This patch emulates the CMPS instruction. I made corrections requested
by Avi (removed macro and added the memory access). I fixed an
inversion between arguments VCPU_REGS_RSI and VCPU_REGS_RDI in function
register_address(). I also added the test if DS segment is overridden
with a segment override prefix (ES segment cannot be overriden).
Signed-off-by: Guillaume Thouvenin [EMAIL PROTECTED]
---
drivers/kvm/x86_emulate.c | 58 +++--
1 files changed, 56 insertions(+), 2 deletions(-)
diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index cee60eb..9eb9922 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -1540,10 +1540,31 @@ special_insn:
break;
}
if (c-rep_prefix) {
+ /* All REP prefixes have the same first termination condition */
if (c-regs[VCPU_REGS_RCX] == 0) {
ctxt-vcpu-rip = c-eip;
goto done;
}
+ /* The second termination condition only applies for REPE
+* and REPNE. Test if the repeat string operation prefix is
+* REPE/REPZ or REPNE/REPNZ and if it's the case it tests the
+* corresponding termination condition according to:
+* - if REPE/REPZ and ZF = 0 then done
+* - if REPNE/REPNZ and ZF = 1 then done
+*/
+ if ((c-b == 0xa6) || (c-b == 0xa7) ||
+ (c-b == 0xae) || (c-b == 0xaf)) {
+ if ((c-rep_prefix == REPE_PREFIX)
+ ((ctxt-eflags EFLG_ZF) == 0)) {
+ ctxt-vcpu-rip = c-eip;
+ goto done;
+ }
+ if ((c-rep_prefix == REPNE_PREFIX)
+ ((ctxt-eflags EFLG_ZF) == EFLG_ZF)) {
+ ctxt-vcpu-rip = c-eip;
+ goto done;
+ }
+ }
c-regs[VCPU_REGS_RCX]--;
c-eip = ctxt-vcpu-rip;
}
@@ -1570,8 +1591,41 @@ special_insn:
: c-dst.bytes);
break;
case 0xa6 ... 0xa7: /* cmps */
- DPRINTF(Urk! I don't handle CMPS.\n);
- goto cannot_emulate;
+ c-src.type = OP_NONE; /* Disable writeback. */
+ c-src.bytes = (c-d ByteOp) ? 1 : c-op_bytes;
+ c-src.ptr = (unsigned long *)register_address(
+ c-override_base ? *c-override_base :
+ ctxt-ds_base,
+ c-regs[VCPU_REGS_RSI]);
+ if ((rc = ops-read_emulated((unsigned long)c-src.ptr,
+ c-src.val,
+ c-src.bytes,
+ ctxt-vcpu)) != 0)
+ goto done;
+
+ c-dst.type = OP_NONE; /* Disable writeback. */
+ c-dst.bytes = (c-d ByteOp) ? 1 : c-op_bytes;
+ c-dst.ptr = (unsigned long *)register_address(
+ ctxt-es_base,
+ c-regs[VCPU_REGS_RDI]);
+ if ((rc = ops-read_emulated((unsigned long)c-dst.ptr,
+ c-dst.val,
+ c-dst.bytes,
+ ctxt-vcpu)) != 0)
+ goto done;
+
+ DPRINTF(cmps: mem1=0x%p mem2=0x%p\n, c-src.ptr, c-dst.ptr);
+
+ emulate_2op_SrcV(cmp, c-src, c-dst, ctxt-eflags);
+
+ register_address_increment(c-regs[VCPU_REGS_RSI],
+ (ctxt-eflags EFLG_DF) ? -c-src.bytes
+ : c-src.bytes);
+ register_address_increment(c-regs[VCPU_REGS_RDI],
+ (ctxt-eflags EFLG_DF) ? -c-dst.bytes
+ : c-dst.bytes);
+
+ break;
case 0xaa ... 0xab: /* stos */
c-dst.type = OP_MEM;
c-dst.bytes = (c-d ByteOp) ? 1 : c-op_bytes;
-
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