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-rw-r--r--arch/x86/Kconfig2
-rw-r--r--arch/x86/kernel/cpu/perf_counter.c230
-rw-r--r--include/linux/perf_counter.h15
-rw-r--r--kernel/perf_counter.c68
4 files changed, 137 insertions, 178 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f2fdc1867241..fe94490bab61 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -643,7 +643,7 @@ config X86_UP_IOAPIC
config X86_LOCAL_APIC
def_bool y
depends on X86_64 || (X86_32 && (X86_UP_APIC || (SMP && !X86_VOYAGER) || X86_GENERICARCH))
- select HAVE_PERF_COUNTERS
+ select HAVE_PERF_COUNTERS if (!M386 && !M486)
config X86_IO_APIC
def_bool y
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index b903f8df72bb..5afae13d8d59 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -54,6 +54,48 @@ const int intel_perfmon_event_map[] =
const int max_intel_perfmon_events = ARRAY_SIZE(intel_perfmon_event_map);
/*
+ * Propagate counter elapsed time into the generic counter.
+ * Can only be executed on the CPU where the counter is active.
+ * Returns the delta events processed.
+ */
+static void
+x86_perf_counter_update(struct perf_counter *counter,
+ struct hw_perf_counter *hwc, int idx)
+{
+ u64 prev_raw_count, new_raw_count, delta;
+
+ WARN_ON_ONCE(counter->state != PERF_COUNTER_STATE_ACTIVE);
+ /*
+ * Careful: an NMI might modify the previous counter 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 counter atomically:
+ */
+again:
+ prev_raw_count = atomic64_read(&hwc->prev_count);
+ rdmsrl(hwc->counter_base + idx, new_raw_count);
+
+ if (atomic64_cmpxchg(&hwc->prev_count, prev_raw_count,
+ new_raw_count) != prev_raw_count)
+ goto again;
+
+ /*
+ * Now we have the new raw value and have updated the prev
+ * timestamp already. We can now calculate the elapsed delta
+ * (counter-)time and add that to the generic counter.
+ *
+ * Careful, not all hw sign-extends above the physical width
+ * of the count, so we do that by clipping the delta to 32 bits:
+ */
+ delta = (u64)(u32)((s32)new_raw_count - (s32)prev_raw_count);
+ WARN_ON_ONCE((int)delta < 0);
+
+ atomic64_add(delta, &counter->count);
+ atomic64_sub(delta, &hwc->period_left);
+}
+
+/*
* Setup the hardware configuration for a given hw_event_type
*/
static int __hw_perf_counter_init(struct perf_counter *counter)
@@ -90,10 +132,10 @@ static int __hw_perf_counter_init(struct perf_counter *counter)
* so we install an artificial 1<<31 period regardless of
* the generic counter period:
*/
- if (!hwc->irq_period)
+ if ((s64)hwc->irq_period <= 0 || hwc->irq_period > 0x7FFFFFFF)
hwc->irq_period = 0x7FFFFFFF;
- hwc->next_count = -(s32)hwc->irq_period;
+ atomic64_set(&hwc->period_left, hwc->irq_period);
/*
* Raw event type provide the config in the event structure
@@ -118,12 +160,6 @@ void hw_perf_enable_all(void)
wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, perf_counter_mask, 0);
}
-void hw_perf_restore(u64 ctrl)
-{
- wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, ctrl, 0);
-}
-EXPORT_SYMBOL_GPL(hw_perf_restore);
-
u64 hw_perf_save_disable(void)
{
u64 ctrl;
@@ -134,27 +170,74 @@ u64 hw_perf_save_disable(void)
}
EXPORT_SYMBOL_GPL(hw_perf_save_disable);
+void hw_perf_restore(u64 ctrl)
+{
+ wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, ctrl, 0);
+}
+EXPORT_SYMBOL_GPL(hw_perf_restore);
+
static inline void
-__x86_perf_counter_disable(struct hw_perf_counter *hwc, unsigned int idx)
+__x86_perf_counter_disable(struct perf_counter *counter,
+ struct hw_perf_counter *hwc, unsigned int idx)
{
- wrmsr(hwc->config_base + idx, hwc->config, 0);
+ int err;
+
+ err = wrmsr_safe(hwc->config_base + idx, hwc->config, 0);
+ WARN_ON_ONCE(err);
}
-static DEFINE_PER_CPU(u64, prev_next_count[MAX_HW_COUNTERS]);
+static DEFINE_PER_CPU(u64, prev_left[MAX_HW_COUNTERS]);
-static void __hw_perf_counter_set_period(struct hw_perf_counter *hwc, int idx)
+/*
+ * Set the next IRQ period, based on the hwc->period_left value.
