| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * 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 |
| * Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com> |
| */ |
| |
| #include <linux/perf_event.h> |
| #include <linux/vmalloc.h> |
| #include <linux/slab.h> |
| #include <linux/circ_buf.h> |
| #include <linux/poll.h> |
| #include <linux/nospec.h> |
| |
| #include "internal.h" |
| |
| static void perf_output_wakeup(struct perf_output_handle *handle) |
| { |
| atomic_set(&handle->rb->poll, EPOLLIN); |
| |
| handle->event->pending_wakeup = 1; |
| irq_work_queue(&handle->event->pending); |
| } |
| |
| /* |
| * 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 *rb = handle->rb; |
| |
| preempt_disable(); |
| |
| /* |
| * Avoid an explicit LOAD/STORE such that architectures with memops |
| * can use them. |
| */ |
| (*(volatile unsigned int *)&rb->nest)++; |
| handle->wakeup = local_read(&rb->wakeup); |
| } |
| |
| static void perf_output_put_handle(struct perf_output_handle *handle) |
| { |
| struct perf_buffer *rb = handle->rb; |
| unsigned long head; |
| unsigned int nest; |
| |
| /* |
| * If this isn't the outermost nesting, we don't have to update |
| * @rb->user_page->data_head. |
| */ |
| nest = READ_ONCE(rb->nest); |
| if (nest > 1) { |
| WRITE_ONCE(rb->nest, nest - 1); |
| goto out; |
| } |
| |
| again: |
| /* |
| * In order to avoid publishing a head value that goes backwards, |
| * we must ensure the load of @rb->head happens after we've |
| * incremented @rb->nest. |
| * |
| * Otherwise we can observe a @rb->head value before one published |
| * by an IRQ/NMI happening between the load and the increment. |
| */ |
| barrier(); |
| head = local_read(&rb->head); |
| |
| /* |
| * IRQ/NMI can happen here and advance @rb->head, causing our |
| * load above to be stale. |
| */ |
| |
| /* |
| * Since the mmap() consumer (userspace) can run on a different CPU: |
| * |
| * kernel user |
| * |
| * if (LOAD ->data_tail) { LOAD ->data_head |
| * (A) smp_rmb() (C) |
| * STORE $data LOAD $data |
| * smp_wmb() (B) smp_mb() (D) |
| * STORE ->data_head STORE ->data_tail |
| * } |
| * |
| * Where A pairs with D, and B pairs with C. |
| * |
| * In our case (A) is a control dependency that separates the load of |
| * the ->data_tail and the stores of $data. In case ->data_tail |
| * indicates there is no room in the buffer to store $data we do not. |
| * |
| * D needs to be a full barrier since it separates the data READ |
| * from the tail WRITE. |
| * |
| * For B a WMB is sufficient since it separates two WRITEs, and for C |
| * an RMB is sufficient since it separates two READs. |
| * |
| * See perf_output_begin(). |
| */ |
| smp_wmb(); /* B, matches C */ |
| WRITE_ONCE(rb->user_page->data_head, head); |
| |
| /* |
| * We must publish the head before decrementing the nest count, |
| * otherwise an IRQ/NMI can publish a more recent head value and our |
| * write will (temporarily) publish a stale value. |
| */ |
| barrier(); |
| WRITE_ONCE(rb->nest, 0); |
| |
| /* |
| * Ensure we decrement @rb->nest before we validate the @rb->head. |
| * Otherwise we cannot be sure we caught the 'last' nested update. |
| */ |
| barrier(); |
| if (unlikely(head != local_read(&rb->head))) { |
| WRITE_ONCE(rb->nest, 1); |
| goto again; |
| } |
| |
| if (handle->wakeup != local_read(&rb->wakeup)) |
