// SPDX-License-Identifier: GPL-2.0
/*
 * Save/restore floating point context for signal handlers.
 *
 * Copyright (C) 1999, 2000  Kaz Kojima & Niibe Yutaka
 * Copyright (C) 2006  ST Microelectronics Ltd. (denorm support)
 *
 * FIXME! These routines have not been tested for big endian case.
 */
#include <linux/sched/signal.h>
#include <linux/io.h>
#include <cpu/fpu.h>
#include <asm/processor.h>
#include <asm/fpu.h>
#include <asm/traps.h>

/* The PR (precision) bit in the FP Status Register must be clear when
 * an frchg instruction is executed, otherwise the instruction is undefined.
 * Executing frchg with PR set causes a trap on some SH4 implementations.
 */

#define FPSCR_RCHG 0x00000000
extern unsigned long long float64_div(unsigned long long a,
                                      unsigned long long b);
extern unsigned long int float32_div(unsigned long int a, unsigned long int b);
extern unsigned long long float64_mul(unsigned long long a,
                                      unsigned long long b);
extern unsigned long int float32_mul(unsigned long int a, unsigned long int b);
extern unsigned long long float64_add(unsigned long long a,
                                      unsigned long long b);
extern unsigned long int float32_add(unsigned long int a, unsigned long int b);
extern unsigned long long float64_sub(unsigned long long a,
                                      unsigned long long b);
extern unsigned long int float32_sub(unsigned long int a, unsigned long int b);
extern unsigned long int float64_to_float32(unsigned long long a);
static unsigned int fpu_exception_flags;

/*
 * Save FPU registers onto task structure.
 */
void save_fpu(struct task_struct *tsk)
{
        unsigned long dummy;

        enable_fpu();
        asm volatile ("sts.l    fpul, @-%0\n\t"
                      "sts.l    fpscr, @-%0\n\t"
                      "lds      %2, fpscr\n\t"
                      "frchg\n\t"
                      "fmov.s   fr15, @-%0\n\t"
                      "fmov.s   fr14, @-%0\n\t"
                      "fmov.s   fr13, @-%0\n\t"
                      "fmov.s   fr12, @-%0\n\t"
                      "fmov.s   fr11, @-%0\n\t"
                      "fmov.s   fr10, @-%0\n\t"
                      "fmov.s   fr9, @-%0\n\t"
                      "fmov.s   fr8, @-%0\n\t"
                      "fmov.s   fr7, @-%0\n\t"
                      "fmov.s   fr6, @-%0\n\t"
                      "fmov.s   fr5, @-%0\n\t"
                      "fmov.s   fr4, @-%0\n\t"
                      "fmov.s   fr3, @-%0\n\t"
                      "fmov.s   fr2, @-%0\n\t"
                      "fmov.s   fr1, @-%0\n\t"
                      "fmov.s   fr0, @-%0\n\t"
                      "frchg\n\t"
                      "fmov.s   fr15, @-%0\n\t"
                      "fmov.s   fr14, @-%0\n\t"
                      "fmov.s   fr13, @-%0\n\t"
                      "fmov.s   fr12, @-%0\n\t"
                      "fmov.s   fr11, @-%0\n\t"
                      "fmov.s   fr10, @-%0\n\t"
                      "fmov.s   fr9, @-%0\n\t"
                      "fmov.s   fr8, @-%0\n\t"
                      "fmov.s   fr7, @-%0\n\t"
                      "fmov.s   fr6, @-%0\n\t"
                      "fmov.s   fr5, @-%0\n\t"
                      "fmov.s   fr4, @-%0\n\t"
                      "fmov.s   fr3, @-%0\n\t"
                      "fmov.s   fr2, @-%0\n\t"
                      "fmov.s   fr1, @-%0\n\t"
                      "fmov.s   fr0, @-%0\n\t"
                      "lds      %3, fpscr\n\t":"=r" (dummy)
                      :"0"((char *)(&tsk->thread.xstate->hardfpu.status)),
                      "r"(FPSCR_RCHG), "r"(FPSCR_INIT)
                      :"memory");

        disable_fpu();
}

void restore_fpu(struct task_struct *tsk)
{
        unsigned long dummy;

