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-rw-r--r--kernel/perf_counter.c943
1 files changed, 943 insertions, 0 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
new file mode 100644
index 000000000000..20508f053658
--- /dev/null
+++ b/kernel/perf_counter.c
@@ -0,0 +1,943 @@
+/*
+ * Performance counter core code
+ *
+ * Copyright(C) 2008 Thomas Gleixner <tglx@linutronix.de>
+ * Copyright(C) 2008 Red Hat, Inc., Ingo Molnar
+ *
+ * For licencing details see kernel-base/COPYING
+ */
+
+#include <linux/fs.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
+#include <linux/poll.h>
+#include <linux/sysfs.h>
+#include <linux/ptrace.h>
+#include <linux/percpu.h>
+#include <linux/uaccess.h>
+#include <linux/syscalls.h>
+#include <linux/anon_inodes.h>
+#include <linux/perf_counter.h>
+
+/*
+ * Each CPU has a list of per CPU counters:
+ */
+DEFINE_PER_CPU(struct perf_cpu_context, perf_cpu_context);
+
+int perf_max_counters __read_mostly;
+static int perf_reserved_percpu __read_mostly;
+static int perf_overcommit __read_mostly = 1;
+
+/*
+ * Mutex for (sysadmin-configurable) counter reservations:
+ */
+static DEFINE_MUTEX(perf_resource_mutex);
+
+/*
+ * Architecture provided APIs - weak aliases:
+ */
+
+int __weak hw_perf_counter_init(struct perf_counter *counter, u32 hw_event_type)
+{
+ return -EINVAL;
+}
+
+void __weak hw_perf_counter_enable(struct perf_counter *counter) { }
+void __weak hw_perf_counter_disable(struct perf_counter *counter) { }
+void __weak hw_perf_counter_read(struct perf_counter *counter) { }
+void __weak hw_perf_disable_all(void) { }
+void __weak hw_perf_enable_all(void) { }
+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_read_counter_safe(struct perf_counter *counter)
+{
+ return (u64) atomic64_read(&counter->count);
+}
+
+#else
+
+/*
+ * Read the cached counter in counter safe against cross CPU / NMI
+ * modifications. 32 bit version.
+ */
+static u64 perf_read_counter_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;
+}
+
+#endif
+
+/*
+ * Cross CPU call to remove a performance counter
+ *
+ * We disable the counter on the hardware level first. After that we
+ * remove it from the context list.
+ */
+static void __perf_remove_from_context(void *info)
+{
+ struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+ struct perf_counter *counter = info;
+ struct perf_counter_context *ctx = counter->ctx;
+
+ /*
+ * If this is a task context, we need to check whether it is
+ * the current task context of this cpu. If not it has been
+ * scheduled out before the smp call arrived.
+ */
+ if (ctx->task && cpuctx->task_ctx != ctx)
+ return;
+
+ spin_lock(&ctx->lock);
+
+ if (counter->active) {
+ hw_perf_counter_disable(counter);
+ counter->active = 0;
+ ctx->nr_active--;
+ cpuctx->active_oncpu--;
+ counter->task = NULL;
+ }
+ ctx->nr_counters--;
+
+ /*
+ * Protect the list operation against NMI by disabling the
+ * counters on a global level. NOP for non NMI based counters.
+ */
+ hw_perf_disable_all();
+ list_del_init(&counter->list);
+ hw_perf_enable_all();
+
+ if (!ctx->task) {
+ /*
+ * Allow more per task counters with respect to the
+ * reservation:
+ */
+ cpuctx->max_pertask =
+ min(perf_max_counters - ctx->nr_counters,
+ perf_max_counters - perf_reserved_percpu);
+ }
+
+ spin_unlock(&ctx->lock);
+}
+
+
+/*
+ * Remove the counter from a task's (or a CPU's) list of counters.
+ *
+ * Must be called with counter->mutex held.
+ *
+ * CPU counters are removed with a smp call. For task counters we only
+ * call when the task is on a CPU.
