- 根目录:
- arch
- powerpc
- kernel
- vecemu.c
/*
* Routines to emulate some Altivec/VMX instructions, specifically
* those that can trap when given denormalized operands in Java mode.
*/
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <asm/ptrace.h>
#include <asm/processor.h>
#include <asm/uaccess.h>
/* Functions in vector.S */
extern void vaddfp(vector128 *dst, vector128 *a, vector128 *b);
extern void vsubfp(vector128 *dst, vector128 *a, vector128 *b);
extern void vmaddfp(vector128 *dst, vector128 *a, vector128 *b, vector128 *c);
extern void vnmsubfp(vector128 *dst, vector128 *a, vector128 *b, vector128 *c);
extern void vrefp(vector128 *dst, vector128 *src);
extern void vrsqrtefp(vector128 *dst, vector128 *src);
extern void vexptep(vector128 *dst, vector128 *src);
static unsigned int exp2s[8] = {
0x800000,
0x8b95c2,
0x9837f0,
0xa5fed7,
0xb504f3,
0xc5672a,
0xd744fd,
0xeac0c7
};
/*
* Computes an estimate of 2^x. The `s' argument is the 32-bit
* single-precision floating-point representation of x.
*/
static unsigned int eexp2(unsigned int s)
{
int exp, pwr;
unsigned int mant, frac;
/* extract exponent field from input */
exp = ((s >> 23) & 0xff) - 127;
if (exp > 7) {
/* check for NaN input */
if (exp == 128 && (s & 0x7fffff) != 0)
return s | 0x400000; /* return QNaN */
/* 2^-big = 0, 2^+big = +Inf */
return (s & 0x80000000)? 0: 0x7f800000; /* 0 or +Inf */
}
if (exp < -23)
return 0x3f800000; /* 1.0 */
/* convert to fixed point integer in 9.23 representation */
pwr = (s & 0x7fffff) | 0x800000;
if (exp > 0)
pwr <<= exp;
else
pwr >>= -exp;
if (s & 0x80000000)
pwr = -pwr;
/* extract integer part, which becomes exponent part of result */
exp = (pwr >> 23) + 126;
if (exp >= 254)
return 0x7f800000;
if (exp < -23)
return 0;
/* table lookup on top 3 bits of fraction to get mantissa */
mant = exp2s[(pwr >> 20) & 7];
/* linear interpolation using remaining 20 bits of fraction */
asm("mulhwu %0,%1,%2" : "=r" (frac)
: "r" (pwr << 12), "r" (0x172b83ff));
asm("mulhwu %0,%1,%2" : "=r" (frac) : "r" (frac), "r" (mant));
mant += frac;
if (exp >= 0)
return mant + (exp << 23);
/* denormalized result */
exp = -exp;
mant += 1 << (exp - 1);
return mant >> exp;
}
/*
* Computes an estimate of log_2(x). The `s' argument is the 32-bit
* single-precision floating-point representation of x.
