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Groups > linux.kernel > #1615921
| From | Will Deacon <will.deacon@arm.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] arm64: perf: Count EL2 events if either of kernel and hyp are not excluded |
| Date | 2017-04-04 13:30 +0200 |
| Message-ID | <tsuOR-4cn-7@gated-at.bofh.it> (permalink) |
| References | <tsuOR-4cn-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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.kulkarni@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
>
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Re: [PATCH] arm64: perf: Count EL2 events if either of kernel and hyp are not excluded Will Deacon <will.deacon@arm.com> - 2017-04-04 13:30 +0200
Re: [PATCH] arm64: perf: Count EL2 events if either of kernel and hyp are not excluded Ganapatrao Kulkarni <gpkulkarni@gmail.com> - 2017-04-04 14:10 +0200
Re: [PATCH] arm64: perf: Count EL2 events if either of kernel and hyp are not excluded Will Deacon <will.deacon@arm.com> - 2017-04-04 14:30 +0200
Re: [PATCH] arm64: perf: Count EL2 events if either of kernel and hyp are not excluded Ganapatrao Kulkarni <gpkulkarni@gmail.com> - 2017-04-05 06:00 +0200
Re: [PATCH] arm64: perf: Count EL2 events if either of kernel and hyp are not excluded Will Deacon <will.deacon@arm.com> - 2017-04-05 10:40 +0200
Re: [PATCH] arm64: perf: Count EL2 events if either of kernel and hyp are not excluded Ganapatrao Kulkarni <gpkulkarni@gmail.com> - 2017-04-05 11:50 +0200
Re: [PATCH] arm64: perf: Count EL2 events if either of kernel and hyp are not excluded Ganapatrao Kulkarni <gpkulkarni@gmail.com> - 2017-04-05 11:50 +0200
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