xref: /freebsd-src/sys/x86/include/fpu.h (revision b9951017bab396e24042e85632e2cc34ee0329ff)

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * William Jolitz.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Floating Point Data Structures and Constants
 * W. Jolitz 1/90
 */

#ifndef _X86_FPU_H_
#define	_X86_FPU_H_

/* Environment information of floating point unit. */
struct env87 {
	int32_t		en_cw;		/* control word (16bits) */
	int32_t		en_sw;		/* status word (16bits) */
	int32_t		en_tw;		/* tag word (16bits) */
	int32_t		en_fip;		/* fp instruction pointer */
	uint16_t	en_fcs;		/* fp code segment selector */
	uint16_t	en_opcode;	/* opcode last executed (11 bits) */
	int32_t		en_foo;		/* fp operand offset */
	int32_t		en_fos;		/* fp operand segment selector */
};

/* Contents of each x87 floating point accumulator. */
struct fpacc87 {
	uint8_t		fp_bytes[10];
};

/* Floating point context. (i386 fnsave/frstor) */
struct save87 {
	struct env87	sv_env;		/* floating point control/status */
	struct fpacc87	sv_ac[8];	/* accumulator contents, 0-7 */
	uint8_t		sv_pad0[4];	/* saved status word (now unused) */
	uint8_t		sv_pad[64];
};

/* Contents of each SSE extended accumulator. */
struct xmmacc {
	uint8_t		xmm_bytes[16];
};

/* Contents of the upper 16 bytes of each AVX extended accumulator. */
struct ymmacc {
	uint8_t		ymm_bytes[16];
};

/* Rename structs below depending on machine architecture. */
#ifdef __i386__
#define	__envxmm32	envxmm
#else
#define	__envxmm32	envxmm32
#define	__envxmm64	envxmm
#endif

struct __envxmm32 {
	uint16_t	en_cw;		/* control word (16bits) */
	uint16_t	en_sw;		/* status word (16bits) */
	uint16_t	en_tw;		/* tag word (16bits) */
	uint16_t	en_opcode;	/* opcode last executed (11 bits) */
	uint32_t	en_fip;		/* fp instruction pointer */
	uint16_t	en_fcs;		/* fp code segment selector */
	uint16_t	en_pad0;	/* padding */
	uint32_t	en_foo;		/* fp operand offset */
	uint16_t	en_fos;		/* fp operand segment selector */
	uint16_t	en_pad1;	/* padding */
	uint32_t	en_mxcsr;	/* SSE control/status register */
	uint32_t	en_mxcsr_mask;	/* valid bits in mxcsr */
};

struct __envxmm64 {
	uint16_t	en_cw;		/* control word (16bits) */
	uint16_t	en_sw;		/* status word (16bits) */
	uint8_t		en_tw;		/* tag word (8bits) */
	uint8_t		en_zero;
	uint16_t	en_opcode;	/* opcode last executed (11 bits ) */
	uint64_t	en_rip;		/* fp instruction pointer */
	uint64_t	en_rdp;		/* fp operand pointer */
	uint32_t	en_mxcsr;	/* SSE control/status register */
	uint32_t	en_mxcsr_mask;	/* valid bits in mxcsr */
};

/* Floating point context. (i386 fxsave/fxrstor) */
struct savexmm {
	struct __envxmm32	sv_env;
	struct {
		struct fpacc87	fp_acc;
		uint8_t		fp_pad[6];      /* padding */
	} sv_fp[8];
	struct xmmacc		sv_xmm[8];
	uint8_t			sv_pad[224];
} __aligned(16);

#ifdef __i386__
union savefpu {
	struct save87	sv_87;
	struct savexmm	sv_xmm;
};
#else
/* Floating point context. (amd64 fxsave/fxrstor) */
struct savefpu {
	struct __envxmm64	sv_env;
	struct {
		struct fpacc87	fp_acc;
		uint8_t		fp_pad[6];	/* padding */
	} sv_fp[8];
	struct xmmacc		sv_xmm[16];
	uint8_t			sv_pad[96];
} __aligned(16);
#endif

struct xstate_hdr {
	uint64_t	xstate_bv;
	uint64_t	xstate_xcomp_bv;
	uint8_t		xstate_rsrv0[8];
	uint8_t		xstate_rsrv[40];
};
#define	XSTATE_XCOMP_BV_COMPACT	(1ULL << 63)

struct savexmm_xstate {
	struct xstate_hdr	sx_hd;
	struct ymmacc		sx_ymm[16];
};

struct savexmm_ymm {
	struct __envxmm32	sv_env;
	struct {
		struct fpacc87	fp_acc;
		int8_t		fp_pad[6];	/* padding */
	} sv_fp[8];
	struct xmmacc		sv_xmm[16];
	uint8_t			sv_pad[96];
	struct savexmm_xstate	sv_xstate;
} __aligned(64);

struct savefpu_xstate {
	struct xstate_hdr	sx_hd;
	struct ymmacc		sx_ymm[16];
};

struct savefpu_ymm {
	struct __envxmm64	sv_env;
	struct {
		struct fpacc87	fp_acc;
		int8_t		fp_pad[6];	/* padding */
	} sv_fp[8];
	struct xmmacc		sv_xmm[16];
	uint8_t			sv_pad[96];
	struct savefpu_xstate	sv_xstate;
} __aligned(64);

#undef __envxmm32
#undef __envxmm64

/*
 * The hardware default control word for i387's and later coprocessors is
 * 0x37F, giving:
 *
 *	round to nearest
 *	64-bit precision
 *	all exceptions masked.
 *
 * FreeBSD/i386 uses 53 bit precision for things like fadd/fsub/fsqrt etc
 * because of the difference between memory and fpu register stack arguments.
 * If its using an intermediate fpu register, it has 80/64 bits to work
 * with.  If it uses memory, it has 64/53 bits to work with.  However,
 * gcc is aware of this and goes to a fair bit of trouble to make the
 * best use of it.
 *
 * This is mostly academic for AMD64, because the ABI prefers the use
 * SSE2 based math.  For FreeBSD/amd64, we go with the default settings.
 */
#define	__INITIAL_FPUCW__	0x037F
#define	__INITIAL_FPUCW_I386__	0x127F
#define	__INITIAL_NPXCW__	__INITIAL_FPUCW_I386__
#define	__INITIAL_MXCSR__	0x1F80
#define	__INITIAL_MXCSR_MASK__	0xFFBF

/*
 * The current value of %xcr0 is saved in the sv_pad[] field of the FPU
 * state in the NT_X86_XSTATE note in core dumps.  This offset is chosen
 * to match the offset used by NT_X86_XSTATE in other systems.
 */
#define	X86_XSTATE_XCR0_OFFSET	464

#ifdef _KERNEL
/*
 * CR0_MP and CR0_EM are always set.  Use CR0_TS to force traps when
 * FPU access is disabled.
 */
#define	fpu_enable()	clts()
#define	fpu_disable()	load_cr0(rcr0() | CR0_TS)

bool	xsave_extfeature_supported(uint64_t feature, bool supervisor);
bool	xsave_extension_supported(uint64_t extension);
size_t	xsave_area_hdr_offset(void);
size_t	xsave_area_offset(uint64_t xstate_bv, uint64_t feature, bool compact,
    bool supervisor);
size_t	xsave_area_size(uint64_t xstate_bv, bool compact, bool supervisor);
#endif

#endif /* !_X86_FPU_H_ */