+ */
+static void perf_remove_from_context(struct perf_counter *counter)
+{
+ struct perf_counter_context *ctx = counter->ctx;
+ struct task_struct *task = ctx->task;
+
+ if (!task) {
+ /*
+ * Per cpu counters are removed via an smp call and
+ * the removal is always sucessful.
+ */
+ smp_call_function_single(counter->cpu,
+ __perf_remove_from_context,
+ counter, 1);
+ return;
+ }
+
+retry:
+ task_oncpu_function_call(task, __perf_remove_from_context,
+ counter);
+
+ spin_lock_irq(&ctx->lock);
+ /*
+ * If the context is active we need to retry the smp call.
+ */
+ if (ctx->nr_active && !list_empty(&counter->list)) {
+ spin_unlock_irq(&ctx->lock);
+ goto retry;
+ }
+
+ /*
+ * The lock prevents that this context is scheduled in so we
+ * can remove the counter safely, if it the call above did not
+ * succeed.
+ */
+ if (!list_empty(&counter->list)) {
+ ctx->nr_counters--;
+ list_del_init(&counter->list);
+ counter->task = NULL;
+ }
+ spin_unlock_irq(&ctx->lock);
+}
+
+/*
+ * Cross CPU call to install and enable a preformance counter
+ */
+static void __perf_install_in_context(void *info)
+{
+ struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+ struct perf_counter *counter = info;
+ struct perf_counter_context *ctx = counter->ctx;
+ int cpu = smp_processor_id();
+
+ /*
+ * If this is a task context, we need to check whether it is
+ * the current task context of this cpu. If not it has been
+ * scheduled out before the smp call arrived.
+ */
+ if (ctx->task && cpuctx->task_ctx != ctx)
+ return;
+
+ spin_lock(&ctx->lock);
+
+ /*
+ * Protect the list operation against NMI by disabling the
+ * counters on a global level. NOP for non NMI based counters.
+ */
+ hw_perf_disable_all();
+ list_add_tail(&counter->list, &ctx->counters);
+ hw_perf_enable_all();
+
+ ctx->nr_counters++;
+
+ if (cpuctx->active_oncpu < perf_max_counters) {
+ hw_perf_counter_enable(counter);
+ counter->active = 1;
+ counter->oncpu = cpu;
+ ctx->nr_active++;
+ cpuctx->active_oncpu++;
+ }
+
+ if (!ctx->task && cpuctx->max_pertask)
+ cpuctx->max_pertask--;
+
+ spin_unlock(&ctx->lock);
+}
+
+/*
+ * Attach a performance counter to a context
+ *
+ * First we add the counter to the list with the hardware enable bit
+ * in counter->hw_config cleared.
+ *
+ * If the counter is attached to a task which is on a CPU we use a smp
+ * call to enable it in the task context. The task might have been
+ * scheduled away, but we check this in the smp call again.
+ */
+static void
+perf_install_in_context(struct perf_counter_context *ctx,
+ struct perf_counter *counter,
+ int cpu)
+{
+ struct task_struct *task = ctx->task;
+
+ counter->ctx = ctx;
+ if (!task) {
+ /*
+ * Per cpu counters are installed via an smp call and
+ * the install is always sucessful.
+ */
+ smp_call_function_single(cpu, __perf_install_in_context,
+ counter, 1);
+ return;
+ }
+
+ counter->task = task;
+retry:
+ task_oncpu_function_call(task, __perf_install_in_context,
+ counter);
+
+ spin_lock_irq(&ctx->lock);
+ /*
+ * If the context is active and the counter has not been added
+ * we need to retry the smp call.
+ */
+ if (ctx->nr_active && list_empty(&counter->list)) {
+ spin_unlock_irq(&ctx->lock);
+ goto retry;
+ }
+
+ /*
+ * The lock prevents that this context is scheduled in so we
+ * can add the counter safely, if it the call above did not
+ * succeed.
