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Commit 2dbd0dd7 authored by Avi Kivity's avatar Avi Kivity
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KVM: x86 emulator: Decode memory operands directly into a 'struct operand' 



Since modrm operand can be either register or memory, decoding it into
a 'struct operand', which can represent both, is simpler.

Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 1f6f0580

arch/x86/include/asm/kvm_emulate.h

+0 −3
Original line number Diff line number Diff line
@@ -203,9 +203,6 @@ struct decode_cache { 
	u8 modrm_rm;

	u8 modrm_seg;

	bool rip_relative;

	unsigned long modrm_ea;

	void *modrm_ptr;

	unsigned long modrm_val;

	struct fetch_cache fetch;

	struct read_cache io_read;

	struct read_cache mem_read;

arch/x86/kvm/emulate.c

+57 −68
Original line number Diff line number Diff line
@@ -581,12 +581,14 @@ static void decode_register_operand(struct operand *op, 
}



static int decode_modrm(struct x86_emulate_ctxt *ctxt,

			struct x86_emulate_ops *ops)

			struct x86_emulate_ops *ops,

			struct operand *op)

{

	struct decode_cache *c = &ctxt->decode;

	u8 sib;

	int index_reg = 0, base_reg = 0, scale;

	int rc = X86EMUL_CONTINUE;

	ulong modrm_ea = 0;



	if (c->rex_prefix) {

		c->modrm_reg = (c->rex_prefix & 4) << 1;	/* REX.R */
@@ -598,16 +600,19 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt, 
	c->modrm_mod |= (c->modrm & 0xc0) >> 6;

	c->modrm_reg |= (c->modrm & 0x38) >> 3;

	c->modrm_rm |= (c->modrm & 0x07);

	c->modrm_ea = 0;

	c->modrm_seg = VCPU_SREG_DS;



	if (c->modrm_mod == 3) {

		c->modrm_ptr = decode_register(c->modrm_rm,

		op->type = OP_REG;

		op->bytes = (c->d & ByteOp) ? 1 : c->op_bytes;

		op->addr.reg = decode_register(c->modrm_rm,

					       c->regs, c->d & ByteOp);

		c->modrm_val = *(unsigned long *)c->modrm_ptr;

		fetch_register_operand(op);

		return rc;

	}



	op->type = OP_MEM;



	if (c->ad_bytes == 2) {

		unsigned bx = c->regs[VCPU_REGS_RBX];

		unsigned bp = c->regs[VCPU_REGS_RBP];
@@ -618,46 +623,46 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt, 
		switch (c->modrm_mod) {

		case 0:

			if (c->modrm_rm == 6)

				c->modrm_ea += insn_fetch(u16, 2, c->eip);

				modrm_ea += insn_fetch(u16, 2, c->eip);

			break;

		case 1:

			c->modrm_ea += insn_fetch(s8, 1, c->eip);

			modrm_ea += insn_fetch(s8, 1, c->eip);

			break;

		case 2:

			c->modrm_ea += insn_fetch(u16, 2, c->eip);

			modrm_ea += insn_fetch(u16, 2, c->eip);

			break;

		}

		switch (c->modrm_rm) {

		case 0:

			c->modrm_ea += bx + si;

			modrm_ea += bx + si;

			break;

		case 1:

			c->modrm_ea += bx + di;

			modrm_ea += bx + di;

			break;

		case 2:

			c->modrm_ea += bp + si;

			modrm_ea += bp + si;

			break;

		case 3:

			c->modrm_ea += bp + di;

			modrm_ea += bp + di;

			break;

		case 4:

			c->modrm_ea += si;

			modrm_ea += si;

			break;

		case 5:

			c->modrm_ea += di;

			modrm_ea += di;

			break;

		case 6:

			if (c->modrm_mod != 0)

				c->modrm_ea += bp;

				modrm_ea += bp;

			break;

		case 7:

			c->modrm_ea += bx;

			modrm_ea += bx;

			break;

