[tip:perf/core] perf: Split up buffer handling from core code

tip-bot for Frederic Weisbecker
2011-06-09T11:43:54Z

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Commit-ID: 76369139ceb955deefc509e6e12ce9d6ce50ccab
Gitweb: http://git.kernel.org/tip/76369139ceb955deefc509e6e12ce9d6ce50ccab
Author: Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Thu, 19 May 2011 19:55:04 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 9 Jun 2011 12:57:54 +0200

perf: Split up buffer handling from core code

And create the internal perf events header.

v2: Keep an internal inlined perf_output_copy()

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Stephane Eranian <eranian@google.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1305827704-5607-1-git-send-email-fweisbec@gmail.com
[ v3: use clearer 'ring_buffer' and 'rb' naming ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/perf_event.h | 33 +---
kernel/events/Makefile | 2 +-
kernel/events/core.c | 568 ++++++-------------------------------------
kernel/events/internal.h | 97 ++++++++
kernel/events/ring_buffer.c | 399 ++++++++++++++++++++++++++++++
5 files changed, 572 insertions(+), 527 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 3412684..779f6ed 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -680,33 +680,6 @@ enum perf_event_active_state {
};

struct file;
-
-#define PERF_BUFFER_WRITABLE 0x01
-
-struct perf_buffer {
- atomic_t refcount;
- struct rcu_head rcu_head;
-#ifdef CONFIG_PERF_USE_VMALLOC
- struct work_struct work;
- int page_order; /* allocation order */
-#endif
- int nr_pages; /* nr of data pages */
- int writable; /* are we writable */
-
- atomic_t poll; /* POLL_ for wakeups */
-
- local_t head; /* write position */
- local_t nest; /* nested writers */
- local_t events; /* event limit */
- local_t wakeup; /* wakeup stamp */
- local_t lost; /* nr records lost */
-
- long watermark; /* wakeup watermark */
-
- struct perf_event_mmap_page *user_page;
- void *data_pages[0];
-};
-
struct perf_sample_data;

typedef void (*perf_overflow_handler_t)(struct perf_event *, int,
@@ -745,6 +718,8 @@ struct perf_cgroup {
};
#endif

+struct ring_buffer;
+
/**
* struct perf_event - performance event kernel representation:
*/
@@ -834,7 +809,7 @@ struct perf_event {
atomic_t mmap_count;
int mmap_locked;
struct user_struct *mmap_user;
- struct perf_buffer *buffer;
+ struct ring_buffer *rb;

/* poll related */
wait_queue_head_t waitq;
@@ -945,7 +920,7 @@ struct perf_cpu_context {

struct perf_output_handle {
struct perf_event *event;
- struct perf_buffer *buffer;
+ struct ring_buffer *rb;
unsigned long wakeup;
unsigned long size;
void *addr;
diff --git a/kernel/events/Makefile b/kernel/events/Makefile
index 1ce23d3..89e5e8a 100644
--- a/kernel/events/Makefile
+++ b/kernel/events/Makefile
@@ -2,5 +2,5 @@ ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_core.o = -pg
endif

-obj-y := core.o
+obj-y := core.o ring_buffer.o
obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 5e8c7b1..5e70f62 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -36,6 +36,8 @@
#include <linux/ftrace_event.h>
#include <linux/hw_breakpoint.h>

+#include "internal.h"
+
#include <asm/irq_regs.h>

struct remote_function_call {
@@ -2886,7 +2888,7 @@ static void free_event_rcu(struct rcu_head *head)
kfree(event);
}

-static void perf_buffer_put(struct perf_buffer *buffer);
+static void ring_buffer_put(struct ring_buffer *rb);

static void free_event(struct perf_event *event)
{
@@ -2909,9 +2911,9 @@ static void free_event(struct perf_event *event)
}
}

- if (event->buffer) {
- perf_buffer_put(event->buffer);
- event->buffer = NULL;
+ if (event->rb) {
+ ring_buffer_put(event->rb);
+ event->rb = NULL;
}

if (is_cgroup_event(event))
@@ -3139,13 +3141,13 @@ perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
static unsigned int perf_poll(struct file *file, poll_table *wait)
{
struct perf_event *event = file->private_data;
- struct perf_buffer *buffer;
+ struct ring_buffer *rb;
unsigned int events = POLL_HUP;

rcu_read_lock();
- buffer = rcu_dereference(event->buffer);
- if (buffer)
- events = atomic_xchg(&buffer->poll, 0);
+ rb = rcu_dereference(event->rb);
+ if (rb)
+ events = atomic_xchg(&rb->poll, 0);
rcu_read_unlock();

poll_wait(file, &event->waitq, wait);
@@ -3356,14 +3358,14 @@ static int perf_event_index(struct perf_event *event)
void perf_event_update_userpage(struct perf_event *event)
{
struct perf_event_mmap_page *userpg;
- struct perf_buffer *buffer;
+ struct ring_buffer *rb;

rcu_read_lock();
- buffer = rcu_dereference(event->buffer);
- if (!buffer)
+ rb = rcu_dereference(event->rb);
+ if (!rb)
goto unlock;

- userpg = buffer->user_page;
+ userpg = rb->user_page;

