[PATCH v2 0/5] MIPS/Perf-events: Sync with mainline upper layer (v2)

[PATCH v2 0/5] MIPS/Perf-events: Sync with mainline upper layer (v2)

[Deng-Cheng Zhu]

Current MIPS Perf-events uses older interfaces to the generic layer. So it
will not work. This patch set fixes this issue (reported by Wu Zhangjin) by
adding MIPS counterparts for a list of previous commits that went to
mainline earlier.

Changes:
v2 - v1:
o Corrected the return value of the event check in validate_event().

Deng-Cheng Zhu (5):
  MIPS/Perf-events: Work with irq_work
  MIPS/Perf-events: Work with the new PMU interface
  MIPS/Perf-events: Fix event check in validate_event()
  MIPS/Perf-events: Work with the new callchain interface
  MIPS/Perf-events: Use unsigned delta for right shift in event update

 arch/mips/Kconfig                    |    1 +
 arch/mips/include/asm/perf_event.h   |   12 +-
 arch/mips/kernel/perf_event.c        |  345 ++++++++++++++++------------------
 arch/mips/kernel/perf_event_mipsxx.c |    4 +-
 4 files changed, 171 insertions(+), 191 deletions(-)

[PATCH v2 1/5] MIPS/Perf-events: Work with irq_work

[Deng-Cheng Zhu]

This is the MIPS part of the commit:

e360adbe29241a0194e10e20595360dd7b98a2b3

Reported-by: Wu Zhangjin <wuzhangjin@gmail.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
---
 arch/mips/Kconfig                    |    1 +
 arch/mips/include/asm/perf_event.h   |   12 +-----------
 arch/mips/kernel/perf_event_mipsxx.c |    2 +-
 3 files changed, 3 insertions(+), 12 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 67a2fa2..c44c38d 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -4,6 +4,7 @@ config MIPS
 	select HAVE_GENERIC_DMA_COHERENT
 	select HAVE_IDE
 	select HAVE_OPROFILE
+	select HAVE_IRQ_WORK
 	select HAVE_PERF_EVENTS
 	select PERF_USE_VMALLOC
 	select HAVE_ARCH_KGDB
diff --git a/arch/mips/include/asm/perf_event.h b/arch/mips/include/asm/perf_event.h
index e00007c..d0c7749 100644
--- a/arch/mips/include/asm/perf_event.h
+++ b/arch/mips/include/asm/perf_event.h
@@ -11,15 +11,5 @@
 
 #ifndef __MIPS_PERF_EVENT_H__
 #define __MIPS_PERF_EVENT_H__
-
-/*
- * MIPS performance counters do not raise NMI upon overflow, a regular
- * interrupt will be signaled. Hence we can do the pending perf event
- * work at the tail of the irq handler.
- */
-static inline void
-set_perf_event_pending(void)
-{
-}
-
+/* Leave it empty here. The file is required by linux/perf_event.h */
 #endif /* __MIPS_PERF_EVENT_H__ */
diff --git a/arch/mips/kernel/perf_event_mipsxx.c b/arch/mips/kernel/perf_event_mipsxx.c
index 5c7c6fc..fa00edc 100644
--- a/arch/mips/kernel/perf_event_mipsxx.c
+++ b/arch/mips/kernel/perf_event_mipsxx.c
@@ -696,7 +696,7 @@ static int mipsxx_pmu_handle_shared_irq(void)
 	 * interrupt, not NMI.
 	 */
 	if (handled == IRQ_HANDLED)
-		perf_event_do_pending();
+		irq_work_run();
 
 #ifdef CONFIG_MIPS_MT_SMP
 	read_unlock(&pmuint_rwlock);
-- 
1.7.1

Re: [PATCH v2 1/5] MIPS/Perf-events: Work with irq_work

[Matt Fleming]

On Fri, Nov 26, 2010 at 11:05:03AM +0800, Deng-Cheng Zhu wrote:
> This is the MIPS part of the commit:
> 
> e360adbe29241a0194e10e20595360dd7b98a2b3

Wouldn't it be a good idea to include the title of the commit here?

Re: [PATCH v2 1/5] MIPS/Perf-events: Work with irq_work

[Sergei Shtylyov]

Hello.