		}

		if (c->modrm_rm == 2 || c->modrm_rm == 3 ||

		    (c->modrm_rm == 6 && c->modrm_mod != 0))

			c->modrm_seg = VCPU_SREG_SS;

		c->modrm_ea = (u16)c->modrm_ea;

		modrm_ea = (u16)modrm_ea;

	} else {

		/* 32/64-bit ModR/M decode. */

		if ((c->modrm_rm & 7) == 4) {
@@ -667,48 +672,51 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt, 
			scale = sib >> 6;



			if ((base_reg & 7) == 5 && c->modrm_mod == 0)

				c->modrm_ea += insn_fetch(s32, 4, c->eip);

				modrm_ea += insn_fetch(s32, 4, c->eip);

			else

				c->modrm_ea += c->regs[base_reg];

				modrm_ea += c->regs[base_reg];

			if (index_reg != 4)

				c->modrm_ea += c->regs[index_reg] << scale;

				modrm_ea += c->regs[index_reg] << scale;

		} else if ((c->modrm_rm & 7) == 5 && c->modrm_mod == 0) {

			if (ctxt->mode == X86EMUL_MODE_PROT64)

				c->rip_relative = 1;

		} else

			c->modrm_ea += c->regs[c->modrm_rm];

			modrm_ea += c->regs[c->modrm_rm];

		switch (c->modrm_mod) {

		case 0:

			if (c->modrm_rm == 5)

				c->modrm_ea += insn_fetch(s32, 4, c->eip);

				modrm_ea += insn_fetch(s32, 4, c->eip);

			break;

		case 1:

			c->modrm_ea += insn_fetch(s8, 1, c->eip);

			modrm_ea += insn_fetch(s8, 1, c->eip);

			break;

		case 2:

			c->modrm_ea += insn_fetch(s32, 4, c->eip);

			modrm_ea += insn_fetch(s32, 4, c->eip);

			break;

		}

	}

	op->addr.mem = modrm_ea;

done:

	return rc;

}



static int decode_abs(struct x86_emulate_ctxt *ctxt,

		      struct x86_emulate_ops *ops)

		      struct x86_emulate_ops *ops,

		      struct operand *op)

{

	struct decode_cache *c = &ctxt->decode;

	int rc = X86EMUL_CONTINUE;



	op->type = OP_MEM;

	switch (c->ad_bytes) {

	case 2:

		c->modrm_ea = insn_fetch(u16, 2, c->eip);

		op->addr.mem = insn_fetch(u16, 2, c->eip);

		break;

	case 4:

		c->modrm_ea = insn_fetch(u32, 4, c->eip);

		op->addr.mem = insn_fetch(u32, 4, c->eip);

		break;

	case 8:

		c->modrm_ea = insn_fetch(u64, 8, c->eip);

		op->addr.mem = insn_fetch(u64, 8, c->eip);

		break;

	}

done:
@@ -2280,6 +2288,7 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt) 
	int mode = ctxt->mode;

	int def_op_bytes, def_ad_bytes, dual, goffset;

	struct opcode opcode, *g_mod012, *g_mod3;

	struct operand memop = { .type = OP_NONE };



	/* we cannot decode insn before we complete previous rep insn */

	WARN_ON(ctxt->restart);
@@ -2418,25 +2427,25 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt) 


	/* ModRM and SIB bytes. */

	if (c->d & ModRM) {

		rc = decode_modrm(ctxt, ops);

		rc = decode_modrm(ctxt, ops, &memop);

		if (!c->has_seg_override)

			set_seg_override(c, c->modrm_seg);

