/*      $OpenBSD: fpu.h,v 1.20 2024/04/14 09:59:04 kettenis Exp $       */
/*      $NetBSD: fpu.h,v 1.1 2003/04/26 18:39:40 fvdl Exp $     */

#ifndef _MACHINE_FPU_H_
#define _MACHINE_FPU_H_

#include <sys/types.h>

/*
 * If the CPU supports xsave/xrstor then we use them so that we can provide
 * AVX support.  Otherwise we require fxsave/fxrstor, as the SSE registers
 * are part of the ABI for passing floating point values.
 * While fxsave/fxrstor only required 16-byte alignment for the save area,
 * xsave/xrstor requires the save area to have 64-byte alignment.
 */

struct fxsave64 {
        u_int16_t  fx_fcw;
        u_int16_t  fx_fsw;
        u_int8_t   fx_ftw;
        u_int8_t   fx_unused1;
        u_int16_t  fx_fop;
        u_int64_t  fx_rip;
        u_int64_t  fx_rdp;
        u_int32_t  fx_mxcsr;
        u_int32_t  fx_mxcsr_mask;
        u_int64_t  fx_st[8][2];   /* 8 normal FP regs */
        u_int64_t  fx_xmm[16][2]; /* 16 SSE2 registers */
        u_int8_t   fx_unused3[96];
} __packed;

struct xstate_hdr {
        uint64_t        xstate_bv;
        uint64_t        xstate_xcomp_bv;
        uint8_t         xstate_rsrv0[8];
        uint8_t         xstate_rsrv[40];
} __packed;

struct savefpu {
        struct fxsave64 fp_fxsave;      /* see above */
        struct xstate_hdr fp_xstate;
        u_int64_t fp_ymm[16][2];
        u_int8_t fp_components[1856];   /* enough for AVX-512 */
};

/*
 * The i387 defaults to Intel extended precision mode and round to nearest,
 * with all exceptions masked.
 */
#define __INITIAL_NPXCW__       0x037f
#define __INITIAL_MXCSR__       0x1f80
#define __INITIAL_MXCSR_MASK__  0xffbf

#ifdef _KERNEL
/*
 * XXX
 */
struct trapframe;
struct cpu_info;

extern size_t   fpu_save_len;
extern uint32_t fpu_mxcsr_mask;
extern uint64_t xsave_mask;
extern int cpu_use_xsaves;

void fpuinit(struct cpu_info *);
int fputrap(int _type);
void fpusave(struct savefpu *);
void fpusavereset(struct savefpu *);
void fpu_kernel_enter(void);
void fpu_kernel_exit(void);

/* pointer to fxsave/xsave/xsaves data with everything reset */
#define fpu_cleandata   (&proc0.p_addr->u_pcb.pcb_savefpu)

int     xrstor_user(struct savefpu *_addr, uint64_t _mask);
void    xrstor_kern(struct savefpu *_addr, uint64_t _mask);
#define fpureset() \
        xrstor_kern(fpu_cleandata, xsave_mask)
int     xsetbv_user(uint32_t _reg, uint64_t _mask);

#define fninit()                __asm("fninit")
#define fwait()                 __asm("fwait")
/* should be fxsave64, but where we use this it doesn't matter */
#define fxsave(addr)            __asm("fxsave %0" : "=m" (*addr))
#define ldmxcsr(addr)           __asm("ldmxcsr %0" : : "m" (*addr))
#define fldcw(addr)             __asm("fldcw %0" : : "m" (*addr))

static inline void
xsave(struct savefpu *addr, uint64_t mask)
{
        uint32_t lo, hi;

        lo = mask;
        hi = mask >> 32;
        __asm volatile("xsave64 %0" : "+m" (*addr) : "a" (lo), "d" (hi));
}

static inline void
xrstors(const struct savefpu *addr, uint64_t mask)
{
        uint32_t lo, hi;

        lo = mask;
        hi = mask >> 32;
        __asm volatile("xrstors64 %0" : : "m" (*addr), "a" (lo), "d" (hi));
}

#endif

#endif /* _MACHINE_FPU_H_ */