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coresight: tmc-etr: Fix updating buffer in not-snapshot mode.

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TMC etr always copies all available data to perf aux buffer, which
may exceed the available space in perf aux buffer. It isn't suitable
for not-snapshot mode, because:
1) It may overwrite previously written data.
2) It may make the perf_event_mmap_page->aux_head report having more
or less data than the reality.

So change to only copy the latest data fitting the available space in
perf aux buffer.

Signed-off-by: Yabin Cui <yabinc@google.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20190829202842.580-14-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Yabin Cui 2019-08-29 14:28:38 -06:00 • committed by Greg Kroah-Hartman
parent 89e89b05ef
commit 13af88f312
1 changed files with 11 additions and 7 deletions
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18
drivers/hwtracing/coresight/coresight-tmc-etr.c
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@ -1414,9 +1414,10 @@ free_etr_perf_buffer:
* tmc_etr_sync_perf_buffer: Copy the actual trace data from the hardware * tmc_etr_sync_perf_buffer: Copy the actual trace data from the hardware
* buffer to the perf ring buffer. * buffer to the perf ring buffer.
*/ */
static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf) static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf,
unsigned long to_copy)
{ {
long bytes, to_copy; long bytes;
long pg_idx, pg_offset, src_offset; long pg_idx, pg_offset, src_offset;
unsigned long head = etr_perf->head; unsigned long head = etr_perf->head;
char **dst_pages, *src_buf; char **dst_pages, *src_buf;
@ -1426,8 +1427,7 @@ static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf)
pg_idx = head >> PAGE_SHIFT; pg_idx = head >> PAGE_SHIFT;
pg_offset = head & (PAGE_SIZE - 1); pg_offset = head & (PAGE_SIZE - 1);
dst_pages = (char **)etr_perf->pages; dst_pages = (char **)etr_perf->pages;
src_offset = etr_buf->offset; src_offset = etr_buf->offset + etr_buf->len - to_copy;
to_copy = etr_buf->len;
while (to_copy > 0) { while (to_copy > 0) {
/* /*
@ -1438,6 +1438,8 @@ static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf)
* 3) what is available in the destination page. * 3) what is available in the destination page.
* in one iteration. * in one iteration.
*/ */
if (src_offset >= etr_buf->size)
src_offset -= etr_buf->size;
bytes = tmc_etr_buf_get_data(etr_buf, src_offset, to_copy, bytes = tmc_etr_buf_get_data(etr_buf, src_offset, to_copy,
&src_buf); &src_buf);
if (WARN_ON_ONCE(bytes <= 0)) if (WARN_ON_ONCE(bytes <= 0))
@ -1458,8 +1460,6 @@ static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf)
/* Move source pointers */ /* Move source pointers */
src_offset += bytes; src_offset += bytes;
if (src_offset >= etr_buf->size)
src_offset -= etr_buf->size;
} }
} }
@ -1505,7 +1505,11 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
spin_unlock_irqrestore(&drvdata->spinlock, flags); spin_unlock_irqrestore(&drvdata->spinlock, flags);
size = etr_buf->len; size = etr_buf->len;
tmc_etr_sync_perf_buffer(etr_perf); if (!etr_perf->snapshot && size > handle->size) {
size = handle->size;
lost = true;
}
tmc_etr_sync_perf_buffer(etr_perf, size);
/* /*
* In snapshot mode we simply increment the head by the number of byte * In snapshot mode we simply increment the head by the number of byte