[Patch v9 19/24] perf/x86: Support eGPRs sampling using sample_regs_* fields

[Dapeng Mi <dapeng1.mi@linux.intel.com>]

Support sampling of APX eGPRs (R16 ~ R31) via the sample_regs_* fields.

To sample eGPRs, the sample_simd_regs_enabled field must be set. This
allows the spare space (reclaimed from the original XMM space) in the
sample_regs_* fields to be used for representing eGPRs.

The perf_reg_value() function needs to check if the
PERF_SAMPLE_REGS_ABI_SIMD flag is set first, and then determine whether
to output eGPRs or legacy XMM registers to userspace.

The perf_reg_validate() function first checks the simd_enabled argument
to determine if the eGPRs bitmap is represented in sample_regs_* fields.
It then validates the eGPRs bitmap accordingly.

Currently, eGPRs sampling is only supported on the x86_64 architecture, as
APX is only available on x86_64 platforms.

APX eGPRs sampling will be enabled in a subsequent patch that sets
PERF_PMU_CAP_SIMD_REGS.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Co-developed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
---
 arch/x86/events/core.c                | 39 +++++++++++++++------
 arch/x86/events/intel/core.c          |  4 ++-
 arch/x86/events/perf_event.h          | 16 +++++++++
 arch/x86/include/asm/perf_event.h     |  4 +++
 arch/x86/include/uapi/asm/perf_regs.h | 26 ++++++++++++++
 arch/x86/kernel/perf_regs.c           | 50 +++++++++++++++++----------
 6 files changed, 109 insertions(+), 30 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index de07747e939e..f4f1f80ed6f4 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -708,20 +708,23 @@ int x86_pmu_hw_config(struct perf_event *event)
 	}
 
 	if (event->attr.sample_type & (PERF_SAMPLE_REGS_INTR | PERF_SAMPLE_REGS_USER)) {
-		/*
-		 * Besides the general purpose registers, XMM registers may
-		 * be collected as well.
-		 */
-		if (event_has_extended_regs(event)) {
-			if (!(event->pmu->capabilities & PERF_PMU_CAP_EXTENDED_REGS))
-				return -EINVAL;
-			if (event->attr.sample_simd_regs_enabled)
-				return -EINVAL;
-		}
-
 		if (event_has_simd_regs(event)) {
+			u64 reserved = ~GENMASK_ULL(PERF_REG_MISC_MAX - 1, 0);
+
 			if (!(event->pmu->capabilities & PERF_PMU_CAP_SIMD_REGS))
 				return -EINVAL;
+			/*
+			 * The XMM space in the perf_event_x86_regs is reclaimed
+			 * for eGPRs and other general registers.
+			 */
+			if (((event->attr.sample_type & PERF_SAMPLE_REGS_INTR) &&
+			     (event->attr.sample_regs_intr & reserved)) ||
+			    ((event->attr.sample_type & PERF_SAMPLE_REGS_USER) &&
+			     (event->attr.sample_regs_user & reserved)))
+				return -EINVAL;
+			if (event_needs_egprs(event) &&
+			    !(x86_pmu.ext_regs_mask & XFEATURE_MASK_APX))
+				return -EINVAL;
 			/* The vector registers set is not supported */
 			if (event_needs_xmm(event) &&
 			    !(x86_pmu.ext_regs_mask & XFEATURE_MASK_SSE))
@@ -738,6 +741,15 @@ int x86_pmu_hw_config(struct perf_event *event)
 			if (event_needs_opmask(event) &&
 			    !(x86_pmu.ext_regs_mask & XFEATURE_MASK_OPMASK))
 				return -EINVAL;
+		} else {
+			/*
+			 * Besides the general purpose registers, XMM registers may
+			 * be collected as well.
+			 */
+			if (event_has_extended_regs(event)) {
+				if (!(event->pmu->capabilities & PERF_PMU_CAP_EXTENDED_REGS))
+					return -EINVAL;
+			}
 		}
 	}
 
@@ -1786,6 +1798,7 @@ void x86_pmu_clear_perf_regs(struct pt_regs *regs)
 	perf_regs->zmmh_regs = NULL;
 	perf_regs->h16zmm_regs = NULL;
 	perf_regs->opmask_regs = NULL;
+	perf_regs->egpr_regs = NULL;
 }
 
 static void update_perf_regs(struct x86_perf_regs *perf_regs,
@@ -1809,6 +1822,8 @@ static void update_perf_regs(struct x86_perf_regs *perf_regs,
 		perf_regs->h16zmm = get_xsave_addr(xsave, XFEATURE_Hi16_ZMM);
 	if (mask & XFEATURE_MASK_OPMASK)
 		perf_regs->opmask = get_xsave_addr(xsave, XFEATURE_OPMASK);
+	if (mask & XFEATURE_MASK_APX)
+		perf_regs->egpr = get_xsave_addr(xsave, XFEATURE_APX);
 }
 