| perf_output_wakeup(handle); |
| |
| out: |
| preempt_enable(); |
| } |
| |
| static __always_inline bool |
| ring_buffer_has_space(unsigned long head, unsigned long tail, |
| unsigned long data_size, unsigned int size, |
| bool backward) |
| { |
| if (!backward) |
| return CIRC_SPACE(head, tail, data_size) >= size; |
| else |
| return CIRC_SPACE(tail, head, data_size) >= size; |
| } |
| |
| static __always_inline int |
| __perf_output_begin(struct perf_output_handle *handle, |
| struct perf_sample_data *data, |
| struct perf_event *event, unsigned int size, |
| bool backward) |
| { |
| struct perf_buffer *rb; |
| unsigned long tail, offset, head; |
| int have_lost, page_shift; |
| 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 (unlikely(!rb)) |
| goto out; |
| |
| if (unlikely(rb->paused)) { |
| if (rb->nr_pages) |
| local_inc(&rb->lost); |
| goto out; |
| } |
| |
| handle->rb = rb; |
| handle->event = event; |
| |
| have_lost = local_read(&rb->lost); |
| if (unlikely(have_lost)) { |
| size += sizeof(lost_event); |
| if (event->attr.sample_id_all) |
| size += event->id_header_size; |
| } |
| |
| perf_output_get_handle(handle); |
| |
| do { |
| tail = READ_ONCE(rb->user_page->data_tail); |
| offset = head = local_read(&rb->head); |
| if (!rb->overwrite) { |
| if (unlikely(!ring_buffer_has_space(head, tail, |
| perf_data_size(rb), |
| size, backward))) |
| goto fail; |
| } |
| |
| /* |
| * The above forms a control dependency barrier separating the |
| * @tail load above from the data stores below. Since the @tail |
| * load is required to compute the branch to fail below. |
| * |
| * A, matches D; the full memory barrier userspace SHOULD issue |
| * after reading the data and before storing the new tail |
| * position. |
| * |
| * See perf_output_put_handle(). |
| */ |
| |
| if (!backward) |
| head += size; |
| else |
| head -= size; |
| } while (local_cmpxchg(&rb->head, offset, head) != offset); |
| |
| if (backward) { |
| offset = head; |
| head = (u64)(-head); |
| } |
| |
| /* |
| * We rely on the implied barrier() by local_cmpxchg() to ensure |
| * none of the data stores below can be lifted up by the compiler. |
| */ |
| |
| if (unlikely(head - local_read(&rb->wakeup) > rb->watermark)) |
| local_add(rb->watermark, &rb->wakeup); |
| |
| page_shift = PAGE_SHIFT + page_order(rb); |
| |
| handle->page = (offset >> page_shift) & (rb->nr_pages - 1); |
| offset &= (1UL << page_shift) - 1; |
| handle->addr = rb->data_pages[handle->page] + offset; |
| handle->size = (1UL << page_shift) - offset; |
| |
| if (unlikely(have_lost)) { |
| lost_event.header.size = sizeof(lost_event); |
| 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); |
| |
| /* XXX mostly redundant; @data is already fully initializes */ |
| perf_event_header__init_id(&lost_event.header, data, event); |
| perf_output_put(handle, lost_event); |
| perf_event__output_id_sample(event, handle, data); |
| } |
| |
| return 0; |
| |
| fail: |
| local_inc(&rb->lost); |
| perf_output_put_handle(handle); |
| out: |
| rcu_read_unlock(); |
| |
| return -ENOSPC; |
| } |
| |
| int perf_output_begin_forward(struct perf_output_handle *handle, |
| struct perf_sample_data *data, |
| struct perf_event *event, unsigned int size) |
| { |
| return __perf_output_begin(handle, data, event, size, false); |
| } |
| |
| int perf_output_begin_backward(struct perf_output_handle *handle, |