+ * To be called with the counter disabled in hw:
+ */
+static void
+__hw_perf_counter_set_period(struct perf_counter *counter,
+ struct hw_perf_counter *hwc, int idx)
{
- per_cpu(prev_next_count[idx], smp_processor_id()) = hwc->next_count;
+ s32 left = atomic64_read(&hwc->period_left);
+ s32 period = hwc->irq_period;
+
+ WARN_ON_ONCE(period <= 0);
+
+ /*
+ * If we are way outside a reasoable range then just skip forward:
+ */
+ if (unlikely(left <= -period)) {
+ left = period;
+ atomic64_set(&hwc->period_left, left);
+ }
+
+ if (unlikely(left <= 0)) {
+ left += period;
+ atomic64_set(&hwc->period_left, left);
+ }
- wrmsr(hwc->counter_base + idx, hwc->next_count, 0);
+ WARN_ON_ONCE(left <= 0);
+
+ per_cpu(prev_left[idx], smp_processor_id()) = left;
+
+ /*
+ * The hw counter starts counting from this counter offset,
+ * mark it to be able to extra future deltas:
+ */
+ atomic64_set(&hwc->prev_count, (u64)(s64)-left);
+
+ wrmsr(hwc->counter_base + idx, -left, 0);
}
-static void __x86_perf_counter_enable(struct hw_perf_counter *hwc, int idx)
+static void
+__x86_perf_counter_enable(struct perf_counter *counter,
+ struct hw_perf_counter *hwc, int idx)
{
wrmsr(hwc->config_base + idx,
hwc->config | ARCH_PERFMON_EVENTSEL0_ENABLE, 0);
}
+/*
+ * Find a PMC slot for the freshly enabled / scheduled in counter:
+ */
static void x86_perf_counter_enable(struct perf_counter *counter)
{
struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
@@ -170,55 +253,17 @@ static void x86_perf_counter_enable(struct perf_counter *counter)
perf_counters_lapic_init(hwc->nmi);
- __x86_perf_counter_disable(hwc, idx);
+ __x86_perf_counter_disable(counter, hwc, idx);
cpuc->counters[idx] = counter;
- __hw_perf_counter_set_period(hwc, idx);
- __x86_perf_counter_enable(hwc, idx);
-}
-
-static void __hw_perf_save_counter(struct perf_counter *counter,
- struct hw_perf_counter *hwc, int idx)
-{
- s64 raw = -1;
- s64 delta;
-
- /*
- * Get the raw hw counter value:
- */
- rdmsrl(hwc->counter_base + idx, raw);
-
- /*
- * Rebase it to zero (it started counting at -irq_period),
- * to see the delta since ->prev_count:
- */
- delta = (s64)hwc->irq_period + (s64)(s32)raw;
-
- atomic64_counter_set(counter, hwc->prev_count + delta);
-
- /*
- * Adjust the ->prev_count offset - if we went beyond
- * irq_period of units, then we got an IRQ and the counter
- * was set back to -irq_period:
- */
- while (delta >= (s64)hwc->irq_period) {
- hwc->prev_count += hwc->irq_period;
- delta -= (s64)hwc->irq_period;
- }
-
- /*
- * Calculate the next raw counter value we'll write into
- * the counter at the next sched-in time:
- */
- delta -= (s64)hwc->irq_period;
-
- hwc->next_count = (s32)delta;
+ __hw_perf_counter_set_period(counter, hwc, idx);
+ __x86_perf_counter_enable(counter, hwc, idx);
}
void perf_counter_print_debug(void)
{
- u64 ctrl, status, overflow, pmc_ctrl, pmc_count, next_count;
+ u64 ctrl, status, overflow, pmc_ctrl, pmc_count, prev_left;
int cpu, idx;
if (!nr_hw_counters)
@@ -241,14 +286,14 @@ void perf_counter_print_debug(void)
rdmsrl(MSR_ARCH_PERFMON_EVENTSEL0 + idx, pmc_ctrl);
rdmsrl(MSR_ARCH_PERFMON_PERFCTR0 + idx, pmc_count);
- next_count = per_cpu(prev_next_count[idx], cpu);
+ prev_left = per_cpu(prev_left[idx], cpu);
printk(KERN_INFO "CPU#%d: PMC%d ctrl: %016llx\n",
cpu, idx, pmc_ctrl);
printk(KERN_INFO "CPU#%d: PMC%d count: %016llx\n",
cpu, idx, pmc_count);
- printk(KERN_INFO "CPU#%d: PMC%d next: %016llx\n",
- cpu, idx, next_count);
+ printk(KERN_INFO "CPU#%d: PMC%d left: %016llx\n",
+ cpu, idx, prev_left);
}
local_irq_enable();
}
@@ -259,29 +304,16 @@ static void x86_perf_counter_disable(struct perf_counter *counter)
struct hw_perf_counter *hwc = &counter->hw;
unsigned int idx = hwc->idx;
- __x86_perf_counter_disable(hwc, idx);
+ __x86_perf_counter_disable(counter, hwc, idx);
clear_bit(idx, cpuc->used);
cpuc->counters[idx] = NULL;
- __hw_perf_save_counter(counter, hwc, idx);
