coresight: etm4x: Fix access to resource selector registers

Resource selector pair 0 is always implemented and reserved. We must not
touch it, even during save/restore for CPU Idle. Rest of the driver is
well behaved. Fix the offending ones.

Reported-by: Yabin Cui <yabinc@google.com>
Fixes: f188b5e76aae ("coresight: etm4x: Save/restore state across CPU low power states")
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Tested-by: Yabin Cui <yabinc@google.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Link: https://lore.kernel.org/r/20240412142702.2882478-5-suzuki.poulose@arm.com

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 8643b77e50f4133991eb4f013a9a37b8d0614f41..a0bdfabddbc683e32c41788278b282aa3e034bee 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -1758,7 +1758,8 @@ static int __etm4_cpu_save(struct etmv4_drvdata *drvdata)
                state->trccntvr[i] = etm4x_read32(csa, TRCCNTVRn(i));
        }
 
-       for (i = 0; i < drvdata->nr_resource * 2; i++)
+       /* Resource selector pair 0 is reserved */
+       for (i = 2; i < drvdata->nr_resource * 2; i++)
                state->trcrsctlr[i] = etm4x_read32(csa, TRCRSCTLRn(i));
 
        for (i = 0; i < drvdata->nr_ss_cmp; i++) {
@@ -1889,7 +1890,8 @@ static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata)
                etm4x_relaxed_write32(csa, state->trccntvr[i], TRCCNTVRn(i));
        }
 
-       for (i = 0; i < drvdata->nr_resource * 2; i++)
+       /* Resource selector pair 0 is reserved */
+       for (i = 2; i < drvdata->nr_resource * 2; i++)
                etm4x_relaxed_write32(csa, state->trcrsctlr[i], TRCRSCTLRn(i));
 
        for (i = 0; i < drvdata->nr_ss_cmp; i++) {