| struct perf_sample_data *data, |
| struct perf_event *event, unsigned int size) |
| { |
| return __perf_output_begin(handle, data, event, size, true); |
| } |
| |
| int perf_output_begin(struct perf_output_handle *handle, |
| struct perf_sample_data *data, |
| struct perf_event *event, unsigned int size) |
| { |
| |
| return __perf_output_begin(handle, data, event, size, |
| unlikely(is_write_backward(event))); |
| } |
| |
| unsigned int perf_output_copy(struct perf_output_handle *handle, |
| const void *buf, unsigned int len) |
| { |
| return __output_copy(handle, buf, len); |
| } |
| |
| unsigned int perf_output_skip(struct perf_output_handle *handle, |
| unsigned int len) |
| { |
| return __output_skip(handle, NULL, len); |
| } |
| |
| void perf_output_end(struct perf_output_handle *handle) |
| { |
| perf_output_put_handle(handle); |
| rcu_read_unlock(); |
| } |
| |
| static void |
| ring_buffer_init(struct perf_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->overwrite = 0; |
| else |
| rb->overwrite = 1; |
| |
| refcount_set(&rb->refcount, 1); |
| |
| INIT_LIST_HEAD(&rb->event_list); |
| spin_lock_init(&rb->event_lock); |
| |
| /* |
| * perf_output_begin() only checks rb->paused, therefore |
| * rb->paused must be true if we have no pages for output. |
| */ |
| if (!rb->nr_pages) |
| rb->paused = 1; |
| } |
| |
| void perf_aux_output_flag(struct perf_output_handle *handle, u64 flags) |
| { |
| /* |
| * OVERWRITE is determined by perf_aux_output_end() and can't |
| * be passed in directly. |
| */ |
| if (WARN_ON_ONCE(flags & PERF_AUX_FLAG_OVERWRITE)) |
| return; |
| |
| handle->aux_flags |= flags; |
| } |
| EXPORT_SYMBOL_GPL(perf_aux_output_flag); |
| |
| /* |
| * This is called before hardware starts writing to the AUX area to |
| * obtain an output handle and make sure there's room in the buffer. |
| * When the capture completes, call perf_aux_output_end() to commit |
| * the recorded data to the buffer. |
| * |
| * The ordering is similar to that of perf_output_{begin,end}, with |
| * the exception of (B), which should be taken care of by the pmu |
| * driver, since ordering rules will differ depending on hardware. |
| * |
| * Call this from pmu::start(); see the comment in perf_aux_output_end() |
| * about its use in pmu callbacks. Both can also be called from the PMI |
| * handler if needed. |
| */ |
| void *perf_aux_output_begin(struct perf_output_handle *handle, |
| struct perf_event *event) |
| { |
| struct perf_event *output_event = event; |
| unsigned long aux_head, aux_tail; |
| struct perf_buffer *rb; |
| unsigned int nest; |
| |
| if (output_event->parent) |
| output_event = output_event->parent; |
| |
| /* |
| * Since this will typically be open across pmu::add/pmu::del, we |
| * grab ring_buffer's refcount instead of holding rcu read lock |
| * to make sure it doesn't disappear under us. |
| */ |
| rb = ring_buffer_get(output_event); |
| if (!rb) |
| return NULL; |
| |
| if (!rb_has_aux(rb)) |
| goto err; |
| |
| /* |
| * If aux_mmap_count is zero, the aux buffer is in perf_mmap_close(), |
| * about to get freed, so we leave immediately. |
| * |
| * Checking rb::aux_mmap_count and rb::refcount has to be done in |
| * the same order, see perf_mmap_close. Otherwise we end up freeing |
| * aux pages in this path, which is a bug, because in_atomic(). |
| */ |
