From 1c73ef66502311d9aff7fed7d7f970288329c6cb Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Thu, 1 Nov 2007 06:31:28 +0200 Subject: [PATCH] KVM: x86 emulator: Hoist modrm and abs decoding into separate functions Signed-off-by: Avi Kivity --- drivers/kvm/x86_emulate.c | 337 ++++++++++++++++++++------------------ 1 file changed, 177 insertions(+), 160 deletions(-) diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c index b352a6c4d4..64888a6edc 100644 --- a/drivers/kvm/x86_emulate.c +++ b/drivers/kvm/x86_emulate.c @@ -548,14 +548,182 @@ static void decode_register_operand(struct operand *op, op->orig_val = op->val; } +static int decode_modrm(struct x86_emulate_ctxt *ctxt, + struct x86_emulate_ops *ops) +{ + struct decode_cache *c = &ctxt->decode; + u8 sib; + int index_reg = 0, base_reg = 0, scale, rip_relative = 0; + int rc = 0; + + if (c->rex_prefix) { + c->modrm_reg = (c->rex_prefix & 4) << 1; /* REX.R */ + index_reg = (c->rex_prefix & 2) << 2; /* REX.X */ + c->modrm_rm = base_reg = (c->rex_prefix & 1) << 3; /* REG.B */ + } + + c->modrm = insn_fetch(u8, 1, c->eip); + c->modrm_mod |= (c->modrm & 0xc0) >> 6; + c->modrm_reg |= (c->modrm & 0x38) >> 3; + c->modrm_rm |= (c->modrm & 0x07); + c->modrm_ea = 0; + c->use_modrm_ea = 1; + + if (c->modrm_mod == 3) { + c->modrm_val = *(unsigned long *) + decode_register(c->modrm_rm, c->regs, c->d & ByteOp); + return rc; + } + + if (c->ad_bytes == 2) { + unsigned bx = c->regs[VCPU_REGS_RBX]; + unsigned bp = c->regs[VCPU_REGS_RBP]; + unsigned si = c->regs[VCPU_REGS_RSI]; + unsigned di = c->regs[VCPU_REGS_RDI]; + + /* 16-bit ModR/M decode. */ + switch (c->modrm_mod) { + case 0: + if (c->modrm_rm == 6) + c->modrm_ea += insn_fetch(u16, 2, c->eip); + break; + case 1: + c->modrm_ea += insn_fetch(s8, 1, c->eip); + break; + case 2: + c->modrm_ea += insn_fetch(u16, 2, c->eip); + break; + } + switch (c->modrm_rm) { + case 0: + c->modrm_ea += bx + si; + break; + case 1: + c->modrm_ea += bx + di; + break; + case 2: + c->modrm_ea += bp + si; + break; + case 3: + c->modrm_ea += bp + di; + break; + case 4: + c->modrm_ea += si; + break; + case 5: + c->modrm_ea += di; + break; + case 6: + if (c->modrm_mod != 0) + c->modrm_ea += bp; + break; + case 7: + c->modrm_ea += bx; + break; + } + if (c->modrm_rm == 2 || c->modrm_rm == 3 || + (c->modrm_rm == 6 && c->modrm_mod != 0)) + if (!c->override_base) + c->override_base = &ctxt->ss_base; + c->modrm_ea = (u16)c->modrm_ea; + } else { + /* 32/64-bit ModR/M decode. */ + switch (c->modrm_rm) { + case 4: + case 12: + sib = insn_fetch(u8, 1, c->eip); + index_reg |= (sib >> 3) & 7; + base_reg |= sib & 7; + scale = sib >> 6; + + switch (base_reg) { + case 5: + if (c->modrm_mod != 0) + c->modrm_ea += c->regs[base_reg]; + else + c->modrm_ea += + insn_fetch(s32, 4, c->eip); + break; + default: + c->modrm_ea += c->regs[base_reg]; + } + switch (index_reg) { + case 4: + break; + default: + c->modrm_ea += c->regs[index_reg] << scale; + } + break; + case 5: + if (c->modrm_mod != 0) + c->modrm_ea += c->regs[c->modrm_rm]; + else if (ctxt->mode == X86EMUL_MODE_PROT64) + rip_relative = 1; + break; + default: + c->modrm_ea += c->regs[c->modrm_rm]; + break; + } + switch (c->modrm_mod) { + case 0: + if (c->modrm_rm == 5) + c->modrm_ea += insn_fetch(s32, 4, c->eip); + break; + case 1: + c->modrm_ea += insn_fetch(s8, 1, c->eip); + break; + case 2: + c->modrm_ea += insn_fetch(s32, 4, c->eip); + break; + } + } + if (rip_relative) { + c->modrm_ea += c->eip; + switch (c->d & SrcMask) { + case SrcImmByte: + c->modrm_ea += 1; + break; + case SrcImm: + if (c->d & ByteOp) + c->modrm_ea += 1; + else + if (c->op_bytes == 8) + c->modrm_ea += 4; + else + c->modrm_ea += c->op_bytes; + } + } +done: + return rc; +} + +static int decode_abs(struct x86_emulate_ctxt *ctxt, + struct x86_emulate_ops *ops) +{ + struct decode_cache *c = &ctxt->decode; + int rc = 0; + + switch (c->ad_bytes) { + case 2: + c->modrm_ea = insn_fetch(u16, 2, c->eip); + break; + case 4: + c->modrm_ea = insn_fetch(u32, 4, c->eip); + break; + case 