When REP-string instruction is preceded with an address-size prefix,
ECX/EDI/ESI are used as the operation counter and pointers. When they are
updated, the high 32-bits of RCX/RDI/RSI are cleared, similarly to the way they
are updated on every 32-bit register operation. Fix it.
Signed-off-by: Nadav Amit <na...@cs.technion.ac.il>
---
arch/x86/kvm/emulate.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index c1bc650..296d58e 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -524,13 +524,9 @@ static void masked_increment(ulong *reg, ulong mask, int
inc)
static inline void
register_address_increment(struct x86_emulate_ctxt *ctxt, int reg, int inc)
{
- ulong mask;
+ ulong *preg = reg_rmw(ctxt, reg);
- if (ctxt->ad_bytes == sizeof(unsigned long))
- mask = ~0UL;
- else
- mask = ad_mask(ctxt);
- masked_increment(reg_rmw(ctxt, reg), mask, inc);
+ assign_register(preg, *preg + inc, ctxt->ad_bytes);
}
static void rsp_increment(struct x86_emulate_ctxt *ctxt, int inc)
--
2.1.4
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