On 26-11-2010 6:05, Deng-Cheng Zhu wrote:

> This is the MIPS part of the commit:

> e360adbe29241a0194e10e20595360dd7b98a2b3

    Linus has asked to also specify the commit summary in parens.

> Reported-by: Wu Zhangjin<wuzhangjin@gmail.com>
> Acked-by: Peter Zijlstra<a.p.zijlstra@chello.nl>
> Signed-off-by: Deng-Cheng Zhu<dengcheng.zhu@gmail.com>

WBR, Sergei

[PATCH v2 2/5] MIPS/Perf-events: Work with the new PMU interface

[Deng-Cheng Zhu]

This is the MIPS part of the following commits by Peter Zijlstra:

a4eaf7f14675cb512d69f0c928055e73d0c6d252
	perf: Rework the PMU methods
33696fc0d141bbbcb12f75b69608ea83282e3117
	perf: Per PMU disable
24cd7f54a0d47e1d5b3de29e2456bfbd2d8447b7
	perf: Reduce perf_disable() usage
b0a873ebbf87bf38bf70b5e39a7cadc96099fa13
	perf: Register PMU implementations
51b0fe39549a04858001922919ab355dee9bdfcf
	perf: Deconstify struct pmu

Reported-by: Wu Zhangjin <wuzhangjin@gmail.com>
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
---
 arch/mips/kernel/perf_event.c        |  275 +++++++++++++++++++---------------
 arch/mips/kernel/perf_event_mipsxx.c |    2 +
 2 files changed, 158 insertions(+), 119 deletions(-)

diff --git a/arch/mips/kernel/perf_event.c b/arch/mips/kernel/perf_event.c
index 2b7f3f7..1ee44a3 100644
--- a/arch/mips/kernel/perf_event.c
+++ b/arch/mips/kernel/perf_event.c
@@ -161,41 +161,6 @@ mipspmu_event_set_period(struct perf_event *event,
 	return ret;
 }
 
-static int mipspmu_enable(struct perf_event *event)
-{
-	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
-	struct hw_perf_event *hwc = &event->hw;
-	int idx;
-	int err = 0;
-
-	/* To look for a free counter for this event. */
-	idx = mipspmu->alloc_counter(cpuc, hwc);
-	if (idx < 0) {
-		err = idx;
-		goto out;
-	}
-
-	/*
-	 * If there is an event in the counter we are going to use then
-	 * make sure it is disabled.
-	 */
-	event->hw.idx = idx;
-	mipspmu->disable_event(idx);
-	cpuc->events[idx] = event;
-
-	/* Set the period for the event. */
-	mipspmu_event_set_period(event, hwc, idx);
-
-	/* Enable the event. */
-	mipspmu->enable_event(hwc, idx);
-
-	/* Propagate our changes to the userspace mapping. */
-	perf_event_update_userpage(event);
-
-out:
-	return err;
-}
-
 static void mipspmu_event_update(struct perf_event *event,
 			struct hw_perf_event *hwc,
 			int idx)
@@ -231,32 +196,90 @@ again:
 	return;
 }
 
-static void mipspmu_disable(struct perf_event *event)
+static void mipspmu_start(struct perf_event *event, int flags)
+{
+	struct hw_perf_event *hwc = &event->hw;
+
+	if (!mipspmu)
+		return;
+
+	if (flags & PERF_EF_RELOAD)
+		WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));
+
+	hwc->state = 0;
+
+	/* Set the period for the event. */
+	mipspmu_event_set_period(event, hwc, hwc->idx);
+
+	/* Enable the event. */
+	mipspmu->enable_event(hwc, hwc->idx);
+}
+
+static void mipspmu_stop(struct perf_event *event, int flags)
+{
+	struct hw_perf_event *hwc = &event->hw;
+
+	if (!mipspmu)
+		return;
+
+	if (!(hwc->state & PERF_HES_STOPPED)) {
+		/* We are working on a local event. */
+		mipspmu->disable_event(hwc->idx);
+		barrier();
+		mipspmu_event_update(event, hwc, hwc->idx);
+		hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
+	}
+}
+
+static int mipspmu_add(struct perf_event *event, int flags)
 {
 	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 	struct hw_perf_event *hwc = &event->hw;
-	int idx = hwc->idx;
+	int idx;
+	int err = 0;
 
