1 files changed, 351 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/vecemu.c b/arch/powerpc/kernel/vecemu.c
new file mode 100644
index 000000000..ae6325694
--- /dev/null
+++ b/arch/powerpc/kernel/vecemu.c
@@ -0,0 +1,351 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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/switch_to.h>
+#include <linux/uaccess.h>
+#include <asm/inst.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)
+{
+	struct ppc_inst instr;
+	unsigned int i, word;
+	unsigned int va, vb, vc, vd;
+	vector128 *vrs;
+
+	if (get_user_instr(instr, (void __user *)regs->nip))
+		return -EFAULT;
+
+	word = ppc_inst_val(instr);
+	if (ppc_inst_primary_opcode(instr) != 4)
+		return -EINVAL;		/* not an altivec instruction */
+	vd = (word >> 21) & 0x1f;
+	va = (word >> 16) & 0x1f;
+	vb = (word >> 11) & 0x1f;
+	vc = (word >> 6) & 0x1f;
+
+	vrs = current->thread.vr_state.vr;
+	switch (word & 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,
+					&current->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,
+					&current->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;
+}