/*
* Disable preemption so as to not let the corresponding user-space
@@ -3390,220 +3392,10 @@ unlock:
rcu_read_unlock();
}

-static unsigned long perf_data_size(struct perf_buffer *buffer);
-
-static void
-perf_buffer_init(struct perf_buffer *buffer, long watermark, int flags)
-{
- long max_size = perf_data_size(buffer);
-
- if (watermark)
- buffer->watermark = min(max_size, watermark);
-
- if (!buffer->watermark)
- buffer->watermark = max_size / 2;
-
- if (flags & PERF_BUFFER_WRITABLE)
- buffer->writable = 1;
-
- atomic_set(&buffer->refcount, 1);
-}
-
-#ifndef CONFIG_PERF_USE_VMALLOC
-
-/*
- * Back perf_mmap() with regular GFP_KERNEL-0 pages.
- */
-
-static struct page *
-perf_mmap_to_page(struct perf_buffer *buffer, unsigned long pgoff)
-{
- if (pgoff > buffer->nr_pages)
- return NULL;
-
- if (pgoff == 0)
- return virt_to_page(buffer->user_page);
-
- return virt_to_page(buffer->data_pages[pgoff - 1]);
-}
-
-static void *perf_mmap_alloc_page(int cpu)
-{
- struct page *page;
- int node;
-
- node = (cpu == -1) ? cpu : cpu_to_node(cpu);
- page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
- if (!page)
- return NULL;
-
- return page_address(page);
-}
-
-static struct perf_buffer *
-perf_buffer_alloc(int nr_pages, long watermark, int cpu, int flags)
-{
- struct perf_buffer *buffer;
- unsigned long size;
- int i;
-
- size = sizeof(struct perf_buffer);
- size += nr_pages * sizeof(void *);
-
- buffer = kzalloc(size, GFP_KERNEL);
- if (!buffer)
- goto fail;
-
- buffer->user_page = perf_mmap_alloc_page(cpu);
- if (!buffer->user_page)
- goto fail_user_page;
-
- for (i = 0; i < nr_pages; i++) {
- buffer->data_pages[i] = perf_mmap_alloc_page(cpu);
- if (!buffer->data_pages[i])
- goto fail_data_pages;
- }
-
- buffer->nr_pages = nr_pages;
-
- perf_buffer_init(buffer, watermark, flags);
-
- return buffer;
-
-fail_data_pages:
- for (i--; i >= 0; i--)
- free_page((unsigned long)buffer->data_pages[i]);
-
- free_page((unsigned long)buffer->user_page);
-
-fail_user_page:
- kfree(buffer);
-
-fail:
- return NULL;
-}
-
-static void perf_mmap_free_page(unsigned long addr)
-{
- struct page *page = virt_to_page((void *)addr);
-
- page->mapping = NULL;
- __free_page(page);
-}
-
-static void perf_buffer_free(struct perf_buffer *buffer)
-{
- int i;
-
- perf_mmap_free_page((unsigned long)buffer->user_page);
- for (i = 0; i < buffer->nr_pages; i++)
- perf_mmap_free_page((unsigned long)buffer->data_pages[i]);
- kfree(buffer);
-}
-
-static inline int page_order(struct perf_buffer *buffer)
-{
- return 0;
-}
-
-#else
-
-/*
- * Back perf_mmap() with vmalloc memory.
- *
- * Required for architectures that have d-cache aliasing issues.
- */
-
-static inline int page_order(struct perf_buffer *buffer)
-{
- return buffer->page_order;
-}
-
-static struct page *
-perf_mmap_to_page(struct perf_buffer *buffer, unsigned long pgoff)
-{
- if (pgoff > (1UL << page_order(buffer)))
- return NULL;
-
- return vmalloc_to_page((void *)buffer->user_page + pgoff * PAGE_SIZE);
-}
-
-static void perf_mmap_unmark_page(void *addr)
-{
- struct page *page = vmalloc_to_page(addr);
-
- page->mapping = NULL;
-}
-
-static void perf_buffer_free_work(struct work_struct *work)
-{
- struct perf_buffer *buffer;
- void *base;
- int i, nr;
-
- buffer = container_of(work, struct perf_buffer, work);
- nr = 1 << page_order(buffer);
-
- base = buffer->user_page;
- for (i = 0; i < nr + 1; i++)
- perf_mmap_unmark_page(base + (i * PAGE_SIZE));
-
- vfree(base);
- kfree(buffer);
-}
-
-static void perf_buffer_free(struct perf_buffer *buffer)
-{
- schedule_work(&buffer->work);
-}
-
-static struct perf_buffer *
-perf_buffer_alloc(int nr_pages, long watermark, int cpu, int flags)
-{
- struct perf_buffer *buffer;
- unsigned long size;
- void *all_buf;
-
- size = sizeof(struct perf_buffer);
- size += sizeof(void *);
-
- buffer = kzalloc(size, GFP_KERNEL);
- if (!buffer)
- goto fail;
-
- INIT_WORK(&buffer->work, perf_buffer_free_work);
-
- all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE);
- if (!all_buf)
- goto fail_all_buf;
-
- buffer->user_page = all_buf;
- buffer->data_pages[0] = all_buf + PAGE_SIZE;
- buffer->page_order = ilog2(nr_pages);
- buffer->nr_pages = 1;
-
- perf_buffer_init(buffer, watermark, flags);
-
- return buffer;
-
-fail_all_buf:
- kfree(buffer);
-
-fail:
- return NULL;
-}
-
-#endif
-
-static unsigned long perf_data_size(struct perf_buffer *buffer)
-{
- return buffer->nr_pages << (PAGE_SHIFT + page_order(buffer));
-}
-
static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct perf_event *event = vma->vm_file->private_data;
- struct perf_buffer *buffer;
+ struct ring_buffer *rb;
int ret = VM_FAULT_SIGBUS;