	} else if (c->d & MemAbs)

		rc = decode_abs(ctxt, ops);

		rc = decode_abs(ctxt, ops, &memop);

	if (rc != X86EMUL_CONTINUE)

		goto done;



	if (!c->has_seg_override)

		set_seg_override(c, VCPU_SREG_DS);



	if (!(!c->twobyte && c->b == 0x8d))

		c->modrm_ea += seg_override_base(ctxt, ops, c);

	if (memop.type == OP_MEM && !(!c->twobyte && c->b == 0x8d))

		memop.addr.mem += seg_override_base(ctxt, ops, c);



	if (c->ad_bytes != 8)

		c->modrm_ea = (u32)c->modrm_ea;

	if (memop.type == OP_MEM && c->ad_bytes != 8)

		memop.addr.mem = (u32)memop.addr.mem;



	if (c->rip_relative)

		c->modrm_ea += c->eip;

	if (memop.type == OP_MEM && c->rip_relative)

		memop.addr.mem += c->eip;



	/*

	 * Decode and fetch the source operand: register, memory
@@ -2449,31 +2458,16 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt) 
		decode_register_operand(&c->src, c, 0);

		break;

	case SrcMem16:

		c->src.bytes = 2;

		memop.bytes = 2;

		goto srcmem_common;

	case SrcMem32:

		c->src.bytes = 4;

		memop.bytes = 4;

		goto srcmem_common;

	case SrcMem:

		c->src.bytes = (c->d & ByteOp) ? 1 :

		memop.bytes = (c->d & ByteOp) ? 1 :

							   c->op_bytes;

		/* Don't fetch the address for invlpg: it could be unmapped. */

		if (c->d & NoAccess)

			break;

	srcmem_common:

		/*

		 * For instructions with a ModR/M byte, switch to register

		 * access if Mod = 3.

		 */

		if ((c->d & ModRM) && c->modrm_mod == 3) {

			c->src.type = OP_REG;

			c->src.val = c->modrm_val;

			c->src.addr.reg = c->modrm_ptr;

			break;

		}

		c->src.type = OP_MEM;

		c->src.addr.mem = c->modrm_ea;

		c->src.val = 0;

		c->src = memop;

		break;

	case SrcImm:

	case SrcImmU:
@@ -2543,9 +2537,8 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt) 
		insn_fetch_arr(c->src.valptr, c->src.bytes, c->eip);

		break;

	case SrcMemFAddr:

		c->src.type = OP_MEM;

		c->src.addr.mem = c->modrm_ea;

		c->src.bytes = c->op_bytes + 2;

		memop.bytes = c->op_bytes + 2;

		goto srcmem_common;

		break;

	}
@@ -2583,26 +2576,18 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt) 
		break;

	case DstMem:

	case DstMem64:

		if ((c->d & ModRM) && c->modrm_mod == 3) {

			c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;

			c->dst.type = OP_REG;

			c->dst.val = c->dst.orig_val = c->modrm_val;

			c->dst.addr.reg = c->modrm_ptr;

			break;

		}

		c->dst.type = OP_MEM;

		c->dst.addr.mem = c->modrm_ea;

		c->dst = memop;

		if ((c->d & DstMask) == DstMem64)

			c->dst.bytes = 8;

		else

			c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;

		c->dst.val = 0;

		if (c->d & BitOp) {

		if (c->dst.type == OP_MEM && (c->d & BitOp)) {

			unsigned long mask = ~(c->dst.bytes * 8 - 1);



			c->dst.addr.mem = c->dst.addr.mem +

						   (c->src.val & mask) / 8;

		}

		c->dst.orig_val = c->dst.val;

		break;

	case DstAcc:

		c->dst.type = OP_REG;
@@ -2682,11 +2667,15 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt) 
	}



	if (c->src.type == OP_MEM) {

		if (c->d & NoAccess)

			goto no_fetch;

		rc = read_emulated(ctxt, ops, c->src.addr.mem,

					c->src.valptr, c->src.bytes);

		if (rc != X86EMUL_CONTINUE)

			goto done;

		c->src.orig_val64 = c->src.val64;

	no_fetch:

		;

	}



	if (c->src2.type == OP_MEM) {