// SPDX-License-Identifier: GPL-2.0
/*
* Save/restore floating point context for signal handlers.
*
* Copyright (C) 1999, 2000 Kaz Kojima & Niibe Yutaka
*
* FIXME! These routines can be optimized in big endian case.
*/
#include <linux/sched/signal.h>
#include <linux/signal.h>
#include <asm/processor.h>
#include <asm/io.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
/*
* 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"
"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("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"
"lds.l @%0+, fpscr\n\t"
"lds.l @%0+, fpul\n\t"
: "=r" (dummy)
: "0" (tsk->thread.xstate), "r" (FPSCR_RCHG)
: "memory");
disable_fpu();
}
/*
* Emulate arithmetic ops on denormalized number for some FPU insns.
*/
/* denormalized float * float */
static int denormal_mulf(int hx, int hy)
{
unsigned int ix, iy;
unsigned long long m, n;
int exp, w;
ix = hx & 0x7fffffff;
iy = hy & 0x7fffffff;
if (iy < 0x00800000 || ix == 0)
return ((hx ^ hy) & 0x80000000);
exp = (iy & 0x7f800000) >> 23;
ix &= 0x007fffff;
iy = (iy & 0x007fffff) | 0x00800000;
m = (unsigned long long)ix * iy;
n = m;
w = -1;
while (n) { n >>= 1; w++; }
/* FIXME: use guard bits */
exp += w - 126 - 46;
if (exp > 0)
ix = ((int) (m >> (w - 23)) & 0x007fffff) | (exp << 23);
else if (exp + 22 >= 0)
ix = (int) (m >> (w - 22 - exp)) & 0x007fffff;
else
ix = 0;
ix |= (hx ^ hy) & 0x80000000;
return ix;
}
/* denormalized double * double */
static void mult64(unsigned long long x, unsigned long long y,
unsigned long long *highp, unsigned long long *lowp)
{
unsigned long long sub0, sub1, sub2, sub3;
unsigned long long high, low;
sub0 = (x >> 32) * (unsigned long) (y >> 32);
sub1 = (x & 0xffffffffLL) * (unsigned long) (y >> 32);
sub2 = (x >> 32) * (unsigned long) (y & 0xffffffffLL);
sub3 = (x & 0xffffffffLL) * (unsigned long) (y & 0xffffffffLL);
low = sub3;
high = 0LL;
sub3 += (sub1 << 32);
if (low > sub3)
high++;
low = sub3;
sub3 += (sub2 << 32);
if (low > sub3)
high++;
low = sub3;
high += (sub1 >> 32) + (sub2 >> 32);
high += sub0;
*lowp = low;
*highp = high;
}
static inline long long rshift64(unsigned long long mh,
unsigned long long ml, int n)
{
if (n >= 64)
return mh >> (n - 64);
return (mh << (64 - n)) | (ml >> n);
}
static long long denormal_muld(long long hx, long long hy)
{
unsigned long long ix, iy;
unsigned long long mh, ml, nh, nl;
int exp, w;
ix = hx & 0x7fffffffffffffffLL;
iy = hy & 0x7fffffffffffffffLL;
if (iy < 0x0010000000000000LL || ix == 0)
return ((hx ^ hy) & 0x8000000000000000LL);
exp = (iy & 0x7ff0000000000000LL) >> 52;
ix &= 0x000fffffffffffffLL;
iy = (iy & 0x000fffffffffffffLL) | 0x0010000000000000LL;
mult64(ix, iy, &mh, &ml);
nh = mh;
nl = ml;
w = -1;
if (nh) {
while (nh) { nh >>= 1; w++;}
w += 64;
} else
while (nl) { nl >>= 1; w++;}
/* FIXME: use guard bits */
exp += w - 1022 - 52 * 2;
if (exp > 0)
ix = (rshift64(mh, ml, w - 52) & 0x000fffffffffffffLL)
| ((long long)exp << 52);
else if (exp + 51 >= 0)
ix = rshift64(mh, ml, w - 51 - exp) & 0x000fffffffffffffLL;
else
ix = 0;
ix |= (hx ^ hy) & 0x8000000000000000LL;
return ix;
}
/* ix - iy where iy: denormal and ix, iy >= 0 */
static int denormal_subf1(unsigned int ix, unsigned int iy)
{
int frac;
int exp;
if (ix < 0x00800000)
return ix - iy;
exp = (ix & 0x7f800000) >> 23;
if (exp - 1 > 31)
return ix;
iy >>= exp - 1;
if (iy == 0)
return ix;
frac = (ix & 0x007fffff) | 0x00800000;
frac -= iy;
while (frac < 0x00800000) {
if (--exp == 0)
return frac;
frac <<= 1;
}
return (exp << 23) | (frac & 0x007fffff);
}
/* ix + iy where iy: denormal and ix, iy >= 0 */
static int denormal_addf1(unsigned int ix, unsigned int iy)
{
int frac;
int exp;
if (ix < 0x00800000)
return ix + iy;
exp = (ix & 0x7f800000) >> 23;
if (exp - 1 > 31)
return ix;
iy >>= exp - 1;
if (iy == 0)
return ix;
frac = (ix & 0x007fffff) | 0x00800000;
frac += iy;
if (frac >= 0x01000000) {
frac >>= 1;
++exp;
}
return (exp << 23) | (frac & 0x007fffff);
}
static int denormal_addf(int hx, int hy)
{
unsigned int ix, iy;
int sign;
if ((hx ^ hy) & 0x80000000) {
sign = hx & 0x80000000;
ix = hx & 0x7fffffff;
iy = hy & 0x7fffffff;
if (iy < 0x00800000) {
ix = denormal_subf1(ix, iy);