-}
-static void x86_perf_counter_read(struct perf_counter *counter)
-{
- struct hw_perf_counter *hwc = &counter->hw;
- unsigned long addr = hwc->counter_base + hwc->idx;
- s64 offs, val = -1LL;
- s32 val32;
-
- /* Careful: NMI might modify the counter offset */
- do {
- offs = hwc->prev_count;
- rdmsrl(addr, val);
- } while (offs != hwc->prev_count);
-
- val32 = (s32) val;
- val = (s64)hwc->irq_period + (s64)val32;
- atomic64_counter_set(counter, hwc->prev_count + val);
+ /*
+ * Drain the remaining delta count out of a counter
+ * that we are disabling:
+ */
+ x86_perf_counter_update(counter, hwc, idx);
}
static void perf_store_irq_data(struct perf_counter *counter, u64 data)
@@ -299,7 +331,8 @@ static void perf_store_irq_data(struct perf_counter *counter, u64 data)
}
/*
- * NMI-safe enable method:
+ * Save and restart an expired counter. Called by NMI contexts,
+ * so it has to be careful about preempting normal counter ops:
*/
static void perf_save_and_restart(struct perf_counter *counter)
{
@@ -309,45 +342,25 @@ static void perf_save_and_restart(struct perf_counter *counter)
rdmsrl(MSR_ARCH_PERFMON_EVENTSEL0 + idx, pmc_ctrl);
- __hw_perf_save_counter(counter, hwc, idx);
- __hw_perf_counter_set_period(hwc, idx);
+ x86_perf_counter_update(counter, hwc, idx);
+ __hw_perf_counter_set_period(counter, hwc, idx);
if (pmc_ctrl & ARCH_PERFMON_EVENTSEL0_ENABLE)
- __x86_perf_counter_enable(hwc, idx);
+ __x86_perf_counter_enable(counter, hwc, idx);
}
static void
perf_handle_group(struct perf_counter *sibling, u64 *status, u64 *overflown)
{
struct perf_counter *counter, *group_leader = sibling->group_leader;
- int bit;
-
- /*
- * Store the counter's own timestamp first:
- */
- perf_store_irq_data(sibling, sibling->hw_event.type);
- perf_store_irq_data(sibling, atomic64_counter_read(sibling));
/*
- * Then store sibling timestamps (if any):
+ * Store sibling timestamps (if any):
*/
list_for_each_entry(counter, &group_leader->sibling_list, list_entry) {
- if (counter->state != PERF_COUNTER_STATE_ACTIVE) {
- /*
- * When counter was not in the overflow mask, we have to
- * read it from hardware. We read it as well, when it
- * has not been read yet and clear the bit in the
- * status mask.
- */
- bit = counter->hw.idx;
- if (!test_bit(bit, (unsigned long *) overflown) ||
- test_bit(bit, (unsigned long *) status)) {
- clear_bit(bit, (unsigned long *) status);
- perf_save_and_restart(counter);
- }
- }
+ x86_perf_counter_update(counter, &counter->hw, counter->hw.idx);
perf_store_irq_data(sibling, counter->hw_event.type);
- perf_store_irq_data(sibling, atomic64_counter_read(counter));
+ perf_store_irq_data(sibling, atomic64_read(&counter->count));
}
}
@@ -540,6 +553,11 @@ void __init init_hw_perf_counters(void)
perf_counters_initialized = true;
}
+static void x86_perf_counter_read(struct perf_counter *counter)
+{
+ x86_perf_counter_update(counter, &counter->hw, counter->hw.idx);
+}
+
static const struct hw_perf_counter_ops x86_perf_counter_ops = {
.hw_perf_counter_enable = x86_perf_counter_enable,
.hw_perf_counter_disable = x86_perf_counter_disable,
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 8cb095fa442c..72460289c654 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -91,14 +91,16 @@ struct perf_counter_hw_event {
* struct hw_perf_counter - performance counter hardware details:
*/
struct hw_perf_counter {
+#ifdef CONFIG_PERF_COUNTERS
u64 config;
unsigned long config_base;
unsigned long counter_base;
int nmi;
unsigned int idx;
- u64 prev_count;
+ atomic64_t prev_count;
u64 irq_period;
- s32 next_count;
+ atomic64_t period_left;
+#endif
};
/*
@@ -140,17 +142,15 @@ enum perf_counter_active_state {
* struct perf_counter - performance counter kernel representation:
*/
struct perf_counter {
+#ifdef CONFIG_PERF_COUNTERS
struct list_head list_entry;
struct list_head sibling_list;
struct perf_counter *group_leader;
