lkml.org 
[lkml]   [2017]   [Apr]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2] arm64: perf: Use only exclude_kernel attribute when kernel is running in HYP
On Wed, Apr 19, 2017 at 11:14:06PM +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 exclude_hv. This change is breaking some applications (observed with hhvm)
> when ran on VHE enabled platforms.
>
> Adding fix to consider only exclude_kernel attribute when kernel is
> running in HYP. Also adding sysfs file to notify the bhehaviour
> of attribute exclude_hv.
>
> Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
> ---
>
> Changelog:
>
> V2:
> - Changes as per Will Deacon's suggestion.
>
> V1: Initial patch
>
> arch/arm64/kernel/perf_event.c | 28 ++++++++++++++++++++++++----
> include/linux/perf/arm_pmu.h | 1 +
> 2 files changed, 25 insertions(+), 4 deletions(-)
>
> @@ -871,14 +890,13 @@ 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() && !attr->exclude_kernel)
> + 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)
> + if (!is_kernel_in_hyp_mode() && !attr->exclude_hv)
> config_base |= ARMV8_PMU_INCLUDE_EL2;

This isn't quite what Will suggested.

The idea was that userspace would read sysfs, then use that to determine
the correct exclusion parameters [1,2]. This logic was not expected to
change; it correctly validates whether we can provide what the user
requests.

Thanks,
Mark.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2017-April/499224.html
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2017-April/499493.html

>
> /*
> @@ -1008,6 +1026,8 @@ static int armv8_pmuv3_init(struct arm_pmu *cpu_pmu)
> &armv8_pmuv3_events_attr_group;
> cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_FORMATS] =
> &armv8_pmuv3_format_attr_group;
> + cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_ATTR] =
> + &armv8_pmuv3_attr_group;
> return armv8pmu_probe_pmu(cpu_pmu);
> }
>
> diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
> index 8462da2..a26ffc7 100644
> --- a/include/linux/perf/arm_pmu.h
> +++ b/include/linux/perf/arm_pmu.h
> @@ -81,6 +81,7 @@ enum armpmu_attr_groups {
> ARMPMU_ATTR_GROUP_COMMON,
> ARMPMU_ATTR_GROUP_EVENTS,
> ARMPMU_ATTR_GROUP_FORMATS,
> + ARMPMU_ATTR_GROUP_ATTR,
> ARMPMU_NR_ATTR_GROUPS
> };
>
> --
> 1.8.1.4
>

\
 
 \ /
  Last update: 2017-04-20 10:51    [W:0.374 / U:7.032 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site