From: Yabin Cui <yabinc@google.com>
To: Mathieu Poirier <mathieu.poirier@linaro.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Yabin Cui <yabinc@google.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH] coresight: tmc-etr: Fix updating buffer in not-snapshot mode.
Date: Mon, 5 Aug 2019 16:37:38 -0700 [thread overview]
Message-ID: <20190805233738.136357-1-yabinc@google.com> (raw)
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.
Signed-off-by: Yabin Cui <yabinc@google.com>
---
drivers/hwtracing/coresight/coresight-tmc-etr.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index 17006705287a..697e68d492af 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -1410,9 +1410,10 @@ static void tmc_free_etr_buffer(void *config)
* tmc_etr_sync_perf_buffer: Copy the actual trace data from the hardware
* 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;
unsigned long head = etr_perf->head;
char **dst_pages, *src_buf;
@@ -1423,7 +1424,6 @@ static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf)
pg_offset = head & (PAGE_SIZE - 1);
dst_pages = (char **)etr_perf->pages;
src_offset = etr_buf->offset;
- to_copy = etr_buf->len;
while (to_copy > 0) {
/*
@@ -1501,7 +1501,11 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
spin_unlock_irqrestore(&drvdata->spinlock, flags);
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
--
2.22.0.770.g0f2c4a37fd-goog
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next reply other threads:[~2019-08-05 23:38 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-05 23:37 Yabin Cui [this message]
2019-08-06 11:15 ` [PATCH] coresight: tmc-etr: Fix updating buffer in not-snapshot mode Suzuki K Poulose
2019-08-12 19:52 ` Mathieu Poirier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190805233738.136357-1-yabinc@google.com \
--to=yabinc@google.com \
--cc=alexander.shishkin@linux.intel.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mathieu.poirier@linaro.org \
--cc=suzuki.poulose@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).