Commit 4179bb02 authored by Takuya Yoshikawa's avatar Takuya Yoshikawa Committed by Avi Kivity
Browse files

KVM: x86 emulator: Make emulate_push() store the value directly 



PUSH emulation stores the value by calling writeback() after setting
the dst operand appropriately in emulate_push().

This writeback() using dst is not needed at all because we know the
target is the stack.  So this patch makes emulate_push() call, newly
introduced, segmented_write() directly.

By this, many inlined writeback()'s are removed.

Signed-off-by: default avatarTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 575e7c14

arch/x86/kvm/emulate.c

+34 −53
Original line number Diff line number Diff line
@@ -1345,17 +1345,19 @@ static inline int writeback(struct x86_emulate_ctxt *ctxt, 
	return X86EMUL_CONTINUE;

}



static inline void emulate_push(struct x86_emulate_ctxt *ctxt,

static int emulate_push(struct x86_emulate_ctxt *ctxt,

			struct x86_emulate_ops *ops)

{

	struct decode_cache *c = &ctxt->decode;

	struct segmented_address addr;



	c->dst.type  = OP_MEM;

	c->dst.bytes = c->op_bytes;

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

	register_address_increment(c, &c->regs[VCPU_REGS_RSP], -c->op_bytes);

	c->dst.addr.mem.ea = register_address(c, c->regs[VCPU_REGS_RSP]);

	c->dst.addr.mem.seg = VCPU_SREG_SS;

	addr.ea = register_address(c, c->regs[VCPU_REGS_RSP]);

	addr.seg = VCPU_SREG_SS;



	/* Disable writeback. */

	c->dst.type = OP_NONE;

	return segmented_write(ctxt, addr, &c->src.val, c->op_bytes);

}



static int emulate_pop(struct x86_emulate_ctxt *ctxt,
@@ -1417,14 +1419,14 @@ static int emulate_popf(struct x86_emulate_ctxt *ctxt, 
	return rc;

}



static void emulate_push_sreg(struct x86_emulate_ctxt *ctxt,

static int emulate_push_sreg(struct x86_emulate_ctxt *ctxt,

			     struct x86_emulate_ops *ops, int seg)

{

	struct decode_cache *c = &ctxt->decode;



	c->src.val = ops->get_segment_selector(seg, ctxt->vcpu);



	emulate_push(ctxt, ops);

	return emulate_push(ctxt, ops);

}



static int emulate_pop_sreg(struct x86_emulate_ctxt *ctxt,
@@ -1454,18 +1456,13 @@ static int emulate_pusha(struct x86_emulate_ctxt *ctxt, 
		(reg == VCPU_REGS_RSP) ?

		(c->src.val = old_esp) : (c->src.val = c->regs[reg]);



		emulate_push(ctxt, ops);



		rc = writeback(ctxt, ops);

		rc = emulate_push(ctxt, ops);

		if (rc != X86EMUL_CONTINUE)

			return rc;



		++reg;

	}



	/* Disable writeback. */

	c->dst.type = OP_NONE;



	return rc;

}
@@ -1503,27 +1500,22 @@ int emulate_int_real(struct x86_emulate_ctxt *ctxt, 


	/* TODO: Add limit checks */

	c->src.val = ctxt->eflags;

	emulate_push(ctxt, ops);

	rc = writeback(ctxt, ops);

	rc = emulate_push(ctxt, ops);

	if (rc != X86EMUL_CONTINUE)

		return rc;



	ctxt->eflags &= ~(EFLG_IF | EFLG_TF | EFLG_AC);



	c->src.val = ops->get_segment_selector(VCPU_SREG_CS, ctxt->vcpu);

	emulate_push(ctxt, ops);

	rc = writeback(ctxt, ops);

	rc = emulate_push(ctxt, ops);

	if (rc != X86EMUL_CONTINUE)

		return rc;



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

	emulate_push(ctxt, ops);

	rc = writeback(ctxt, ops);

	rc = emulate_push(ctxt, ops);

	if (rc != X86EMUL_CONTINUE)

		return rc;



	c->dst.type = OP_NONE;



	ops->get_idt(&dt, ctxt->vcpu);



	eip_addr = dt.address + (irq << 2);
@@ -1713,6 +1705,7 @@ static inline int emulate_grp45(struct x86_emulate_ctxt *ctxt, 
			       struct x86_emulate_ops *ops)

{

	struct decode_cache *c = &ctxt->decode;

	int rc = X86EMUL_CONTINUE;



	switch (c->modrm_reg) {

	case 0:	/* inc */
@@ -1726,17 +1719,17 @@ static inline int emulate_grp45(struct x86_emulate_ctxt *ctxt, 
		old_eip = c->eip;

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

		c->src.val = old_eip;

		emulate_push(ctxt, ops);

		rc = emulate_push(ctxt, ops);

		break;

	}

	case 4: /* jmp abs */

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

		break;

	case 6:	/* push */

		emulate_push(ctxt, ops);

		rc = emulate_push(ctxt, ops);

		break;

	}

	return X86EMUL_CONTINUE;

	return rc;

}



static inline int emulate_grp9(struct x86_emulate_ctxt *ctxt,
@@ -2380,7 +2373,7 @@ static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt, 
		c->op_bytes = c->ad_bytes = (next_tss_desc.type & 8) ? 4 : 2;

		c->lock_prefix = 0;

		c->src.val = (unsigned long) error_code;

		emulate_push(ctxt, ops);

		ret = emulate_push(ctxt, ops);

