On Tue, Apr 04, 2017 at 04:10:55PM +0530, Ganapatrao Kulkarni wrote:
> commit d98ecda (arm64: perf: Count EL2 events if the kernel is running in HYP)
> is returning error for perf syscall with mixed attribute set for
> exclude_kernel
> and exlude_hv.
>
> This change is breaking some applications (observed with hhvm) when
> ran with VHE enabled. Adding change to enable EL2 event counting,
> if either of or both of exclude_kernel and exlude_hv are not set.
>
> Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulka...@cavium.com>
> ---
> arch/arm64/kernel/perf_event.c | 19 ++++++++++++-------
> 1 file changed, 12 insertions(+), 7 deletions(-)
Hmm. When we have VHE, we can't distinguish between hypervisor and kernel,
so this patch doesn't seem right to me. The code currently requires
both exclude_kernel and exclude_hv to be clear before we enable profiling
EL2, otherwise we're failing to exclude samples that were asked to be
excluded.
Will
> diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
> index daf95919..ea5848a 100644
> --- a/arch/arm64/kernel/perf_event.c
> +++ b/arch/arm64/kernel/perf_event.c
> @@ -871,15 +871,20 @@ static int armv8pmu_set_event_filter(struct
> hw_perf_event *event,
>
> if (attr->exclude_idle)
> return -EPERM;
> - if (is_kernel_in_hyp_mode() &&
> - attr->exclude_kernel != attr->exclude_hv)
> - return -EINVAL;
> + if (is_kernel_in_hyp_mode()) {
> + /* include EL2 events, if either of not excluded */
> + if ((attr->exclude_kernel != attr->exclude_hv) ||
> + !attr->exclude_kernel ||
> + !attr->exclude_hv)
> + config_base |= ARMV8_PMU_INCLUDE_EL2;
> + } else {
> + if (attr->exclude_kernel)
> + config_base |= ARMV8_PMU_EXCLUDE_EL1;
> + if (!attr->exclude_hv)
> + config_base |= ARMV8_PMU_INCLUDE_EL2;
> + }
> if (attr->exclude_user)
> config_base |= ARMV8_PMU_EXCLUDE_EL0;
> - if (!is_kernel_in_hyp_mode() && attr->exclude_kernel)
> - config_base |= ARMV8_PMU_EXCLUDE_EL1;
> - if (!attr->exclude_hv)
> - config_base |= ARMV8_PMU_INCLUDE_EL2;
>
> /*
> * Install the filter into config_base as this is used to
> --
> 1.8.1.4
>
