This is a note to let you know that I've just added the patch titled
coresight: etm4x: Skip accessing TRCPDCR in save/restore
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
coresight-etm4x-skip-accessing-trcpdcr-in-save-resto.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 75a98833038241ab7e19d0497526074a5a9beab9
Author: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Date: Mon Feb 1 11:13:24 2021 -0700
coresight: etm4x: Skip accessing TRCPDCR in save/restore
[ Upstream commit df81b43802f43c0954a55e5d513e8750a1ab4d31 ]
When the ETM is affected by Qualcomm errata, modifying the
TRCPDCR could cause the system hang. Even though this is
taken care of during enable/disable ETM, the ETM state
save/restore could still access the TRCPDCR. Make sure
we skip the access during the save/restore.
Found by code inspection.
Link: https://lore.kernel.org/r/20210110224850.1880240-3-suzuki.poulose@xxxxxxx
Fixes: 02510a5aa78d ("coresight: etm4x: Add support to skip trace unit power up")
Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Mike Leach <mike.leach@xxxxxxxxxx>
Cc: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
Cc: Tingwei Zhang <tingwei@xxxxxxxxxxxxxx>
Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
Reviewed-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210201181351.1475223-5-mathieu.poirier@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 95b54b0a36252..8b6666e6fddbf 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -1254,7 +1254,8 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
state->trcclaimset = readl(drvdata->base + TRCCLAIMCLR);
- state->trcpdcr = readl(drvdata->base + TRCPDCR);
+ if (!drvdata->skip_power_up)
+ state->trcpdcr = readl(drvdata->base + TRCPDCR);
/* wait for TRCSTATR.IDLE to go up */
if (coresight_timeout(drvdata->base, TRCSTATR, TRCSTATR_IDLE_BIT, 1)) {
@@ -1272,9 +1273,9 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
* potentially save power on systems that respect the TRCPDCR_PU
* despite requesting software to save/restore state.
*/
- writel_relaxed((state->trcpdcr & ~TRCPDCR_PU),
- drvdata->base + TRCPDCR);
-
+ if (!drvdata->skip_power_up)
+ writel_relaxed((state->trcpdcr & ~TRCPDCR_PU),
+ drvdata->base + TRCPDCR);
out:
CS_LOCK(drvdata->base);
return ret;
@@ -1368,7 +1369,8 @@ static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
writel_relaxed(state->trcclaimset, drvdata->base + TRCCLAIMSET);
- writel_relaxed(state->trcpdcr, drvdata->base + TRCPDCR);
+ if (!drvdata->skip_power_up)
+ writel_relaxed(state->trcpdcr, drvdata->base + TRCPDCR);
drvdata->state_needs_restore = false;
