On Tue, Sep 1, 2009 at 2:57 PM, Marcelo Tosatti<mtosatti@xxxxxxxxxx> wrote:
> 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?
Right. Perhaps this is a little too paranoid since we'll fail anyway
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