diff options
| author | dp-arm <dimitris.papastamos@arm.com> | 2016-10-31 17:17:21 +0000 |
|---|---|---|
| committer | dp-arm <dimitris.papastamos@arm.com> | 2016-11-03 16:02:53 +0000 |
| commit | bfef610667b75e731d0d263b069369f7695c6c83 (patch) | |
| tree | fe7406afd0c50903ea14b94d3b719205fb15bcab /services | |
| parent | fc1d1e2df02e61279c16d280f4f48c83f8fa7927 (diff) | |
Perform a cache flush after ENTER PSCI timestamp capture
Without an explicit cache flush, the next timestamp captured might have
a bogus value.
This can happen if the following operations happen in order,
on a CPU that's being powered down.
1) ENTER PSCI timestamp is captured with caches enabled.
2) The next timestamp (ENTER_HW_LOW_PWR) is captured with caches
disabled.
3) On a system that uses a write-back cache configuration, the
cache line that holds the PMF timestamps is evicted.
After step 1), the ENTER_PSCI timestamp is cached and not in main memory.
After step 2), the ENTER_HW_LOW_PWR timestamp is stored in main memory.
Before the CPU power down happens, the hardware evicts the cache line that
contains the PMF timestamps for this service. As a result, the timestamp
captured in step 2) is overwritten with a bogus value.
Change-Id: Ic1bd816498d1a6d4dc16540208ed3a5efe43f529
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>
Diffstat (limited to 'services')
| -rw-r--r-- | services/std_svc/std_svc_setup.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/services/std_svc/std_svc_setup.c b/services/std_svc/std_svc_setup.c index 97a9fbd6..010bb8f7 100644 --- a/services/std_svc/std_svc_setup.c +++ b/services/std_svc/std_svc_setup.c @@ -81,9 +81,14 @@ uintptr_t std_svc_smc_handler(uint32_t smc_fid, uint64_t ret; #if ENABLE_RUNTIME_INSTRUMENTATION + + /* + * Flush cache line so that even if CPU power down happens + * the timestamp update is reflected in memory. + */ PMF_WRITE_TIMESTAMP(rt_instr_svc, RT_INSTR_ENTER_PSCI, - PMF_NO_CACHE_MAINT, + PMF_CACHE_MAINT, get_cpu_data(cpu_data_pmf_ts[CPU_DATA_PMF_TS0_IDX])); #endif |