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authorSuzuki K Poulose <suzuki.poulose@arm.com>2016-06-14 11:17:14 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-06-16 00:13:06 -0700
commitf3b8172fe15fbed0d0d33d99780e122213e00684 (patch)
tree1fb8f8fd7e32d778e158045e1ac2824454639174 /drivers/hwtracing
parent8e215298a15d5b93c6fa22895c406da538769bca (diff)
downloadlinux-f3b8172fe15fbed0d0d33d99780e122213e00684.tar.bz2
coresight: Fix erroneous memset in tmc_read_unprepare_etr
At the end of a trace collection, we try to clear the entire buffer and enable the ETR back if it was already enabled. But, we would have adjusted the drvdata->buf to point to the beginning of the trace data in the trace buffer @drvdata->vaddr. So, the following code which clears the buffer is dangerous and can cause crashes, like below : memset(drvdata->buf, 0, drvdata->size); Unable to handle kernel paging request at virtual address ffffff800a145000 pgd = ffffffc974726000 *pgd=00000009f3e91003, *pud=00000009f3e91003, *pmd=0000000000000000 PREEMPT SMP Modules linked in: CPU: 4 PID: 1692 Comm: dd Not tainted 4.7.0-rc2+ #1721 Hardware name: ARM Juno development board (r0) (DT) task: ffffffc9734a0080 ti: ffffffc974460000 task.ti: ffffffc974460000 PC is at __memset+0x1ac/0x200 LR is at tmc_read_unprepare_etr+0x144/0x1bc pc : [<ffffff80083a05ac>] lr : [<ffffff800859c984>] pstate: 200001c5 ... [<ffffff80083a05ac>] __memset+0x1ac/0x200 [<ffffff800859b2e4>] tmc_release+0x90/0x94 [<ffffff8008202f58>] __fput+0xa8/0x1ec [<ffffff80082030f4>] ____fput+0xc/0x14 [<ffffff80080c3ef8>] task_work_run+0xb0/0xe4 [<ffffff8008088bf4>] do_notify_resume+0x64/0x6c [<ffffff8008084d5c>] work_pending+0x10/0x14 Code: 91010108 54ffff4a 8b040108 cb050042 (d50b7428) Since we clear the buffer anyway in the following call to tmc_etr_enable_hw(), remove the erroneous memset(). Fixes: commit de5461970b3e9e1 ("coresight: tmc: allocating memory when needed") Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hwtracing')
-rw-r--r--drivers/hwtracing/coresight/coresight-tmc-etr.c9
1 files changed, 3 insertions, 6 deletions
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index 3369d7a80a51..688be9e060fc 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -300,13 +300,10 @@ int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata)
if (local_read(&drvdata->mode) == CS_MODE_SYSFS) {
/*
* The trace run will continue with the same allocated trace
- * buffer. As such zero-out the buffer so that we don't end
- * up with stale data.
- *
- * Since the tracer is still enabled drvdata::buf
- * can't be NULL.
+ * buffer. The trace buffer is cleared in tmc_etr_enable_hw(),
+ * so we don't have to explicitly clear it. Also, since the
+ * tracer is still enabled drvdata::buf can't be NULL.
*/
- memset(drvdata->buf, 0, drvdata->size);
tmc_etr_enable_hw(drvdata);
} else {
/*