From 26c26ff17aabf675863b9882eee186fafbb5ff4e Mon Sep 17 00:00:00 2001 From: Keir Fraser Date: Fri, 25 Jul 2008 14:00:27 +0100 Subject: [PATCH] x86_emulate: fix unintended writeback on cmp/test instructions This patch fixes an issue when x86_emulate is called with force_writeback=1 set. It resulted in cmp and test instructions with memory operands to have the mem value written back after instruction emulation finished. This caused false alarms on writes to RO mem, and might have caused other issues if unintended writes occured to device registers in mmio space. Signed-off-by: Trolle Selander --- xen/arch/x86/x86_emulate/x86_emulate.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c index 600705ff84..6fc1955783 100644 --- a/xen/arch/x86/x86_emulate/x86_emulate.c +++ b/xen/arch/x86/x86_emulate/x86_emulate.c @@ -1606,6 +1606,7 @@ x86_emulate( dst.val = _regs.eax; case 0x38 ... 0x3b: cmp: /* cmp */ emulate_2op_SrcV("cmp", src, dst, _regs.eflags); + dst.type = OP_NONE; break; case 0x62: /* bound */ { @@ -1707,6 +1708,7 @@ x86_emulate( dst.val = _regs.eax; case 0x84 ... 0x85: test: /* test */ emulate_2op_SrcV("test", src, dst, _regs.eflags); + dst.type = OP_NONE; break; case 0x86 ... 0x87: xchg: /* xchg */ -- 2.30.2