fix(pmu): unconditionally save PMCR_EL0
Reading back a RES0 bit does not necessarily mean it will be read as 0.
The Arm ARM explicitly warns against doing this. The PMU initialisation
code tries to set such bits to 1 (in MDCR_EL3) regardless of whether
they are in use or are RES0, checking their value could be wrong and
PMCR_EL0 might not end up being saved.
Save PMCR_EL0 unconditionally to prevent this. Remove the security state
change as the outgoing state is not relevant to what the root world
context should look like.
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Change-Id: Id43667d37b0e2da3ded0beaf23fa0d4f9013f470
diff --git a/bl1/aarch64/bl1_exceptions.S b/bl1/aarch64/bl1_exceptions.S
index c54219f..eaaf59a 100644
--- a/bl1/aarch64/bl1_exceptions.S
+++ b/bl1/aarch64/bl1_exceptions.S
@@ -218,9 +218,7 @@
smc_handler:
/* -----------------------------------------------------
* Save x0-x29 and ARMv8.3-PAuth (if enabled) registers.
- * If Secure Cycle Counter is not disabled in MDCR_EL3
- * when ARMv8.5-PMU is implemented, save PMCR_EL0 and
- * disable Cycle Counter.
+ * Save PMCR_EL0 and disable Cycle Counter.
* TODO: Revisit to store only SMCCC specified registers.
* -----------------------------------------------------
*/