On Tue, Mar 09, 2021 at 05:44:12PM -0700, Rob Herring wrote:
> Commit 0fdf1bb75953 ("arm64: perf: Avoid PMXEV* indirection") changed
> armv8pmu_read_evcntr() to return a u32 instead of u64. The result is
> silent truncation of the event counter when using 64-bit counters. Given
> the offending commit appears to have passed thru several folks, it seems
> likely this was a bad rebase after v8.5 PMU 64-bit counters landed.IIRC I wrote the indirection patch first, so this does sound like an oversight when rebasing or reworking the patch. Comparing against commit 0fdf1bb75953, this does appear to be the only point of truncation given read_pmevcntrn() directly returns the result of read_sysreg(), so: Acked-by: Mark Rutland <[email protected]> Will, could you pick this up? Thanks, Mark. > Fixes: 0fdf1bb75953 ("arm64: perf: Avoid PMXEV* indirection") > Cc: Alexandru Elisei <[email protected]> > Cc: Julien Thierry <[email protected]> > Cc: Mark Rutland <[email protected]> > Cc: Will Deacon <[email protected]> > Cc: Catalin Marinas <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Arnaldo Carvalho de Melo <[email protected]> > Cc: Alexander Shishkin <[email protected]> > Cc: Jiri Olsa <[email protected]> > Cc: Namhyung Kim <[email protected]> > Signed-off-by: Rob Herring <[email protected]> > --- > arch/arm64/kernel/perf_event.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c > index 7d2318f80955..4658fcf88c2b 100644 > --- a/arch/arm64/kernel/perf_event.c > +++ b/arch/arm64/kernel/perf_event.c > @@ -460,7 +460,7 @@ static inline int armv8pmu_counter_has_overflowed(u32 > pmnc, int idx) > return pmnc & BIT(ARMV8_IDX_TO_COUNTER(idx)); > } > > -static inline u32 armv8pmu_read_evcntr(int idx) > +static inline u64 armv8pmu_read_evcntr(int idx) > { > u32 counter = ARMV8_IDX_TO_COUNTER(idx); > > -- > 2.27.0 >