        enable_fpu();
        asm volatile ("lds      %2, fpscr\n\t"
                      "fmov.s   @%0+, fr0\n\t"
                      "fmov.s   @%0+, fr1\n\t"
                      "fmov.s   @%0+, fr2\n\t"
                      "fmov.s   @%0+, fr3\n\t"
                      "fmov.s   @%0+, fr4\n\t"
                      "fmov.s   @%0+, fr5\n\t"
                      "fmov.s   @%0+, fr6\n\t"
                      "fmov.s   @%0+, fr7\n\t"
                      "fmov.s   @%0+, fr8\n\t"
                      "fmov.s   @%0+, fr9\n\t"
                      "fmov.s   @%0+, fr10\n\t"
                      "fmov.s   @%0+, fr11\n\t"
                      "fmov.s   @%0+, fr12\n\t"
                      "fmov.s   @%0+, fr13\n\t"
                      "fmov.s   @%0+, fr14\n\t"
                      "fmov.s   @%0+, fr15\n\t"
                      "frchg\n\t"
                      "fmov.s   @%0+, fr0\n\t"
                      "fmov.s   @%0+, fr1\n\t"
                      "fmov.s   @%0+, fr2\n\t"
                      "fmov.s   @%0+, fr3\n\t"
                      "fmov.s   @%0+, fr4\n\t"
                      "fmov.s   @%0+, fr5\n\t"
                      "fmov.s   @%0+, fr6\n\t"
                      "fmov.s   @%0+, fr7\n\t"
                      "fmov.s   @%0+, fr8\n\t"
                      "fmov.s   @%0+, fr9\n\t"
                      "fmov.s   @%0+, fr10\n\t"
                      "fmov.s   @%0+, fr11\n\t"
                      "fmov.s   @%0+, fr12\n\t"
                      "fmov.s   @%0+, fr13\n\t"
                      "fmov.s   @%0+, fr14\n\t"
                      "fmov.s   @%0+, fr15\n\t"
                      "frchg\n\t"
                      "lds.l    @%0+, fpscr\n\t"
                      "lds.l    @%0+, fpul\n\t"
                      :"=r" (dummy)
                      :"0" (tsk->thread.xstate), "r" (FPSCR_RCHG)
                      :"memory");
        disable_fpu();
}

/**
 *      denormal_to_double - Given denormalized float number,
 *                           store double float
 *
 *      @fpu: Pointer to sh_fpu_hard structure
 *      @n: Index to FP register
 */
static void denormal_to_double(struct sh_fpu_hard_struct *fpu, int n)
{
        unsigned long du, dl;
        unsigned long x = fpu->fpul;
        int exp = 1023 - 126;

        if (x != 0 && (x & 0x7f800000) == 0) {
                du = (x & 0x80000000);
                while ((x & 0x00800000) == 0) {
                        x <<= 1;
                        exp--;
                }
                x &= 0x007fffff;
                du |= (exp << 20) | (x >> 3);
                dl = x << 29;

                fpu->fp_regs[n] = du;
                fpu->fp_regs[n + 1] = dl;
        }
}

/**
 *      ieee_fpe_handler - Handle denormalized number exception
 *
 *      @regs: Pointer to register structure
 *
 *      Returns 1 when it's handled (should not cause exception).
 */
static int ieee_fpe_handler(struct pt_regs *regs)
{
        unsigned short insn = *(unsigned short *)regs->pc;
        unsigned short finsn;
        unsigned long nextpc;
        int nib[4] = {
                (insn >> 12) & 0xf,
                (insn >> 8) & 0xf,
                (insn >> 4) & 0xf,
                insn & 0xf
        };

        if (nib[0] == 0xb || (nib[0] == 0x4 && nib[2] == 0x0 && nib[3] == 0xb))
                regs->pr = regs->pc + 4;  /* bsr & jsr */

        if (nib[0] == 0xa || nib[0] == 0xb) {
                /* bra & bsr */
                nextpc = regs->pc + 4 + ((short)((insn & 0xfff) << 4) >> 3);
                finsn = *(unsigned short *)(regs->pc + 2);
        } else if (nib[0] == 0x8 && nib[1] == 0xd) {
                /* bt/s */
                if (regs->sr & 1)
                        nextpc = regs->pc + 4 + ((char)(insn & 0xff) << 1);
                else
                        nextpc = regs->pc + 4;
                finsn = *(unsigned short *)(regs->pc + 2);
        } else if (nib[0] == 0x8 && nib[1] == 0xf) {
                /* bf/s */
                if (regs->sr & 1)
                        nextpc = regs->pc + 4;
                else
                        nextpc = regs->pc + 4 + ((char)(insn & 0xff) << 1);
                finsn = *(unsigned short *)(regs->pc + 2);
        } else if (nib[0] == 0x4 && nib[3] == 0xb &&
                   (nib[2] == 0x0 || nib[2] == 0x2)) {
                /* jmp & jsr */
                nextpc = regs->regs[nib[1]];
                finsn = *(unsigned short *)(regs->pc + 2);
        } else if (nib[0] == 0x0 && nib[3] == 0x3 &&
                   (nib[2] == 0x0 || nib[2] == 0x2)) {
                /* braf & bsrf */
                nextpc = regs->pc + 4 + regs->regs[nib[1]];
                finsn = *(unsigned short *)(regs->pc + 2);
        } else if (insn == 0x000b) {
                /* rts */
                nextpc = regs->pr;
                finsn = *(unsigned short *)(regs->pc + 2);
        } else {
                nextpc = regs->pc + instruction_size(insn);
                finsn = insn;
        }

