCRA, cpuhw->mmcr.mmcra & ~MMCRA_SAMPLE_ENABLE); mtspr(SPRN_MMCR1, cpuhw->mmcr.mmcr1); if (ppmu->flags & PPMU_ARCH_31) @@ -2337,6 +2418,14 @@ static void __perf_event_interrupt(struct pt_regs *regs) break; } } + + /* + * Clear PACA_IRQ_PMI in case it was set by + * set_pmi_irq_pending() when PMU was enabled + * after accounting for interrupts. + */ + clear_pmi_irq_pending(); + if (!active) /* reset non active counters that have overflowed */ write_pmc(i + 1, 0); @@ -2356,6 +2445,13 @@ static void __perf_event_interrupt(struct pt_regs *regs) } } } + + /* + * During system wide profling or while specific CPU is monitored for an + * event, some corner cases could cause PMC to overflow in idle path. This + * will trigger a PMI after waking up from idle. Since counter values are _not_ + * saved/restored in idle path, can lead to below "Can't find PMC" message. + */ if (unlikely(!found) && !arch_irq_disabled_regs(regs)) printk_ratelimited(KERN_WARNING "Can't find PMC that caused IRQ\n"); @@ -2392,7 +2488,7 @@ static int power_pmu_prepare_cpu(unsigned int cpu) return 0; } -int register_power_pmu(struct power_pmu *pmu) +int __init register_power_pmu(struct power_pmu *pmu) { if (ppmu) return -EBUSY; /* something's already registered */ |