Add PMF instrumentation points in TF
In order to quantify the overall time spent in the PSCI software
implementation, an initial collection of PMF instrumentation points
has been added.
Instrumentation has been added to the following code paths:
- Entry to PSCI SMC handler. The timestamp is captured as early
as possible during the runtime exception and stored in memory
before entering the PSCI SMC handler.
- Exit from PSCI SMC handler. The timestamp is captured after
normal return from the PSCI SMC handler or if a low power state
was requested it is captured in the bl31 warm boot path before
return to normal world.
- Entry to low power state. The timestamp is captured before entry
to a low power state which implies either standby or power down.
As these power states are mutually exclusive, only one timestamp
is defined to describe both. It is possible to differentiate between
the two power states using the PSCI STAT interface.
- Exit from low power state. The timestamp is captured after a standby
or power up operation has completed.
To calculate the number of cycles spent running code in Trusted Firmware
one can perform the following calculation:
(exit_psci - enter_psci) - (exit_low_pwr - enter_low_pwr).
The resulting number of cycles can be converted to time given the
frequency of the counter.
Change-Id: Ie3b8f3d16409b6703747093b3a2d5c7429ad0166
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>
diff --git a/bl31/aarch64/runtime_exceptions.S b/bl31/aarch64/runtime_exceptions.S
index 799062e..f333bf1 100644
--- a/bl31/aarch64/runtime_exceptions.S
+++ b/bl31/aarch64/runtime_exceptions.S
@@ -31,6 +31,7 @@
#include <arch.h>
#include <asm_macros.S>
#include <context.h>
+#include <cpu_data.h>
#include <interrupt_mgmt.h>
#include <platform_def.h>
#include <runtime_svc.h>
@@ -47,6 +48,21 @@
msr daifclr, #DAIF_ABT_BIT
str x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR]
+
+#if ENABLE_RUNTIME_INSTRUMENTATION
+
+ /*
+ * Read the timestamp value and store it in per-cpu data.
+ * The value will be extracted from per-cpu data by the
+ * C level SMC handler and saved to the PMF timestamp region.
+ */
+ mrs x30, cntpct_el0
+ str x29, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X29]
+ mrs x29, tpidr_el3
+ str x30, [x29, #CPU_DATA_PMF_TS0_OFFSET]
+ ldr x29, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X29]
+#endif
+
mrs x30, esr_el3
ubfx x30, x30, #ESR_EC_SHIFT, #ESR_EC_LENGTH