+	perf_pmu_disable(event->pmu);
 
-	WARN_ON(idx < 0 || idx >= mipspmu->num_counters);
+	/* To look for a free counter for this event. */
+	idx = mipspmu->alloc_counter(cpuc, hwc);
+	if (idx < 0) {
+		err = idx;
+		goto out;
+	}
 
-	/* We are working on a local event. */
+	/*
+	 * If there is an event in the counter we are going to use then
+	 * make sure it is disabled.
+	 */
+	event->hw.idx = idx;
 	mipspmu->disable_event(idx);
+	cpuc->events[idx] = event;
 
-	barrier();
-
-	mipspmu_event_update(event, hwc, idx);
-	cpuc->events[idx] = NULL;
-	clear_bit(idx, cpuc->used_mask);
+	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
+	if (flags & PERF_EF_START)
+		mipspmu_start(event, PERF_EF_RELOAD);
 
+	/* Propagate our changes to the userspace mapping. */
 	perf_event_update_userpage(event);
+
+out:
+	perf_pmu_enable(event->pmu);
+	return err;
 }
 
-static void mipspmu_unthrottle(struct perf_event *event)
+static void mipspmu_del(struct perf_event *event, int flags)
 {
+	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 	struct hw_perf_event *hwc = &event->hw;
+	int idx = hwc->idx;
 
-	mipspmu->enable_event(hwc, hwc->idx);
+	WARN_ON(idx < 0 || idx >= mipspmu->num_counters);
+
+	mipspmu_stop(event, PERF_EF_UPDATE);
+	cpuc->events[idx] = NULL;
+	clear_bit(idx, cpuc->used_mask);
+
+	perf_event_update_userpage(event);
 }
 
 static void mipspmu_read(struct perf_event *event)
@@ -270,12 +293,17 @@ static void mipspmu_read(struct perf_event *event)
 	mipspmu_event_update(event, hwc, hwc->idx);
 }
 
-static struct pmu pmu = {
-	.enable		= mipspmu_enable,
-	.disable	= mipspmu_disable,
-	.unthrottle	= mipspmu_unthrottle,
-	.read		= mipspmu_read,
-};
+static void mipspmu_enable(struct pmu *pmu)
+{
+	if (mipspmu)
+		mipspmu->start();
+}
+
+static void mipspmu_disable(struct pmu *pmu)
+{
+	if (mipspmu)
+		mipspmu->stop();
+}
 
 static atomic_t active_events = ATOMIC_INIT(0);
 static DEFINE_MUTEX(pmu_reserve_mutex);
@@ -318,6 +346,82 @@ static void mipspmu_free_irq(void)
 		perf_irq = save_perf_irq;
 }
 
