Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
[platform/adaptation/renesas_rcar/renesas_kernel.git] / kernel / events / ring_buffer.c
1 /*
2  * Performance events ring-buffer code:
3  *
4  *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
5  *  Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
6  *  Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
7  *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
8  *
9  * For licensing details see kernel-base/COPYING
10  */
11
12 #include <linux/perf_event.h>
13 #include <linux/vmalloc.h>
14 #include <linux/slab.h>
15
16 #include "internal.h"
17
18 static bool perf_output_space(struct ring_buffer *rb, unsigned long tail,
19                               unsigned long offset, unsigned long head)
20 {
21         unsigned long mask;
22
23         if (!rb->writable)
24                 return true;
25
26         mask = perf_data_size(rb) - 1;
27
28         offset = (offset - tail) & mask;
29         head   = (head   - tail) & mask;
30
31         if ((int)(head - offset) < 0)
32                 return false;
33
34         return true;
35 }
36
37 static void perf_output_wakeup(struct perf_output_handle *handle)
38 {
39         atomic_set(&handle->rb->poll, POLL_IN);
40
41         handle->event->pending_wakeup = 1;
42         irq_work_queue(&handle->event->pending);
43 }
44
45 /*
46  * We need to ensure a later event_id doesn't publish a head when a former
47  * event isn't done writing. However since we need to deal with NMIs we
48  * cannot fully serialize things.
49  *
50  * We only publish the head (and generate a wakeup) when the outer-most
51  * event completes.
52  */
53 static void perf_output_get_handle(struct perf_output_handle *handle)
54 {
55         struct ring_buffer *rb = handle->rb;
56
57         preempt_disable();
58         local_inc(&rb->nest);
59         handle->wakeup = local_read(&rb->wakeup);
60 }
61
62 static void perf_output_put_handle(struct perf_output_handle *handle)
63 {
64         struct ring_buffer *rb = handle->rb;
65         unsigned long head;
66
67 again:
68         head = local_read(&rb->head);
69
70         /*
71          * IRQ/NMI can happen here, which means we can miss a head update.
72          */
73
74         if (!local_dec_and_test(&rb->nest))
75                 goto out;
76
77         /*
78          * Publish the known good head. Rely on the full barrier implied
79          * by atomic_dec_and_test() order the rb->head read and this
80          * write.
81          */
82         rb->user_page->data_head = head;
83
84         /*
85          * Now check if we missed an update, rely on the (compiler)
86          * barrier in atomic_dec_and_test() to re-read rb->head.
87          */
88         if (unlikely(head != local_read(&rb->head))) {
89                 local_inc(&rb->nest);
90                 goto again;
91         }
92
93         if (handle->wakeup != local_read(&rb->wakeup))
94                 perf_output_wakeup(handle);
95
96 out:
97         preempt_enable();
98 }
99
100 int perf_output_begin(struct perf_output_handle *handle,
101                       struct perf_event *event, unsigned int size)
102 {
103         struct ring_buffer *rb;
104         unsigned long tail, offset, head;
105         int have_lost;
106         struct perf_sample_data sample_data;
107         struct {
108                 struct perf_event_header header;
109                 u64                      id;
110                 u64                      lost;
111         } lost_event;
112
113         rcu_read_lock();
114         /*
115          * For inherited events we send all the output towards the parent.
116          */
117         if (event->parent)
118                 event = event->parent;
119
120         rb = rcu_dereference(event->rb);
121         if (!rb)
122                 goto out;
123
124         handle->rb      = rb;
125         handle->event   = event;
126
127         if (!rb->nr_pages)
128                 goto out;
129
130         have_lost = local_read(&rb->lost);
131         if (have_lost) {
132                 lost_event.header.size = sizeof(lost_event);
133                 perf_event_header__init_id(&lost_event.header, &sample_data,
134                                            event);
135                 size += lost_event.header.size;
136         }
137
138         perf_output_get_handle(handle);
139
140         do {
141                 /*
142                  * Userspace could choose to issue a mb() before updating the
143                  * tail pointer. So that all reads will be completed before the
144                  * write is issued.
145                  */
146                 tail = ACCESS_ONCE(rb->user_page->data_tail);
147                 smp_rmb();
148                 offset = head = local_read(&rb->head);
149                 head += size;
150                 if (unlikely(!perf_output_space(rb, tail, offset, head)))
151                         goto fail;
152         } while (local_cmpxchg(&rb->head, offset, head) != offset);
153
154         if (head - local_read(&rb->wakeup) > rb->watermark)
155                 local_add(rb->watermark, &rb->wakeup);
156
157         handle->page = offset >> (PAGE_SHIFT + page_order(rb));
158         handle->page &= rb->nr_pages - 1;
159         handle->size = offset & ((PAGE_SIZE << page_order(rb)) - 1);
160         handle->addr = rb->data_pages[handle->page];
161         handle->addr += handle->size;
162         handle->size = (PAGE_SIZE << page_order(rb)) - handle->size;
163
164         if (have_lost) {
165                 lost_event.header.type = PERF_RECORD_LOST;
166                 lost_event.header.misc = 0;
167                 lost_event.id          = event->id;
168                 lost_event.lost        = local_xchg(&rb->lost, 0);
169
170                 perf_output_put(handle, lost_event);
171                 perf_event__output_id_sample(event, handle, &sample_data);
172         }
173
174         return 0;
175
176 fail:
177         local_inc(&rb->lost);
178         perf_output_put_handle(handle);
179 out:
180         rcu_read_unlock();
181
182         return -ENOSPC;
183 }
184
185 void perf_output_copy(struct perf_output_handle *handle,
186                       const void *buf, unsigned int len)
187 {
188         __output_copy(handle, buf, len);
189 }
190
191 void perf_output_end(struct perf_output_handle *handle)
192 {
193         perf_output_put_handle(handle);
194         rcu_read_unlock();
195 }
196
197 static void
198 ring_buffer_init(struct ring_buffer *rb, long watermark, int flags)
199 {
200         long max_size = perf_data_size(rb);
201
202         if (watermark)
203                 rb->watermark = min(max_size, watermark);
204
205         if (!rb->watermark)
206                 rb->watermark = max_size / 2;
207
208         if (flags & RING_BUFFER_WRITABLE)
209                 rb->writable = 1;
210
211         atomic_set(&rb->refcount, 1);
212
213         INIT_LIST_HEAD(&rb->event_list);
214         spin_lock_init(&rb->event_lock);
215 }
216
217 #ifndef CONFIG_PERF_USE_VMALLOC
218
219 /*
220  * Back perf_mmap() with regular GFP_KERNEL-0 pages.
