From db98c5faf8cb350212ea3af786cb3ba0d4e7a01e Mon Sep 17 00:00:00 2001 From: Robert Richter Date: Thu, 15 Dec 2011 17:56:39 +0100 Subject: [PATCH] perf/x86: Implement 64-bit counter support for IBS This patch implements 64 bit counter support for IBS. The sampling period is no longer limited to the hw counter width. The functions perf_event_set_period() and perf_event_try_update() can be used as generic functions. They can replace similar code that is duplicate across architectures. Signed-off-by: Robert Richter Acked-by: Peter Zijlstra Cc: Stephane Eranian Link: http://lkml.kernel.org/r/1323968199-9326-5-git-send-email-robert.richter@amd.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/perf_event.h | 2 + arch/x86/kernel/cpu/perf_event_amd_ibs.c | 204 +++++++++++++++++++++++++++---- 2 files changed, 185 insertions(+), 21 deletions(-) diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h index e8fb2c7a5f4f..9cf66965141d 100644 --- a/arch/x86/include/asm/perf_event.h +++ b/arch/x86/include/asm/perf_event.h @@ -177,6 +177,8 @@ struct x86_pmu_capability { #define IBS_FETCH_MAX_CNT 0x0000FFFFULL /* IbsOpCtl bits */ +/* lower 4 bits of the current count are ignored: */ +#define IBS_OP_CUR_CNT (0xFFFF0ULL<<32) #define IBS_OP_CNT_CTL (1ULL<<19) #define IBS_OP_VAL (1ULL<<18) #define IBS_OP_ENABLE (1ULL<<17) diff --git a/arch/x86/kernel/cpu/perf_event_amd_ibs.c b/arch/x86/kernel/cpu/perf_event_amd_ibs.c index 40a6d9d5dd23..573d24873459 100644 --- a/arch/x86/kernel/cpu/perf_event_amd_ibs.c +++ b/arch/x86/kernel/cpu/perf_event_amd_ibs.c @@ -44,9 +44,11 @@ struct perf_ibs { u64 cnt_mask; u64 enable_mask; u64 valid_mask; + u64 max_period; unsigned long offset_mask[1]; int offset_max; struct cpu_perf_ibs __percpu *pcpu; + u64 (*get_count)(u64 config); }; struct perf_ibs_data { @@ -58,6 +60,78 @@ struct perf_ibs_data { u64 regs[MSR_AMD64_IBS_REG_COUNT_MAX]; }; +static int +perf_event_set_period(struct hw_perf_event *hwc, u64 min, u64 max, u64 *count) +{ + s64 left = local64_read(&hwc->period_left); + s64 period = hwc->sample_period; + int overflow = 0; + + /* + * If we are way outside a reasonable range then just skip forward: + */ + if (unlikely(left <= -period)) { + left = period; + local64_set(&hwc->period_left, left); + hwc->last_period = period; + overflow = 1; + } + + if (unlikely(left <= 0)) { + left += period; + local64_set(&hwc->period_left, left); + hwc->last_period = period; + overflow = 1; + } + + if (unlikely(left < min)) + left = min; + + if (left > max) + left = max; + + *count = (u64)left; + + return overflow; +} + +static int +perf_event_try_update(struct perf_event *event, u64 new_raw_count, int width) +{ + struct hw_perf_event *hwc = &event->hw; + int shift = 64 - width; + u64 prev_raw_count; + u64 delta; + + /* + * Careful: an NMI might modify the previous event value. + * + * Our tactic to handle this is to first atomically read and + * exchange a new raw count - then add that new-prev delta + * count to the generic event atomically: + */ + prev_raw_count = local64_read(&hwc->prev_count); + if (local64_cmpxchg(&hwc->prev_count, prev_raw_count, + new_raw_count) != prev_raw_count) + return 0; + + /* + * Now we have the new raw value and have updated the prev + * timestamp already. We can now calculate the elapsed delta + * (event-)time and add that to the generic