+/*
+ * mipsxx/rm9000/loongson2 have different performance counters, they have
+ * specific low-level init routines.
+ */
+static void reset_counters(void *arg);
+static int __hw_perf_event_init(struct perf_event *event);
+
+static void hw_perf_event_destroy(struct perf_event *event)
+{
+	if (atomic_dec_and_mutex_lock(&active_events,
+				&pmu_reserve_mutex)) {
+		/*
+		 * We must not call the destroy function with interrupts
+		 * disabled.
+		 */
+		on_each_cpu(reset_counters,
+			(void *)(long)mipspmu->num_counters, 1);
+		mipspmu_free_irq();
+		mutex_unlock(&pmu_reserve_mutex);
+	}
+}
+
+static int mipspmu_event_init(struct perf_event *event)
+{
+	int err = 0;
+
+	switch (event->attr.type) {
+	case PERF_TYPE_RAW:
+	case PERF_TYPE_HARDWARE:
+	case PERF_TYPE_HW_CACHE:
+		break;
+
+	default:
+		return -ENOENT;
+	}
+
+	if (!mipspmu || event->cpu >= nr_cpumask_bits ||
+		(event->cpu >= 0 && !cpu_online(event->cpu)))
+		return -ENODEV;
+
+	if (!atomic_inc_not_zero(&active_events)) {
+		if (atomic_read(&active_events) > MIPS_MAX_HWEVENTS) {
+			atomic_dec(&active_events);
+			return -ENOSPC;
+		}
+
+		mutex_lock(&pmu_reserve_mutex);
+		if (atomic_read(&active_events) == 0)
+			err = mipspmu_get_irq();
+
+		if (!err)
+			atomic_inc(&active_events);
+		mutex_unlock(&pmu_reserve_mutex);
+	}
+
+	if (err)
+		return err;
+
+	err = __hw_perf_event_init(event);
+	if (err)
+		hw_perf_event_destroy(event);
+
+	return err;
+}
+
+static struct pmu pmu = {
+	.pmu_enable	= mipspmu_enable,
+	.pmu_disable	= mipspmu_disable,
+	.event_init	= mipspmu_event_init,
+	.add		= mipspmu_add,
+	.del		= mipspmu_del,
+	.start		= mipspmu_start,
+	.stop		= mipspmu_stop,
+	.read		= mipspmu_read,
+};
+
 static inline unsigned int
 mipspmu_perf_event_encode(const struct mips_perf_event *pev)
 {
@@ -409,73 +513,6 @@ static int validate_group(struct perf_event *event)
 	return 0;
 }
 
-/*
- * mipsxx/rm9000/loongson2 have different performance counters, they have
- * specific low-level init routines.
- */
-static void reset_counters(void *arg);
-static int __hw_perf_event_init(struct perf_event *event);
-
-static void hw_perf_event_destroy(struct perf_event *event)
-{
-	if (atomic_dec_and_mutex_lock(&active_events,
-				&pmu_reserve_mutex)) {
-		/*
-		 * We must not call the destroy function with interrupts
-		 * disabled.
-		 */
-		on_each_cpu(reset_counters,
-			(void *)(long)mipspmu->num_counters, 1);
-		mipspmu_free_irq();
-		mutex_unlock(&pmu_reserve_mutex);
-	}
-}
-
-const struct pmu *hw_perf_event_init(struct perf_event *event)
-{
-	int err = 0;
-
-	if (!mipspmu || event->cpu >= nr_cpumask_bits ||
-		(event->cpu >= 0 && !cpu_online(event->cpu)))
-		return ERR_PTR(-ENODEV);
-
-	if (!atomic_inc_not_zero(&active_events)) {
-		if (atomic_read(&active_events) > MIPS_MAX_HWEVENTS) {
-			atomic_dec(&active_events);
-			return ERR_PTR(-ENOSPC);
-		}
-
-		mutex_lock(&pmu_reserve_mutex);
-		if (atomic_read(&active_events) == 0)
-			err = mipspmu_get_irq();
-
-		if (!err)
-			atomic_inc(&active_events);
-		mutex_unlock(&pmu_reserve_mutex);
-	}
-
-	if (err)
-		return ERR_PTR(err);
-
-	err = __hw_perf_event_init(event);
-	if (err)
-		hw_perf_event_destroy(event);
-
-	return err ? ERR_PTR(err) : &pmu;
-}
-
-void hw_perf_enable(void)
-{
-	if (mipspmu)
-		mipspmu->start();
-}
-
-void hw_perf_disable(void)
-{
-	if (mipspmu)
-		mipspmu->stop();
-}
-
 /* This is needed by specific irq handlers in perf_event_*.c */
 static void
 handle_associated_event(struct cpu_hw_events *cpuc,
diff --git a/arch/mips/kernel/perf_event_mipsxx.c b/arch/mips/kernel/perf_event_mipsxx.c
index fa00edc..c9406d6 100644
--- a/arch/mips/kernel/perf_event_mipsxx.c
+++ b/arch/mips/kernel/perf_event_mipsxx.c
@@ -1045,6 +1045,8 @@ init_hw_perf_events(void)
 			"CPU, irq %d%s\n", mipspmu->name, counters, irq,
 			irq < 0 ? " (share with timer interrupt)" : "");
 
+	perf_pmu_register(&pmu);
+
 	return 0;
 }
 arch_initcall(init_hw_perf_events);
-- 
1.7.1

[PATCH v2 3/5] MIPS/Perf-events: Fix event check in validate_event()

[Deng-Cheng Zhu]

Ignore events that are in off/error state or belong to a different PMU.

