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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 501D3C433EF for ; Mon, 18 Oct 2021 09:16:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 38B2B610A6 for ; Mon, 18 Oct 2021 09:16:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231611AbhJRJSu (ORCPT ); Mon, 18 Oct 2021 05:18:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60192 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231570AbhJRJSn (ORCPT ); Mon, 18 Oct 2021 05:18:43 -0400 Received: from mail-pj1-x1036.google.com (mail-pj1-x1036.google.com [IPv6:2607:f8b0:4864:20::1036]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D8A70C061768; Mon, 18 Oct 2021 02:16:31 -0700 (PDT) Received: by mail-pj1-x1036.google.com with SMTP id g13-20020a17090a3c8d00b00196286963b9so14014294pjc.3; Mon, 18 Oct 2021 02:16:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:subject:to:cc:references:in-reply-to:mime-version :message-id:content-transfer-encoding; bh=bk4CmdQz8HPJtWkdQrroAn/KfmHvlYv0QT69F5KgUYY=; b=SIY6SmxSooe6c5+WSnMw0wpVs8QY7NiY+XZuBJ+D71+hWvHEdC2Vbwe6t160uJL/aH SxAjedhuo7/GPRc5DJ/SEAzpZfnAKWBOZFVYti9AdvfYsJcQ4rL3+DM2dFweZBuHNa2+ +plqntehvZ9SJWnhWeMNJxgbPzWwOsSXBy+aWPK6JCymQrSbx9dlArY4Er+FBijnqB2+ KaAdeks2O345KWfd39ueUFOjpMJSBOKHlggozA8hAbjjoen/SEHYJ6ZGB4a5AA4ymoTX S+O+sY98XhFR6qaduHBAgc9j1zJ+556dXM7nA9EQbpd+M4xKLyV6Ni7/OoKNvSsZa2tY Ga4w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:subject:to:cc:references:in-reply-to :mime-version:message-id:content-transfer-encoding; bh=bk4CmdQz8HPJtWkdQrroAn/KfmHvlYv0QT69F5KgUYY=; b=5nYtRgq2Toy28qbK2Vhl6j+WwkAJ11wQq+duvX+5EuTlX3Cpjjq5oM5AEgg4tpnA3A WyFLsUHfmyQCtKy2VWbaEJNBxvOGnXiT4yIA3FhDy8MnVZ7AudNbtCFeXAf6xjnbuAW8 HqbU+ksjJCQrVw+xuCmSigYZMCTu9QO8CKAqVIMUu6z0DLhivu5gIGflNUWvsY96P2Z3 AC0zt7u2FcRZwHDccLRne/8kdHMf3JSdgOu+mTsNqLDOC/8hX1txBm+go27UzvXx2ro6 azP8GQJyoVVFw94HYtI4H+fra99KnS2VA6dI9HG17x/ZaTZVWW9/HcFyFCYQucvL7Z+D vVjg== X-Gm-Message-State: AOAM531mwAf/DTq/s4u6PBmWrnM23b8R7855l0ZFWlxIeX00Oxgkmwj+ kY0gQUs61uZ0iVpOpsQ1QR4= X-Google-Smtp-Source: ABdhPJzhlLMrCQ4LZ3XWVQonDSXYo92dxUzu1RcvXP5BET6OhlsHPRAv2Q264erQZkrgYN002t+nDA== X-Received: by 2002:a17:90a:2c02:: with SMTP id m2mr17579869pjd.109.1634548591342; Mon, 18 Oct 2021 02:16:31 -0700 (PDT) Received: from localhost ([58.171.214.181]) by smtp.gmail.com with ESMTPSA id rj2sm13068038pjb.32.2021.10.18.02.16.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 Oct 2021 02:16:31 -0700 (PDT) Date: Mon, 18 Oct 2021 19:16:25 +1000 From: Nicholas Piggin Subject: Re: [PATCH v3 07/12] asm-generic: Define 'func_desc_t' to commonly describe function descriptors To: Andrew Morton , Arnd Bergmann , Benjamin Herrenschmidt , Christophe Leroy , Helge Deller , Greg Kroah-Hartman , "James E.J. Bottomley" , Kees Cook , Michael Ellerman , Paul Mackerras Cc: linux-arch@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <1634538449.eah9b31bbz.astroid@bobo.none> <802b3ff9-8ada-b45b-2b69-b6a23f0c3664@csgroup.eu> In-Reply-To: <802b3ff9-8ada-b45b-2b69-b6a23f0c3664@csgroup.eu> MIME-Version: 1.0 Message-Id: <1634546857.xamu59z8sr.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org Excerpts from Christophe Leroy's message of October 18, 2021 5:07 pm: >=20 >=20 > Le 18/10/2021 =C3=A0 08:29, Nicholas Piggin a =C3=A9crit=C2=A0: >> Excerpts from Christophe Leroy's message of October 17, 2021 10:38 pm: >>> We have three architectures using function descriptors, each with its >>> own type and name. >>> >>> Add a common typedef that can be used in generic code. >>> >>> Also add a stub typedef for architecture without function descriptors, >>> to avoid a forest of #ifdefs. >>> >>> It replaces the similar 'func_desc_t' previously defined in >>> arch/powerpc/kernel/module_64.c >>> >>> Reviewed-by: Kees Cook >>> Acked-by: Arnd Bergmann >>> Signed-off-by: Christophe Leroy >>> --- >>=20 >> [...] >>=20 >>> diff --git a/include/asm-generic/sections.h b/include/asm-generic/secti= ons.h >>> index a918388d9bf6..33b51efe3a24 100644 >>> --- a/include/asm-generic/sections.h >>> +++ b/include/asm-generic/sections.h >>> @@ -63,6 +63,9 @@ extern __visible const void __nosave_begin, __nosave_= end; >>> #else >>> #define dereference_function_descriptor(p) ((void *)(p)) >>> #define dereference_kernel_function_descriptor(p) ((void *)(p)) >>> +typedef struct { >>> + unsigned long addr; >>> +} func_desc_t; >>> #endif >>> =20 >>=20 >> I think that deserves a comment. If it's just to allow ifdef to be >> avoided, I guess that's okay with a comment. Would be nice if you could >> cause it to generate a link time error if it was ever used like >> undefined functions, but I guess you can't. It's not a necessity though. >>=20 >=20 > I tried to explain it in the commit message, but I can add a comment=20 > here in addition for sure. Thanks. >=20 > By the way, it IS used in powerpc's module_64.c: Ah yes of course. I guess the point is function descriptors don't exist=20 so it should not be used (in general). powerpc module code knows what it is doing, I guess it's okay for it to use it. Thanks, Nick