x86: Add XSAVE support

* i386/i386/fpu.h (CPU_XCR0_X87, CPU_XCR0_SSE, CPU_XCR0_AVX,
CPU_XCR0_MPX, CPU_XCR0_AVX512): New macros.
(xsave): Pass fp_xsave_support to xsave.
(fpu_save_context): When fp_kind is FP_387X, use xsave.
(fp_xsave_support): New variable declaration.
* i386/i386/proc_reg.h (cpuid): New macro.
* linux/src/include/asm-i386/processor.h (cpuid): Disable macro.
* i386/include/mach/i386/fp_reg.h: Include <stdint.h>
(i386_xfp_xstate_header): New structure.
(i386_xfp_save): Add xsave fields.
* i386/i386/fpu.c (fp_xsave_support): New variable.
(init_fpu): Look for XSAVE feature; if available, get the supported
parts and set fp_kind to FP_387X.
(fpu_module_init): Set ifps_cache alignment to alignof(struct
i386_fpsave_state).
(fpu_set_state): Make sure to clear all the ifps structure.
Reuse the FP_387FX for the FP_387X case.
(fpu_get_state, fpexterrflt, fpastintr, fp_state_alloc): Reuse the FP_387FX
for the FP_387X case.
(fp_save): When fp_kind is FP_387X, use xsave.
(fp_load): When fp_kind is FP_387X, use xrstor.
Reuse the FP_387FX for the FP_387X case.

4 files changed, 122 insertions, 27 deletions

diff --git a/i386/i386/fpu.c b/i386/i386/fpu.c
index 5cbfcb2f..517764d6 100644
--- a/i386/i386/fpu.c
+++ b/i386/i386/fpu.c
@@ -70,6 +70,7 @@
 #endif
 
 int		fp_kind = FP_387;	/* 80387 present */
+uint64_t	fp_xsave_support;	/* Bitmap of supported XSAVE save areas */
 struct kmem_cache	ifps_cache;	/* cache for FPU save area */
 static unsigned long	mxcsr_feature_mask = 0xffffffff;	/* Always AND user-provided mxcsr with this security mask */
 
@@ -148,21 +149,58 @@ init_fpu(void)
 		/*
 		 * We have a 387.
 		 */
-		if (CPU_HAS_FEATURE(CPU_FEATURE_FXSR)) {
-		    static /* because we _need_ alignment */
-		    struct i386_xfp_save save;
-		    unsigned long mask;
-		    fp_kind = FP_387FX;
+		fp_kind = FP_387;
+
+		if (CPU_HAS_FEATURE(CPU_FEATURE_XSAVE)) {
+		    unsigned eax, ebx, ecx, edx;
+
+		    eax = 0xd;
+		    ecx = 0x0;
+		    cpuid(eax, ebx, ecx, edx);
+
+		    fp_xsave_support = eax + (((uint64_t) edx) << 32);
+		    fp_xsave_support &= CPU_XCR0_SUPPORTED;
+#ifndef MACH_RING1
+		    set_cr4(get_cr4() | CR4_OSFXSR | CR4_OSXSAVE);
+		    set_xcr0(fp_xsave_support);
+#endif /* MACH_RING1 */
+
+		    eax = 0xd;
+		    ecx = 0x0;
+		    cpuid(eax, ebx, ecx, edx);
+
+		    if (ebx > sizeof(struct i386_xfp_save)) {
+			    /* TODO: rather make struct unbound and set size
+			     * in fpu_module_init */
+			    printf("XSAVE area size %u larger than provisioned "
+				   "%u, not enabling XSAVE\n",
+				   ebx, sizeof(struct i386_xfp_save));
+#ifndef MACH_RING1
+			    set_cr4(get_cr4() & ~(CR4_OSFXSR | CR4_OSXSAVE));
+#endif /* MACH_RING1 */
+		    } else {
+			    fp_kind = FP_387X;
+		    }
+		}
+
+		if (fp_kind == FP_387 && CPU_HAS_FEATURE(CPU_FEATURE_FXSR)) {
 #ifndef MACH_RING1
 		    set_cr4(get_cr4() | CR4_OSFXSR);
 #endif /* MACH_RING1 */
+		    fp_kind = FP_387FX;
+		}
+
+		if (fp_kind == FP_387X || fp_kind == FP_387FX) {
+		    /* Compute mxcsr_feature_mask.  */
+		    static /* because we _need_ alignment */
+		    struct i386_xfp_save save;
+		    unsigned long mask;
 		    fxsave(&save);
 		    mask = save.fp_mxcsr_mask;
 		    if (!mask)
 			mask = 0x0000ffbf;
 		    mxcsr_feature_mask &= mask;
-		} else
-		    fp_kind = FP_387;
+		}
 	    }
 #ifdef MACH_RING1
 	    set_ts();
@@ -188,7 +226,8 @@ void
 fpu_module_init(void)
 {
 	kmem_cache_init(&ifps_cache, "i386_fpsave_state",
-			sizeof(struct i386_fpsave_state), 16,
+			sizeof(struct i386_fpsave_state),
+			alignof(struct i386_fpsave_state),
 			NULL, 0);
 }
 
