[Patch v7 22/24] perf/x86/intel: Enable arch-PEBS based SIMD/eGPRs/SSP sampling

Dapeng Mi
2026-03-24T00:47:35Z

This patch enables arch-PEBS based SIMD/eGPRs/SSP registers sampling.

Arch-PEBS supports sampling of these registers, with all except SSP
placed into the XSAVE-Enabled Registers (XER) group with the layout
described below.

Field Name Registers Used Size

XSTATE_BV XINUSE for groups 8 B
Reserved Reserved 8 B
SSER XMM0-XMM15 16 regs * 16 B = 256 B
YMMHIR Upper 128 bits of YMM0-YMM15 16 regs * 16 B = 256 B
EGPR R16-R31 16 regs * 8 B = 128 B
OPMASKR K0-K7 8 regs * 8 B = 64 B
ZMMHIR Upper 256 bits of ZMM0-ZMM15 16 regs * 32 B = 512 B
Hi16ZMMR ZMM16-ZMM31 16 regs * 64 B = 1024 B

Memory space in the output buffer is allocated for these sub-groups as
long as the corresponding Format.XER[55:49] bits in the PEBS record
header are set. However, the arch-PEBS hardware engine does not write
the sub-group if it is not used (in INIT state). In such cases, the
corresponding bit in the XSTATE_BV bitmap is set to 0. Therefore, the
XSTATE_BV field is checked to determine if the register data is actually
written for each PEBS record. If not, the register data is not outputted
to userspace.

The SSP register is sampled and placed into the GPRs group by arch-PEBS.

Additionally, the MSRs IA32_PMC_{GPn|FXm}_CFG_C.[55:49] bits are used to
manage which types of these registers need to be sampled.

Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
---
arch/x86/events/intel/core.c | 75 ++++++++++++++++++++++--------
arch/x86/events/intel/ds.c | 77 ++++++++++++++++++++++++++++---
arch/x86/include/asm/msr-index.h | 7 +++
arch/x86/include/asm/perf_event.h | 8 +++-
4 files changed, 142 insertions(+), 25 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 0a32a0367647..e0dd57906bca 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3221,6 +3221,21 @@ static void intel_pmu_enable_event_ext(struct perf_event *event)
if (pebs_data_cfg & PEBS_DATACFG_XMMS)
ext |= ARCH_PEBS_VECR_XMM & cap.caps;

+ if (pebs_data_cfg & PEBS_DATACFG_YMMHS)
+ ext |= ARCH_PEBS_VECR_YMMH & cap.caps;
+
+ if (pebs_data_cfg & PEBS_DATACFG_EGPRS)
+ ext |= ARCH_PEBS_VECR_EGPRS & cap.caps;
+
+ if (pebs_data_cfg & PEBS_DATACFG_OPMASKS)
+ ext |= ARCH_PEBS_VECR_OPMASK & cap.caps;
+
+ if (pebs_data_cfg & PEBS_DATACFG_ZMMHS)
+ ext |= ARCH_PEBS_VECR_ZMMH & cap.caps;
+
+ if (pebs_data_cfg & PEBS_DATACFG_H16ZMMS)
+ ext |= ARCH_PEBS_VECR_H16ZMM & cap.caps;
+
if (pebs_data_cfg & PEBS_DATACFG_LBRS)
ext |= ARCH_PEBS_LBR & cap.caps;

@@ -4416,6 +4431,34 @@ static void intel_pebs_aliases_skl(struct perf_event *event)
return intel_pebs_aliases_precdist(event);
}

