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Date: Tue, 28 May 2019 10:56:01 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: kan.liang@...ux.intel.com
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 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 ?
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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