@@ -359,9 +398,9 @@ ASSERT_IPL(SPL0);
 	    /*
 	     * Ensure that reserved parts of the environment are 0.
 	     */
-	    memset(&ifps->fp_save_state, 0, sizeof(struct i386_fp_save));
+	    memset(ifps, 0, sizeof(*ifps));
 
-	    if (fp_kind == FP_387FX) {
+	    if (fp_kind == FP_387X || fp_kind == FP_387FX) {
 		int i;
 
 		ifps->xfp_save_state.fp_control = user_fp_state->fp_control;
@@ -454,7 +493,7 @@ ASSERT_IPL(SPL0);
 	     */
 	    memset(user_fp_state,  0, sizeof(struct i386_fp_save));
 
-	    if (fp_kind == FP_387FX) {
+	    if (fp_kind == FP_387X || fp_kind == FP_387FX) {
 		int i;
 
 		user_fp_state->fp_control = ifps->xfp_save_state.fp_control;
@@ -697,7 +736,7 @@ fpexterrflt(void)
 	 */
 	i386_exception(EXC_ARITHMETIC,
 		       EXC_I386_EXTERR,
-		       fp_kind == FP_387FX ?
+		       fp_kind == FP_387X || fp_kind == FP_387FX ?
 		           thread->pcb->ims.ifps->xfp_save_state.fp_status :
 		           thread->pcb->ims.ifps->fp_save_state.fp_status);
 	/*NOTREACHED*/
@@ -755,7 +794,7 @@ ASSERT_IPL(SPL0);
 	 */
 	i386_exception(EXC_ARITHMETIC,
 		       EXC_I386_EXTERR,
-		       fp_kind == FP_387FX ?
+		       fp_kind == FP_387X || fp_kind == FP_387FX ?
 		           thread->pcb->ims.ifps->xfp_save_state.fp_status :
 		           thread->pcb->ims.ifps->fp_save_state.fp_status);
 	/*NOTREACHED*/
@@ -779,10 +818,12 @@ fp_save(thread_t thread)
 	if (ifps != 0 && !ifps->fp_valid) {
 	    /* registers are in FPU */
 	    ifps->fp_valid = TRUE;
-	    if (fp_kind == FP_387FX)
-	    	fxsave(&ifps->xfp_save_state);
+	    if (fp_kind == FP_387X)
+		xsave(&ifps->xfp_save_state);
+	    else if (fp_kind == FP_387FX)
+		fxsave(&ifps->xfp_save_state);
 	    else
-	    	fnsave(&ifps->fp_save_state);
+		fnsave(&ifps->fp_save_state);
 	}
 }
 
