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linux/arch/sh/kernel/cpu/sh2a/fpu.c
Paul Mundt 0ea820cf9b sh: Move over to dynamically allocated FPU context. 
This follows the x86 xstate changes and implements a task_xstate slab
cache that is dynamically sized to match one of hard FP/soft FP/FPU-less.

This also tidies up and consolidates some of the SH-2A/SH-4 FPU
fragmentation. Now fpu state restorers are commonly defined, with the
init_fpu()/fpu_init() mess reworked to follow the x86 convention.
The fpu_init() register initialization has been replaced by xstate setup
followed by writing out to hardware via the standard restore path.

As init_fpu() now performs a slab allocation a secondary lighterweight
restorer is also introduced for the context switch.

In the future the DSP state will be rolled in here, too.

More work remains for math emulation and the SH-5 FPU, which presently
uses its own special (UP-only) interfaces.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2010-01-13 12:51:40 +09:00

574 lines
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/*
* Save/restore floating point context for signal handlers.
*
* Copyright (C) 1999, 2000 Kaz Kojima & Niibe Yutaka
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* FIXME! These routines can be optimized in big endian case.
*/
#include <linux/sched.h>
#include <linux/signal.h>
#include <asm/processor.h>
#include <asm/io.h>
#include <asm/fpu.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, tsk);
}
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