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Date: Tue, 28 May 2019 09:33:40 -0400
From: "Liang, Kan" <kan.liang@...ux.intel.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: mingo@...nel.org, acme@...hat.com, vincent.weaver@...ne.edu,
linux-kernel@...r.kernel.org, alexander.shishkin@...ux.intel.com,
ak@...ux.intel.com, jolsa@...hat.com, eranian@...gle.com
Subject: Re: [PATCH V2 1/3] perf/x86: Disable non generic regs for
software/probe events
On 5/28/2019 4:56 AM, Peter Zijlstra wrote:
> On Mon, May 27, 2019 at 12:07:55PM -0700, kan.liang@...ux.intel.com wrote:
>> diff --git a/arch/x86/include/uapi/asm/perf_regs.h b/arch/x86/include/uapi/asm/perf_regs.h
>> index ac67bbe..3a96971 100644
>> --- a/arch/x86/include/uapi/asm/perf_regs.h
>> +++ b/arch/x86/include/uapi/asm/perf_regs.h
>> @@ -52,4 +52,7 @@ enum perf_event_x86_regs {
>> /* These include both GPRs and XMMX registers */
>> PERF_REG_X86_XMM_MAX = PERF_REG_X86_XMM15 + 2,
>> };
>> +
>> +#define PERF_REG_NON_GENERIC_MASK (~((1ULL << PERF_REG_X86_XMM0) - 1))
>> +
>> #endif /* _ASM_X86_PERF_REGS_H */
>> diff --git a/include/linux/perf_regs.h b/include/linux/perf_regs.h
>> index 4767474..1d794355 100644
>> --- a/include/linux/perf_regs.h
>> +++ b/include/linux/perf_regs.h
>> @@ -11,6 +11,11 @@ struct perf_regs {
>>
>> #ifdef CONFIG_HAVE_PERF_REGS
>> #include <asm/perf_regs.h>
>> +
>> +#ifndef PERF_REG_NON_GENERIC_MASK
>> +#define PERF_REG_NON_GENERIC_MASK 0
>> +#endif
>> +
>> u64 perf_reg_value(struct pt_regs *regs, int idx);
>> int perf_reg_validate(u64 mask);
>> u64 perf_reg_abi(struct task_struct *task);
>> @@ -18,6 +23,9 @@ void perf_get_regs_user(struct perf_regs *regs_user,
>> struct pt_regs *regs,
>> struct pt_regs *regs_user_copy);
>> #else
>> +
>> +#define PERF_REG_NON_GENERIC_MASK 0
>> +
>> static inline u64 perf_reg_value(struct pt_regs *regs, int idx)
>> {
>> return 0;
>
> Much better than the last version; however..
>
>> diff --git a/kernel/events/core.c b/kernel/events/core.c
>> index abbd4b3..4865bdf 100644
>> --- a/kernel/events/core.c
>> +++ b/kernel/events/core.c
>> @@ -8457,6 +8457,12 @@ static void sw_perf_event_destroy(struct perf_event *event)
>> swevent_hlist_put();
>> }
>>
>> +static inline bool has_non_generic_regs(struct perf_event *event)
>> +{
>> + return (event->attr.sample_regs_user & PERF_REG_NON_GENERIC_MASK) ||
>> + (event->attr.sample_regs_intr & PERF_REG_NON_GENERIC_MASK);
>> +}
>> +
>> static int perf_swevent_init(struct perf_event *event)
>> {
>> u64 event_id = event->attr.config;
>> @@ -8470,6 +8476,10 @@ static int perf_swevent_init(struct perf_event *event)
>> if (has_branch_stack(event))
>> return -EOPNOTSUPP;
>>
>> + /* Only support generic registers */
>> + if (has_non_generic_regs(event))
>> + return -EOPNOTSUPP;
>> +
>> switch (event_id) {
>> case PERF_COUNT_SW_CPU_CLOCK:
>> case PERF_COUNT_SW_TASK_CLOCK:
>> @@ -8633,6 +8643,10 @@ static int perf_tp_event_init(struct perf_event *event)
>> if (has_branch_stack(event))
>> return -EOPNOTSUPP;
>>
>> + /* Only support generic registers */
>> + if (has_non_generic_regs(event))
>> + return -EOPNOTSUPP;
>> +
>> err = perf_trace_init(event);
>> if (err)
>> return err;
>> @@ -8722,6 +8736,10 @@ static int perf_kprobe_event_init(struct perf_event *event)
>> if (has_branch_stack(event))
>> return -EOPNOTSUPP;
>>
>> + /* Only support generic registers */
>> + if (has_non_generic_regs(event))
>> + return -EOPNOTSUPP;
>> +
>> is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;
>> err = perf_kprobe_init(event, is_retprobe);
>> if (err)
>> @@ -8782,6 +8800,10 @@ static int perf_uprobe_event_init(struct perf_event *event)
>> if (has_branch_stack(event))