if (vmf->flags & FAULT_FLAG_MKWRITE) {
@@ -3613,14 +3405,14 @@ static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
}

rcu_read_lock();
- buffer = rcu_dereference(event->buffer);
- if (!buffer)
+ rb = rcu_dereference(event->rb);
+ if (!rb)
goto unlock;

if (vmf->pgoff && (vmf->flags & FAULT_FLAG_WRITE))
goto unlock;

- vmf->page = perf_mmap_to_page(buffer, vmf->pgoff);
+ vmf->page = perf_mmap_to_page(rb, vmf->pgoff);
if (!vmf->page)
goto unlock;

@@ -3635,35 +3427,35 @@ unlock:
return ret;
}

-static void perf_buffer_free_rcu(struct rcu_head *rcu_head)
+static void rb_free_rcu(struct rcu_head *rcu_head)
{
- struct perf_buffer *buffer;
+ struct ring_buffer *rb;

- buffer = container_of(rcu_head, struct perf_buffer, rcu_head);
- perf_buffer_free(buffer);
+ rb = container_of(rcu_head, struct ring_buffer, rcu_head);
+ rb_free(rb);
}

-static struct perf_buffer *perf_buffer_get(struct perf_event *event)
+static struct ring_buffer *ring_buffer_get(struct perf_event *event)
{
- struct perf_buffer *buffer;
+ struct ring_buffer *rb;

rcu_read_lock();
- buffer = rcu_dereference(event->buffer);
- if (buffer) {
- if (!atomic_inc_not_zero(&buffer->refcount))
- buffer = NULL;
+ rb = rcu_dereference(event->rb);
+ if (rb) {
+ if (!atomic_inc_not_zero(&rb->refcount))
+ rb = NULL;
}
rcu_read_unlock();

- return buffer;
+ return rb;
}

-static void perf_buffer_put(struct perf_buffer *buffer)
+static void ring_buffer_put(struct ring_buffer *rb)
{
- if (!atomic_dec_and_test(&buffer->refcount))
+ if (!atomic_dec_and_test(&rb->refcount))
return;

- call_rcu(&buffer->rcu_head, perf_buffer_free_rcu);
+ call_rcu(&rb->rcu_head, rb_free_rcu);
}

static void perf_mmap_open(struct vm_area_struct *vma)
@@ -3678,16 +3470,16 @@ static void perf_mmap_close(struct vm_area_struct *vma)
struct perf_event *event = vma->vm_file->private_data;

if (atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) {
- unsigned long size = perf_data_size(event->buffer);
+ unsigned long size = perf_data_size(event->rb);
struct user_struct *user = event->mmap_user;
- struct perf_buffer *buffer = event->buffer;
+ struct ring_buffer *rb = event->rb;

atomic_long_sub((size >> PAGE_SHIFT) + 1, &user->locked_vm);
vma->vm_mm->locked_vm -= event->mmap_locked;
- rcu_assign_pointer(event->buffer, NULL);
+ rcu_assign_pointer(event->rb, NULL);
mutex_unlock(&event->mmap_mutex);

- perf_buffer_put(buffer);
+ ring_buffer_put(rb);
free_uid(user);
}
}
@@ -3705,7 +3497,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
unsigned long user_locked, user_lock_limit;
struct user_struct *user = current_user();
unsigned long locked, lock_limit;
- struct perf_buffer *buffer;
+ struct ring_buffer *rb;
unsigned long vma_size;
unsigned long nr_pages;
long user_extra, extra;
@@ -3714,7 +3506,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
/*
* Don't allow mmap() of inherited per-task counters. This would
* create a performance issue due to all children writing to the
- * same buffer.
+ * same rb.
*/
if (event->cpu == -1 && event->attr.inherit)
return -EINVAL;
@@ -3726,7 +3518,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
nr_pages = (vma_size / PAGE_SIZE) - 1;

/*
- * If we have buffer pages ensure they're a power-of-two number, so we
+ * If we have rb pages ensure they're a power-of-two number, so we
* can do bitmasks instead of modulo.
*/
if (nr_pages != 0 && !is_power_of_2(nr_pages))
@@ -3740,9 +3532,9 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)

WARN_ON_ONCE(event->ctx->parent_ctx);
mutex_lock(&event->mmap_mutex);
- if (event->buffer) {
- if (event->buffer->nr_pages == nr_pages)
- atomic_inc(&event->buffer->refcount);
+ if (event->rb) {
+ if (event->rb->nr_pages == nr_pages)
+ atomic_inc(&event->rb->refcount);
else
ret = -EINVAL;
goto unlock;
@@ -3772,18 +3564,18 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
goto unlock;
}

