On Tue, Sep 01, 2009 at 03:26:30AM +0200, Mohammed Gamal wrote:
> This adds pusha and popa instructions (opcodes 0x60-0x61), this enables booting
> MINIX with invalid guest state emulation on.
>
> Signed-off-by: Mohammed Gamal <m.gamal005@xxxxxxxxx>
> ---
> arch/x86/kvm/emulate.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 51 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index db0820d..9be2e6e 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -139,7 +139,8 @@ static u32 opcode_table[256] = {
> DstReg | Stack, DstReg | Stack, DstReg | Stack, DstReg | Stack,
> DstReg | Stack, DstReg | Stack, DstReg | Stack, DstReg | Stack,
> /* 0x60 - 0x67 */
> - 0, 0, 0, DstReg | SrcMem32 | ModRM | Mov /* movsxd (x86/64) */ ,
> + ImplicitOps | Stack | No64, ImplicitOps | Stack | No64,
> + 0, DstReg | SrcMem32 | ModRM | Mov /* movsxd (x86/64) */ ,
> 0, 0, 0, 0,
> /* 0x68 - 0x6F */
> SrcImm | Mov | Stack, 0, SrcImmByte | Mov | Stack, 0,
> @@ -1225,6 +1226,47 @@ static int emulate_pop_sreg(struct x86_emulate_ctxt *ctxt,
> return rc;
> }
>
> +static void emulate_pusha(struct x86_emulate_ctxt *ctxt)
> +{
> + struct decode_cache *c = &ctxt->decode;
> + unsigned long old_esp = c->regs[VCPU_REGS_RSP];
> + int reg = VCPU_REGS_RAX;
> +
> + while (reg <= VCPU_REGS_RDI) {
> + (reg == VCPU_REGS_RSP) ?
> + (c->src.val = old_esp) : (c->src.val = c->regs[reg]);
> +
> + emulate_push(ctxt);
> + ++reg;
> + }
> +}
> +
> +static int emulate_popa(struct x86_emulate_ctxt *ctxt,
> + struct x86_emulate_ops *ops)
> +{
> + struct decode_cache *c = &ctxt->decode;
> + unsigned long old_esp = c->regs[VCPU_REGS_RSP];
> + int rc = 0;
> + int reg = VCPU_REGS_RDI;
> +
> + while (reg >= VCPU_REGS_RAX) {
> + if (reg == VCPU_REGS_RSP) {
> + register_address_increment(c, &c->regs[VCPU_REGS_RSP],
> + c->op_bytes);
> + --reg;
> + }
> +
> + rc = emulate_pop(ctxt, ops, &c->regs[reg], c->op_bytes);
> + if (rc != 0) {
> + c->regs[VCPU_REGS_RSP] = old_esp;
Why is it necessary to restore the local VCPU_REGS_RSP copy on failure?
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