*/
static unsigned int elog2(unsigned int s)
{
int exp, mant, lz, frac;
exp = s & 0x7f800000;
mant = s & 0x7fffff;
if (exp == 0x7f800000) { /* Inf or NaN */
if (mant != 0)
s |= 0x400000; /* turn NaN into QNaN */
return s;
}
if ((exp | mant) == 0) /* +0 or -0 */
return 0xff800000; /* return -Inf */
if (exp == 0) {
/* denormalized */
asm("cntlzw %0,%1" : "=r" (lz) : "r" (mant));
mant <<= lz - 8;
exp = (-118 - lz) << 23;
} else {
mant |= 0x800000;
exp -= 127 << 23;
}
if (mant >= 0xb504f3) { /* 2^0.5 * 2^23 */
exp |= 0x400000; /* 0.5 * 2^23 */
asm("mulhwu %0,%1,%2" : "=r" (mant)
: "r" (mant), "r" (0xb504f334)); /* 2^-0.5 * 2^32 */
}
if (mant >= 0x9837f0) { /* 2^0.25 * 2^23 */
exp |= 0x200000; /* 0.25 * 2^23 */
asm("mulhwu %0,%1,%2" : "=r" (mant)
: "r" (mant), "r" (0xd744fccb)); /* 2^-0.25 * 2^32 */
}
if (mant >= 0x8b95c2) { /* 2^0.125 * 2^23 */
exp |= 0x100000; /* 0.125 * 2^23 */
asm("mulhwu %0,%1,%2" : "=r" (mant)
: "r" (mant), "r" (0xeac0c6e8)); /* 2^-0.125 * 2^32 */
}
if (mant > 0x800000) { /* 1.0 * 2^23 */
/* calculate (mant - 1) * 1.381097463 */
/* 1.381097463 == 0.125 / (2^0.125 - 1) */
asm("mulhwu %0,%1,%2" : "=r" (frac)
: "r" ((mant - 0x800000) << 1), "r" (0xb0c7cd3a));
exp += frac;
}
s = exp & 0x80000000;
if (exp != 0) {
if (s)
exp = -exp;
asm("cntlzw %0,%1" : "=r" (lz) : "r" (exp));
lz = 8 - lz;
if (lz > 0)
exp >>= lz;
else if (lz < 0)
exp <<= -lz;
s += ((lz + 126) << 23) + exp;
}
return s;
}
#define VSCR_SAT 1
static int ctsxs(unsigned int x, int scale, unsigned int *vscrp)
{
int exp, mant;
exp = (x >> 23) & 0xff;
mant = x & 0x7fffff;
if (exp == 255 && mant != 0)
return 0; /* NaN -> 0 */
exp = exp - 127 + scale;
if (exp < 0)
return 0; /* round towards zero */
if (exp >= 31) {
/* saturate, unless the result would be -2^31 */
if (x + (scale << 23) != 0xcf000000)
*vscrp |= VSCR_SAT;
return (x & 0x80000000)? 0x80000000: 0x7fffffff;
}
mant |= 0x800000;
mant = (mant << 7) >> (30 - exp);
return (x & 0x80000000)? -mant: mant;
}
static unsigned int ctuxs(unsigned int x, int scale, unsigned int *vscrp)
{
int exp;
unsigned int mant;
exp = (x >> 23) & 0xff;
mant = x & 0x7fffff;
if (exp == 255 && mant != 0)
return 0; /* NaN -> 0 */
exp = exp - 127 + scale;
if (exp < 0)
return 0; /* round towards zero */
if (x & 0x80000000) {
/* negative => saturate to 0 */
*vscrp |= VSCR_SAT;
return 0;
}
if (exp >= 32) {
/* saturate */
*vscrp |= VSCR_SAT;
return 0xffffffff;
}
mant |= 0x800000;
mant = (mant << 8) >> (31 - exp);
return mant;
}
/* Round to floating integer, towards 0 */
static unsigned int rfiz(unsigned int x)
{
int exp;
exp = ((x >> 23) & 0xff) - 127;
if (exp == 128 && (x & 0x7fffff) != 0)
return x | 0x400000; /* NaN -> make it a QNaN */
if (exp >= 23)
return x; /* it's an integer already (or Inf) */
if (exp < 0)
return x & 0x80000000; /* |x| < 1.0 rounds to 0 */
return x & ~(0x7fffff >> exp);
}
/* Round to floating integer, towards +/- Inf */