- WARN_ON(event->buffer);
+ WARN_ON(event->rb);

if (vma->vm_flags & VM_WRITE)
- flags |= PERF_BUFFER_WRITABLE;
+ flags |= RING_BUFFER_WRITABLE;

- buffer = perf_buffer_alloc(nr_pages, event->attr.wakeup_watermark,
+ rb = rb_alloc(nr_pages, event->attr.wakeup_watermark,
event->cpu, flags);
- if (!buffer) {
+ if (!rb) {
ret = -ENOMEM;
goto unlock;
}
- rcu_assign_pointer(event->buffer, buffer);
+ rcu_assign_pointer(event->rb, rb);

atomic_long_add(user_extra, &user->locked_vm);
event->mmap_locked = extra;
@@ -3882,117 +3674,6 @@ int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
}
EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);

-/*
- * Output
- */
-static bool perf_output_space(struct perf_buffer *buffer, unsigned long tail,
- unsigned long offset, unsigned long head)
-{
- unsigned long mask;
-
- if (!buffer->writable)
- return true;
-
- mask = perf_data_size(buffer) - 1;
-
- offset = (offset - tail) & mask;
- head = (head - tail) & mask;
-
- if ((int)(head - offset) < 0)
- return false;
-
- return true;
-}
-
-static void perf_output_wakeup(struct perf_output_handle *handle)
-{
- atomic_set(&handle->buffer->poll, POLL_IN);
-
- if (handle->nmi) {
- handle->event->pending_wakeup = 1;
- irq_work_queue(&handle->event->pending);
- } else
- perf_event_wakeup(handle->event);
-}
-
-/*
- * We need to ensure a later event_id doesn't publish a head when a former
- * event isn't done writing. However since we need to deal with NMIs we
- * cannot fully serialize things.
- *
- * We only publish the head (and generate a wakeup) when the outer-most
- * event completes.
- */
-static void perf_output_get_handle(struct perf_output_handle *handle)
-{
- struct perf_buffer *buffer = handle->buffer;
-
- preempt_disable();
- local_inc(&buffer->nest);
- handle->wakeup = local_read(&buffer->wakeup);
-}
-
-static void perf_output_put_handle(struct perf_output_handle *handle)
-{
- struct perf_buffer *buffer = handle->buffer;
- unsigned long head;
-
-again:
- head = local_read(&buffer->head);
-
- /*
- * IRQ/NMI can happen here, which means we can miss a head update.
- */
-
- if (!local_dec_and_test(&buffer->nest))
- goto out;
-
- /*
- * Publish the known good head. Rely on the full barrier implied
- * by atomic_dec_and_test() order the buffer->head read and this
- * write.
- */
- buffer->user_page->data_head = head;
-
- /*
- * Now check if we missed an update, rely on the (compiler)
- * barrier in atomic_dec_and_test() to re-read buffer->head.
- */
- if (unlikely(head != local_read(&buffer->head))) {
- local_inc(&buffer->nest);
- goto again;
- }
-
- if (handle->wakeup != local_read(&buffer->wakeup))
- perf_output_wakeup(handle);
-
-out:
- preempt_enable();
-}
-
-__always_inline void perf_output_copy(struct perf_output_handle *handle,
- const void *buf, unsigned int len)
-{
- do {
- unsigned long size = min_t(unsigned long, handle->size, len);
-
- memcpy(handle->addr, buf, size);
-
- len -= size;
- handle->addr += size;
- buf += size;
- handle->size -= size;
- if (!handle->size) {
- struct perf_buffer *buffer = handle->buffer;
-
- handle->page++;
- handle->page &= buffer->nr_pages - 1;
- handle->addr = buffer->data_pages[handle->page];
- handle->size = PAGE_SIZE << page_order(buffer);
- }
- } while (len);
-}
-
static void __perf_event_header__init_id(struct perf_event_header *header,
struct perf_sample_data *data,
struct perf_event *event)
@@ -4023,9 +3704,9 @@ static void __perf_event_header__init_id(struct perf_event_header *header,
}
}

-static void perf_event_header__init_id(struct perf_event_header *header,
- struct perf_sample_data *data,
- struct perf_event *event)
+void perf_event_header__init_id(struct perf_event_header *header,
+ struct perf_sample_data *data,
+ struct perf_event *event)
{
if (event->attr.sample_id_all)
__perf_event_header__init_id(header, data, event);
@@ -4052,121 +3733,14 @@ static void __perf_event__output_id_sample(struct perf_output_handle *handle,
perf_output_put(handle, data->cpu_entry);
}

-static void perf_event__output_id_sample(struct perf_event *event,
- struct perf_output_handle *handle,
- struct perf_sample_data *sample)
+void perf_event__output_id_sample(struct perf_event *event,
+ struct perf_output_handle *handle,
+ struct perf_sample_data *sample)
{
if (event->attr.sample_id_all)
__perf_event__output_id_sample(handle, sample);
}