| if (!atomic_read(&rb->aux_mmap_count)) |
| goto err; |
| |
| if (!refcount_inc_not_zero(&rb->aux_refcount)) |
| goto err; |
| |
| nest = READ_ONCE(rb->aux_nest); |
| /* |
| * Nesting is not supported for AUX area, make sure nested |
| * writers are caught early |
| */ |
| if (WARN_ON_ONCE(nest)) |
| goto err_put; |
| |
| WRITE_ONCE(rb->aux_nest, nest + 1); |
| |
| aux_head = rb->aux_head; |
| |
| handle->rb = rb; |
| handle->event = event; |
| handle->head = aux_head; |
| handle->size = 0; |
| handle->aux_flags = 0; |
| |
| /* |
| * In overwrite mode, AUX data stores do not depend on aux_tail, |
| * therefore (A) control dependency barrier does not exist. The |
| * (B) <-> (C) ordering is still observed by the pmu driver. |
| */ |
| if (!rb->aux_overwrite) { |
| aux_tail = READ_ONCE(rb->user_page->aux_tail); |
| handle->wakeup = rb->aux_wakeup + rb->aux_watermark; |
| if (aux_head - aux_tail < perf_aux_size(rb)) |
| handle->size = CIRC_SPACE(aux_head, aux_tail, perf_aux_size(rb)); |
| |
| /* |
| * handle->size computation depends on aux_tail load; this forms a |
| * control dependency barrier separating aux_tail load from aux data |
| * store that will be enabled on successful return |
| */ |
| if (!handle->size) { /* A, matches D */ |
| event->pending_disable = smp_processor_id(); |
| perf_output_wakeup(handle); |
| WRITE_ONCE(rb->aux_nest, 0); |
| goto err_put; |
| } |
| } |
| |
| return handle->rb->aux_priv; |
| |
| err_put: |
| /* can't be last */ |
| rb_free_aux(rb); |
| |
| err: |
| ring_buffer_put(rb); |
| handle->event = NULL; |
| |
| return NULL; |
| } |
| EXPORT_SYMBOL_GPL(perf_aux_output_begin); |
| |
| static __always_inline bool rb_need_aux_wakeup(struct perf_buffer *rb) |
| { |
| if (rb->aux_overwrite) |
| return false; |
| |
| if (rb->aux_head - rb->aux_wakeup >= rb->aux_watermark) { |
| rb->aux_wakeup = rounddown(rb->aux_head, rb->aux_watermark); |
| return true; |
| } |
| |
| return false; |
| } |
| |
| /* |
| * Commit the data written by hardware into the ring buffer by adjusting |
| * aux_head and posting a PERF_RECORD_AUX into the perf buffer. It is the |
| * pmu driver's responsibility to observe ordering rules of the hardware, |
| * so that all the data is externally visible before this is called. |
| * |
| * Note: this has to be called from pmu::stop() callback, as the assumption |
| * of the AUX buffer management code is that after pmu::stop(), the AUX |
| * transaction must be stopped and therefore drop the AUX reference count. |
| */ |
| void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size) |
| { |
| bool wakeup = !!(handle->aux_flags & PERF_AUX_FLAG_TRUNCATED); |
| struct perf_buffer *rb = handle->rb; |
| unsigned long aux_head; |
| |
| /* in overwrite mode, driver provides aux_head via handle */ |
| if (rb->aux_overwrite) { |
| handle->aux_flags |= PERF_AUX_FLAG_OVERWRITE; |
| |
| aux_head = handle->head; |
| rb->aux_head = aux_head; |
| } else { |
| handle->aux_flags &= ~PERF_AUX_FLAG_OVERWRITE; |
| |
| aux_head = rb->aux_head; |
| rb->aux_head += size; |
| } |
| |
| /* |
| * Only send RECORD_AUX if we have something useful to communicate |
| * |
| * Note: the OVERWRITE records by themselves are not considered |
| * useful, as they don't communicate any *new* information, |
| * aside from the short-lived offset, that becomes history at |