+ */
+ if (list_empty(&counter->list)) {
+ list_add_tail(&counter->list, &ctx->counters);
+ ctx->nr_counters++;
+ }
+ spin_unlock_irq(&ctx->lock);
+}
+
+/*
+ * Called from scheduler to remove the counters of the current task,
+ * with interrupts disabled.
+ *
+ * We stop each counter and update the counter value in counter->count.
+ *
+ * This does not protect us against NMI, but hw_perf_counter_disable()
+ * sets the disabled bit in the control field of counter _before_
+ * accessing the counter control register. If a NMI hits, then it will
+ * not restart the counter.
+ */
+void perf_counter_task_sched_out(struct task_struct *task, int cpu)
+{
+ struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
+ struct perf_counter_context *ctx = &task->perf_counter_ctx;
+ struct perf_counter *counter;
+
+ if (likely(!cpuctx->task_ctx))
+ return;
+
+ spin_lock(&ctx->lock);
+ list_for_each_entry(counter, &ctx->counters, list) {
+ if (!ctx->nr_active)
+ break;
+ if (counter->active) {
+ hw_perf_counter_disable(counter);
+ counter->active = 0;
+ counter->oncpu = -1;
+ ctx->nr_active--;
+ cpuctx->active_oncpu--;
+ }
+ }
+ spin_unlock(&ctx->lock);
+ cpuctx->task_ctx = NULL;
+}
+
+/*
+ * Called from scheduler to add the counters of the current task
+ * with interrupts disabled.
+ *
+ * We restore the counter value and then enable it.
+ *
+ * This does not protect us against NMI, but hw_perf_counter_enable()
+ * sets the enabled bit in the control field of counter _before_
+ * accessing the counter control register. If a NMI hits, then it will
+ * keep the counter running.
+ */
+void perf_counter_task_sched_in(struct task_struct *task, int cpu)
+{
+ struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
+ struct perf_counter_context *ctx = &task->perf_counter_ctx;
+ struct perf_counter *counter;
+
+ if (likely(!ctx->nr_counters))
+ return;
+
+ spin_lock(&ctx->lock);
+ list_for_each_entry(counter, &ctx->counters, list) {
+ if (ctx->nr_active == cpuctx->max_pertask)
+ break;
+ if (counter->cpu != -1 && counter->cpu != cpu)
+ continue;
+
+ hw_perf_counter_enable(counter);
+ counter->active = 1;
+ counter->oncpu = cpu;
+ ctx->nr_active++;
+ cpuctx->active_oncpu++;
+ }
+ spin_unlock(&ctx->lock);
+ cpuctx->task_ctx = ctx;
+}
+
+void perf_counter_task_tick(struct task_struct *curr, int cpu)
+{
+ struct perf_counter_context *ctx = &curr->perf_counter_ctx;
+ struct perf_counter *counter;
+
+ if (likely(!ctx->nr_counters))
+ return;
+
+ perf_counter_task_sched_out(curr, cpu);
+
+ spin_lock(&ctx->lock);
+
+ /*
+ * Rotate the first entry last:
+ */
+ hw_perf_disable_all();
+ list_for_each_entry(counter, &ctx->counters, list) {
+ list_del(&counter->list);
+ list_add_tail(&counter->list, &ctx->counters);
+ break;
+ }
+ hw_perf_enable_all();
+
+ spin_unlock(&ctx->lock);
+
+ perf_counter_task_sched_in(curr, cpu);
+}
+
+/*
+ * Initialize the perf_counter context in task_struct
+ */
+void perf_counter_init_task(struct task_struct *task)
+{
+ struct perf_counter_context *ctx = &task->perf_counter_ctx;
+
+ spin_lock_init(&ctx->lock);
+ INIT_LIST_HEAD(&ctx->counters);
+ ctx->nr_counters = 0;
+ ctx->task = task;
+}
+
+/*
+ * Cross CPU call to read the hardware counter
+ */
+static void __hw_perf_counter_read(void *info)
+{
+ hw_perf_counter_read(info);
+}
+
+static u64 perf_read_counter(struct perf_counter *counter)
+{
+ /*
+ * If counter is enabled and currently active on a CPU, update the
+ * value in the counter structure:
+ */
+ if (counter->active) {
+ smp_call_function_single(counter->oncpu,
+ __hw_perf_counter_read, counter, 1);
+ }
+
+ return perf_read_counter_safe(counter);
+}
+
+/*
+ * Cross CPU call to switch performance data pointers
+ */
+static void __perf_switch_irq_data(void *info)
+{
+ struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+ struct perf_counter *counter = info;
+ struct perf_counter_context *ctx = counter->ctx;
+ struct perf_data *oldirqdata = counter->irqdata;
+
+ /*
+ * If this is a task context, we need to check whether it is
+ * the current task context of this cpu. If not it has been
+ * scheduled out before the smp call arrived.