-int perf_output_begin(struct perf_output_handle *handle,
- struct perf_event *event, unsigned int size,
- int nmi, int sample)
-{
- struct perf_buffer *buffer;
- unsigned long tail, offset, head;
- int have_lost;
- struct perf_sample_data sample_data;
- struct {
- struct perf_event_header header;
- u64 id;
- u64 lost;
- } lost_event;
-
- rcu_read_lock();
- /*
- * For inherited events we send all the output towards the parent.
- */
- if (event->parent)
- event = event->parent;
-
- buffer = rcu_dereference(event->buffer);
- if (!buffer)
- goto out;
-
- handle->buffer = buffer;
- handle->event = event;
- handle->nmi = nmi;
- handle->sample = sample;
-
- if (!buffer->nr_pages)
- goto out;
-
- have_lost = local_read(&buffer->lost);
- if (have_lost) {
- lost_event.header.size = sizeof(lost_event);
- perf_event_header__init_id(&lost_event.header, &sample_data,
- event);
- size += lost_event.header.size;
- }
-
- perf_output_get_handle(handle);
-
- do {
- /*
- * Userspace could choose to issue a mb() before updating the
- * tail pointer. So that all reads will be completed before the
- * write is issued.
- */
- tail = ACCESS_ONCE(buffer->user_page->data_tail);
- smp_rmb();
- offset = head = local_read(&buffer->head);
- head += size;
- if (unlikely(!perf_output_space(buffer, tail, offset, head)))
- goto fail;
- } while (local_cmpxchg(&buffer->head, offset, head) != offset);
-
- if (head - local_read(&buffer->wakeup) > buffer->watermark)
- local_add(buffer->watermark, &buffer->wakeup);
-
- handle->page = offset >> (PAGE_SHIFT + page_order(buffer));
- handle->page &= buffer->nr_pages - 1;
- handle->size = offset & ((PAGE_SIZE << page_order(buffer)) - 1);
- handle->addr = buffer->data_pages[handle->page];
- handle->addr += handle->size;
- handle->size = (PAGE_SIZE << page_order(buffer)) - handle->size;
-
- if (have_lost) {
- lost_event.header.type = PERF_RECORD_LOST;
- lost_event.header.misc = 0;
- lost_event.id = event->id;
- lost_event.lost = local_xchg(&buffer->lost, 0);
-
- perf_output_put(handle, lost_event);
- perf_event__output_id_sample(event, handle, &sample_data);
- }
-
- return 0;
-
-fail:
- local_inc(&buffer->lost);
- perf_output_put_handle(handle);
-out:
- rcu_read_unlock();
-
- return -ENOSPC;
-}
-
-void perf_output_end(struct perf_output_handle *handle)
-{
- struct perf_event *event = handle->event;
- struct perf_buffer *buffer = handle->buffer;
-
- int wakeup_events = event->attr.wakeup_events;
-
- if (handle->sample && wakeup_events) {
- int events = local_inc_return(&buffer->events);
- if (events >= wakeup_events) {
- local_sub(wakeup_events, &buffer->events);
- local_inc(&buffer->wakeup);
- }
- }
-
- perf_output_put_handle(handle);
- rcu_read_unlock();
-}
-
static void perf_output_read_one(struct perf_output_handle *handle,
struct perf_event *event,
u64 enabled, u64 running)
@@ -4187,7 +3761,7 @@ static void perf_output_read_one(struct perf_output_handle *handle,
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(event);

- perf_output_copy(handle, values, n * sizeof(u64));
+ __output_copy(handle, values, n * sizeof(u64));
}

/*
@@ -4217,7 +3791,7 @@ static void perf_output_read_group(struct perf_output_handle *handle,
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(leader);

- perf_output_copy(handle, values, n * sizeof(u64));
+ __output_copy(handle, values, n * sizeof(u64));

list_for_each_entry(sub, &leader->sibling_list, group_entry) {
n = 0;
@@ -4229,7 +3803,7 @@ static void perf_output_read_group(struct perf_output_handle *handle,
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(sub);

- perf_output_copy(handle, values, n * sizeof(u64));
+ __output_copy(handle, values, n * sizeof(u64));
}
}

@@ -4309,7 +3883,7 @@ void perf_output_sample(struct perf_output_handle *handle,

size *= sizeof(u64);

- perf_output_copy(handle, data->callchain, size);
+ __output_copy(handle, data->callchain, size);
} else {
u64 nr = 0;
perf_output_put(handle, nr);
@@ -4319,8 +3893,8 @@ void perf_output_sample(struct perf_output_handle *handle,
if (sample_type & PERF_SAMPLE_RAW) {
if (data->raw) {
perf_output_put(handle, data->raw->size);
- perf_output_copy(handle, data->raw->data,
- data->raw->size);
+ __output_copy(handle, data->raw->data,
+ data->raw->size);
} else {
struct {
u32 size;
@@ -4617,7 +4191,7 @@ static void perf_event_comm_output(struct perf_event *event,
comm_event->event_id.tid = perf_event_tid(event, comm_event->task);

perf_output_put(&handle, comm_event->event_id);
- perf_output_copy(&handle, comm_event->comm,
+ __output_copy(&handle, comm_event->comm,
comm_event->comm_size);

perf_event__output_id_sample(event, &handle, &sample);
@@ -4763,7 +4337,7 @@ static void perf_event_mmap_output(struct perf_event *event,
mmap_event->event_id.tid = perf_event_tid(event, current);

perf_output_put(&handle, mmap_event->event_id);
- perf_output_copy(&handle, mmap_event->file_name,
+ __output_copy(&handle, mmap_event->file_name,
mmap_event->file_size);

perf_event__output_id_sample(event, &handle, &sample);
@@ -4819,7 +4393,7 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)

if (file) {
/*
- * d_path works from the end of the buffer backwards, so we
+ * d_path works from the end of the rb backwards, so we
* need to add enough zero bytes after the string to handle
* the 64bit alignment we do later.
*/
@@ -6346,7 +5920,7 @@ err_size:
static int
perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
{
- struct perf_buffer *buffer = NULL, *old_buffer = NULL;
+ struct ring_buffer *rb = NULL, *old_rb = NULL;
int ret = -EINVAL;

if (!output_event)
@@ -6363,7 +5937,7 @@ perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
goto out;