+static inline bool intel_pebs_support_regs(struct perf_event *event, u64 regs)
+{
+ struct arch_pebs_cap cap = hybrid(event->pmu, arch_pebs_cap);
+ int pebs_format = x86_pmu.intel_cap.pebs_format;
+ bool supported = true;
+
+ /* SSP */
+ if (regs & PEBS_DATACFG_GP)
+ supported &= x86_pmu.arch_pebs && (ARCH_PEBS_GPR & cap.caps);
+ if (regs & PEBS_DATACFG_XMMS) {
+ supported &= x86_pmu.arch_pebs ?
+ ARCH_PEBS_VECR_XMM & cap.caps :
+ pebs_format > 3 && x86_pmu.intel_cap.pebs_baseline;
+ }
+ if (regs & PEBS_DATACFG_YMMHS)
+ supported &= x86_pmu.arch_pebs && (ARCH_PEBS_VECR_YMMH & cap.caps);
+ if (regs & PEBS_DATACFG_EGPRS)
+ supported &= x86_pmu.arch_pebs && (ARCH_PEBS_VECR_EGPRS & cap.caps);
+ if (regs & PEBS_DATACFG_OPMASKS)
+ supported &= x86_pmu.arch_pebs && (ARCH_PEBS_VECR_OPMASK & cap.caps);
+ if (regs & PEBS_DATACFG_ZMMHS)
+ supported &= x86_pmu.arch_pebs && (ARCH_PEBS_VECR_ZMMH & cap.caps);
+ if (regs & PEBS_DATACFG_H16ZMMS)
+ supported &= x86_pmu.arch_pebs && (ARCH_PEBS_VECR_H16ZMM & cap.caps);
+
+ return supported;
+}
+
static unsigned long intel_pmu_large_pebs_flags(struct perf_event *event)
{
unsigned long flags = x86_pmu.large_pebs_flags;
@@ -4425,24 +4468,20 @@ static unsigned long intel_pmu_large_pebs_flags(struct perf_event *event)
if (!event->attr.exclude_kernel)
flags &= ~PERF_SAMPLE_REGS_USER;
if (event->attr.sample_simd_regs_enabled) {
- u64 nolarge = PERF_X86_EGPRS_MASK | BIT_ULL(PERF_REG_X86_SSP);
-
- /*
- * PEBS HW can only collect the XMM0-XMM15 for now.
- * Disable large PEBS for other vector registers, predicate
- * registers, eGPRs, and SSP.
- */
- if (event->attr.sample_regs_user & nolarge ||
- fls64(event->attr.sample_simd_vec_reg_user) > PERF_X86_H16ZMM_BASE ||
- event->attr.sample_simd_pred_reg_user)
- flags &= ~PERF_SAMPLE_REGS_USER;
-
- if (event->attr.sample_regs_intr & nolarge ||
- fls64(event->attr.sample_simd_vec_reg_intr) > PERF_X86_H16ZMM_BASE ||
- event->attr.sample_simd_pred_reg_intr)
- flags &= ~PERF_SAMPLE_REGS_INTR;
-
- if (event->attr.sample_simd_vec_reg_qwords > PERF_X86_XMM_QWORDS)
+ if ((event_needs_ssp(event) &&
+ !intel_pebs_support_regs(event, PEBS_DATACFG_GP)) ||
+ (event_needs_xmm(event) &&
+ !intel_pebs_support_regs(event, PEBS_DATACFG_XMMS)) ||
+ (event_needs_ymm(event) &&
+ !intel_pebs_support_regs(event, PEBS_DATACFG_YMMHS)) ||
+ (event_needs_egprs(event) &&
+ !intel_pebs_support_regs(event, PEBS_DATACFG_EGPRS)) ||
+ (event_needs_opmask(event) &&
+ !intel_pebs_support_regs(event, PEBS_DATACFG_OPMASKS)) ||
+ (event_needs_low16_zmm(event) &&
+ !intel_pebs_support_regs(event, PEBS_DATACFG_ZMMHS)) ||
+ (event_needs_high16_zmm(event) &&
+ !intel_pebs_support_regs(event, PEBS_DATACFG_H16ZMMS)))
flags &= ~(PERF_SAMPLE_REGS_USER | PERF_SAMPLE_REGS_INTR);
} else {
if (event->attr.sample_regs_user & ~PEBS_GP_REGS)
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index 3a2fb623e0ab..4743bdfb4ed4 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1740,11 +1740,22 @@ static u64 pebs_update_adaptive_cfg(struct perf_event *event)
((attr->config & INTEL_ARCH_EVENT_MASK) ==
x86_pmu.rtm_abort_event);

- if (gprs || (attr->precise_ip < 2) || tsx_weight)
+ if (gprs || (attr->precise_ip < 2) ||
+ tsx_weight || event_needs_ssp(event))
pebs_data_cfg |= PEBS_DATACFG_GP;

if (event_needs_xmm(event))
pebs_data_cfg |= PEBS_DATACFG_XMMS;
+ if (event_needs_ymm(event))
+ pebs_data_cfg |= PEBS_DATACFG_YMMHS;
+ if (event_needs_low16_zmm(event))
+ pebs_data_cfg |= PEBS_DATACFG_ZMMHS;
+ if (event_needs_high16_zmm(event))
+ pebs_data_cfg |= PEBS_DATACFG_H16ZMMS;
+ if (event_needs_opmask(event))
+ pebs_data_cfg |= PEBS_DATACFG_OPMASKS;
+ if (event_needs_egprs(event))
+ pebs_data_cfg |= PEBS_DATACFG_EGPRS;

if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
/*
@@ -2705,15 +2716,69 @@ static void setup_arch_pebs_sample_data(struct perf_event *event,
meminfo->tsx_tuning, ax);
}

- if (header->xmm) {
+ if (header->xmm || header->ymmh || header->egpr ||
+ header->opmask || header->zmmh || header->h16zmm) {
+ struct arch_pebs_xer_header *xer_header = next_record;
struct pebs_xmm *xmm;
+ struct ymmh_struct *ymmh;
+ struct avx_512_zmm_uppers_state *zmmh;
+ struct avx_512_hi16_state *h16zmm;
+ struct avx_512_opmask_state *opmask;
+ struct apx_state *egpr;

next_record += sizeof(struct arch_pebs_xer_header);