| * the next event sched-in and therefore isn't useful. |
| * The userspace that needs to copy out AUX data in overwrite |
| * mode should know to use user_page::aux_head for the actual |
| * offset. So, from now on we don't output AUX records that |
| * have *only* OVERWRITE flag set. |
| */ |
| if (size || (handle->aux_flags & ~(u64)PERF_AUX_FLAG_OVERWRITE)) |
| perf_event_aux_event(handle->event, aux_head, size, |
| handle->aux_flags); |
| |
| WRITE_ONCE(rb->user_page->aux_head, rb->aux_head); |
| if (rb_need_aux_wakeup(rb)) |
| wakeup = true; |
| |
| if (wakeup) { |
| if (handle->aux_flags & PERF_AUX_FLAG_TRUNCATED) |
| handle->event->pending_disable = smp_processor_id(); |
| perf_output_wakeup(handle); |
| } |
| |
| handle->event = NULL; |
| |
| WRITE_ONCE(rb->aux_nest, 0); |
| /* can't be last */ |
| rb_free_aux(rb); |
| ring_buffer_put(rb); |
| } |
| EXPORT_SYMBOL_GPL(perf_aux_output_end); |
| |
| /* |
| * Skip over a given number of bytes in the AUX buffer, due to, for example, |
| * hardware's alignment constraints. |
| */ |
| int perf_aux_output_skip(struct perf_output_handle *handle, unsigned long size) |
| { |
| struct perf_buffer *rb = handle->rb; |
| |
| if (size > handle->size) |
| return -ENOSPC; |
| |
| rb->aux_head += size; |
| |
| WRITE_ONCE(rb->user_page->aux_head, rb->aux_head); |
| if (rb_need_aux_wakeup(rb)) { |
| perf_output_wakeup(handle); |
| handle->wakeup = rb->aux_wakeup + rb->aux_watermark; |
| } |
| |
| handle->head = rb->aux_head; |
| handle->size -= size; |
| |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(perf_aux_output_skip); |
| |
| void *perf_get_aux(struct perf_output_handle *handle) |
| { |
| /* this is only valid between perf_aux_output_begin and *_end */ |
| if (!handle->event) |
| return NULL; |
| |
| return handle->rb->aux_priv; |
| } |
| EXPORT_SYMBOL_GPL(perf_get_aux); |
| |
| /* |
| * Copy out AUX data from an AUX handle. |
| */ |
| long perf_output_copy_aux(struct perf_output_handle *aux_handle, |
| struct perf_output_handle *handle, |
| unsigned long from, unsigned long to) |
| { |
| struct perf_buffer *rb = aux_handle->rb; |
| unsigned long tocopy, remainder, len = 0; |
| void *addr; |
| |
| from &= (rb->aux_nr_pages << PAGE_SHIFT) - 1; |
| to &= (rb->aux_nr_pages << PAGE_SHIFT) - 1; |
| |
| do { |
| tocopy = PAGE_SIZE - offset_in_page(from); |
| if (to > from) |
| tocopy = min(tocopy, to - from); |
| if (!tocopy) |
| break; |
| |
| addr = rb->aux_pages[from >> PAGE_SHIFT]; |
| addr += offset_in_page(from); |
| |
| remainder = perf_output_copy(handle, addr, tocopy); |
| if (remainder) |
| return -EFAULT; |
| |
| len += tocopy; |
| from += tocopy; |
| from &= (rb->aux_nr_pages << PAGE_SHIFT) - 1; |
| } while (to != from); |
| |
| return len; |
| } |
| |
| #define PERF_AUX_GFP (GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | __GFP_NORETRY) |
| |
| static struct page *rb_alloc_aux_page(int node, int order) |
| { |
| struct page *page; |
| |
| if (order > MAX_ORDER) |
| order = MAX_ORDER; |
| |
| do { |
| page = alloc_pages_node(node, PERF_AUX_GFP, order); |
| } while (!page && order--); |
| |
| if (page && order) { |
| /* |
| * Communicate the allocation size to the driver: |
| * if we managed to secure a high-order allocation, |
| * set its first page's private to this order; |
| * !PagePrivate(page) means it's just a normal page. |
| */ |
| split_page(page, order); |