221  */
222
223 struct page *
224 perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
225 {
226         if (pgoff > rb->nr_pages)
227                 return NULL;
228
229         if (pgoff == 0)
230                 return virt_to_page(rb->user_page);
231
232         return virt_to_page(rb->data_pages[pgoff - 1]);
233 }
234
235 static void *perf_mmap_alloc_page(int cpu)
236 {
237         struct page *page;
238         int node;
239
240         node = (cpu == -1) ? cpu : cpu_to_node(cpu);
241         page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
242         if (!page)
243                 return NULL;
244
245         return page_address(page);
246 }
247
248 struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
249 {
250         struct ring_buffer *rb;
251         unsigned long size;
252         int i;
253
254         size = sizeof(struct ring_buffer);
255         size += nr_pages * sizeof(void *);
256
257         rb = kzalloc(size, GFP_KERNEL);
258         if (!rb)
259                 goto fail;
260
261         rb->user_page = perf_mmap_alloc_page(cpu);
262         if (!rb->user_page)
263                 goto fail_user_page;
264
265         for (i = 0; i < nr_pages; i++) {
266                 rb->data_pages[i] = perf_mmap_alloc_page(cpu);
267                 if (!rb->data_pages[i])
268                         goto fail_data_pages;
269         }
270
271         rb->nr_pages = nr_pages;
272
273         ring_buffer_init(rb, watermark, flags);
274
275         return rb;
276
277 fail_data_pages:
278         for (i--; i >= 0; i--)
279                 free_page((unsigned long)rb->data_pages[i]);
280
281         free_page((unsigned long)rb->user_page);
282
283 fail_user_page:
284         kfree(rb);
285
286 fail:
287         return NULL;
288 }
289
290 static void perf_mmap_free_page(unsigned long addr)
291 {
292         struct page *page = virt_to_page((void *)addr);
293
294         page->mapping = NULL;
295         __free_page(page);
296 }
297
298 void rb_free(struct ring_buffer *rb)
299 {
300         int i;
301
302         perf_mmap_free_page((unsigned long)rb->user_page);
303         for (i = 0; i < rb->nr_pages; i++)
304                 perf_mmap_free_page((unsigned long)rb->data_pages[i]);
305         kfree(rb);
306 }
307
308 #else
309
310 struct page *
311 perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
312 {
313         if (pgoff > (1UL << page_order(rb)))
314                 return NULL;
315
316         return vmalloc_to_page((void *)rb->user_page + pgoff * PAGE_SIZE);
317 }
318
319 static void perf_mmap_unmark_page(void *addr)
320 {
321         struct page *page = vmalloc_to_page(addr);
322
323         page->mapping = NULL;
324 }
325
326 static void rb_free_work(struct work_struct *work)
327 {
328         struct ring_buffer *rb;
329         void *base;
330         int i, nr;
331
332         rb = container_of(work, struct ring_buffer, work);
333         nr = 1 << page_order(rb);
334
335         base = rb->user_page;
336         for (i = 0; i < nr + 1; i++)
337                 perf_mmap_unmark_page(base + (i * PAGE_SIZE));
338
339         vfree(base);
340         kfree(rb);
341 }
342
343 void rb_free(struct ring_buffer *rb)
344 {
345         schedule_work(&rb->work);
346 }
347
348 struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
349 {
350         struct ring_buffer *rb;
351         unsigned long size;
352         void *all_buf;
353
354         size = sizeof(struct ring_buffer);
355         size += sizeof(void *);
356
357         rb = kzalloc(size, GFP_KERNEL);
358         if (!rb)
359                 goto fail;
360
361         INIT_WORK(&rb->work, rb_free_work);
362
363         all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE);
364         if (!all_buf)
365                 goto fail_all_buf;
366
367         rb->user_page = all_buf;
368         rb->data_pages[0] = all_buf + PAGE_SIZE;
369         rb->page_order = ilog2(nr_pages);
370         rb->nr_pages = 1;
371
372         ring_buffer_init(rb, watermark, flags);
373
374         return rb;
375
376 fail_all_buf:
377         kfree(rb);
378
379 fail:
380         return NULL;
381 }
382
383 #endif