        if ((finsn & 0xf1ff) == 0xf0ad) {
                /* fcnvsd */
                struct task_struct *tsk = current;

                if ((tsk->thread.xstate->hardfpu.fpscr & FPSCR_CAUSE_ERROR))
                        /* FPU error */
                        denormal_to_double(&tsk->thread.xstate->hardfpu,
                                           (finsn >> 8) & 0xf);
                else
                        return 0;

                regs->pc = nextpc;
                return 1;
        } else if ((finsn & 0xf00f) == 0xf002) {
                /* fmul */
                struct task_struct *tsk = current;
                int fpscr;
                int n, m, prec;
                unsigned int hx, hy;

                n = (finsn >> 8) & 0xf;
                m = (finsn >> 4) & 0xf;
                hx = tsk->thread.xstate->hardfpu.fp_regs[n];
                hy = tsk->thread.xstate->hardfpu.fp_regs[m];
                fpscr = tsk->thread.xstate->hardfpu.fpscr;
                prec = fpscr & FPSCR_DBL_PRECISION;

                if ((fpscr & FPSCR_CAUSE_ERROR)
                    && (prec && ((hx & 0x7fffffff) < 0x00100000
                                 || (hy & 0x7fffffff) < 0x00100000))) {
                        long long llx, lly;

                        /* FPU error because of denormal (doubles) */
                        llx = ((long long)hx << 32)
                            | tsk->thread.xstate->hardfpu.fp_regs[n + 1];
                        lly = ((long long)hy << 32)
                            | tsk->thread.xstate->hardfpu.fp_regs[m + 1];
                        llx = float64_mul(llx, lly);
                        tsk->thread.xstate->hardfpu.fp_regs[n] = llx >> 32;
                        tsk->thread.xstate->hardfpu.fp_regs[n + 1] = llx & 0xffffffff;
                } else if ((fpscr & FPSCR_CAUSE_ERROR)
                           && (!prec && ((hx & 0x7fffffff) < 0x00800000
                                         || (hy & 0x7fffffff) < 0x00800000))) {
                        /* FPU error because of denormal (floats) */
                        hx = float32_mul(hx, hy);
                        tsk->thread.xstate->hardfpu.fp_regs[n] = hx;
                } else
                        return 0;

                regs->pc = nextpc;
                return 1;
        } else if ((finsn & 0xf00e) == 0xf000) {
                /* fadd, fsub */
                struct task_struct *tsk = current;
                int fpscr;
                int n, m, prec;
                unsigned int hx, hy;

                n = (finsn >> 8) & 0xf;
                m = (finsn >> 4) & 0xf;
                hx = tsk->thread.xstate->hardfpu.fp_regs[n];
                hy = tsk->thread.xstate->hardfpu.fp_regs[m];
                fpscr = tsk->thread.xstate->hardfpu.fpscr;
                prec = fpscr & FPSCR_DBL_PRECISION;

                if ((fpscr & FPSCR_CAUSE_ERROR)
                    && (prec && ((hx & 0x7fffffff) < 0x00100000
                                 || (hy & 0x7fffffff) < 0x00100000))) {
                        long long llx, lly;

                        /* FPU error because of denormal (doubles) */
                        llx = ((long long)hx << 32)
                            | tsk->thread.xstate->hardfpu.fp_regs[n + 1];
                        lly = ((long long)hy << 32)
                            | tsk->thread.xstate->hardfpu.fp_regs[m + 1];
                        if ((finsn & 0xf00f) == 0xf000)
                                llx = float64_add(llx, lly);
                        else
                                llx = float64_sub(llx, lly);
                        tsk->thread.xstate->hardfpu.fp_regs[n] = llx >> 32;
                        tsk->thread.xstate->hardfpu.fp_regs[n + 1] = llx & 0xffffffff;
                } else if ((fpscr & FPSCR_CAUSE_ERROR)
                           && (!prec && ((hx & 0x7fffffff) < 0x00800000
                                         || (hy & 0x7fffffff) < 0x00800000))) {
                        /* FPU error because of denormal (floats) */
                        if ((finsn & 0xf00f) == 0xf000)
                                hx = float32_add(hx, hy);
                        else
                                hx = float32_sub(hx, hy);
                        tsk->thread.xstate->hardfpu.fp_regs[n] = hx;
                } else
                        return 0;

