From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=66.187.233.73; helo=mx1.redhat.com; envelope-from=lersek@redhat.com; receiver=edk2-devel@lists.01.org Received: from mx1.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 302ED226EAC74 for ; Thu, 12 Apr 2018 02:34:03 -0700 (PDT) Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 57C0CEC004; Thu, 12 Apr 2018 09:34:02 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-120-142.rdu2.redhat.com [10.10.120.142]) by smtp.corp.redhat.com (Postfix) with ESMTP id BAA5E10B009A; Thu, 12 Apr 2018 09:34:01 +0000 (UTC) To: Dandan Bi , edk2-devel@lists.01.org Cc: Eric Dong References: <20180412085014.107784-1-dandan.bi@intel.com> From: Laszlo Ersek Message-ID: <7dd6846f-fe34-ad7b-ae20-dc7d55ef84f5@redhat.com> Date: Thu, 12 Apr 2018 11:34:00 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180412085014.107784-1-dandan.bi@intel.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Thu, 12 Apr 2018 09:34:02 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Thu, 12 Apr 2018 09:34:02 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'lersek@redhat.com' RCPT:'' Subject: Re: [patch] UefiCpuPkg/PiSmmCpuDxeSmm: Add "extern" keyword for "gPatchxxx" X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 12 Apr 2018 09:34:03 -0000 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Hello Dandan, On 04/12/18 10:50, Dandan Bi wrote: > Background description: > In SmmProfileInternal.h, ECC check tool report an issue at line 103. > Detailed ECC Error info:Variable definition appears in header file. > Include files should contain only public or only private data and > cannot contain code or define data variables > > ECC report similar issues in PiSmmCpuDxeSmm.h. > > Then we review all the new introduced "gPatchxxx", since they have > been defined in the nasm file, we can add "extern" keyword for them > in the C source or header files. > > Cc: Eric Dong > Cc: Laszlo Ersek > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Dandan Bi > --- > UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h | 8 ++++---- > UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfileInternal.h | 2 +- > UefiCpuPkg/PiSmmCpuDxeSmm/SmramSaveState.c | 6 +++--- > UefiCpuPkg/PiSmmCpuDxeSmm/X64/Semaphore.c | 4 ++-- > 4 files changed, 10 insertions(+), 10 deletions(-) This is a bug (a false positive) in the ECC tool. The following declaration: > X86_ASSEMBLY_PATCH_LABEL gPatchSmmCr0; does not declare an *object* (a variable). Instead, it declares a *function* (and not a pointer to a function!), because (from "MdePkg/Include/Library/BaseLib.h"): > /// > /// Type definition for representing labels in NASM source code that allow for > /// the patching of immediate operands of IA32 and X64 instructions. > /// > /// While the type is technically defined as a function type (note: not a > /// pointer-to-function type), such labels in NASM source code never stand for > /// actual functions, and identifiers declared with this function type should > /// never be called. This is also why the EFIAPI calling convention specifier > /// is missing from the typedef, and why the typedef does not follow the usual > /// edk2 coding style for function (or pointer-to-function) typedefs. The VOID > /// return type and the VOID argument list are merely artifacts. > /// > typedef VOID (X86_ASSEMBLY_PATCH_LABEL) (VOID); That is, when you see > X86_ASSEMBLY_PATCH_LABEL gPatchSmmCr0; That is identical to the following function declaration: > VOID gPatchSmmCr0 (VOID); Now, the ISO C99 standard says: > 6.2.2 Linkages of identifiers > > [...] > > 5 If the declaration of an identifier for a function has no > storage-class specifier, its linkage is determined exactly as if > it were declared with the storage-class specifier /extern/. [...] Thus, the report from ECC is a false positive. I don't mind the patch (the changes don't make any difference at the C-language level, see the spec above); however, the commit message should be 100% clear that the patch works around a limitation with the ECC tool. Can you please submit v2 with an updated commit message? Thanks! Laszlo