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KVM: x86 emulator: implement ENTER

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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: Avi Kivity <avi@redhat.com>
This commit is contained in:
Avi Kivity 2012-06-12 20:03:23 +03:00
parent 51ddff50cb
commit 612e89f015
1 changed files with 27 additions and 1 deletions
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28
arch/x86/kvm/emulate.c
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@ -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 */