From 7584e4be286e43ccfda4c8435549cd22d73200b7 Mon Sep 17 00:00:00 2001 From: "kfraser@localhost.localdomain" Date: Mon, 16 Apr 2007 17:47:37 +0100 Subject: [PATCH] hvm: Fix get_immediate() in mmio decoder by reverting Dexuan Cui's change that breaks the case mod==0, rm==4, sib&7==5. That is, disp32(scaled-index). Also simplify get_immediate with sign extension. Signed-off-by: Keir Fraser --- xen/arch/x86/hvm/platform.c | 31 ++++++++----------------------- 1 file changed, 8 insertions(+), 23 deletions(-) diff --git a/xen/arch/x86/hvm/platform.c b/xen/arch/x86/hvm/platform.c index caa2b377c9..7bad53ab1a 100644 --- a/xen/arch/x86/hvm/platform.c +++ b/xen/arch/x86/hvm/platform.c @@ -221,6 +221,7 @@ static inline unsigned long get_immediate(int ad_size, const unsigned char *inst inst++; //skip ModR/M byte if ( ad_size != WORD && mod != 3 && rm == 4 ) { + rm = *inst & 7; inst++; //skip SIB byte } @@ -256,31 +257,15 @@ static inline unsigned long get_immediate(int ad_size, const unsigned char *inst return val; } -/* Some instructions, like "add $imm8, r/m16"/"MOV $imm32, r/m64" require - * the src immediate operand be sign-extented befere the op is executed. Here - * we always sign-extend the operand to a "unsigned long" variable. - * - * Note: to simplify the logic here, the sign-extension here may be performed - * redundantly against some instructions, like "MOV $imm16, r/m16" -- however - * this is harmless, since we always remember the operand's size. - */ -static inline unsigned long get_immediate_sign_ext(int ad_size, - const unsigned char *inst, - int op_size) +static inline unsigned long get_immediate_sign_ext( + int ad_size, const unsigned char *inst, int op_size) { unsigned long result = get_immediate(ad_size, inst, op_size); - - if ( op_size == QUAD ) - op_size = LONG; - - ASSERT( op_size == BYTE || op_size == WORD || op_size == LONG ); - - if ( result & (1UL << ((8*op_size) - 1)) ) - { - unsigned long mask = ~0UL >> (8 * (sizeof(mask) - op_size)); - result = ~mask | (result & mask); - } - return result; + if ( op_size == BYTE ) + return (int8_t)result; + if ( op_size == WORD ) + return (int16_t)result; + return (int32_t)result; } static inline int get_index(const unsigned char *inst, unsigned char rex) -- 2.30.2