From: Alexandru Elisei alexandru.elisei@arm.com
[ Upstream commit 490d7b7c0845eacf5593db333fd2ae7715416e16 ]
Writes to the PMXEVTYPER_EL0 register are not self-synchronising. In armv8pmu_enable_event(), the PE can reorder configuring the event type after we have enabled the counter and the interrupt. This can lead to an interrupt being asserted because of the previous event type that we were counting using the same counter, not the one that we've just configured.
The same rationale applies to writes to the PMINTENSET_EL1 register. The PE can reorder enabling the interrupt at any point in the future after we have enabled the event.
Prevent both situations from happening by adding an ISB just before we enable the event counter.
Fixes: 030896885ade ("arm64: Performance counters support") Reported-by: Julien Thierry julien.thierry@arm.com Signed-off-by: Alexandru Elisei alexandru.elisei@arm.com Tested-by: Sumit Garg sumit.garg@linaro.org (Developerbox) Cc: Julien Thierry julien.thierry.kdev@gmail.com Cc: Will Deacon will.deacon@arm.com Cc: Mark Rutland mark.rutland@arm.com Cc: Peter Zijlstra peterz@infradead.org Cc: Ingo Molnar mingo@redhat.com Cc: Arnaldo Carvalho de Melo acme@kernel.org Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Jiri Olsa jolsa@redhat.com Cc: Namhyung Kim namhyung@kernel.org Cc: Catalin Marinas catalin.marinas@arm.com Link: https://lore.kernel.org/r/20200924110706.254996-2-alexandru.elisei@arm.com Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm64/kernel/perf_event.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index 462f9a9cc44be..481d48e3872b8 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -532,6 +532,11 @@ static u32 armv8pmu_event_cnten_mask(struct perf_event *event)
static inline void armv8pmu_enable_counter(u32 mask) { + /* + * Make sure event configuration register writes are visible before we + * enable the counter. + * */ + isb(); write_sysreg(mask, pmcntenset_el0); }