+ */
+ if (ctx->task) {
+ if (cpuctx->task_ctx != ctx)
+ return;
+ spin_lock(&ctx->lock);
+ }
+
+ /* Change the pointer NMI safe */
+ atomic_long_set((atomic_long_t *)&counter->irqdata,
+ (unsigned long) counter->usrdata);
+ counter->usrdata = oldirqdata;
+
+ if (ctx->task)
+ spin_unlock(&ctx->lock);
+}
+
+static struct perf_data *perf_switch_irq_data(struct perf_counter *counter)
+{
+ struct perf_counter_context *ctx = counter->ctx;
+ struct perf_data *oldirqdata = counter->irqdata;
+ struct task_struct *task = ctx->task;
+
+ if (!task) {
+ smp_call_function_single(counter->cpu,
+ __perf_switch_irq_data,
+ counter, 1);
+ return counter->usrdata;
+ }
+
+retry:
+ spin_lock_irq(&ctx->lock);
+ if (!counter->active) {
+ counter->irqdata = counter->usrdata;
+ counter->usrdata = oldirqdata;
+ spin_unlock_irq(&ctx->lock);
+ return oldirqdata;
+ }
+ spin_unlock_irq(&ctx->lock);
+ task_oncpu_function_call(task, __perf_switch_irq_data, counter);
+ /* Might have failed, because task was scheduled out */
+ if (counter->irqdata == oldirqdata)
+ goto retry;
+
+ return counter->usrdata;
+}
+
+static void put_context(struct perf_counter_context *ctx)
+{
+ if (ctx->task)
+ put_task_struct(ctx->task);
+}
+
+static struct perf_counter_context *find_get_context(pid_t pid, int cpu)
+{
+ struct perf_cpu_context *cpuctx;
+ struct perf_counter_context *ctx;
+ struct task_struct *task;
+
+ /*
+ * If cpu is not a wildcard then this is a percpu counter:
+ */
+ if (cpu != -1) {
+ /* Must be root to operate on a CPU counter: */
+ if (!capable(CAP_SYS_ADMIN))
+ return ERR_PTR(-EACCES);
+
+ if (cpu < 0 || cpu > num_possible_cpus())
+ return ERR_PTR(-EINVAL);
+
+ /*
+ * We could be clever and allow to attach a counter to an
+ * offline CPU and activate it when the CPU comes up, but
+ * that's for later.
+ */
+ if (!cpu_isset(cpu, cpu_online_map))
+ return ERR_PTR(-ENODEV);
+
+ cpuctx = &per_cpu(perf_cpu_context, cpu);
+ ctx = &cpuctx->ctx;
+
+ WARN_ON_ONCE(ctx->task);
+ return ctx;
+ }
+
+ rcu_read_lock();
+ if (!pid)
+ task = current;
+ else
+ task = find_task_by_vpid(pid);
+ if (task)
+ get_task_struct(task);
+ rcu_read_unlock();
+
+ if (!task)
+ return ERR_PTR(-ESRCH);
+
+ ctx = &task->perf_counter_ctx;
+ ctx->task = task;
+
+ /* Reuse ptrace permission checks for now. */
+ if (!ptrace_may_access(task, PTRACE_MODE_READ)) {
+ put_context(ctx);
+ return ERR_PTR(-EACCES);
+ }
+
+ return ctx;
+}
+
+/*
+ * Called when the last reference to the file is gone.
