On 15/02/16 17:22, Will Deacon wrote:
> On Thu, Feb 11, 2016 at 06:40:01PM +0000, Marc Zyngier wrote:
>> When the kernel is running in HYP (with VHE), it is necessary to
>> include EL2 events if the user requests counting kernel or
>> hypervisor events.
>>
>> Reviewed-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
>> Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
>> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
>> ---
>> arch/arm64/kernel/perf_event.c | 14 ++++++++++----
>> 1 file changed, 10 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
>> index f7ab14c..6013a38 100644
>> --- a/arch/arm64/kernel/perf_event.c
>> +++ b/arch/arm64/kernel/perf_event.c
>> @@ -20,6 +20,7 @@
>> */
>>
>> #include <asm/irq_regs.h>
>> +#include <asm/virt.h>
>>
>> #include <linux/of.h>
>> #include <linux/perf/arm_pmu.h>
>> @@ -693,10 +694,15 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event,
>> return -EPERM;
>> if (attr->exclude_user)
>> config_base |= ARMV8_EXCLUDE_EL0;
>> - if (attr->exclude_kernel)
>> - config_base |= ARMV8_EXCLUDE_EL1;
>> - if (!attr->exclude_hv)
>> - config_base |= ARMV8_INCLUDE_EL2;
>> + if (is_kernel_in_hyp_mode()) {
>> + if (!attr->exclude_kernel || !attr->exclude_hv)
>> + config_base |= ARMV8_INCLUDE_EL2;
>
> Hmm, so if userspace sets exclude_kernel but not exclude_user and
> exclude_hv, what should we do? I'm slightly tempted to reject the
> filter with -EINVAL...
I was angling for the minimum level of surprise for the user, but
I guess that the results are going to be troubling anyway.
How about something like this on top:
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index 6013a38..8c00ed4 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -695,7 +695,10 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event,
if (attr->exclude_user)
config_base |= ARMV8_EXCLUDE_EL0;
if (is_kernel_in_hyp_mode()) {
- if (!attr->exclude_kernel || !attr->exclude_hv)
+ /* Demand that kernel and hv are consistent */
+ if (attr->exclude_kernel != attr->exclude_hv)
+ return -EINVAL;
+ if (!attr->exclude_hv)
config_base |= ARMV8_INCLUDE_EL2;
} else {
if (attr->exclude_kernel)
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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