if ((int) ix < 0) {
ix = -ix;
sign ^= 0x80000000;
}
} else {
ix = denormal_subf1(iy, ix);
sign ^= 0x80000000;
}
} else {
sign = hx & 0x80000000;
ix = hx & 0x7fffffff;
iy = hy & 0x7fffffff;
if (iy < 0x00800000)
ix = denormal_addf1(ix, iy);
else
ix = denormal_addf1(iy, ix);
}
return sign | ix;
}
/* ix - iy where iy: denormal and ix, iy >= 0 */
static long long denormal_subd1(unsigned long long ix, unsigned long long iy)
{
long long frac;
int exp;
if (ix < 0x0010000000000000LL)
return ix - iy;
exp = (ix & 0x7ff0000000000000LL) >> 52;
if (exp - 1 > 63)
return ix;
iy >>= exp - 1;
if (iy == 0)
return ix;
frac = (ix & 0x000fffffffffffffLL) | 0x0010000000000000LL;
frac -= iy;
while (frac < 0x0010000000000000LL) {
if (--exp == 0)
return frac;
frac <<= 1;
}
return ((long long)exp << 52) | (frac & 0x000fffffffffffffLL);
}
/* ix + iy where iy: denormal and ix, iy >= 0 */
static long long denormal_addd1(unsigned long long ix, unsigned long long iy)
{
long long frac;
long long exp;
if (ix < 0x0010000000000000LL)
return ix + iy;
exp = (ix & 0x7ff0000000000000LL) >> 52;
if (exp - 1 > 63)
return ix;
iy >>= exp - 1;
if (iy == 0)
return ix;
frac = (ix & 0x000fffffffffffffLL) | 0x0010000000000000LL;
frac += iy;
if (frac >= 0x0020000000000000LL) {
frac >>= 1;
++exp;
}
return (exp << 52) | (frac & 0x000fffffffffffffLL);
}
static long long denormal_addd(long long hx, long long hy)
{
unsigned long long ix, iy;
long long sign;
if ((hx ^ hy) & 0x8000000000000000LL) {
sign = hx & 0x8000000000000000LL;
ix = hx & 0x7fffffffffffffffLL;
iy = hy & 0x7fffffffffffffffLL;
if (iy < 0x0010000000000000LL) {
ix = denormal_subd1(ix, iy);
if ((int) ix < 0) {
ix = -ix;
sign ^= 0x8000000000000000LL;
}
} else {
ix = denormal_subd1(iy, ix);
sign ^= 0x8000000000000000LL;
}
} else {
sign = hx & 0x8000000000000000LL;
ix = hx & 0x7fffffffffffffffLL;
iy = hy & 0x7fffffffffffffffLL;
if (iy < 0x0010000000000000LL)
ix = denormal_addd1(ix, iy);
else
ix = denormal_addd1(iy, ix);
}
return sign | ix;
}
/**
* 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)) /* bsr & jsr */
regs->pr = regs->pc + 4;
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 + 2;
finsn = insn;
}
#define FPSCR_FPU_ERROR (1 << 17)
if ((finsn & 0xf1ff) == 0xf0ad) { /* fcnvsd */
struct task_struct *tsk = current;
if ((tsk->thread.xstate->hardfpu.fpscr & FPSCR_FPU_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 & (1 << 19);
if ((fpscr & FPSCR_FPU_ERROR)
&& (prec && ((hx & 0x7fffffff) < 0x00100000
|| (hy & 0x7fffffff) < 0x00100000))) {
long long llx, lly;
/* FPU error because of denormal */
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 ((hx & 0x7fffffff) >= 0x00100000)
llx = denormal_muld(lly, llx);
else
llx = denormal_muld(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_FPU_ERROR)
&& (!prec && ((hx & 0x7fffffff) < 0x00800000
|| (hy & 0x7fffffff) < 0x00800000))) {
/* FPU error because of denormal */
if ((hx & 0x7fffffff) >= 0x00800000)
hx = denormal_mulf(hy, hx);
else
hx = denormal_mulf(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 & (1 << 19);
if ((fpscr & FPSCR_FPU_ERROR)
&& (prec && ((hx & 0x7fffffff) < 0x00100000
|| (hy & 0x7fffffff) < 0x00100000))) {
long long llx, lly;
/* FPU error because of denormal */
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 = denormal_addd(llx, lly);
else
llx = denormal_addd(llx, lly ^ (1LL << 63));
tsk->thread.xstate->hardfpu.fp_regs[n] = llx >> 32;
tsk->thread.xstate->hardfpu.fp_regs[n+1] = llx & 0xffffffff;
} else if ((fpscr & FPSCR_FPU_ERROR)
&& (!prec && ((hx & 0x7fffffff) < 0x00800000
|| (hy & 0x7fffffff) < 0x00800000))) {
/* FPU error because of denormal */
if ((finsn & 0xf00f) == 0xf000)
hx = denormal_addf(hx, hy);
else
hx = denormal_addf(hx, hy ^ 0x80000000);
tsk->thread.xstate->hardfpu.fp_regs[n] = hx;
} else
return 0;
regs->pc = nextpc;
return 1;
}
return 0;
}
BUILD_TRAP_HANDLER(fpu_error)
{
struct task_struct *tsk = current;
TRAP_HANDLER_DECL;
__unlazy_fpu(tsk, regs);
if (ieee_fpe_handler(regs)) {
tsk->thread.xstate->hardfpu.fpscr &=
~(FPSCR_CAUSE_MASK | FPSCR_FLAG_MASK);
grab_fpu(regs);
restore_fpu(tsk);
task_thread_info(tsk)->status |= TS_USEDFPU;
return;
}
force_sig(SIGFPE);
}