Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753208AbbBSA0O (ORCPT ); Wed, 18 Feb 2015 19:26:14 -0500 Received: from terminus.zytor.com ([198.137.202.10]:47572 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753120AbbBSA0L (ORCPT ); Wed, 18 Feb 2015 19:26:11 -0500 Date: Wed, 18 Feb 2015 16:25:57 -0800 From: tip-bot for Denys Vlasenko Message-ID: Cc: dvlasenk@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, mingo@kernel.org, tglx@linutronix.de, oleg@redhat.com, masami.hiramatsu.pt@hitachi.com Reply-To: masami.hiramatsu.pt@hitachi.com, tglx@linutronix.de, oleg@redhat.com, mingo@kernel.org, linux-kernel@vger.kernel.org, hpa@zytor.com, dvlasenk@redhat.com In-Reply-To: <1423768017-31766-1-git-send-email-dvlasenk@redhat.com> References: <1423768017-31766-1-git-send-email-dvlasenk@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/asm] x86/asm/decoder: Explain CALLW discrepancy between Intel and AMD Git-Commit-ID: cbb53b9623a70f012e1fdfb6fc0af6878df4762b X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2644 Lines: 72 Commit-ID: cbb53b9623a70f012e1fdfb6fc0af6878df4762b Gitweb: http://git.kernel.org/tip/cbb53b9623a70f012e1fdfb6fc0af6878df4762b Author: Denys Vlasenko AuthorDate: Thu, 12 Feb 2015 20:06:57 +0100 Committer: Ingo Molnar CommitDate: Wed, 18 Feb 2015 21:01:59 +0100 x86/asm/decoder: Explain CALLW discrepancy between Intel and AMD In 64-bit mode, AMD and Intel CPUs treat 0x66 prefix before branch insns differently. For near branches, it affects decode too since immediate offset's width is different. See these empirical tests: http://marc.info/?l=linux-kernel&m=139714939728946&w=2 Signed-off-by: Denys Vlasenko Cc: Masami Hiramatsu Cc: Oleg Nesterov Link: http://lkml.kernel.org/r/1423768017-31766-1-git-send-email-dvlasenk@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/lib/x86-opcode-map.txt | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/x86/lib/x86-opcode-map.txt b/arch/x86/lib/x86-opcode-map.txt index 1a2be7c..816488c 100644 --- a/arch/x86/lib/x86-opcode-map.txt +++ b/arch/x86/lib/x86-opcode-map.txt @@ -273,6 +273,9 @@ dd: ESC de: ESC df: ESC # 0xe0 - 0xef +# Note: "forced64" is Intel CPU behavior: they ignore 0x66 prefix +# in 64-bit mode. AMD CPUs accept 0x66 prefix, it causes RIP truncation +# to 16 bits. In 32-bit mode, 0x66 is accepted by both Intel and AMD. e0: LOOPNE/LOOPNZ Jb (f64) e1: LOOPE/LOOPZ Jb (f64) e2: LOOP Jb (f64) @@ -281,6 +284,10 @@ e4: IN AL,Ib e5: IN eAX,Ib e6: OUT Ib,AL e7: OUT Ib,eAX +# With 0x66 prefix in 64-bit mode, for AMD CPUs immediate offset +# in "near" jumps and calls is 16-bit. For CALL, +# push of return address is 16-bit wide, RSP is decremented by 2 +# but is not truncated to 16 bits, unlike RIP. e8: CALL Jz (f64) e9: JMP-near Jz (f64) ea: JMP-far Ap (i64) @@ -456,6 +463,7 @@ AVXcode: 1 7e: movd/q Ey,Pd | vmovd/q Ey,Vy (66),(v1) | vmovq Vq,Wq (F3),(v1) 7f: movq Qq,Pq | vmovdqa Wx,Vx (66) | vmovdqu Wx,Vx (F3) # 0x0f 0x80-0x8f +# Note: "forced64" is Intel CPU behavior (see comment about CALL insn). 80: JO Jz (f64) 81: JNO Jz (f64) 82: JB/JC/JNAE Jz (f64) @@ -842,6 +850,7 @@ EndTable GrpTable: Grp5 0: INC Ev 1: DEC Ev +# Note: "forced64" is Intel CPU behavior (see comment about CALL insn). 2: CALLN Ev (f64) 3: CALLF Ep 4: JMPN Ev (f64) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/