 /*
@@ -2008,6 +2023,8 @@ static void x86_pmu_sample_xregs(struct perf_event *event,
 		mask |= XFEATURE_MASK_Hi16_ZMM;
 	if (event_needs_opmask(event))
 		mask |= XFEATURE_MASK_OPMASK;
+	if (event_needs_egprs(event))
+		mask |= XFEATURE_MASK_APX;
 
 	mask &= x86_pmu.ext_regs_mask;
 	if ((sample_type & PERF_SAMPLE_REGS_USER) && data->regs_user.regs) {
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 69294bc57225..cfe5478aa5a4 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4697,7 +4697,9 @@ static void intel_pebs_aliases_skl(struct perf_event *event)
 static unsigned long intel_pmu_large_pebs_flags(struct perf_event *event)
 {
 	unsigned long flags = x86_pmu.large_pebs_flags;
-	u64 gprs_mask = PEBS_GP_REGS | PERF_REG_EXTENDED_MASK;
+	u64 gprs_mask = event->attr.sample_simd_regs_enabled ?
+			PEBS_GP_REGS :
+			PEBS_GP_REGS | PERF_REG_EXTENDED_MASK;
 
 	if (event->attr.use_clockid)
 		flags &= ~PERF_SAMPLE_TIME;
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index f15dc414c57a..840ef8a44b52 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -222,6 +222,22 @@ static inline bool event_needs_opmask(struct perf_event *event)
 	return false;
 }
 
+static inline bool event_needs_egprs(struct perf_event *event)
+{
+	if (!event->attr.sample_simd_regs_enabled)
+		return false;
+
+	if ((event->attr.sample_type & PERF_SAMPLE_REGS_USER) &&
+	    (event->attr.sample_regs_user & PERF_X86_EGPRS_MASK))
+		return true;
+
+	if ((event->attr.sample_type & PERF_SAMPLE_REGS_INTR) &&
+	    (event->attr.sample_regs_intr & PERF_X86_EGPRS_MASK))
+		return true;
+
+	return false;
+}
+
 struct amd_nb {
 	int nb_id;  /* NorthBridge id */
 	int refcnt; /* reference count */
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index 49112e097e99..bc05f8c17464 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -749,6 +749,10 @@ struct x86_perf_regs {
 		u64	*opmask_regs;
 		struct avx_512_opmask_state *opmask;
 	};
+	union {
+		u64	*egpr_regs;
+		struct apx_state *egpr;
+	};
 };
 
 extern unsigned long perf_arch_instruction_pointer(struct pt_regs *regs);
diff --git a/arch/x86/include/uapi/asm/perf_regs.h b/arch/x86/include/uapi/asm/perf_regs.h
index 61aec60623f1..977831bd7a9d 100644
--- a/arch/x86/include/uapi/asm/perf_regs.h
+++ b/arch/x86/include/uapi/asm/perf_regs.h
@@ -29,9 +29,34 @@ enum perf_event_x86_regs {
 	PERF_REG_X86_R13,
 	PERF_REG_X86_R14,
 	PERF_REG_X86_R15,
+	/*
+	 * The eGPRs and XMM have overlaps. Only one can be used
+	 * at a time. The ABI PERF_SAMPLE_REGS_ABI_SIMD is used to
+	 * distinguish which one is used. If PERF_SAMPLE_REGS_ABI_SIMD
+	 * is set, then eGPRs is used, otherwise, XMM is used.
+	 *
+	 * Extended GPRs (eGPRs)
+	 */
+	PERF_REG_X86_R16,
+	PERF_REG_X86_R17,
+	PERF_REG_X86_R18,
+	PERF_REG_X86_R19,
+	PERF_REG_X86_R20,
+	PERF_REG_X86_R21,
+	PERF_REG_X86_R22,
+	PERF_REG_X86_R23,
+	PERF_REG_X86_R24,
+	PERF_REG_X86_R25,
+	PERF_REG_X86_R26,
+	PERF_REG_X86_R27,
+	PERF_REG_X86_R28,
+	PERF_REG_X86_R29,
+	PERF_REG_X86_R30,
+	PERF_REG_X86_R31,
 	/* These are the limits for the GPRs. */
 	PERF_REG_X86_32_MAX = PERF_REG_X86_GS + 1,
 	PERF_REG_X86_64_MAX = PERF_REG_X86_R15 + 1,
+	PERF_REG_MISC_MAX = PERF_REG_X86_R31 + 1,
 
 	/* These all need two bits set because they are 128bit */
 	PERF_REG_X86_XMM0  = 32,
@@ -56,6 +81,7 @@ enum perf_event_x86_regs {
 };
 
