From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: [PATCH 6/8] KVM: x86 emulator: convert DIV/IDIV to fastop Date: Sat, 9 Feb 2013 11:31:49 +0200 Message-ID: <1360402311-19904-7-git-send-email-avi.kivity@gmail.com> References: <1360402311-19904-1-git-send-email-avi.kivity@gmail.com> Cc: kvm@vger.kernel.org To: Gleb Natapov , Marcelo Tosatti Return-path: Received: from mail-wg0-f43.google.com ([74.125.82.43]:47474 "EHLO mail-wg0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752496Ab3BIJcG (ORCPT ); Sat, 9 Feb 2013 04:32:06 -0500 Received: by mail-wg0-f43.google.com with SMTP id e12so3541320wge.10 for ; Sat, 09 Feb 2013 01:32:05 -0800 (PST) In-Reply-To: <1360402311-19904-1-git-send-email-avi.kivity@gmail.com> Sender: kvm-owner@vger.kernel.org List-ID: Since DIV and IDIV can generate exceptions, we need an additional output parameter indicating whether an execption has occured. To avoid increasing register pressure on i386, we use %rsi, which is already allocated for the fastop code pointer. Signed-off-by: Avi Kivity --- arch/x86/kvm/emulate.c | 51 +++++++++++++++++++++++++------------------------- 1 file changed, 26 insertions(+), 25 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 0f0c15e..89f56bb 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -180,6 +180,7 @@ * src: rdx (in/out) * src2: rcx (in) * flags: rflags (in/out) + * ex: rsi (in:nonzero, out:zero if exception) * * Moreover, they are all exactly FASTOP_SIZE bytes long, so functions for * different operand sizes can be reached by calculation, rather than a jump @@ -467,7 +468,10 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *)); #define FOPNOP() FOP_ALIGN FOP_RET #define FOP1E(op, dst) \ - FOP_ALIGN #op " %" #dst " \n\t" FOP_RET + FOP_ALIGN "10: " #op " %" #dst " \n\t" FOP_RET + +#define FOP1EEX(op, dst) \ + FOP1E(op, dst) _ASM_EXTABLE(10b, kvm_fastop_exception) #define FASTOP1(op) \ FOP_START(op) \ @@ -486,6 +490,15 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *)); ON64(FOP1E(op, rcx)) \ FOP_END +/* 1-operand, using src2 (for MUL/DIV r/m), with exceptions */ +#define FASTOP1SRC2EX(op, name) \ + FOP_START(name) \ + FOP1EEX(op, cl) \ + FOP1EEX(op, cx) \ + FOP1EEX(op, ecx) \ + ON64(FOP1EEX(op, rcx)) \ + FOP_END + #define FOP2E(op, dst, src) \ FOP_ALIGN #op " %" #src ", %" #dst " \n\t" FOP_RET @@ -530,6 +543,9 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *)); /* Special case for SETcc - 1 instruction per cc */ #define FOP_SETCC(op) ".align 4; " #op " %al; ret \n\t" +asm(".global kvm_fastop_exception \n" + "kvm_fastop_exception: xor %esi, %esi; ret"); + FOP_START(setcc) FOP_SETCC(seto) FOP_SETCC(setno) @@ -1001,6 +1017,8 @@ FASTOP2(test); FASTOP1SRC2(mul, mul_ex); FASTOP1SRC2(imul, imul_ex); +FASTOP1SRC2EX(div, div_ex); +FASTOP1SRC2EX(idiv, idiv_ex); FASTOP3WCL(shld); FASTOP3WCL(shrd); @@ -2116,26 +2134,6 @@ static int em_jmp_far(struct x86_emulate_ctxt *ctxt) return X86EMUL_CONTINUE; } -static int em_div_ex(struct x86_emulate_ctxt *ctxt) -{ - u8 de = 0; - - emulate_1op_rax_rdx(ctxt, "div", de); - if (de) - return emulate_de(ctxt); - return X86EMUL_CONTINUE; -} - -static int em_idiv_ex(struct x86_emulate_ctxt *ctxt) -{ - u8 de = 0; - - emulate_1op_rax_rdx(ctxt, "idiv", de); - if (de) - return emulate_de(ctxt); - return X86EMUL_CONTINUE; -} - static int em_grp45(struct x86_emulate_ctxt *ctxt) { int rc = X86EMUL_CONTINUE; @@ -3700,8 +3698,8 @@ static const struct opcode group3[] = { F(DstMem | SrcNone | Lock, em_neg), F(DstXacc | Src2Mem, em_mul_ex), F(DstXacc | Src2Mem, em_imul_ex), - I(DstXacc | Src2Mem, em_div_ex), - I(DstXacc | Src2Mem, em_idiv_ex), + F(DstXacc | Src2Mem, em_div_ex), + F(DstXacc | Src2Mem, em_idiv_ex), }; static const struct opcode group4[] = { @@ -4518,9 +4516,12 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *)) if (!(ctxt->d & ByteOp)) fop += __ffs(ctxt->dst.bytes) * FASTOP_SIZE; asm("push %[flags]; popf; call *%[fastop]; pushf; pop %[flags]\n" - : "+a"(ctxt->dst.val), "+d"(ctxt->src.val), [flags]"+D"(flags) - : "c"(ctxt->src2.val), [fastop]"S"(fop)); + : "+a"(ctxt->dst.val), "+d"(ctxt->src.val), [flags]"+D"(flags), + [fastop]"+S"(fop) + : "c"(ctxt->src2.val)); ctxt->eflags = (ctxt->eflags & ~EFLAGS_MASK) | (flags & EFLAGS_MASK); + if (!fop) + return emulate_de(ctxt); return X86EMUL_CONTINUE; } -- 1.8.1.2