| SetPagePrivate(page); |
| set_page_private(page, order); |
| } |
| |
| return page; |
| } |
| |
| static void rb_free_aux_page(struct perf_buffer *rb, int idx) |
| { |
| struct page *page = virt_to_page(rb->aux_pages[idx]); |
| |
| ClearPagePrivate(page); |
| page->mapping = NULL; |
| __free_page(page); |
| } |
| |
| static void __rb_free_aux(struct perf_buffer *rb) |
| { |
| int pg; |
| |
| /* |
| * Should never happen, the last reference should be dropped from |
| * perf_mmap_close() path, which first stops aux transactions (which |
| * in turn are the atomic holders of aux_refcount) and then does the |
| * last rb_free_aux(). |
| */ |
| WARN_ON_ONCE(in_atomic()); |
| |
| if (rb->aux_priv) { |
| rb->free_aux(rb->aux_priv); |
| rb->free_aux = NULL; |
| rb->aux_priv = NULL; |
| } |
| |
| if (rb->aux_nr_pages) { |
| for (pg = 0; pg < rb->aux_nr_pages; pg++) |
| rb_free_aux_page(rb, pg); |
| |
| kfree(rb->aux_pages); |
| rb->aux_nr_pages = 0; |
| } |
| } |
| |
| int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event, |
| pgoff_t pgoff, int nr_pages, long watermark, int flags) |
| { |
| bool overwrite = !(flags & RING_BUFFER_WRITABLE); |
| int node = (event->cpu == -1) ? -1 : cpu_to_node(event->cpu); |
| int ret = -ENOMEM, max_order; |
| |
| if (!has_aux(event)) |
| return -EOPNOTSUPP; |
| |
| if (!overwrite) { |
| /* |
| * Watermark defaults to half the buffer, and so does the |
| * max_order, to aid PMU drivers in double buffering. |
| */ |
| if (!watermark) |
| watermark = nr_pages << (PAGE_SHIFT - 1); |
| |
| /* |
| * Use aux_watermark as the basis for chunking to |
| * help PMU drivers honor the watermark. |
| */ |
| max_order = get_order(watermark); |
| } else { |
| /* |
| * We need to start with the max_order that fits in nr_pages, |
| * not the other way around, hence ilog2() and not get_order. |
| */ |
| max_order = ilog2(nr_pages); |
| watermark = 0; |
| } |
| |
| rb->aux_pages = kcalloc_node(nr_pages, sizeof(void *), GFP_KERNEL, |
| node); |
| if (!rb->aux_pages) |
| return -ENOMEM; |
| |
| rb->free_aux = event->pmu->free_aux; |
| for (rb->aux_nr_pages = 0; rb->aux_nr_pages < nr_pages;) { |
| struct page *page; |
| int last, order; |
| |
| order = min(max_order, ilog2(nr_pages - rb->aux_nr_pages)); |
| page = rb_alloc_aux_page(node, order); |
| if (!page) |
| goto out; |
| |
| for (last = rb->aux_nr_pages + (1 << page_private(page)); |
| last > rb->aux_nr_pages; rb->aux_nr_pages++) |
| rb->aux_pages[rb->aux_nr_pages] = page_address(page++); |
| } |
| |
| /* |
| * In overwrite mode, PMUs that don't support SG may not handle more |
| * than one contiguous allocation, since they rely on PMI to do double |
| * buffering. In this case, the entire buffer has to be one contiguous |
| * chunk. |
| */ |
| if ((event->pmu->capabilities & PERF_PMU_CAP_AUX_NO_SG) && |
| overwrite) { |
| struct page *page = virt_to_page(rb->aux_pages[0]); |
| |
| if (page_private(page) != max_order) |
| goto out; |
| } |
| |
| rb->aux_priv = event->pmu->setup_aux(event, rb->aux_pages, nr_pages, |
| overwrite); |
| if (!rb->aux_priv) |
| goto out; |
| |
| ret = 0; |
| |
| /* |
| * aux_pages (and pmu driver's private data, aux_priv) will be |
| * referenced in both producer's and consumer's contexts, thus |
| * we keep a refcount here to make sure either of the two can |
| * reference them safely. |
| */ |