8: + c->modrm_ea = insn_fetch(u64, 8, c->eip); + break; + } +done: + return rc; +} + int x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) { struct decode_cache *c = &ctxt->decode; - u8 sib; int rc = 0; int mode = ctxt->mode; - int index_reg = 0, base_reg = 0, scale, rip_relative = 0; /* Shadow copy of register state. Committed on successful emulation. */ @@ -637,13 +805,9 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) done_prefixes: /* REX prefix. */ - if (c->rex_prefix) { + if (c->rex_prefix) if (c->rex_prefix & 8) c->op_bytes = 8; /* REX.W */ - c->modrm_reg = (c->rex_prefix & 4) << 1; /* REX.R */ - index_reg = (c->rex_prefix & 2) << 2; /* REX.X */ - c->modrm_rm = base_reg = (c->rex_prefix & 1) << 3; /* REG.B */ - } /* Opcode byte(s). */ c->d = opcode_table[c->b]; @@ -663,159 +827,12 @@ done_prefixes: } /* ModRM and SIB bytes. */ - if (c->d & ModRM) { - c->modrm = insn_fetch(u8, 1, c->eip); - c->modrm_mod |= (c->modrm & 0xc0) >> 6; - c->modrm_reg |= (c->modrm & 0x38) >> 3; - c->modrm_rm |= (c->modrm & 0x07); - c->modrm_ea = 0; - c->use_modrm_ea = 1; - - if (c->modrm_mod == 3) { - c->modrm_val = *(unsigned long *) - decode_register(c->modrm_rm, c->regs, c->d & ByteOp); - goto modrm_done; - } - - if (c->ad_bytes == 2) { - unsigned bx = c->regs[VCPU_REGS_RBX]; - unsigned bp = c->regs[VCPU_REGS_RBP]; - unsigned si = c->regs[VCPU_REGS_RSI]; - unsigned di = c->regs[VCPU_REGS_RDI]; - - /* 16-bit ModR/M decode. */ - switch (c->modrm_mod) { - case 0: - if (c->modrm_rm == 6) - c->modrm_ea += - insn_fetch(u16, 2, c->eip); - break; - case 1: - c->modrm_ea += insn_fetch(s8, 1, c->eip); - break; - case 2: - c->modrm_ea += insn_fetch(u16, 2, c->eip); - break; - } - switch (c->modrm_rm) { - case 0: - c->modrm_ea += bx + si; - break; - case 1: - c->modrm_ea += bx + di; - break; - case 2: - c->modrm_ea += bp + si; - break; - case 3: - c->modrm_ea += bp + di; - break; - case 4: - c->modrm_ea += si; - break; - case 5: - c->modrm_ea += di; - break; - case 6: - if (c->modrm_mod != 0) - c->modrm_ea += bp; - break; - case 7: - c->modrm_ea += bx; - break; - } - if (c->modrm_rm == 2 || c->modrm_rm == 3 || - (c->modrm_rm == 6 && c->modrm_mod != 0)) - if (!c->override_base) - c->override_base = &ctxt->ss_base; - c->modrm_ea = (u16)c->modrm_ea; - } else { - /* 32/64-bit ModR/M decode. */ - switch (c->modrm_rm) { - case 4: - case 12: - sib = insn_fetch(u8, 1, c->eip); - index_reg |= (sib >> 3) & 7; - base_reg |= sib & 7; - scale = sib >> 6; - - switch (base_reg) { - case 5: - if (c->modrm_mod != 0) - c->modrm_ea += - c->regs[base_reg]; - else - c->modrm_ea += - insn_fetch(s32, 4, c->eip); - break; - default: - c->modrm_ea += c->regs[base_reg]; - } - switch (index_reg) { - case 4: - break; - default: - c->modrm_ea += - c->regs[index_reg] << scale; - - } - break; - case 5: - if (c->modrm_mod != 0) - c->modrm_ea += c->regs[c->modrm_rm]; - else if (mode == X86EMUL_MODE_PROT64) - rip_relative = 1; - break; - default: - c->modrm_ea += c->regs[c->modrm_rm]; - break; - } - switch (c->modrm_mod) { - case 0: - if (c->modrm_rm == 5) - c->modrm_ea += - insn_fetch(s32, 4, c->eip); - break; - case 1: - c->modrm_ea += insn_fetch(s8, 1, c->eip); - break; - case 2: - c->modrm_ea += insn_fetch(s32, 4, c->eip); - break; - } - } - if (rip_relative) { - c->modrm_ea += c->eip; - switch (c->d & SrcMask) { - case SrcImmByte: - c->modrm_ea += 1; - break; - case SrcImm: - if (c->d & ByteOp) - c->modrm_ea += 1; - else - if (c->op_bytes == 8) - c->modrm_ea += 4; - else - c->modrm_ea += c->op_bytes; - } - } -modrm_done: - ; - } else if (c->d & MemAbs) { - switch (c->ad_bytes) { - case 2: - c->modrm_ea = insn_fetch(u16, 2, c->eip); - break; - case 4: - c->modrm_ea = insn_fetch(u32, 4, c->eip); - break; - case 8: - c->modrm_ea = insn_fetch(u64, 8, c->eip); - break; - } - - } + if (c->d & ModRM) + rc = decode_modrm(ctxt, ops); + else if (c->d & MemAbs) + rc = decode_abs(ctxt, ops); + if (rc) + goto done; if (!c->override_base) c->override_base = &ctxt->ds_base; -- 2.39.5