This patch originates from the following commit for ARM by Will Deacon:

65b4711ff513767341aa1915c822de6ec0de65cb
	ARM: 6352/1: perf: fix event validation

Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
---
 arch/mips/kernel/perf_event.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/mips/kernel/perf_event.c b/arch/mips/kernel/perf_event.c
index 1ee44a3..3d55761 100644
--- a/arch/mips/kernel/perf_event.c
+++ b/arch/mips/kernel/perf_event.c
@@ -486,8 +486,9 @@ static int validate_event(struct cpu_hw_events *cpuc,
 {
 	struct hw_perf_event fake_hwc = event->hw;
 
-	if (event->pmu && event->pmu != &pmu)
-		return 0;
+	/* Allow mixed event group. So return 1 to pass validation. */
+	if (event->pmu != &pmu || event->state <= PERF_EVENT_STATE_OFF)
+		return 1;
 
 	return mipspmu->alloc_counter(cpuc, &fake_hwc) >= 0;
 }
-- 
1.7.1

Re: [PATCH v2 3/5] MIPS/Perf-events: Fix event check in validate_event()

[Will Deacon]

On Fri, 2010-11-26 at 03:05 +0000, Deng-Cheng Zhu wrote:
> Ignore events that are in off/error state or belong to a different PMU.
> 
> This patch originates from the following commit for ARM by Will Deacon:
> 
> 65b4711ff513767341aa1915c822de6ec0de65cb
>         ARM: 6352/1: perf: fix event validation
> 
> Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
> ---
>  arch/mips/kernel/perf_event.c |    5 +++--
>  1 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/mips/kernel/perf_event.c b/arch/mips/kernel/perf_event.c
> index 1ee44a3..3d55761 100644
> --- a/arch/mips/kernel/perf_event.c
> +++ b/arch/mips/kernel/perf_event.c
> @@ -486,8 +486,9 @@ static int validate_event(struct cpu_hw_events *cpuc,
>  {
>         struct hw_perf_event fake_hwc = event->hw;
> 
> -       if (event->pmu && event->pmu != &pmu)
> -               return 0;
> +       /* Allow mixed event group. So return 1 to pass validation. */
> +       if (event->pmu != &pmu || event->state <= PERF_EVENT_STATE_OFF)
> +               return 1;
> 
>         return mipspmu->alloc_counter(cpuc, &fake_hwc) >= 0;
>  }


This looks better,

Acked-by: Will Deacon <will.deacon@arm.com>

Will

[PATCH v2 4/5] MIPS/Perf-events: Work with the new callchain interface

[Deng-Cheng Zhu]

This is the MIPS part of the following commits by Frederic Weisbecker:

f72c1a931e311bb7780fee19e41a89ac42cab50e
        perf: Factorize callchain context handling
56962b4449af34070bb1994621ef4f0265eed4d8
        perf: Generalize some arch callchain code
70791ce9ba68a5921c9905ef05d23f62a90bc10c
        perf: Generalize callchain_store()
c1a65932fd7216fdc9a0db8bbffe1d47842f862c
        perf: Drop unappropriate tests on arch callchains

Reported-by: Wu Zhangjin <wuzhangjin@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
---
 arch/mips/kernel/perf_event.c |   63 ++++-------------------------------------
 1 files changed, 6 insertions(+), 57 deletions(-)

diff --git a/arch/mips/kernel/perf_event.c b/arch/mips/kernel/perf_event.c
index 3d55761..8f7d2f8 100644
--- a/arch/mips/kernel/perf_event.c
+++ b/arch/mips/kernel/perf_event.c
@@ -534,21 +534,13 @@ handle_associated_event(struct cpu_hw_events *cpuc,
 #include "perf_event_mipsxx.c"
 
 /* Callchain handling code. */
-static inline void
-callchain_store(struct perf_callchain_entry *entry,
-		u64 ip)
-{
-	if (entry->nr < PERF_MAX_STACK_DEPTH)
-		entry->ip[entry->nr++] = ip;
-}
 
