Messages in this thread Patch in this message | | | From | Nadav Amit <> | Subject | [PATCH 5/5] KVM: x86: Fix wrong masking on relative jump/call | Date | Wed, 7 May 2014 15:32:52 +0300 |
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Relative jumps and calls do the masking according to the operand size, and not according to the address size as the KVM emulator does today. In 64-bit mode, the resulting RIP is always 64-bit. Otherwise it is masked according to the instruction operand-size. Note that when 16-bit address size is used, bits 63:32 are unmodified.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> --- arch/x86/kvm/emulate.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 6833b41..e406705 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -506,7 +506,9 @@ static void rsp_increment(struct x86_emulate_ctxt *ctxt, int inc) static inline void jmp_rel(struct x86_emulate_ctxt *ctxt, int rel) { - register_address_increment(ctxt, &ctxt->_eip, rel); + /* 64-bit mode relative jumps are always 64-bit; otherwise mask */ + int op_bytes = ctxt->mode == X86EMUL_MODE_PROT64 ? 8 : ctxt->op_bytes; + masked_increment(&ctxt->eip, op_bytes, rel); } static u32 desc_limit_scaled(struct desc_struct *desc) -- 1.9.1
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