/*
- * If its not a per-cpu buffer, it must be the same task.
+ * If its not a per-cpu rb, it must be the same task.
*/
if (output_event->cpu == -1 && output_event->ctx != event->ctx)
goto out;
@@ -6375,20 +5949,20 @@ set:
goto unlock;

if (output_event) {
- /* get the buffer we want to redirect to */
- buffer = perf_buffer_get(output_event);
- if (!buffer)
+ /* get the rb we want to redirect to */
+ rb = ring_buffer_get(output_event);
+ if (!rb)
goto unlock;
}

- old_buffer = event->buffer;
- rcu_assign_pointer(event->buffer, buffer);
+ old_rb = event->rb;
+ rcu_assign_pointer(event->rb, rb);
ret = 0;
unlock:
mutex_unlock(&event->mmap_mutex);

- if (old_buffer)
- perf_buffer_put(old_buffer);
+ if (old_rb)
+ ring_buffer_put(old_rb);
out:
return ret;
}
diff --git a/kernel/events/internal.h b/kernel/events/internal.h
new file mode 100644
index 0000000..114f27f
--- /dev/null
+++ b/kernel/events/internal.h
@@ -0,0 +1,97 @@
+#ifndef _KERNEL_EVENTS_INTERNAL_H
+#define _KERNEL_EVENTS_INTERNAL_H
+
+#define RING_BUFFER_WRITABLE 0x01
+
+struct ring_buffer {
+ atomic_t refcount;
+ struct rcu_head rcu_head;
+#ifdef CONFIG_PERF_USE_VMALLOC
+ struct work_struct work;
+ int page_order; /* allocation order */
+#endif
+ int nr_pages; /* nr of data pages */
+ int writable; /* are we writable */
+
+ atomic_t poll; /* POLL_ for wakeups */
+
+ local_t head; /* write position */
+ local_t nest; /* nested writers */
+ local_t events; /* event limit */
+ local_t wakeup; /* wakeup stamp */
+ local_t lost; /* nr records lost */
+
+ long watermark; /* wakeup watermark */
+
+ struct perf_event_mmap_page *user_page;
+ void *data_pages[0];
+};
+
+
+extern void rb_free(struct ring_buffer *rb);
+extern struct ring_buffer *
+rb_alloc(int nr_pages, long watermark, int cpu, int flags);
+extern void perf_event_wakeup(struct perf_event *event);
+
+extern void
+perf_event_header__init_id(struct perf_event_header *header,
+ struct perf_sample_data *data,
+ struct perf_event *event);
+extern void
+perf_event__output_id_sample(struct perf_event *event,
+ struct perf_output_handle *handle,
+ struct perf_sample_data *sample);
+
+extern struct page *
+perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff);
+
+#ifdef CONFIG_PERF_USE_VMALLOC
+/*
+ * Back perf_mmap() with vmalloc memory.
+ *
+ * Required for architectures that have d-cache aliasing issues.
+ */
+
+static inline int page_order(struct ring_buffer *rb)
+{
+ return rb->page_order;
+}
+
+#else
+
+static inline int page_order(struct ring_buffer *rb)
+{
+ return 0;
+}
+#endif
+
+static unsigned long perf_data_size(struct ring_buffer *rb)
+{
+ return rb->nr_pages << (PAGE_SHIFT + page_order(rb));
+}
+
+static inline void
+__output_copy(struct perf_output_handle *handle,
+ const void *buf, unsigned int len)
+{
+ do {
+ unsigned long size = min_t(unsigned long, handle->size, len);
+
+ memcpy(handle->addr, buf, size);
+
+ len -= size;
+ handle->addr += size;
+ buf += size;
+ handle->size -= size;
+ if (!handle->size) {
+ struct ring_buffer *rb = handle->rb;
+
+ handle->page++;
+ handle->page &= rb->nr_pages - 1;
+ handle->addr = rb->data_pages[handle->page];
+ handle->size = PAGE_SIZE << page_order(rb);
+ }
+ } while (len);
+}
+
+#endif /* _KERNEL_EVENTS_INTERNAL_H */
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
new file mode 100644
index 0000000..fde5259
--- /dev/null
+++ b/kernel/events/ring_buffer.c
@@ -0,0 +1,399 @@
+/*
+ * Performance events ring-buffer code:
+ *
+ * Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
+ * Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
+ * Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
+ * Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
+ *
+ * For licensing details see kernel-base/COPYING
+ */
+
+#include <linux/perf_event.h>
+#include <linux/vmalloc.h>
+#include <linux/slab.h>
+
+#include "internal.h"
+
+static bool perf_output_space(struct ring_buffer *rb, unsigned long tail,
+ unsigned long offset, unsigned long head)
+{
+ unsigned long mask;
+
