--- /dev/null
+/*
+ * 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;
+}
Code Review / kvmfornfv.git / blobdiff