redonkable/remarkable-linux
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KVM: x86: POP [ESP] is not emulated correctly

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According to Intel SDM: "If the ESP register is used as a base register for
addressing a destination operand in memory, the POP instruction computes the
effective address of the operand after it increments the ESP register."

The current emulation does not behave so. The fix required to waste another
of the precious instruction flags and to check the flag in decode_modrm.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Nadav Amit 2014-12-25 02:52:21 +02:00 committed by Paolo Bonzini
parent 80976dbb5c
commit ab708099a0
1 changed files with 6 additions and 1 deletions
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7
arch/x86/kvm/emulate.c
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@ -170,6 +170,7 @@
#define PrivUD ((u64)1 << 51) /* #UD instead of #GP on CPL > 0 */
#define NearBranch ((u64)1 << 52) /* Near branches */
#define No16 ((u64)1 << 53) /* No 16 bit operand */
#define IncSP ((u64)1 << 54) /* SP is incremented before ModRM calc */
#define DstXacc (DstAccLo | SrcAccHi | SrcWrite)
@ -1227,6 +1228,10 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
else {
modrm_ea += reg_read(ctxt, base_reg);
adjust_modrm_seg(ctxt, base_reg);
/* Increment ESP on POP [ESP] */
if ((ctxt->d & IncSP) &&
base_reg == VCPU_REGS_RSP)
modrm_ea += ctxt->op_bytes;
}
if (index_reg != 4)
modrm_ea += reg_read(ctxt, index_reg) << scale;
@ -3758,7 +3763,7 @@ static const struct opcode group1[] = {
};
static const struct opcode group1A[] = {
I(DstMem | SrcNone | Mov | Stack, em_pop), N, N, N, N, N, N, N,
I(DstMem | SrcNone | Mov | Stack | IncSP, em_pop), N, N, N, N, N, N, N,
};
static const struct opcode group2[] = {