From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3355C433E0 for ; Tue, 16 Mar 2021 21:01:14 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 36A3064F8F for ; Tue, 16 Mar 2021 21:01:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 36A3064F8F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A472C6B0036; Tue, 16 Mar 2021 17:01:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A1D3B6B006C; Tue, 16 Mar 2021 17:01:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8E8766B006E; Tue, 16 Mar 2021 17:01:13 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0132.hostedemail.com [216.40.44.132]) by kanga.kvack.org (Postfix) with ESMTP id 73A646B0036 for ; Tue, 16 Mar 2021 17:01:13 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 2DFBC3626 for ; Tue, 16 Mar 2021 21:01:13 +0000 (UTC) X-FDA: 77926957626.05.B69FCEB Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by imf05.hostedemail.com (Postfix) with ESMTP id E76CEE005F21 for ; Tue, 16 Mar 2021 21:01:11 +0000 (UTC) IronPort-SDR: HFyRczLwMB3w88275OXAPrJZpISk4vEmnD4HtYqrc1Se4uE2lqtJ3YyUilidVtohupgbVBf4ZP RbSmI+rj+PCg== X-IronPort-AV: E=McAfee;i="6000,8403,9925"; a="189428173" X-IronPort-AV: E=Sophos;i="5.81,254,1610438400"; d="scan'208";a="189428173" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2021 14:01:10 -0700 IronPort-SDR: jl9j5Sr8LukusE8rFQ1CMdcCk1xcgInZq6zKKnBJVDNa5Qkmk5nKItZiqHnumNiZuOXqxc5gf8 4v1qN7ImBUuQ== X-IronPort-AV: E=Sophos;i="5.81,254,1610438400"; d="scan'208";a="590805431" Received: from yyu32-mobl1.amr.corp.intel.com (HELO [10.212.191.248]) ([10.212.191.248]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2021 14:01:08 -0700 Subject: Re: [PATCH v23 6/9] x86/entry: Introduce ENDBR macro From: "Yu, Yu-cheng" To: Peter Zijlstra Cc: Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang , Jarkko Sakkinen References: <20210316151320.6123-1-yu-cheng.yu@intel.com> <20210316151320.6123-7-yu-cheng.yu@intel.com> <15966857-9be7-3029-7e93-e40596b4649a@intel.com> <65845773-6cf0-1bdc-1ecf-168de74cc283@intel.com> Message-ID: <9da6397f-326b-7891-5810-a5ac9e0def5d@intel.com> Date: Tue, 16 Mar 2021 14:01:08 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-Stat-Signature: crr5jtpte9edg4mr6jbd17kywbmt97mp X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: E76CEE005F21 Received-SPF: none (intel.com>: No applicable sender policy available) receiver=imf05; identity=mailfrom; envelope-from=""; helo=mga09.intel.com; client-ip=134.134.136.24 X-HE-DKIM-Result: none/none X-HE-Tag: 1615928471-310247 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 3/16/2021 1:26 PM, Yu, Yu-cheng wrote: > On 3/16/2021 1:15 PM, Peter Zijlstra wrote: >> On Tue, Mar 16, 2021 at 01:05:30PM -0700, Yu, Yu-cheng wrote: >>> On 3/16/2021 12:57 PM, Peter Zijlstra wrote: >>>> On Tue, Mar 16, 2021 at 10:12:39AM -0700, Yu, Yu-cheng wrote: >>>>> Alternatively, there is another compiler-defined macro _CET_ENDBR=20 >>>>> that can >>>>> be used.=C2=A0 We can put the following in calling.h: >>>>> >>>>> #ifdef __CET__ >>>>> #include >>>>> #else >>>>> #define _CET_ENDBR >>>>> #endif >>>>> >>>>> and then use _CET_ENDBR in other files.=C2=A0 How is that? >>>>> >>>>> In the future, in case we have kernel-mode IBT, ENDBR macros are=20 >>>>> also needed >>>>> for other assembly files. >>>> >>>> Can we please call it IBT_ENDBR or just ENDBR. CET is a horrible nam= e, >>>> seeing how it is not specific. >>>> >>> >>> _CET_ENDBR is from the compiler and we cannot change it.=C2=A0 We can= do: >>> >>> #define ENDBR _CET_ENDBR >>> >>> How is that? >> >> Do we really want to include compiler headers? AFAICT it's not a >> built-in. Also what about clang? >> >> This thing seems trivial enough to build our own, it's a single damn >> instruction. That also means we don't have to worry about changes to >> header files we don't control. >> >=20 > Then, what about moving what I had earlier to vdso.h? > If we don't want __i386__ either, then make it two macros. >=20 > +.macro ENDBR > +#ifdef CONFIG_X86_CET > +#ifdef __i386__ > +=C2=A0=C2=A0=C2=A0 endbr32 > +#else > +=C2=A0=C2=A0=C2=A0 endbr64 > +#endif > +#endif > +.endm I will make it like the following: diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h index 98aa103eb4ab..4c0262dcb93d 100644 --- a/arch/x86/include/asm/vdso.h +++ b/arch/x86/include/asm/vdso.h @@ -52,6 +52,15 @@ extern int map_vdso_once(const struct vdso_image=20 *image, unsigned long addr); extern bool fixup_vdso_exception(struct pt_regs *regs, int trapnr, unsigned long error_code, unsigned long fault_addr); -#endif /* __ASSEMBLER__ */ +#else /* __ASSEMBLER__ */ + +#ifdef CONFIG_X86_CET +#define ENDBR64 endbr64 +#define ENDBR32 endbr32 +#else /*!CONFIG_X86_CET */ +#define ENDBR64 +#define ENDBR32 +#endif +#endif /* __ASSEMBLER__ */ #endif /* _ASM_X86_VDSO_H */