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linux/arch/sh/kernel/cpu/sh4/fpu.c

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/*
* Save/restore floating point context for signal handlers.
*
* 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.
*
* 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.h>
#include <linux/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, tsk);
}
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