| refcount_set(&rb->aux_refcount, 1); |
| |
| rb->aux_overwrite = overwrite; |
| rb->aux_watermark = watermark; |
| |
| out: |
| if (!ret) |
| rb->aux_pgoff = pgoff; |
| else |
| __rb_free_aux(rb); |
| |
| return ret; |
| } |
| |
| void rb_free_aux(struct perf_buffer *rb) |
| { |
| if (refcount_dec_and_test(&rb->aux_refcount)) |
| __rb_free_aux(rb); |
| } |
| |
| #ifndef CONFIG_PERF_USE_VMALLOC |
| |
| /* |
| * Back perf_mmap() with regular GFP_KERNEL-0 pages. |
| */ |
| |
| static struct page * |
| __perf_mmap_to_page(struct perf_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); |
| } |
| |
| static void perf_mmap_free_page(void *addr) |
| { |
| struct page *page = virt_to_page(addr); |
| |
| page->mapping = NULL; |
| __free_page(page); |
| } |
| |
| struct perf_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags) |
| { |
| struct perf_buffer *rb; |
| unsigned long size; |
| int i, node; |
| |
| size = sizeof(struct perf_buffer); |
| size += nr_pages * sizeof(void *); |
| |
| if (order_base_2(size) >= PAGE_SHIFT+MAX_ORDER) |
| goto fail; |
| |
| node = (cpu == -1) ? cpu : cpu_to_node(cpu); |
| rb = kzalloc_node(size, GFP_KERNEL, node); |
| 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--) |
| perf_mmap_free_page(rb->data_pages[i]); |
| |
| perf_mmap_free_page(rb->user_page); |
| |
| fail_user_page: |
| kfree(rb); |
| |
| fail: |
| return NULL; |
| } |
| |
| void rb_free(struct perf_buffer *rb) |
| { |
| int i; |
| |
| perf_mmap_free_page(rb->user_page); |
| for (i = 0; i < rb->nr_pages; i++) |
| perf_mmap_free_page(rb->data_pages[i]); |
| kfree(rb); |
| } |
| |
| #else |
| static struct page * |
| __perf_mmap_to_page(struct perf_buffer *rb, unsigned long pgoff) |
| { |
| /* The '>' counts in the user page. */ |
| if (pgoff > data_page_nr(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 perf_buffer *rb; |
| void *base; |
| int i, nr; |
| |
| rb = container_of(work, struct perf_buffer, work); |
| nr = data_page_nr(rb); |
| |
| base = rb->user_page; |
| /* The '<=' counts in the user page. */ |
| for (i = 0; i <= nr; i++) |
| perf_mmap_unmark_page(base + (i * PAGE_SIZE)); |
| |
| vfree(base); |
| kfree(rb); |
| } |
| |
| void rb_free(struct perf_buffer *rb) |
| { |
| schedule_work(&rb->work); |
| } |
| |
| struct perf_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags) |
| { |
| struct perf_buffer *rb; |
| unsigned long size; |
| void *all_buf; |
| int node; |
| |
| size = sizeof(struct perf_buffer); |
| size += sizeof(void *); |
| |
| node = (cpu == -1) ? cpu : cpu_to_node(cpu); |
| rb = kzalloc_node(size, GFP_KERNEL, node); |
| 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; |
| if (nr_pages) { |
| rb->nr_pages = 1; |
| rb->page_order = ilog2(nr_pages); |
| } |
| |
| ring_buffer_init(rb, watermark, flags); |
| |
| return rb; |
| |
| fail_all_buf: |
| kfree(rb); |
| |
| fail: |
| return NULL; |
| } |
| |
| #endif |
| |
| struct page * |
| perf_mmap_to_page(struct perf_buffer *rb, unsigned long pgoff) |
| { |
| if (rb->aux_nr_pages) { |
| /* above AUX space */ |
| if (pgoff > rb->aux_pgoff + rb->aux_nr_pages) |
| return NULL; |
| |
| /* AUX space */ |
| if (pgoff >= rb->aux_pgoff) { |
| int aux_pgoff = array_index_nospec(pgoff - rb->aux_pgoff, rb->aux_nr_pages); |
| return virt_to_page(rb->aux_pages[aux_pgoff]); |
| } |
| } |
| |
| return __perf_mmap_to_page(rb, pgoff); |
| } |