+ if (!rb->writable)
+ return true;
+
+ mask = perf_data_size(rb) - 1;
+
+ offset = (offset - tail) & mask;
+ head = (head - tail) & mask;
+
+ if ((int)(head - offset) < 0)
+ return false;
+
+ return true;
+}
+
+static void perf_output_wakeup(struct perf_output_handle *handle)
+{
+ atomic_set(&handle->rb->poll, POLL_IN);
+
+ if (handle->nmi) {
+ handle->event->pending_wakeup = 1;
+ irq_work_queue(&handle->event->pending);
+ } else
+ perf_event_wakeup(handle->event);
+}
+
+/*
+ * We need to ensure a later event_id doesn't publish a head when a former
+ * event isn't done writing. However since we need to deal with NMIs we
+ * cannot fully serialize things.
+ *
+ * We only publish the head (and generate a wakeup) when the outer-most
+ * event completes.
+ */
+static void perf_output_get_handle(struct perf_output_handle *handle)
+{
+ struct ring_buffer *rb = handle->rb;
+
+ preempt_disable();
+ local_inc(&rb->nest);
+ handle->wakeup = local_read(&rb->wakeup);
+}
+
+static void perf_output_put_handle(struct perf_output_handle *handle)
+{
+ struct ring_buffer *rb = handle->rb;
+ unsigned long head;
+
+again:
+ head = local_read(&rb->head);
+
+ /*
+ * IRQ/NMI can happen here, which means we can miss a head update.
+ */
+
+ if (!local_dec_and_test(&rb->nest))
+ goto out;
+
+ /*
+ * Publish the known good head. Rely on the full barrier implied
+ * by atomic_dec_and_test() order the rb->head read and this
+ * write.
+ */
+ rb->user_page->data_head = head;
+
+ /*
+ * Now check if we missed an update, rely on the (compiler)
+ * barrier in atomic_dec_and_test() to re-read rb->head.
+ */
+ if (unlikely(head != local_read(&rb->head))) {
+ local_inc(&rb->nest);
+ goto again;
+ }
+
+ if (handle->wakeup != local_read(&rb->wakeup))
+ perf_output_wakeup(handle);
+
+out:
+ preempt_enable();
+}
+
+int perf_output_begin(struct perf_output_handle *handle,
+ struct perf_event *event, unsigned int size,
+ int nmi, int sample)
+{
+ struct ring_buffer *rb;
+ unsigned long tail, offset, head;
+ int have_lost;
+ struct perf_sample_data sample_data;
+ struct {
+ struct perf_event_header header;
+ u64 id;
+ u64 lost;
+ } lost_event;
+
+ rcu_read_lock();
+ /*
+ * For inherited events we send all the output towards the parent.
+ */
+ if (event->parent)
+ event = event->parent;
+
+ rb = rcu_dereference(event->rb);
+ if (!rb)
+ goto out;
+
+ handle->rb = rb;
+ handle->event = event;
+ handle->nmi = nmi;
+ handle->sample = sample;
+
+ if (!rb->nr_pages)
+ goto out;
+
+ have_lost = local_read(&rb->lost);
+ if (have_lost) {
+ lost_event.header.size = sizeof(lost_event);
+ perf_event_header__init_id(&lost_event.header, &sample_data,
+ event);
+ size += lost_event.header.size;
+ }
+
+ perf_output_get_handle(handle);
+
+ do {
+ /*
+ * Userspace could choose to issue a mb() before updating the
+ * tail pointer. So that all reads will be completed before the
+ * write is issued.
+ */
+ tail = ACCESS_ONCE(rb->user_page->data_tail);
+ smp_rmb();
+ offset = head = local_read(&rb->head);
+ head += size;
+ if (unlikely(!perf_output_space(rb, tail, offset, head)))
+ goto fail;
+ } while (local_cmpxchg(&rb->head, offset, head) != offset);
+
+ if (head - local_read(&rb->wakeup) > rb->watermark)
+ local_add(rb->watermark, &rb->wakeup);
+
+ handle->page = offset >> (PAGE_SHIFT + page_order(rb));
+ handle->page &= rb->nr_pages - 1;
+ handle->size = offset & ((PAGE_SIZE << page_order(rb)) - 1);
+ handle->addr = rb->data_pages[handle->page];
+ handle->addr += handle->size;
+ handle->size = (PAGE_SIZE << page_order(rb)) - handle->size;
+
+ if (have_lost) {
+ lost_event.header.type = PERF_RECORD_LOST;
+ lost_event.header.misc = 0;
+ lost_event.id = event->id;
+ lost_event.lost = local_xchg(&rb->lost, 0);
+
+ perf_output_put(handle, lost_event);
+ perf_event__output_id_sample(event, handle, &sample_data);
+ }
+
+ return 0;
+
+fail:
+ local_inc(&rb->lost);
+ perf_output_put_handle(handle);
+out:
+ rcu_read_unlock();
+
+ return -ENOSPC;
+}
+
+void perf_output_copy(struct perf_output_handle *handle,
