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perf: Split up buffer handling from core code

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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>
This commit is contained in:
Frederic Weisbecker 2011-05-19 19:55:04 +02:00 committed by Ingo Molnar
parent b58f6b0dd3
commit 76369139ce
5 changed files with 572 additions and 527 deletions
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33
include/linux/perf_event.h
View File

@ -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;

2
kernel/events/Makefile
View File

@ -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

568
kernel/events/core.c
View File

@ -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 @@ void perf_event_update_userpage(struct perf_event *event)
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 @@ static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
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 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
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 @@ perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
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;
}

97
kernel/events/internal.h Normal file
View File

@ -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 */

399
kernel/events/ring_buffer.c Normal file
View File

@ -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