 /*
  * Leave userspace callchain empty for now. When we find a way to trace
  * the user stack callchains, we add here.
  */
-static void
-perf_callchain_user(struct pt_regs *regs,
-		    struct perf_callchain_entry *entry)
+void perf_callchain_user(struct perf_callchain_entry *entry,
+		    struct pt_regs *regs)
 {
 }
 
@@ -561,23 +553,21 @@ static void save_raw_perf_callchain(struct perf_callchain_entry *entry,
 	while (!kstack_end(sp)) {
 		addr = *sp++;
 		if (__kernel_text_address(addr)) {
-			callchain_store(entry, addr);
+			perf_callchain_store(entry, addr);
 			if (entry->nr >= PERF_MAX_STACK_DEPTH)
 				break;
 		}
 	}
 }
 
-static void
-perf_callchain_kernel(struct pt_regs *regs,
-		      struct perf_callchain_entry *entry)
+void perf_callchain_kernel(struct perf_callchain_entry *entry,
+		      struct pt_regs *regs)
 {
 	unsigned long sp = regs->regs[29];
 #ifdef CONFIG_KALLSYMS
 	unsigned long ra = regs->regs[31];
 	unsigned long pc = regs->cp0_epc;
 
-	callchain_store(entry, PERF_CONTEXT_KERNEL);
 	if (raw_show_trace || !__kernel_text_address(pc)) {
 		unsigned long stack_page =
 			(unsigned long)task_stack_page(current);
@@ -587,53 +577,12 @@ perf_callchain_kernel(struct pt_regs *regs,
 		return;
 	}
 	do {
-		callchain_store(entry, pc);
+		perf_callchain_store(entry, pc);
 		if (entry->nr >= PERF_MAX_STACK_DEPTH)
 			break;
 		pc = unwind_stack(current, &sp, pc, &ra);
 	} while (pc);
 #else
-	callchain_store(entry, PERF_CONTEXT_KERNEL);
 	save_raw_perf_callchain(entry, sp);
 #endif
 }
-
-static void
-perf_do_callchain(struct pt_regs *regs,
-		  struct perf_callchain_entry *entry)
-{
-	int is_user;
-
-	if (!regs)
-		return;
-
-	is_user = user_mode(regs);
-
-	if (!current || !current->pid)
-		return;
-
-	if (is_user && current->state != TASK_RUNNING)
-		return;
-
-	if (!is_user) {
-		perf_callchain_kernel(regs, entry);
-		if (current->mm)
-			regs = task_pt_regs(current);
-		else
-			regs = NULL;
-	}
-	if (regs)
-		perf_callchain_user(regs, entry);
-}
-
-static DEFINE_PER_CPU(struct perf_callchain_entry, pmc_irq_entry);
-
-struct perf_callchain_entry *
-perf_callchain(struct pt_regs *regs)
-{
-	struct perf_callchain_entry *entry = &__get_cpu_var(pmc_irq_entry);
-
-	entry->nr = 0;
-	perf_do_callchain(regs, entry);
-	return entry;
-}
-- 
1.7.1

[PATCH v2 5/5] MIPS/Perf-events: Use unsigned delta for right shift in event update

[Deng-Cheng Zhu]

Leverage the commit for ARM by Will Deacon:

446a5a8b1eb91a6990e5c8fe29f14e7a95b69132
        ARM: 6205/1: perf: ensure counter delta is treated as unsigned

Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
---
 arch/mips/kernel/perf_event.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/mips/kernel/perf_event.c b/arch/mips/kernel/perf_event.c
index 8f7d2f8..a824485 100644
--- a/arch/mips/kernel/perf_event.c
+++ b/arch/mips/kernel/perf_event.c
@@ -169,7 +169,7 @@ static void mipspmu_event_update(struct perf_event *event,
 	unsigned long flags;
 	int shift = 64 - TOTAL_BITS;
 	s64 prev_raw_count, new_raw_count;
-	s64 delta;
+	u64 delta;
 
 again:
 	prev_raw_count = local64_read(&hwc->prev_count);
-- 
1.7.1