	}



	return ret;
@@ -2400,11 +2393,8 @@ int emulator_task_switch(struct x86_emulate_ctxt *ctxt, 
	rc = emulator_do_task_switch(ctxt, ops, tss_selector, reason,

				     has_error_code, error_code);



	if (rc == X86EMUL_CONTINUE) {

		rc = writeback(ctxt, ops);

	if (rc == X86EMUL_CONTINUE)

		ctxt->eip = c->eip;

	}



	return (rc == X86EMUL_UNHANDLEABLE) ? EMULATION_FAILED : EMULATION_OK;

}
@@ -2422,8 +2412,7 @@ static void string_addr_inc(struct x86_emulate_ctxt *ctxt, unsigned seg, 


static int em_push(struct x86_emulate_ctxt *ctxt)

{

	emulate_push(ctxt, ctxt->ops);

	return X86EMUL_CONTINUE;

	return emulate_push(ctxt, ctxt->ops);

}



static int em_das(struct x86_emulate_ctxt *ctxt)
@@ -2483,20 +2472,12 @@ static int em_call_far(struct x86_emulate_ctxt *ctxt) 
	memcpy(&c->eip, c->src.valptr, c->op_bytes);



	c->src.val = old_cs;

	emulate_push(ctxt, ctxt->ops);

	rc = writeback(ctxt, ctxt->ops);

	rc = emulate_push(ctxt, ctxt->ops);

	if (rc != X86EMUL_CONTINUE)

		return rc;



	c->src.val = old_eip;

	emulate_push(ctxt, ctxt->ops);

	rc = writeback(ctxt, ctxt->ops);

	if (rc != X86EMUL_CONTINUE)

		return rc;



	c->dst.type = OP_NONE;



	return X86EMUL_CONTINUE;

	return emulate_push(ctxt, ctxt->ops);

}



static int em_ret_near_imm(struct x86_emulate_ctxt *ctxt)
@@ -3625,7 +3606,7 @@ special_insn: 
		emulate_2op_SrcV("add", c->src, c->dst, ctxt->eflags);

		break;

	case 0x06:		/* push es */

		emulate_push_sreg(ctxt, ops, VCPU_SREG_ES);

		rc = emulate_push_sreg(ctxt, ops, VCPU_SREG_ES);

		break;

	case 0x07:		/* pop es */

		rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_ES);
@@ -3635,14 +3616,14 @@ special_insn: 
		emulate_2op_SrcV("or", c->src, c->dst, ctxt->eflags);

		break;

	case 0x0e:		/* push cs */

		emulate_push_sreg(ctxt, ops, VCPU_SREG_CS);

		rc = emulate_push_sreg(ctxt, ops, VCPU_SREG_CS);

		break;

	case 0x10 ... 0x15:

	      adc:		/* adc */

		emulate_2op_SrcV("adc", c->src, c->dst, ctxt->eflags);

		break;

	case 0x16:		/* push ss */

		emulate_push_sreg(ctxt, ops, VCPU_SREG_SS);

		rc = emulate_push_sreg(ctxt, ops, VCPU_SREG_SS);

		break;

	case 0x17:		/* pop ss */

		rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_SS);
@@ -3652,7 +3633,7 @@ special_insn: 
		emulate_2op_SrcV("sbb", c->src, c->dst, ctxt->eflags);

		break;

	case 0x1e:		/* push ds */

		emulate_push_sreg(ctxt, ops, VCPU_SREG_DS);

		rc = emulate_push_sreg(ctxt, ops, VCPU_SREG_DS);

		break;

	case 0x1f:		/* pop ds */

		rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_DS);
@@ -3789,7 +3770,7 @@ special_insn: 
		break;

	case 0x9c: /* pushf */

		c->src.val =  (unsigned long) ctxt->eflags;

		emulate_push(ctxt, ops);

		rc = emulate_push(ctxt, ops);

		break;

	case 0x9d: /* popf */

		c->dst.type = OP_REG;
@@ -3864,7 +3845,7 @@ special_insn: 
		long int rel = c->src.val;

		c->src.val = (unsigned long) c->eip;

		jmp_rel(c, rel);

		emulate_push(ctxt, ops);

		rc = emulate_push(ctxt, ops);

		break;

	}

	case 0xe9: /* jmp rel */
@@ -4157,7 +4138,7 @@ twobyte_insn: 
		c->dst.val = test_cc(c->b, ctxt->eflags);

		break;

	case 0xa0:	  /* push fs */

		emulate_push_sreg(ctxt, ops, VCPU_SREG_FS);

		rc = emulate_push_sreg(ctxt, ops, VCPU_SREG_FS);

		break;

	case 0xa1:	 /* pop fs */

		rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_FS);
@@ -4174,7 +4155,7 @@ twobyte_insn: 
		emulate_2op_cl("shld", c->src2, c->src, c->dst, ctxt->eflags);

		break;

	case 0xa8:	/* push gs */

		emulate_push_sreg(ctxt, ops, VCPU_SREG_GS);

		rc = emulate_push_sreg(ctxt, ops, VCPU_SREG_GS);

		break;

	case 0xa9:	/* pop gs */

		rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_GS);

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