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=-11.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no 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 B347FC4363A for ; Tue, 27 Oct 2020 20:36:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 67D6E20790 for ; Tue, 27 Oct 2020 20:36:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="La6FRGr/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1829212AbgJ0Ugd (ORCPT ); Tue, 27 Oct 2020 16:36:33 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:46203 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1796922AbgJ0Ugc (ORCPT ); Tue, 27 Oct 2020 16:36:32 -0400 Received: by mail-pl1-f195.google.com with SMTP id x10so1368396plm.13 for ; Tue, 27 Oct 2020 13:36:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=33VjU+F7xAlvSJckVmNE4QUId8MWatGSN2KXkENeBPE=; b=La6FRGr/jeDbtsIvtAxz+uiQhOjm4dAyWcaXp8Bqngku+6eQxP7PosB8B+goA+kSqN vre0Yh4pGYryxRzhBbj4WTAawGpKZXq8Q+xPmH9Zynqe3X5rtfcpPxwKfvRLiasuYvJS lYVbQeLtj9n49BX32DstNGop1I1QBd0qFZjDtslG4IJ5dZyxg+g7qbQ4zI31ec4EwbA/ ZDtEGqpX1SibS06EBpU+DuE1qpkKhWs8jccGCYiXAGNMeadZ88esGcIw/ZBfVFgKEPFv rJT1EKacmQ+dYTEVHzy4S9Kf5DJX2+4TgmZ5Kqv74555mr4NtUjjpGWRLdH1y4keHXjw pSkw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=33VjU+F7xAlvSJckVmNE4QUId8MWatGSN2KXkENeBPE=; b=OO9+BT5n9kk0L+wEFlB8Xf/AQ2PTr4HVfrieHVnm/qzqQnjcMrlW7Z805f28NGSit/ uj2651uGOzJzJhIX3euex8CT8lzg3GFAAlL1j+KTZQmiT9K5a1URb96t5JUKxBOxFrcr 5vOaiquEh/yXTaDHxvQQ+0+20OeJ7US3hcquTgT4e/S7mhN+8kogyV/Ad2P1eQinBXys W7y1OwgoU+s6IaQqzE2kEqLGU2i31FQEZUUO6Xqp3ZYWs9/QuWMuImpMeTwCBCOBavWU PvYwjtcNJ11D9GUf0kqvxyv+Nca/5dddGZ03SFM1t8TWDaIEsGMDa+qoNUv+BIKA+UhA 1W7Q== X-Gm-Message-State: AOAM530ps4mNchX2P1VlRnMrpoGN1M6UjyQWYtbWG4wyg999vAQs8Fde E+gQ7SyeXHtSS9BZBAXjJu5rUJcZIhxavvzR3Z3+pg== X-Google-Smtp-Source: ABdhPJyYjkI+PB3DKa7DZijWYM08uiHSD3LXT+KkzFwyEX8TmBIceh63CEoOK884l4tYvAjukIuxCjNXYggMXH//kmc= X-Received: by 2002:a17:90a:6b04:: with SMTP id v4mr3652441pjj.101.1603830991134; Tue, 27 Oct 2020 13:36:31 -0700 (PDT) MIME-Version: 1.0 References: <20201027203210.GB1833548@rani.riverdale.lan> In-Reply-To: <20201027203210.GB1833548@rani.riverdale.lan> From: Nick Desaulniers Date: Tue, 27 Oct 2020 13:36:20 -0700 Message-ID: Subject: Re: [PATCH v6 13/29] arm64/build: Assert for unwanted sections To: Arvind Sankar Cc: Ard Biesheuvel , Geert Uytterhoeven , Kees Cook , Ingo Molnar , Catalin Marinas , Mark Rutland , Peter Collingbourne , James Morse , Borislav Petkov , Ingo Molnar , Russell King , Masahiro Yamada , Nathan Chancellor , Arnd Bergmann , "the arch/x86 maintainers" , clang-built-linux , Linux-Arch , linux-efi , Linux ARM , Linux Kernel Mailing List , Linux-Renesas , Josh Poimboeuf , Miguel Ojeda , linux-toolchains@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 27, 2020 at 1:32 PM Arvind Sankar wrote: > > On Tue, Oct 27, 2020 at 01:28:02PM -0700, Nick Desaulniers wrote: > > > commit 3193c0836f203a91bef96d88c64cccf0be090d9c > > > Author: Josh Poimboeuf > > > Date: Wed Jul 17 20:36:45 2019 -0500 > > > > > > bpf: Disable GCC -fgcse optimization for ___bpf_prog_run() > > > > > > has > > > > > > Fixes: e55a73251da3 ("bpf: Fix ORC unwinding in non-JIT BPF code") > > > > > > and mentions objtool and CONFIG_RETPOLINE. > > > > Thanks for the context. It might be time to revisit the above commit. > > If I revert it (small conflict that's easy to fixup), > > kernel/bpf/core.o builds cleanly with defconfig+GCC-9.3, so maybe > > obtool did get smart enough to handle that case? Probably regresses > > the performance of that main dispatch loop for BPF, but not sure what > > folks are expecting when retpolines are enabled. > > -- > > Thanks, > > ~Nick Desaulniers > > The objtool issue was with RETPOLINE disabled. Ah, sorry, in that case default-CONFIG_RETPOLINE+gcc-9.3: kernel/bpf/core.o: warning: objtool: ___bpf_prog_run()+0x8d4: sibling call from callable instruction with modified stack frame -- Thanks, ~Nick Desaulniers