+ */
+static int perf_release(struct inode *inode, struct file *file)
+{
+ struct perf_counter *counter = file->private_data;
+ struct perf_counter_context *ctx = counter->ctx;
+
+ file->private_data = NULL;
+
+ mutex_lock(&counter->mutex);
+
+ perf_remove_from_context(counter);
+ put_context(ctx);
+
+ mutex_unlock(&counter->mutex);
+
+ kfree(counter);
+
+ return 0;
+}
+
+/*
+ * Read the performance counter - simple non blocking version for now
+ */
+static ssize_t
+perf_read_hw(struct perf_counter *counter, char __user *buf, size_t count)
+{
+ u64 cntval;
+
+ if (count != sizeof(cntval))
+ return -EINVAL;
+
+ mutex_lock(&counter->mutex);
+ cntval = perf_read_counter(counter);
+ mutex_unlock(&counter->mutex);
+
+ return put_user(cntval, (u64 __user *) buf) ? -EFAULT : sizeof(cntval);
+}
+
+static ssize_t
+perf_copy_usrdata(struct perf_data *usrdata, char __user *buf, size_t count)
+{
+ if (!usrdata->len)
+ return 0;
+
+ count = min(count, (size_t)usrdata->len);
+ if (copy_to_user(buf, usrdata->data + usrdata->rd_idx, count))
+ return -EFAULT;
+
+ /* Adjust the counters */
+ usrdata->len -= count;
+ if (!usrdata->len)
+ usrdata->rd_idx = 0;
+ else
+ usrdata->rd_idx += count;
+
+ return count;
+}
+
+static ssize_t
+perf_read_irq_data(struct perf_counter *counter,
+ char __user *buf,
+ size_t count,
+ int nonblocking)
+{
+ struct perf_data *irqdata, *usrdata;
+ DECLARE_WAITQUEUE(wait, current);
+ ssize_t res;
+
+ irqdata = counter->irqdata;
+ usrdata = counter->usrdata;
+
+ if (usrdata->len + irqdata->len >= count)
+ goto read_pending;
+
+ if (nonblocking)
+ return -EAGAIN;
+
+ spin_lock_irq(&counter->waitq.lock);
+ __add_wait_queue(&counter->waitq, &wait);
+ for (;;) {
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (usrdata->len + irqdata->len >= count)
+ break;
+
+ if (signal_pending(current))
+ break;
+
+ spin_unlock_irq(&counter->waitq.lock);
+ schedule();
+ spin_lock_irq(&counter->waitq.lock);
+ }
+ __remove_wait_queue(&counter->waitq, &wait);
+ __set_current_state(TASK_RUNNING);
+ spin_unlock_irq(&counter->waitq.lock);
+
+ if (usrdata->len + irqdata->len < count)
+ return -ERESTARTSYS;
+read_pending:
+ mutex_lock(&counter->mutex);
+
+ /* Drain pending data first: */
+ res = perf_copy_usrdata(usrdata, buf, count);
+ if (res < 0 || res == count)
+ goto out;
+
+ /* Switch irq buffer: */
+ usrdata = perf_switch_irq_data(counter);
+ if (perf_copy_usrdata(usrdata, buf + res, count - res) < 0) {
+ if (!res)
+ res = -EFAULT;
+ } else {
+ res = count;
+ }
+out:
+ mutex_unlock(&counter->mutex);
+
+ return res;
+}
+
+static ssize_t
+perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+ struct perf_counter *counter = file->private_data;
+
+ switch (counter->record_type) {
+ case PERF_RECORD_SIMPLE:
+ return perf_read_hw(counter, buf, count);
+
+ case PERF_RECORD_IRQ:
+ case PERF_RECORD_GROUP:
+ return perf_read_irq_data(counter, buf, count,
+ file->f_flags & O_NONBLOCK);
+ }