@@ -822,7 +863,7 @@ ASSERT_IPL(SPL0);
 		 */
 		i386_exception(EXC_ARITHMETIC,
 			       EXC_I386_EXTERR,
-			       fp_kind == FP_387FX ?
+			       fp_kind == FP_387X || fp_kind == FP_387FX ?
 			           thread->pcb->ims.ifps->xfp_save_state.fp_status :
 			           thread->pcb->ims.ifps->fp_save_state.fp_status);
 		/*NOTREACHED*/
@@ -831,7 +872,9 @@ ASSERT_IPL(SPL0);
 		printf("fp_load: invalid FPU state!\n");
 		fninit ();
 	} else {
-	    if (fp_kind == FP_387FX)
+	    if (fp_kind == FP_387X)
+		xrstor(ifps->xfp_save_state);
+	    else if (fp_kind == FP_387FX)
 		fxrstor(ifps->xfp_save_state);
 	    else
 		frstor(ifps->fp_save_state);
@@ -857,7 +900,7 @@ fp_state_alloc(void)
 
 	ifps->fp_valid = TRUE;
 
-	if (fp_kind == FP_387FX) {
+	if (fp_kind == FP_387X || fp_kind == FP_387FX) {
 		ifps->xfp_save_state.fp_control = (0x037f
 				& ~(FPC_IM|FPC_ZM|FPC_OM|FPC_PC))
 				| (FPC_PC_64|FPC_IC_AFF);
diff --git a/i386/i386/fpu.h b/i386/i386/fpu.h
index 3c5b73c5..dc503606 100644
--- a/i386/i386/fpu.h
+++ b/i386/i386/fpu.h
@@ -96,8 +96,20 @@ static inline void set_xcr0(uint64_t value) {
 	xsetbv(0, value);
 }
 
+#define CPU_XCR0_X87	(1 << 0)
+#define CPU_XCR0_SSE	(1 << 1)
+#define CPU_XCR0_AVX	(1 << 2)
+#define CPU_XCR0_MPX	(3 << 3)
+#define CPU_XCR0_AVX512	(7 << 5)
+
+/* This is the set we support for now in our struct i386_xfp_save */
+#define CPU_XCR0_SUPPORTED (CPU_XCR0_X87 | CPU_XCR0_SSE | CPU_XCR0_AVX)
+
 #define	xsave(state) \
-	asm volatile("xsave %0" : "=m" (*state))
+	asm volatile("xsave %0" \
+			: "=m" (*state) \
+			: "a" ((unsigned) fp_xsave_support) \
+			, "d" ((unsigned) (fp_xsave_support >> 32))) \
 
 #define	xrstor(state) \
 	asm volatile("xrstor %0" : : "m" (state))
@@ -121,7 +133,9 @@ static inline void set_xcr0(uint64_t value) {
 	if (ifps != 0 && !ifps->fp_valid) { \
 	    /* registers are in FPU - save to memory */ \
 	    ifps->fp_valid = TRUE; \
-	    if (fp_kind == FP_387FX) \
+	    if (fp_kind == FP_387X) \
+		xsave(&ifps->xfp_save_state); \
+	    else if (fp_kind == FP_387FX) \
 		fxsave(&ifps->xfp_save_state); \
 	    else \
 		fnsave(&ifps->fp_save_state); \
@@ -138,6 +152,7 @@ static inline void set_xcr0(uint64_t value) {
 #endif	/* NCPUS == 1 */
 
 extern int	fp_kind;
+extern uint64_t	fp_xsave_support;
 extern void fp_save(thread_t thread);
 extern void fp_load(thread_t thread);
 extern void fp_free(struct i386_fpsave_state *fps);
diff --git a/i386/i386/proc_reg.h b/i386/i386/proc_reg.h
index 624819c6..a83ca0d8 100644
--- a/i386/i386/proc_reg.h
+++ b/i386/i386/proc_reg.h
@@ -379,6 +379,28 @@ extern unsigned long cr3;
     })
 #endif
 
