Messages in this thread | | | Date | Fri, 1 Dec 2017 08:26:39 -0800 | From | Stephen Boyd <> | Subject | Re: [PATCH v2 18/18] perf: arm_spe: Disallow userspace profiling when arm_kernel_unmapped_at_el0() |
| |
On 11/30, Will Deacon wrote: > When running with the kernel unmapped whilst at EL0, the virtually-addressed > SPE buffer is also unmapped, which can lead to buffer faults if userspace > profiling is enabled. > > This patch prohibits SPE profiling of userspace when > arm_kernel_unmapped_at_el0(). > > Signed-off-by: Will Deacon <will.deacon@arm.com> > --- > drivers/perf/arm_spe_pmu.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c > index 8ce262fc2561..c028db8973a4 100644 > --- a/drivers/perf/arm_spe_pmu.c > +++ b/drivers/perf/arm_spe_pmu.c > @@ -675,6 +675,13 @@ static int arm_spe_pmu_event_init(struct perf_event *event) > return -EOPNOTSUPP; > > /* > + * If kernelspace is unmapped when running at EL0, then the SPE > + * buffer will fault and prematurely terminate the AUX session. > + */ > + if (arm64_kernel_unmapped_at_el0() && !attr->exclude_user) > + dev_warn_once(&spe_pmu->pdev->dev, "unable to write to profiling buffer from EL0. Try passing \"kaiser=off\" on the kernel command line");
Missing newline on that print?
-- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
| |