static unsigned int rfii(unsigned int x)
{
int exp, mask;
exp = ((x >> 23) & 0xff) - 127;
if (exp == 128 && (x & 0x7fffff) != 0)
return x | 0x400000; /* NaN -> make it a QNaN */
if (exp >= 23)
return x; /* it's an integer already (or Inf) */
if ((x & 0x7fffffff) == 0)
return x; /* +/-0 -> +/-0 */
if (exp < 0)
/* 0 < |x| < 1.0 rounds to +/- 1.0 */
return (x & 0x80000000) | 0x3f800000;
mask = 0x7fffff >> exp;
/* mantissa overflows into exponent - that's OK,
it can't overflow into the sign bit */
return (x + mask) & ~mask;
}
/* Round to floating integer, to nearest */
static unsigned int rfin(unsigned int x)
{
int exp, half;
exp = ((x >> 23) & 0xff) - 127;
if (exp == 128 && (x & 0x7fffff) != 0)
return x | 0x400000; /* NaN -> make it a QNaN */
if (exp >= 23)
return x; /* it's an integer already (or Inf) */
if (exp < -1)
return x & 0x80000000; /* |x| < 0.5 -> +/-0 */
if (exp == -1)
/* 0.5 <= |x| < 1.0 rounds to +/- 1.0 */
return (x & 0x80000000) | 0x3f800000;
half = 0x400000 >> exp;
/* add 0.5 to the magnitude and chop off the fraction bits */
return (x + half) & ~(0x7fffff >> exp);
}
int emulate_altivec(struct pt_regs *regs)
{
unsigned int instr, i;
unsigned int va, vb, vc, vd;
vector128 *vrs;
if (get_user(instr, (unsigned int __user *) regs->nip))
return -EFAULT;
if ((instr >> 26) != 4)
return -EINVAL; /* not an altivec instruction */
vd = (instr >> 21) & 0x1f;
va = (instr >> 16) & 0x1f;
vb = (instr >> 11) & 0x1f;
vc = (instr >> 6) & 0x1f;
vrs = current->thread.vr_state.vr;
switch (instr & 0x3f) {
case 10:
switch (vc) {
case 0: /* vaddfp */
vaddfp(&vrs[vd], &vrs[va], &vrs[vb]);
break;
case 1: /* vsubfp */
vsubfp(&vrs[vd], &vrs[va], &vrs[vb]);
break;
case 4: /* vrefp */
vrefp(&vrs[vd], &vrs[vb]);
break;
case 5: /* vrsqrtefp */
vrsqrtefp(&vrs[vd], &vrs[vb]);
break;
case 6: /* vexptefp */
for (i = 0; i < 4; ++i)
vrs[vd].u[i] = eexp2(vrs[vb].u[i]);
break;
case 7: /* vlogefp */
for (i = 0; i < 4; ++i)
vrs[vd].u[i] = elog2(vrs[vb].u[i]);
break;
case 8: /* vrfin */
for (i = 0; i < 4; ++i)
vrs[vd].u[i] = rfin(vrs[vb].u[i]);
break;
case 9: /* vrfiz */
for (i = 0; i < 4; ++i)
vrs[vd].u[i] = rfiz(vrs[vb].u[i]);
break;
case 10: /* vrfip */
for (i = 0; i < 4; ++i) {
u32 x = vrs[vb].u[i];
x = (x & 0x80000000)? rfiz(x): rfii(x);
vrs[vd].u[i] = x;
}
break;
case 11: /* vrfim */
for (i = 0; i < 4; ++i) {
u32 x = vrs[vb].u[i];
x = (x & 0x80000000)? rfii(x): rfiz(x);
vrs[vd].u[i] = x;
}
break;
case 14: /* vctuxs */
for (i = 0; i < 4; ++i)
vrs[vd].u[i] = ctuxs(vrs[vb].u[i], va,
¤t->thread.vr_state.vscr.u[3]);
break;
case 15: /* vctsxs */
for (i = 0; i < 4; ++i)
vrs[vd].u[i] = ctsxs(vrs[vb].u[i], va,
¤t->thread.vr_state.vscr.u[3]);
break;
default:
return -EINVAL;
}
break;
case 46: /* vmaddfp */
vmaddfp(&vrs[vd], &vrs[va], &vrs[vb], &vrs[vc]);
break;
case 47: /* vnmsubfp */
vnmsubfp(&vrs[vd], &vrs[va], &vrs[vb], &vrs[vc]);
break;
default:
return -EINVAL;
}
return 0;
}