Commit 612e89f0 authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: x86 emulator: implement ENTER 



Opcode C8.

Only ENTER with lexical nesting depth 0 is implemented, since others are
very rare.  We'll fail emulation if nonzero lexical depth is used so data
is not corrupted.

Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 51ddff50

arch/x86/kvm/emulate.c

+27 −1
Original line number Diff line number Diff line
@@ -454,6 +454,11 @@ static ulong stack_mask(struct x86_emulate_ctxt *ctxt) 
	return ~0U >> ((ss.d ^ 1) * 16);  /* d=0: 0xffff; d=1: 0xffffffff */

}



static int stack_size(struct x86_emulate_ctxt *ctxt)

{

	return (__fls(stack_mask(ctxt)) + 1) >> 3;

}



/* Access/update address held in a register, based on addressing mode. */

static inline unsigned long

address_mask(struct x86_emulate_ctxt *ctxt, unsigned long reg)
@@ -1592,6 +1597,26 @@ static int em_popf(struct x86_emulate_ctxt *ctxt) 
	return emulate_popf(ctxt, &ctxt->dst.val, ctxt->op_bytes);

}



static int em_enter(struct x86_emulate_ctxt *ctxt)

{

	int rc;

	unsigned frame_size = ctxt->src.val;

	unsigned nesting_level = ctxt->src2.val & 31;



	if (nesting_level)

		return X86EMUL_UNHANDLEABLE;



	rc = push(ctxt, &ctxt->regs[VCPU_REGS_RBP], stack_size(ctxt));

	if (rc != X86EMUL_CONTINUE)

		return rc;

	assign_masked(&ctxt->regs[VCPU_REGS_RBP], ctxt->regs[VCPU_REGS_RSP],

		      stack_mask(ctxt));

	assign_masked(&ctxt->regs[VCPU_REGS_RSP],

		      ctxt->regs[VCPU_REGS_RSP] - frame_size,

		      stack_mask(ctxt));

	return X86EMUL_CONTINUE;

}



static int em_leave(struct x86_emulate_ctxt *ctxt)

{

	assign_masked(&ctxt->regs[VCPU_REGS_RSP], ctxt->regs[VCPU_REGS_RBP],
@@ -3657,7 +3682,8 @@ static struct opcode opcode_table[256] = { 
	I(DstReg | SrcMemFAddr | ModRM | No64 | Src2DS, em_lseg),

	G(ByteOp, group11), G(0, group11),

	/* 0xC8 - 0xCF */

	N, I(Stack, em_leave), N, I(ImplicitOps | Stack, em_ret_far),

	I(Stack | SrcImmU16 | Src2ImmByte, em_enter), I(Stack, em_leave),

	N, I(ImplicitOps | Stack, em_ret_far),

	D(ImplicitOps), DI(SrcImmByte, intn),

	D(ImplicitOps | No64), II(ImplicitOps, em_iret, iret),

	/* 0xD0 - 0xD7 */