const struct hw_perf_counter_ops *hw_ops;
enum perf_counter_active_state state;
-#if BITS_PER_LONG == 64
atomic64_t count;
-#else
- atomic_t count32[2];
-#endif
+
struct perf_counter_hw_event hw_event;
struct hw_perf_counter hw;
@@ -172,6 +172,7 @@ struct perf_counter {
struct perf_data *irqdata;
struct perf_data *usrdata;
struct perf_data data[2];
+#endif
};
/**
@@ -220,8 +221,6 @@ extern void perf_counter_notify(struct pt_regs *regs);
extern void perf_counter_print_debug(void);
extern u64 hw_perf_save_disable(void);
extern void hw_perf_restore(u64 ctrl);
-extern void atomic64_counter_set(struct perf_counter *counter, u64 val64);
-extern u64 atomic64_counter_read(struct perf_counter *counter);
extern int perf_counter_task_disable(void);
extern int perf_counter_task_enable(void);
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 559130b8774d..416861ce8b27 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -44,67 +44,9 @@ hw_perf_counter_init(struct perf_counter *counter)
}
u64 __weak hw_perf_save_disable(void) { return 0; }
-void __weak hw_perf_restore(u64 ctrl) { }
+void __weak hw_perf_restore(u64 ctrl) { }
void __weak hw_perf_counter_setup(void) { }
-#if BITS_PER_LONG == 64
-
-/*
- * Read the cached counter in counter safe against cross CPU / NMI
- * modifications. 64 bit version - no complications.
- */
-static inline u64 perf_counter_read_safe(struct perf_counter *counter)
-{
- return (u64) atomic64_read(&counter->count);
-}
-
-void atomic64_counter_set(struct perf_counter *counter, u64 val)
-{
- atomic64_set(&counter->count, val);
-}
-
-u64 atomic64_counter_read(struct perf_counter *counter)
-{
- return atomic64_read(&counter->count);
-}
-
-#else
-
-/*
- * Read the cached counter in counter safe against cross CPU / NMI
- * modifications. 32 bit version.
- */
-static u64 perf_counter_read_safe(struct perf_counter *counter)
-{
- u32 cntl, cnth;
-
- local_irq_disable();
- do {
- cnth = atomic_read(&counter->count32[1]);
- cntl = atomic_read(&counter->count32[0]);
- } while (cnth != atomic_read(&counter->count32[1]));
-
- local_irq_enable();
-
- return cntl | ((u64) cnth) << 32;
-}
-
-void atomic64_counter_set(struct perf_counter *counter, u64 val64)
-{
- u32 *val32 = (void *)&val64;
-
- atomic_set(counter->count32 + 0, *(val32 + 0));
- atomic_set(counter->count32 + 1, *(val32 + 1));
-}
-
-u64 atomic64_counter_read(struct perf_counter *counter)
-{
- return atomic_read(counter->count32 + 0) |
- (u64) atomic_read(counter->count32 + 1) << 32;
-}
-
-#endif
-
static void
list_add_counter(struct perf_counter *counter, struct perf_counter_context *ctx)
{
@@ -280,11 +222,11 @@ static void __perf_install_in_context(void *info)
ctx->nr_counters++;
if (cpuctx->active_oncpu < perf_max_counters) {
- counter->hw_ops->hw_perf_counter_enable(counter);
counter->state = PERF_COUNTER_STATE_ACTIVE;
counter->oncpu = cpu;
ctx->nr_active++;
cpuctx->active_oncpu++;
+ counter->hw_ops->hw_perf_counter_enable(counter);
}
if (!ctx->task && cpuctx->max_pertask)
@@ -624,7 +566,7 @@ static u64 perf_counter_read(struct perf_counter *counter)
__hw_perf_counter_read, counter, 1);
}
- return perf_counter_read_safe(counter);
+ return atomic64_read(&counter->count);
}
/*
@@ -921,7 +863,7 @@ static void cpu_clock_perf_counter_read(struct perf_counter *counter)
{
int cpu = raw_smp_processor_id();
- atomic64_counter_set(counter, cpu_clock(cpu));
+ atomic64_set(&counter->count, cpu_clock(cpu));
}
static const struct hw_perf_counter_ops perf_ops_cpu_clock = {
@@ -940,7 +882,7 @@ static void task_clock_perf_counter_disable(struct perf_counter *counter)
static void task_clock_perf_counter_read(struct perf_counter *counter)
{
- atomic64_counter_set(counter, current->se.sum_exec_runtime);
+ atomic64_set(&counter->count, current->se.sum_exec_runtime);
}
static const struct hw_perf_counter_ops perf_ops_task_clock = {
generated by cgit v1.2.3-55-g7522 (git 2.39.0) at 2024-06-27 13:44:04 +0200