Messages in this thread Patch in this message | | | From | Alexander Shishkin <> | Subject | [PATCH v4 17/22] perf: Add a helper to copy AUX data in the kernel | Date | Wed, 20 Aug 2014 15:36:14 +0300 |
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This patch adds a helper for the kernel counters that generate AUX data to copy this data around, for example, to output it to the perf ring buffer as a sample record or write it to a core dump file.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> --- kernel/events/internal.h | 5 +++++ kernel/events/ring_buffer.c | 31 +++++++++++++++++++++++++++++++ 2 files changed, 36 insertions(+)
diff --git a/kernel/events/internal.h b/kernel/events/internal.h index f4cfa4cabb..bb035dd645 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -52,6 +52,9 @@ struct ring_buffer { void *data_pages[0]; }; +typedef unsigned long (*aux_copyfn)(void *data, const void *src, + unsigned long len); + extern void rb_free(struct ring_buffer *rb); extern struct ring_buffer * rb_alloc(int nr_pages, long watermark, int cpu, int flags); @@ -59,6 +62,8 @@ extern void perf_event_wakeup(struct perf_event *event); extern int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event, pgoff_t pgoff, int nr_pages, long watermark, int flags); extern void rb_free_aux(struct ring_buffer *rb, struct perf_event *event); +extern long rb_output_aux(struct ring_buffer *rb, unsigned long from, + unsigned long to, aux_copyfn copyfn, void *data); extern struct ring_buffer * rb_alloc_kernel(struct perf_event *event, int nr_pages, int aux_nr_pages); extern void rb_free_kernel(struct ring_buffer *rb, struct perf_event *event); diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 7887601aa5..4cf5a1cd0a 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -345,6 +345,37 @@ void *perf_get_aux(struct perf_output_handle *handle) return handle->rb->aux_priv; } +long rb_output_aux(struct ring_buffer *rb, unsigned long from, + unsigned long to, aux_copyfn copyfn, void *data) +{ + 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 = copyfn(data, 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) -- 2.1.0
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