+ return -EINVAL;
+}
+
+static unsigned int perf_poll(struct file *file, poll_table *wait)
+{
+ struct perf_counter *counter = file->private_data;
+ unsigned int events = 0;
+ unsigned long flags;
+
+ poll_wait(file, &counter->waitq, wait);
+
+ spin_lock_irqsave(&counter->waitq.lock, flags);
+ if (counter->usrdata->len || counter->irqdata->len)
+ events |= POLLIN;
+ spin_unlock_irqrestore(&counter->waitq.lock, flags);
+
+ return events;
+}
+
+static const struct file_operations perf_fops = {
+ .release = perf_release,
+ .read = perf_read,
+ .poll = perf_poll,
+};
+
+/*
+ * Allocate and initialize a counter structure
+ */
+static struct perf_counter *
+perf_counter_alloc(u32 hw_event_period, int cpu, u32 record_type)
+{
+ struct perf_counter *counter = kzalloc(sizeof(*counter), GFP_KERNEL);
+
+ if (!counter)
+ return NULL;
+
+ mutex_init(&counter->mutex);
+ INIT_LIST_HEAD(&counter->list);
+ init_waitqueue_head(&counter->waitq);
+
+ counter->irqdata = &counter->data[0];
+ counter->usrdata = &counter->data[1];
+ counter->cpu = cpu;
+ counter->record_type = record_type;
+ counter->__irq_period = hw_event_period;
+ counter->wakeup_pending = 0;
+
+ return counter;
+}
+
+/**
+ * sys_perf_task_open - open a performance counter associate it to a task
+ * @hw_event_type: event type for monitoring/sampling...
+ * @pid: target pid
+ */
+asmlinkage int
+sys_perf_counter_open(u32 hw_event_type,
+ u32 hw_event_period,
+ u32 record_type,
+ pid_t pid,
+ int cpu)
+{
+ struct perf_counter_context *ctx;
+ struct perf_counter *counter;
+ int ret;
+
+ ctx = find_get_context(pid, cpu);
+ if (IS_ERR(ctx))
+ return PTR_ERR(ctx);
+
+ ret = -ENOMEM;
+ counter = perf_counter_alloc(hw_event_period, cpu, record_type);
+ if (!counter)
+ goto err_put_context;
+
+ ret = hw_perf_counter_init(counter, hw_event_type);
+ if (ret)
+ goto err_free_put_context;
+
+ perf_install_in_context(ctx, counter, cpu);
+
+ ret = anon_inode_getfd("[perf_counter]", &perf_fops, counter, 0);
+ if (ret < 0)
+ goto err_remove_free_put_context;
+
+ return ret;
+
+err_remove_free_put_context:
+ mutex_lock(&counter->mutex);
+ perf_remove_from_context(counter);
+ mutex_unlock(&counter->mutex);
+
+err_free_put_context:
+ kfree(counter);
+
+err_put_context:
+ put_context(ctx);
+
+ return ret;
+}
+
+static void __cpuinit perf_init_cpu(int cpu)
+{
+ struct perf_cpu_context *ctx;
+
+ ctx = &per_cpu(perf_cpu_context, cpu);
+ spin_lock_init(&ctx->ctx.lock);
+ INIT_LIST_HEAD(&ctx->ctx.counters);
+
+ mutex_lock(&perf_resource_mutex);
+ ctx->max_pertask = perf_max_counters - perf_reserved_percpu;
+ mutex_unlock(&perf_resource_mutex);
+ hw_perf_counter_setup();
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void __perf_exit_cpu(void *info)
+{
+ struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+ struct perf_counter_context *ctx = &cpuctx->ctx;
+ struct perf_counter *counter, *tmp;
+
+ list_for_each_entry_safe(counter, tmp, &ctx->counters, list)
