Commit df81b438 authored by Suzuki K Poulose's avatar Suzuki K Poulose Committed by Greg Kroah-Hartman
Browse files

coresight: etm4x: Skip accessing TRCPDCR in save/restore 

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@arm.com


Fixes: 02510a5a ("coresight: etm4x: Add support to skip trace unit power up")
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Cc: Tingwei Zhang <tingwei@codeaurora.org>
Tested-by: default avatarSai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Reviewed-by: default avatarSai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: default avatarMathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20210201181351.1475223-5-mathieu.poirier@linaro.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f6a18f35

drivers/hwtracing/coresight/coresight-etm4x-core.c

+7 −5
Original line number Diff line number Diff line
@@ -1373,6 +1373,7 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata) 


	state->trcclaimset = readl(drvdata->base + TRCCLAIMCLR);



	if (!drvdata->skip_power_up)

		state->trcpdcr = readl(drvdata->base + TRCPDCR);



	/* wait for TRCSTATR.IDLE to go up */
@@ -1391,9 +1392,9 @@ 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.

	 */

	if (!drvdata->skip_power_up)

		writel_relaxed((state->trcpdcr & ~TRCPDCR_PU),

				drvdata->base + TRCPDCR);



out:

	CS_LOCK(drvdata->base);

	return ret;
@@ -1488,6 +1489,7 @@ static void etm4_cpu_restore(struct etmv4_drvdata *drvdata) 


	writel_relaxed(state->trcclaimset, drvdata->base + TRCCLAIMSET);



	if (!drvdata->skip_power_up)

		writel_relaxed(state->trcpdcr, drvdata->base + TRCPDCR);



	drvdata->state_needs_restore = false;