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 99F0FC433F5 for ; Wed, 6 Oct 2021 03:29:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 758F16120C for ; Wed, 6 Oct 2021 03:29:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230261AbhJFDbp (ORCPT ); Tue, 5 Oct 2021 23:31:45 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:38680 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237173AbhJFDbo (ORCPT ); Tue, 5 Oct 2021 23:31:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1633490992; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Py+JZnh73iO8dfi3ucj0KCUA94S2WthHSRpjsAjnr5s=; b=iFmmsPlU2ltQ51ye3w8FiUBlnW5LmLP2XNG5AXru/EW8TIkV0fYb0IlwBbgfIeYZATaHaM y+l7g9Ba40Dgxwu9+09zzsV/HJ7WvP3zkkMXOjt2IHwACeAOiSvHSG0YY5uulUVwPAK/E2 ZP1tikmJBus8yyYLWEN8pzNrLlJ6pDw= Received: from mail-oo1-f71.google.com (mail-oo1-f71.google.com [209.85.161.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-482-T6VHo6vQMmuw-pURbVGn6g-1; Tue, 05 Oct 2021 23:29:50 -0400 X-MC-Unique: T6VHo6vQMmuw-pURbVGn6g-1 Received: by mail-oo1-f71.google.com with SMTP id b3-20020a4a9bc3000000b002b66bb6c794so874748ook.20 for ; Tue, 05 Oct 2021 20:29:49 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=Py+JZnh73iO8dfi3ucj0KCUA94S2WthHSRpjsAjnr5s=; b=CTO00qjD1rQ3jfWQNIQ2YzVuUnXb37FQ+Lfb8QDcHLLfe4c5RThaGSDLhAhAcZ5skh 6oCHUcbavrZbW3qtw9mbr8g97H7yriwpv2sWcrhUlTe51+Uq0vY4mq0dv1eJc5W3CuDi QlSMVBLTUoNVadT8dQYZ+tdI8ea6F3q2hqUJ1xG9PDoARpOXgq4jJAPvxDmlzGG1H+zI msN8xU+QLBySIYoZZmQcOGhN92olXfff5/4zXTg/BPxSGAEzg4nQ/dKWzUvU01fCn9+V 0D30W1jtDylhk5n6xIjdEEoHHzRSLvlwscdiLrjFOC3azjtePXx1JQmseW6CAama/jSw OJfQ== X-Gm-Message-State: AOAM531zbQVjDDXohro2IysVpOUo9nmUQWn3zyZnL/Zty1qggMw3Kmtu 19DK24Ou2GCHiC4StMPo6k13/+WHVQa42IcRiWvM+ybUpur32WDgm8zXzSe0j0rQr9VRYP6KTC2 UwqeLMQJn49RtGXHvmCjdwgcytU4y X-Received: by 2002:a9d:7f89:: with SMTP id t9mr17609235otp.143.1633490989298; Tue, 05 Oct 2021 20:29:49 -0700 (PDT) X-Google-Smtp-Source: ABdhPJz2vFAYge4anWPhwrb90uw13BuOS6xxF266F6ouThw1f6/Zl32C6XLGYYQ1vnCKVEYNl3IbZA== X-Received: by 2002:a9d:7f89:: with SMTP id t9mr17609222otp.143.1633490989040; Tue, 05 Oct 2021 20:29:49 -0700 (PDT) Received: from treble ([2600:1700:6e32:6c00::15]) by smtp.gmail.com with ESMTPSA id bb39sm2950182oib.28.2021.10.05.20.29.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 Oct 2021 20:29:48 -0700 (PDT) Date: Tue, 5 Oct 2021 20:29:45 -0700 From: Josh Poimboeuf To: Sami Tolvanen Cc: x86@kernel.org, Kees Cook , Peter Zijlstra , Nathan Chancellor , Nick Desaulniers , Sedat Dilek , linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Steven Rostedt Subject: Re: [PATCH v4 06/15] ftrace: Use an opaque type for functions not callable from C Message-ID: <20211006032945.axlqh3vehgar6adr@treble> References: <20210930180531.1190642-1-samitolvanen@google.com> <20210930180531.1190642-7-samitolvanen@google.com> MIME-Version: 1.0 In-Reply-To: <20210930180531.1190642-7-samitolvanen@google.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jpoimboe@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On Thu, Sep 30, 2021 at 11:05:22AM -0700, Sami Tolvanen wrote: > With CONFIG_CFI_CLANG, the compiler changes function references to point > to the CFI jump table. As ftrace_call, ftrace_regs_call, and mcount_call > are not called from C, use DECLARE_ASM_FUNC_SYMBOL to declare them. > > Signed-off-by: Sami Tolvanen > --- > include/linux/ftrace.h | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > index 832e65f06754..67de28464aeb 100644 > --- a/include/linux/ftrace.h > +++ b/include/linux/ftrace.h > @@ -578,9 +578,10 @@ extern void ftrace_replace_code(int enable); > extern int ftrace_update_ftrace_func(ftrace_func_t func); > extern void ftrace_caller(void); > extern void ftrace_regs_caller(void); > -extern void ftrace_call(void); > -extern void ftrace_regs_call(void); > -extern void mcount_call(void); > + > +DECLARE_ASM_FUNC_SYMBOL(ftrace_call); > +DECLARE_ASM_FUNC_SYMBOL(ftrace_regs_call); > +DECLARE_ASM_FUNC_SYMBOL(mcount_call); I'm thinking DECLARE_ASM_FUNC_SYMBOL needs a better name. It's not clear from reading it why some asm symbols need the macro and others don't. I guess it means "an asm text symbol which isn't callable from C code (not including alternatives)"? DECLARE_UNCALLED_SYMBOL() maybe? -- Josh