+ const void *buf, unsigned int len)
+{
+ __output_copy(handle, buf, len);
+}
+
+void perf_output_end(struct perf_output_handle *handle)
+{
+ struct perf_event *event = handle->event;
+ struct ring_buffer *rb = handle->rb;
+
+ int wakeup_events = event->attr.wakeup_events;
+
+ if (handle->sample && wakeup_events) {
+ int events = local_inc_return(&rb->events);
+ if (events >= wakeup_events) {
+ local_sub(wakeup_events, &rb->events);
+ local_inc(&rb->wakeup);
+ }
+ }
+
+ perf_output_put_handle(handle);
+ rcu_read_unlock();
+}
+
+static void
+ring_buffer_init(struct ring_buffer *rb, long watermark, int flags)
+{
+ long max_size = perf_data_size(rb);
+
+ if (watermark)
+ rb->watermark = min(max_size, watermark);
+
+ if (!rb->watermark)
+ rb->watermark = max_size / 2;
+
+ if (flags & RING_BUFFER_WRITABLE)
+ rb->writable = 1;
+
+ atomic_set(&rb->refcount, 1);
+}
+
+#ifndef CONFIG_PERF_USE_VMALLOC
+
+/*
+ * Back perf_mmap() with regular GFP_KERNEL-0 pages.
+ */
+
+struct page *
+perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
+{
+ if (pgoff > rb->nr_pages)
+ return NULL;
+
+ if (pgoff == 0)
+ return virt_to_page(rb->user_page);
+
+ return virt_to_page(rb->data_pages[pgoff - 1]);
+}
+
+static void *perf_mmap_alloc_page(int cpu)
+{
+ struct page *page;
+ int node;
+
+ node = (cpu == -1) ? cpu : cpu_to_node(cpu);
+ page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
+ if (!page)
+ return NULL;
+
+ return page_address(page);
+}
+
+struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
+{
+ struct ring_buffer *rb;
+ unsigned long size;
+ int i;
+
+ size = sizeof(struct ring_buffer);
+ size += nr_pages * sizeof(void *);
+
+ rb = kzalloc(size, GFP_KERNEL);
+ if (!rb)
+ goto fail;
+
+ rb->user_page = perf_mmap_alloc_page(cpu);
+ if (!rb->user_page)
+ goto fail_user_page;
+
+ for (i = 0; i < nr_pages; i++) {
+ rb->data_pages[i] = perf_mmap_alloc_page(cpu);
+ if (!rb->data_pages[i])
+ goto fail_data_pages;
+ }
+
+ rb->nr_pages = nr_pages;
+
+ ring_buffer_init(rb, watermark, flags);
+
+ return rb;
+
+fail_data_pages:
+ for (i--; i >= 0; i--)
+ free_page((unsigned long)rb->data_pages[i]);
+
+ free_page((unsigned long)rb->user_page);
+
+fail_user_page:
+ kfree(rb);
+
+fail:
+ return NULL;
+}
+
+static void perf_mmap_free_page(unsigned long addr)
+{
+ struct page *page = virt_to_page((void *)addr);
+
+ page->mapping = NULL;
+ __free_page(page);
+}
+
+void rb_free(struct ring_buffer *rb)
+{
+ int i;
+
+ perf_mmap_free_page((unsigned long)rb->user_page);
+ for (i = 0; i < rb->nr_pages; i++)
+ perf_mmap_free_page((unsigned long)rb->data_pages[i]);
+ kfree(rb);
+}
+
+#else
+
+struct page *
+perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
+{
+ if (pgoff > (1UL << page_order(rb)))
+ return NULL;
+
+ return vmalloc_to_page((void *)rb->user_page + pgoff * PAGE_SIZE);
+}
+
+static void perf_mmap_unmark_page(void *addr)
+{
+ struct page *page = vmalloc_to_page(addr);
+
+ page->mapping = NULL;
+}
+
+static void rb_free_work(struct work_struct *work)
+{
+ struct ring_buffer *rb;
+ void *base;
+ int i, nr;
+
+ rb = container_of(work, struct ring_buffer, work);
+ nr = 1 << page_order(rb);
+
+ base = rb->user_page;
+ for (i = 0; i < nr + 1; i++)
+ perf_mmap_unmark_page(base + (i * PAGE_SIZE));
+
+ vfree(base);
+ kfree(rb);
+}
+
+void rb_free(struct ring_buffer *rb)
+{
+ schedule_work(&rb->work);
+}
+
+struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
+{
+ struct ring_buffer *rb;
+ unsigned long size;
+ void *all_buf;
+
+ size = sizeof(struct ring_buffer);
+ size += sizeof(void *);
+
+ rb = kzalloc(size, GFP_KERNEL);
+ if (!rb)
+ goto fail;
+
+ INIT_WORK(&rb->work, rb_free_work);
+
+ all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE);
+ if (!all_buf)
+ goto fail_all_buf;
+
+ rb->user_page = all_buf;
+ rb->data_pages[0] = all_buf + PAGE_SIZE;
+ rb->page_order = ilog2(nr_pages);
+ rb->nr_pages = 1;
+
+ ring_buffer_init(rb, watermark, flags);
+
+ return rb;
+
+fail_all_buf:
+ kfree(rb);
+
+fail:
+ return NULL;
+}
+
+#endif