                regs->pc = nextpc;
                return 1;
        } else if ((finsn & 0xf003) == 0xf003) {
                /* fdiv */
                struct task_struct *tsk = current;
                int fpscr;
                int n, m, prec;
                unsigned int hx, hy;

                n = (finsn >> 8) & 0xf;
                m = (finsn >> 4) & 0xf;
                hx = tsk->thread.xstate->hardfpu.fp_regs[n];
                hy = tsk->thread.xstate->hardfpu.fp_regs[m];
                fpscr = tsk->thread.xstate->hardfpu.fpscr;
                prec = fpscr & FPSCR_DBL_PRECISION;

                if ((fpscr & FPSCR_CAUSE_ERROR)
                    && (prec && ((hx & 0x7fffffff) < 0x00100000
                                 || (hy & 0x7fffffff) < 0x00100000))) {
                        long long llx, lly;

                        /* FPU error because of denormal (doubles) */
                        llx = ((long long)hx << 32)
                            | tsk->thread.xstate->hardfpu.fp_regs[n + 1];
                        lly = ((long long)hy << 32)
                            | tsk->thread.xstate->hardfpu.fp_regs[m + 1];

                        llx = float64_div(llx, lly);

                        tsk->thread.xstate->hardfpu.fp_regs[n] = llx >> 32;
                        tsk->thread.xstate->hardfpu.fp_regs[n + 1] = llx & 0xffffffff;
                } else if ((fpscr & FPSCR_CAUSE_ERROR)
                           && (!prec && ((hx & 0x7fffffff) < 0x00800000
                                         || (hy & 0x7fffffff) < 0x00800000))) {
                        /* FPU error because of denormal (floats) */
                        hx = float32_div(hx, hy);
                        tsk->thread.xstate->hardfpu.fp_regs[n] = hx;
                } else
                        return 0;

                regs->pc = nextpc;
                return 1;
        } else if ((finsn & 0xf0bd) == 0xf0bd) {
                /* fcnvds - double to single precision convert */
                struct task_struct *tsk = current;
                int m;
                unsigned int hx;

                m = (finsn >> 8) & 0x7;
                hx = tsk->thread.xstate->hardfpu.fp_regs[m];

                if ((tsk->thread.xstate->hardfpu.fpscr & FPSCR_CAUSE_ERROR)
                        && ((hx & 0x7fffffff) < 0x00100000)) {
                        /* subnormal double to float conversion */
                        long long llx;

                        llx = ((long long)tsk->thread.xstate->hardfpu.fp_regs[m] << 32)
                            | tsk->thread.xstate->hardfpu.fp_regs[m + 1];

                        tsk->thread.xstate->hardfpu.fpul = float64_to_float32(llx);
                } else
                        return 0;

                regs->pc = nextpc;
                return 1;
        }

        return 0;
}

void float_raise(unsigned int flags)
{
        fpu_exception_flags |= flags;
}

int float_rounding_mode(void)
{
        struct task_struct *tsk = current;
        int roundingMode = FPSCR_ROUNDING_MODE(tsk->thread.xstate->hardfpu.fpscr);
        return roundingMode;
}

BUILD_TRAP_HANDLER(fpu_error)
{
        struct task_struct *tsk = current;
        TRAP_HANDLER_DECL;

        __unlazy_fpu(tsk, regs);
        fpu_exception_flags = 0;
        if (ieee_fpe_handler(regs)) {
                tsk->thread.xstate->hardfpu.fpscr &=
                    ~(FPSCR_CAUSE_MASK | FPSCR_FLAG_MASK);
                tsk->thread.xstate->hardfpu.fpscr |= fpu_exception_flags;
                /* Set the FPSCR flag as well as cause bits - simply
                 * replicate the cause */
                tsk->thread.xstate->hardfpu.fpscr |= (fpu_exception_flags >> 10);
                grab_fpu(regs);
                restore_fpu(tsk);
                task_thread_info(tsk)->status |= TS_USEDFPU;
                if ((((tsk->thread.xstate->hardfpu.fpscr & FPSCR_ENABLE_MASK) >> 7) &
                     (fpu_exception_flags >> 2)) == 0) {
                        return;
                }
        }

        force_sig(SIGFPE);
}