+/* Note: gcc might want to use bx or the stack for %1 addressing, so we can't
+ * use them :/ */
+#ifdef __x86_64__
+#define cpuid(eax, ebx, ecx, edx) \
+{ \
+	uint64_t sav_rbx; \
+	asm(	"mov %%rbx,%2\n\t" \
+		"cpuid\n\t" \
+		"xchg %2,%%rbx\n\t" \
+		"movl %k2,%1\n\t" \
+		: "+a" (eax), "=m" (ebx), "=&r" (sav_rbx), "+c" (ecx), "=&d" (edx)); \
+}
+#else
+#define cpuid(eax, ebx, ecx, edx) \
+{ \
+	asm (	"mov %%ebx,%1\n\t" \
+		"cpuid\n\t" \
+		"xchg %%ebx,%1\n\t" \
+		: "+a" (eax), "=&SD" (ebx), "+c" (ecx), "=&d" (edx)); \
+}
+#endif
+
 #endif	/* __GNUC__ */
 #endif	/* __ASSEMBLER__ */
 
diff --git a/i386/include/mach/i386/fp_reg.h b/i386/include/mach/i386/fp_reg.h
index 648511ad..5992ea78 100644
--- a/i386/include/mach/i386/fp_reg.h
+++ b/i386/include/mach/i386/fp_reg.h
@@ -26,6 +26,9 @@
 
 #ifndef	_MACH_I386_FP_REG_H_
 #define	_MACH_I386_FP_REG_H_
+
+#include <stdint.h>
+
 /*
  *	Floating point registers and status, as saved
  *	and restored by FP save/restore instructions.
@@ -50,17 +53,24 @@ struct i386_fp_regs {
 					/* space for 8 80-bit FP registers */
 };
 
+struct i386_xfp_xstate_header {
+	uint64_t	xfp_features;
+	uint64_t	xcomp_bv;
+	uint64_t	reserved[6];
+} __attribute__((packed, aligned(64)));
+_Static_assert(sizeof(struct i386_xfp_xstate_header) == 8*8);
+
 struct i386_xfp_save {
 	unsigned short	fp_control;	/* control */
 	unsigned short	fp_status;	/* status */
 	unsigned short	fp_tag;		/* register tags */
 	unsigned short	fp_opcode;	/* opcode of failed instruction */
 	unsigned int	fp_eip;		/* eip at failed instruction */
-	unsigned short	fp_cs;		/* cs at failed instruction */
-	unsigned short	fp_unused_1;
+	unsigned short	fp_cs;		/* cs at failed instruction / eip high */
+	unsigned short	fp_eip3;	/* eip higher */
 	unsigned int	fp_dp;		/* data address */
-	unsigned short	fp_ds;		/* data segment */
-	unsigned short	fp_unused_2;
+	unsigned short	fp_ds;		/* data segment / dp high */
+	unsigned short	fp_dp3;		/* dp higher */
 	unsigned int	fp_mxcsr;	/* MXCSR */
 	unsigned int	fp_mxcsr_mask;	/* MXCSR_MASK */
 	unsigned char	fp_reg_word[8][16];
@@ -68,8 +78,13 @@ struct i386_xfp_save {
 	unsigned char	fp_xreg_word[16][16];
 					/* space for 16 128-bit XMM registers */
 	unsigned int	padding[24];
-} __attribute__((aligned(16)));
-_Static_assert(sizeof(struct i386_xfp_save) == 512);
+	struct i386_xfp_xstate_header header;
+
+	unsigned char	fp_yreg_word[16][16];
+					/* space for the high part of the
+					 * 16 256-bit YMM registers */
+} __attribute__((packed, aligned(64)));
+_Static_assert(sizeof(struct i386_xfp_save) == 512 + 8*8 + 16*16);
 
 /*
  * Control register