- ignore_mask |= XFEATURE_MASK_SSE;
- xmm = next_record;
- perf_regs->xmm_regs = xmm->xmm;
- next_record = xmm + 1;
+ if (header->xmm) {
+ ignore_mask |= XFEATURE_MASK_SSE;
+ xmm = next_record;
+ /*
+ * Only output XMM regs to user space when arch-PEBS
+ * really writes data into xstate area.
+ */
+ if (xer_header->xstate & XFEATURE_MASK_SSE)
+ perf_regs->xmm_regs = xmm->xmm;
+ next_record = xmm + 1;
+ }
+
+ if (header->ymmh) {
+ ignore_mask |= XFEATURE_MASK_YMM;
+ ymmh = next_record;
+ if (xer_header->xstate & XFEATURE_MASK_YMM)
+ perf_regs->ymmh = ymmh;
+ next_record = ymmh + 1;
+ }
+
+ if (header->egpr) {
+ ignore_mask |= XFEATURE_MASK_APX;
+ egpr = next_record;
+ if (xer_header->xstate & XFEATURE_MASK_APX)
+ perf_regs->egpr = egpr;
+ next_record = egpr + 1;
+ }
+
+ if (header->opmask) {
+ ignore_mask |= XFEATURE_MASK_OPMASK;
+ opmask = next_record;
+ if (xer_header->xstate & XFEATURE_MASK_OPMASK)
+ perf_regs->opmask = opmask;
+ next_record = opmask + 1;
+ }
+
+ if (header->zmmh) {
+ ignore_mask |= XFEATURE_MASK_ZMM_Hi256;
+ zmmh = next_record;
+ if (xer_header->xstate & XFEATURE_MASK_ZMM_Hi256)
+ perf_regs->zmmh = zmmh;
+ next_record = zmmh + 1;
+ }
+
+ if (header->h16zmm) {
+ ignore_mask |= XFEATURE_MASK_Hi16_ZMM;
+ h16zmm = next_record;
+ if (xer_header->xstate & XFEATURE_MASK_Hi16_ZMM)
+ perf_regs->h16zmm = h16zmm;
+ next_record = h16zmm + 1;
+ }
}

if (header->lbr) {
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index e25434d21159..4fe796993c97 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -350,6 +350,13 @@
#define ARCH_PEBS_LBR_SHIFT 40
#define ARCH_PEBS_LBR (0x3ull << ARCH_PEBS_LBR_SHIFT)
#define ARCH_PEBS_VECR_XMM BIT_ULL(49)
+#define ARCH_PEBS_VECR_YMMH BIT_ULL(50)
+#define ARCH_PEBS_VECR_EGPRS BIT_ULL(51)
+#define ARCH_PEBS_VECR_OPMASK BIT_ULL(53)
+#define ARCH_PEBS_VECR_ZMMH BIT_ULL(54)
+#define ARCH_PEBS_VECR_H16ZMM BIT_ULL(55)
+#define ARCH_PEBS_VECR_EXT_SHIFT 50
+#define ARCH_PEBS_VECR_EXT (0x3full << ARCH_PEBS_VECR_EXT_SHIFT)
#define ARCH_PEBS_GPR BIT_ULL(61)
#define ARCH_PEBS_AUX BIT_ULL(62)
#define ARCH_PEBS_EN BIT_ULL(63)
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index 0c6d58e6c98f..db8bba43401c 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -148,6 +148,11 @@
#define PEBS_DATACFG_LBRS BIT_ULL(3)
#define PEBS_DATACFG_CNTR BIT_ULL(4)
#define PEBS_DATACFG_METRICS BIT_ULL(5)
+#define PEBS_DATACFG_YMMHS BIT_ULL(6)
+#define PEBS_DATACFG_OPMASKS BIT_ULL(7)
+#define PEBS_DATACFG_ZMMHS BIT_ULL(8)
+#define PEBS_DATACFG_H16ZMMS BIT_ULL(9)
+#define PEBS_DATACFG_EGPRS BIT_ULL(10)
#define PEBS_DATACFG_LBR_SHIFT 24
#define PEBS_DATACFG_CNTR_SHIFT 32
#define PEBS_DATACFG_CNTR_MASK GENMASK_ULL(15, 0)
@@ -545,7 +550,8 @@ struct arch_pebs_header {
rsvd3:7,
xmm:1,
ymmh:1,
- rsvd4:2,
+ egpr:1,
+ rsvd4:1,
opmask:1,
zmmh:1,
h16zmm:1,
--
2.34.1