 #define PERF_REG_EXTENDED_MASK	(~((1ULL << PERF_REG_X86_XMM0) - 1))
+#define PERF_X86_EGPRS_MASK	__GENMASK_ULL(PERF_REG_X86_R31, PERF_REG_X86_R16)
 
 enum {
 	PERF_X86_SIMD_XMM_REGS      = 16,
diff --git a/arch/x86/kernel/perf_regs.c b/arch/x86/kernel/perf_regs.c
index 9576e4e9cbcb..b6f75196da02 100644
--- a/arch/x86/kernel/perf_regs.c
+++ b/arch/x86/kernel/perf_regs.c
@@ -61,14 +61,24 @@ u64 perf_reg_value(struct pt_regs *regs, int idx)
 {
 	struct x86_perf_regs *perf_regs;
 
-	if (idx >= PERF_REG_X86_XMM0 && idx < PERF_REG_X86_XMM_MAX) {
+	if (idx > PERF_REG_X86_R15) {
 		perf_regs = container_of(regs, struct x86_perf_regs, regs);
-		/* SIMD registers are moved to dedicated sample_simd_vec_reg */
-		if (perf_regs->abi & PERF_SAMPLE_REGS_ABI_SIMD)
+		if (perf_regs->abi == PERF_SAMPLE_REGS_ABI_NONE)
 			return 0;
-		if (!perf_regs->xmm_regs)
-			return 0;
-		return perf_regs->xmm_regs[idx - PERF_REG_X86_XMM0];
+
+		if (perf_regs->abi & PERF_SAMPLE_REGS_ABI_SIMD) {
+			if (idx <= PERF_REG_X86_R31) {
+				if (!perf_regs->egpr_regs)
+					return 0;
+				return perf_regs->egpr_regs[idx - PERF_REG_X86_R16];
+			}
+		} else {
+			if (idx >= PERF_REG_X86_XMM0 && idx < PERF_REG_X86_XMM_MAX) {
+				if (!perf_regs->xmm_regs)
+					return 0;
+				return perf_regs->xmm_regs[idx - PERF_REG_X86_XMM0];
+			}
+		}
 	}
 
 	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(pt_regs_offset)))
@@ -186,23 +196,22 @@ int perf_simd_reg_validate(u64 sample_type, u16 simd_enabled,
 	return 0;
 }
 
-#define PERF_REG_X86_RESERVED	(((1ULL << PERF_REG_X86_XMM0) - 1) & \
-				 ~((1ULL << PERF_REG_X86_MAX) - 1))
+#define PERF_REG_X86_RESERVED	(GENMASK_ULL(PERF_REG_X86_XMM0 - 1, PERF_REG_X86_AX) & \
+				 ~GENMASK_ULL(PERF_REG_X86_R15, PERF_REG_X86_AX))
+#define PERF_REG_X86_EXT_RESERVED	(~GENMASK_ULL(PERF_REG_MISC_MAX - 1, PERF_REG_X86_AX))
 
 #ifdef CONFIG_X86_32
-#define REG_NOSUPPORT ((1ULL << PERF_REG_X86_R8) | \
-		       (1ULL << PERF_REG_X86_R9) | \
-		       (1ULL << PERF_REG_X86_R10) | \
-		       (1ULL << PERF_REG_X86_R11) | \
-		       (1ULL << PERF_REG_X86_R12) | \
-		       (1ULL << PERF_REG_X86_R13) | \
-		       (1ULL << PERF_REG_X86_R14) | \
-		       (1ULL << PERF_REG_X86_R15))
+#define REG_NOSUPPORT GENMASK_ULL(PERF_REG_X86_R15, PERF_REG_X86_R8)
 
 int perf_reg_validate(u64 mask, bool simd_enabled)
 {
+	if (!simd_enabled &&
+	    (!mask || (mask & (REG_NOSUPPORT | PERF_REG_X86_RESERVED))))
+		return -EINVAL;
+
 	/* The mask could be 0 if only the SIMD registers are interested */
-	if (mask & (REG_NOSUPPORT | PERF_REG_X86_RESERVED))
+	if (simd_enabled &&
+	    (mask & ~GENMASK_ULL(PERF_REG_X86_GS, PERF_REG_X86_AX)))
 		return -EINVAL;
 
 	return 0;
@@ -221,8 +230,13 @@ u64 perf_reg_abi(struct task_struct *task)
 
 int perf_reg_validate(u64 mask, bool simd_enabled)
 {
+	if (!simd_enabled &&
+	    (!mask || (mask & (REG_NOSUPPORT | PERF_REG_X86_RESERVED))))
+		return -EINVAL;
+
 	/* The mask could be 0 if only the SIMD registers are interested */
-	if (mask & (REG_NOSUPPORT | PERF_REG_X86_RESERVED))
+	if (simd_enabled &&
+	    (mask & (REG_NOSUPPORT | PERF_REG_X86_EXT_RESERVED)))
 		return -EINVAL;
 
 	return 0;
-- 
2.34.1