From e09d082c03e137015bc0a17ca77e4b9dca08a5d7 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Fri, 18 Jan 2008 12:38:59 +0200 Subject: [PATCH] KVM: x86 emulator: add support for group decoding Certain x86 instructions use bits 3:5 of the byte following the opcode as an opcode extension, with the decode sometimes depending on bits 6:7 as well. Add support for this in the main decoding table rather than an ad-hock adaptation per opcode. Signed-off-by: Avi Kivity --- arch/x86/kvm/x86_emulate.c | 33 +++++++++++++++++++++++++++------ 1 file changed, 27 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c index 7958600339..46ecf349a1 100644 --- a/arch/x86/kvm/x86_emulate.c +++ b/arch/x86/kvm/x86_emulate.c @@ -65,6 +65,9 @@ #define MemAbs (1<<9) /* Memory operand is absolute displacement */ #define String (1<<10) /* String instruction (rep capable) */ #define Stack (1<<11) /* Stack instruction (push/pop) */ +#define Group (1<<14) /* Bits 3:5 of modrm byte extend opcode */ +#define GroupDual (1<<15) /* Alternate decoding of mod == 3 */ +#define GroupMask 0xff /* Group number stored in bits 0:7 */ static u16 opcode_table[256] = { /* 0x00 - 0x07 */ @@ -229,6 +232,12 @@ static u16 twobyte_table[256] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; +static u16 group_table[] = { +}; + +static u16 group2_table[] = { +}; + /* EFLAGS bit definitions. */ #define EFLG_OF (1<<11) #define EFLG_DF (1<<10) @@ -763,7 +772,7 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) struct decode_cache *c = &ctxt->decode; int rc = 0; int mode = ctxt->mode; - int def_op_bytes, def_ad_bytes; + int def_op_bytes, def_ad_bytes, group; /* Shadow copy of register state. Committed on successful emulation. */ @@ -864,12 +873,24 @@ done_prefixes: c->b = insn_fetch(u8, 1, c->eip); c->d = twobyte_table[c->b]; } + } - /* Unrecognised? */ - if (c->d == 0) { - DPRINTF("Cannot emulate %02x\n", c->b); - return -1; - } + if (c->d & Group) { + group = c->d & GroupMask; + c->modrm = insn_fetch(u8, 1, c->eip); + --c->eip; + + group = (group << 3) + ((c->modrm >> 3) & 7); + if ((c->d & GroupDual) && (c->modrm >> 6) == 3) + c->d = group2_table[group]; + else + c->d = group_table[group]; + } + + /* Unrecognised? */ + if (c->d == 0) { + DPRINTF("Cannot emulate %02x\n", c->b); + return -1; } if (mode == X86EMUL_MODE_PROT64 && (c->d & Stack)) -- 2.39.5