event. + * + * Careful, not all hw sign-extends above the physical width + * of the count. + */ + delta = (new_raw_count << shift) - (prev_raw_count << shift); + delta >>= shift; + + local64_add(delta, &event->count); + local64_sub(delta, &hwc->period_left); + + return 1; +} + static struct perf_ibs perf_ibs_fetch; static struct perf_ibs perf_ibs_op; @@ -91,18 +165,14 @@ static int perf_ibs_init(struct perf_event *event) if (hwc->sample_period & 0x0f) /* lower 4 bits can not be set in ibs max cnt */ return -EINVAL; - max_cnt = hwc->sample_period >> 4; - if (max_cnt & ~perf_ibs->cnt_mask) - /* out of range */ - return -EINVAL; - config |= max_cnt; } else { max_cnt = config & perf_ibs->cnt_mask; + config &= ~perf_ibs->cnt_mask; event->attr.sample_period = max_cnt << 4; hwc->sample_period = event->attr.sample_period; } - if (!max_cnt) + if (!hwc->sample_period) return -EINVAL; hwc->config_base = perf_ibs->msr; @@ -111,16 +181,71 @@ static int perf_ibs_init(struct perf_event *event) return 0; } +static int perf_ibs_set_period(struct perf_ibs *perf_ibs, + struct hw_perf_event *hwc, u64 *period) +{ + int ret; + + /* ignore lower 4 bits in min count: */ + ret = perf_event_set_period(hwc, 1<<4, perf_ibs->max_period, period); + local64_set(&hwc->prev_count, 0); + + return ret; +} + +static u64 get_ibs_fetch_count(u64 config) +{ + return (config & IBS_FETCH_CNT) >> 12; +} + +static u64 get_ibs_op_count(u64 config) +{ + return (config & IBS_OP_CUR_CNT) >> 32; +} + +static void +perf_ibs_event_update(struct perf_ibs *perf_ibs, struct perf_event *event, + u64 config) +{ + u64 count = perf_ibs->get_count(config); + + while (!perf_event_try_update(event, count, 20)) { + rdmsrl(event->hw.config_base, config); + count = perf_ibs->get_count(config); + } +} + +/* Note: The enable mask must be encoded in the config argument. */ +static inline void perf_ibs_enable_event(struct hw_perf_event *hwc, u64 config) +{ + wrmsrl(hwc->config_base, hwc->config | config); +} + +/* + * We cannot restore the ibs pmu state, so we always needs to update + * the event while stopping it and then reset the state when starting + * again. Thus, ignoring PERF_EF_RELOAD and PERF_EF_UPDATE flags in + * perf_ibs_start()/perf_ibs_stop() and instead always do it. + */ static void perf_ibs_start(struct perf_event *event, int flags) { struct hw_perf_event *hwc = &event->hw; struct perf_ibs *perf_ibs = container_of(event->pmu, struct perf_ibs, pmu); struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu); + u64 config; - if (test_and_set_bit(IBS_STARTED, pcpu->state)) + if (WARN_ON_ONCE(!(hwc->state & PERF_HES_STOPPED))) return; - wrmsrl(hwc->config_base, hwc->config | perf_ibs->enable_mask); + WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE)); + hwc->state = 0; + + perf_ibs_set_period(perf_ibs, hwc, &config); + config = (config >> 4) | perf_ibs->enable_mask; + set_bit(IBS_STARTED, pcpu->state); + perf_ibs_enable_event(hwc, config); + + perf_event_update_userpage(event); } static void perf_ibs_stop(struct perf_event *event, int flags) @@ -129,15 +254,28 @@ static void perf_ibs_stop(struct perf_event *event, int flags) struct perf_ibs *perf_ibs = container_of(event->pmu, struct perf_ibs, pmu); struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu); u64 val; + int stopping; - if (!test_and_clear_bit(IBS_STARTED, pcpu->state)) - return; + stopping = test_and_clear_bit(IBS_STARTED, pcpu->state); - set_bit(IBS_STOPPING, pcpu->state); + if (!stopping && (hwc->state & PERF_HES_UPTODATE)) + return; rdmsrl(hwc->config_base, val); - val &= ~perf_ibs->enable_mask; - wrmsrl(hwc->config_base, val); + + if (stopping) { + set_bit(IBS_STOPPING, pcpu->state); + val &= ~perf_ibs->enable_mask; + wrmsrl(hwc->config_base, val); + WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED); + hwc->state |= PERF_HES_STOPPED; + } + + if (hwc->state & PERF_HES_UPTODATE) + return; + + perf_ibs_event_update(perf_ibs, event, val); + hwc->state |= PERF_HES_UPTODATE; } static int perf_ibs_add(struct perf_event *event, int flags) @@ -148,6 +286,8 @@ static int perf_ibs_add(struct perf_event *event, int flags) if (test_and_set_bit(IBS_ENABLED, pcpu->state)) return -ENOSPC; + event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED; + pcpu->event = event; if (flags & PERF_EF_START) @@ -164,9 +304,11 @@ static void perf_ibs_del(struct perf_event *event, int flags) if (!test_and_clear_bit(IBS_ENABLED, pcpu->state)) return; - perf_ibs_stop(event, 0); + perf_ibs_stop(event, PERF_EF_UPDATE); pcpu->event = NULL; + + perf_event_update_userpage(event); } static void perf_ibs_read(struct perf_event *event) { } @@ -187,8 +329,11 @@ static struct perf_ibs perf_ibs_fetch = { .cnt_mask = IBS_FETCH_MAX_CNT, .enable_mask = IBS_FETCH_ENABLE, .valid_mask = IBS_FETCH_VAL, + .max_period = IBS_FETCH_MAX_CNT << 4, .offset_mask = { MSR_AMD64_IBSFETCH_REG_MASK }, .offset_max = MSR_AMD64_IBSFETCH_REG_COUNT, + + .get_count = get_ibs_fetch_count, }; static struct perf_ibs perf_ibs_op = { @@ -207,8 +352,11 @@ static struct perf_ibs perf_ibs_op = { .cnt_mask = IBS_OP_MAX_CNT, .enable_mask = IBS_OP_ENABLE, .valid_mask = IBS_OP_VAL, + .max_period = IBS_OP_MAX_CNT << 4, .offset_mask = { MSR_AMD64_IBSOP_REG_MASK }, .offset_max = MSR_AMD64_IBSOP_REG_COUNT, + + .get_count = get_ibs_op_count, }; static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs) @@ -220,9 +368,9 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs) struct perf_raw_record raw; struct pt_regs regs; struct perf_ibs_data ibs_data; - int offset, size; + int offset, size, overflow, reenable; unsigned int msr; - u64 *buf; + u64 *buf, config; if (!test_bit(IBS_STARTED, pcpu->state)) { /* Catch spurious interrupts after stopping IBS: */ @@ -257,11 +405,25 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs) regs = *iregs; /* XXX: update ip from ibs sample */ - if (perf_event_overflow(event, &data, ®s)) - ; /* stop */ - else - /* reenable */ - wrmsrl(hwc->config_base, hwc->config | perf_ibs->enable_mask); + /* + * Emulate IbsOpCurCnt in MSRC001_1033 (IbsOpCtl), not + * supported in all cpus. As this triggered an interrupt, we + * set the current count to the max count. + */ + config = ibs_data.regs[0]; + if (perf_ibs == &perf_ibs_op && !(ibs_caps & IBS_CAPS_RDWROPCNT)) { + config &= ~IBS_OP_CUR_CNT; + config |= (config & IBS_OP_MAX_CNT) << 36; + } + + perf_ibs_event_update(perf_ibs, event, config); + + overflow = perf_ibs_set_period(perf_ibs, hwc, &config); + reenable = !(overflow && perf_event_overflow(event, &data, ®s)); + config = (config >> 4) | (reenable ? perf_ibs->enable_mask : 0); + perf_ibs_enable_event(hwc, config); + + perf_event_update_userpage(event); return 1; } -- 2.11.0