+ __perf_remove_from_context(counter);
+
+}
+static void perf_exit_cpu(int cpu)
+{
+ smp_call_function_single(cpu, __perf_exit_cpu, NULL, 1);
+}
+#else
+static inline void perf_exit_cpu(int cpu) { }
+#endif
+
+static int __cpuinit
+perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
+{
+ unsigned int cpu = (long)hcpu;
+
+ switch (action) {
+
+ case CPU_UP_PREPARE:
+ case CPU_UP_PREPARE_FROZEN:
+ perf_init_cpu(cpu);
+ break;
+
+ case CPU_DOWN_PREPARE:
+ case CPU_DOWN_PREPARE_FROZEN:
+ perf_exit_cpu(cpu);
+ break;
+
+ default:
+ break;
+ }
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata perf_cpu_nb = {
+ .notifier_call = perf_cpu_notify,
+};
+
+static int __init perf_counter_init(void)
+{
+ perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_UP_PREPARE,
+ (void *)(long)smp_processor_id());
+ register_cpu_notifier(&perf_cpu_nb);
+
+ return 0;
+}
+early_initcall(perf_counter_init);
+
+static ssize_t perf_show_reserve_percpu(struct sysdev_class *class, char *buf)
+{
+ return sprintf(buf, "%d\n", perf_reserved_percpu);
+}
+
+static ssize_t
+perf_set_reserve_percpu(struct sysdev_class *class,
+ const char *buf,
+ size_t count)
+{
+ struct perf_cpu_context *cpuctx;
+ unsigned long val;
+ int err, cpu, mpt;
+
+ err = strict_strtoul(buf, 10, &val);
+ if (err)
+ return err;
+ if (val > perf_max_counters)
+ return -EINVAL;
+
+ mutex_lock(&perf_resource_mutex);
+ perf_reserved_percpu = val;
+ for_each_online_cpu(cpu) {
+ cpuctx = &per_cpu(perf_cpu_context, cpu);
+ spin_lock_irq(&cpuctx->ctx.lock);
+ mpt = min(perf_max_counters - cpuctx->ctx.nr_counters,
+ perf_max_counters - perf_reserved_percpu);
+ cpuctx->max_pertask = mpt;
+ spin_unlock_irq(&cpuctx->ctx.lock);
+ }
+ mutex_unlock(&perf_resource_mutex);
+
+ return count;
+}
+
+static ssize_t perf_show_overcommit(struct sysdev_class *class, char *buf)
+{
+ return sprintf(buf, "%d\n", perf_overcommit);
+}
+
+static ssize_t
+perf_set_overcommit(struct sysdev_class *class, const char *buf, size_t count)
+{
+ unsigned long val;
+ int err;
+
+ err = strict_strtoul(buf, 10, &val);
+ if (err)
+ return err;
+ if (val > 1)
+ return -EINVAL;
+
+ mutex_lock(&perf_resource_mutex);
+ perf_overcommit = val;
+ mutex_unlock(&perf_resource_mutex);
+
+ return count;
+}
+
+static SYSDEV_CLASS_ATTR(
+ reserve_percpu,
+ 0644,
+ perf_show_reserve_percpu,
+ perf_set_reserve_percpu
+ );
+
+static SYSDEV_CLASS_ATTR(
+ overcommit,
+ 0644,
+ perf_show_overcommit,
+ perf_set_overcommit
+ );
+
+static struct attribute *perfclass_attrs[] = {
+ &attr_reserve_percpu.attr,
+ &attr_overcommit.attr,
+ NULL
+};
+
+static struct attribute_group perfclass_attr_group = {
+ .attrs = perfclass_attrs,
+ .name = "perf_counters",
+};
+
+static int __init perf_counter_sysfs_init(void)
+{
+ return sysfs_create_group(&cpu_sysdev_class.kset.kobj,
+ &perfclass_attr_group);
+}
+device_initcall(perf_counter_sysfs_init);
+
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.