>> return -EOPNOTSUPP;
>>
>> + /* Only support generic registers */
>> + if (has_non_generic_regs(event))
>> + return -EOPNOTSUPP;
>> +
>> is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;
>> ref_ctr_offset = event->attr.config >> PERF_UPROBE_REF_CTR_OFFSET_SHIFT;
>> err = perf_uprobe_init(event, ref_ctr_offset, is_retprobe);
>> @@ -9562,6 +9584,10 @@ static int cpu_clock_event_init(struct perf_event *event)
>> if (has_branch_stack(event))
>> return -EOPNOTSUPP;
>>
>> + /* Only support generic registers */
>> + if (has_non_generic_regs(event))
>> + return -EOPNOTSUPP;
>> +
>> perf_swevent_init_hrtimer(event);
>>
>> return 0;
>> @@ -9643,6 +9669,10 @@ static int task_clock_event_init(struct perf_event *event)
>> if (has_branch_stack(event))
>> return -EOPNOTSUPP;
>>
>> + /* Only support generic registers */
>> + if (has_non_generic_regs(event))
>> + return -EOPNOTSUPP;
>> +
>> perf_swevent_init_hrtimer(event);
>>
>> return 0;
>
> I don't think this is anywhere near sufficient. What happens if we
> request XMM regs for an uncore PMU ?
>
Uncore PMU doesn't support sampling. It will return -EINVAL.
There is no regs support for counting. The request will be ignored.
I think current check for uncore is good enough.
Thanks,
Kan
> I'm thinking you want something along these lines...
>
> ---
> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
> index a5436cee20b1..3ef1c2e0b177 100644
> --- a/arch/x86/events/intel/core.c
> +++ b/arch/x86/events/intel/core.c
> @@ -3281,7 +3281,13 @@ static int intel_pmu_hw_config(struct perf_event *event)
>
> if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
> event->attr.sample_type |= __PERF_SAMPLE_CALLCHAIN_EARLY;
> - }
> +
> + /* we only support extended (XMM) registers for sample_regs_intr */
> + if (event->attr.sample_regs_user & PERF_REGS_EXTENDED_MASK)
> + return -EOPNOTSUPP;
> +
> + } else if (has_extended_regs(event))
> + return -EOPNOTSUPP;
>
> if (needs_branch_stack(event)) {
> ret = intel_pmu_setup_lbr_filter(event);
> diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
> index 5e9bb246b3a6..4fae37f8c7c2 100644
> --- a/arch/x86/events/intel/ds.c
> +++ b/arch/x86/events/intel/ds.c
> @@ -2020,6 +2020,7 @@ void __init intel_ds_init(void)
> PERF_SAMPLE_TIME;
> x86_pmu.flags |= PMU_FL_PEBS_ALL;
> pebs_qual = "-baseline";
> + x86_get_pmu()->capabilities |= PERF_PMU_CAP_EXTENDED_REGS;
> } else {
> /* Only basic record supported */
> x86_pmu.pebs_no_xmm_regs = 1;
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index 0ab99c7b652d..2bca72f3028b 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -241,6 +241,7 @@ struct perf_event;
> #define PERF_PMU_CAP_NO_INTERRUPT 0x01
> #define PERF_PMU_CAP_NO_NMI 0x02
> #define PERF_PMU_CAP_AUX_NO_SG 0x04
> +#define PERF_PMU_CAP_EXTENDED_REGS 0x08
> #define PERF_PMU_CAP_EXCLUSIVE 0x10
> #define PERF_PMU_CAP_ITRACE 0x20
> #define PERF_PMU_CAP_HETEROGENEOUS_CPUS 0x40
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index abbd4b3b96c2..0c4872426b70 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -10064,12 +10064,16 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
> perf_event_ctx_unlock(event->group_leader, ctx);
>
> if (!ret) {
> + if (!(pmu->capabilities & PERF_PMU_CAP_EXTENDED_REGS) &&
> + has_extended_regs(event))
> + ret = -EOPNOTSUPP;
> +
> if (pmu->capabilities & PERF_PMU_CAP_NO_EXCLUDE &&
> - event_has_any_exclude_flag(event)) {
> - if (event->destroy)
> - event->destroy(event);
> + event_has_any_exclude_flag(event))
> ret = -EINVAL;
> - }
> +
> + if (ret && event->destroy)
> + event->destroy(event);
> }
>
> if (ret)
>
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