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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3203C43334 for ; Wed, 20 Jul 2022 18:07:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238110AbiGTSHt (ORCPT ); Wed, 20 Jul 2022 14:07:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57892 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230042AbiGTSHr (ORCPT ); Wed, 20 Jul 2022 14:07:47 -0400 Received: from mail-ed1-x530.google.com (mail-ed1-x530.google.com [IPv6:2a00:1450:4864:20::530]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F27323AE57 for ; Wed, 20 Jul 2022 11:07:46 -0700 (PDT) Received: by mail-ed1-x530.google.com with SMTP id y8so24800635eda.3 for ; Wed, 20 Jul 2022 11:07:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=WfFInv5ImNO15plC0c/RcDxCy7llN2JkDjkw6ed6RCE=; b=AasR9VXxENAmKepuQslkxQbHvFYqU1QK/1I7fRsP60vVlub1ST9OvYs4fSJbB4sEcm /uuI4OPOwHEvMfjfvkYfZmHgUgIQj/7tb/1DxAZaLOkb1ZqRneukGeIqD/J0HdQEDG9/ odV/kjT8UkQOwAjH4LXl8Lun4rxoosQoE+iD8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=WfFInv5ImNO15plC0c/RcDxCy7llN2JkDjkw6ed6RCE=; b=B2cFh+LpI8OIh6lXCaYBKUnXM93LGDICKncU08lNkZDifFenEIrgOC+RSJOAm6S0jL f9tUPtBMzK/GCQULbSOcHVTAtKC+c4gXqc+PWAmQj6/WtN7L0G8J7Vomi/tVoCSrhEbI NM2SNxt8SHdXiEfplGF+9ecBpmyxGMXxNMx0ocN4OfdIcIrhZ3zwMyC4S0XY0ovvVaTR S0aSfcDDtluw8nuq0S6sstwhoLdhbpCjaHiC90LreNlXHSNAQk0nii2rPt0gVrPT7BgY moYh9TUJkQR8DGcgk8R7SJPHMG55j1hNwxLKQqyV2VYzqTWwWRZLSV2Z7TuU9+F6+Doa ZlQA== X-Gm-Message-State: AJIora/+vNashEl7DdFAST3qn1fgQbGTPnPvUIZtxQEcHukm1AXm07MX bIZk7J6EEHbeLMzpqqzBER2xmwuBbxrnHZB9K6g= X-Google-Smtp-Source: AGRyM1tcOsYFocD9SuVauwYs6dZ7vXVXRm60cZiKNVMlMaDTHb9FDCoeX/1nTN7pdzWoW0yxuo+k7g== X-Received: by 2002:aa7:d155:0:b0:43a:bc8d:8d75 with SMTP id r21-20020aa7d155000000b0043abc8d8d75mr52493768edo.322.1658340465357; Wed, 20 Jul 2022 11:07:45 -0700 (PDT) Received: from mail-wr1-f53.google.com (mail-wr1-f53.google.com. [209.85.221.53]) by smtp.gmail.com with ESMTPSA id ez7-20020a056402450700b0043a87e6196esm12569182edb.6.2022.07.20.11.07.42 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 20 Jul 2022 11:07:43 -0700 (PDT) Received: by mail-wr1-f53.google.com with SMTP id bu1so27234333wrb.9 for ; Wed, 20 Jul 2022 11:07:42 -0700 (PDT) X-Received: by 2002:adf:dd91:0:b0:21e:4e97:c146 with SMTP id x17-20020adfdd91000000b0021e4e97c146mr2233216wrl.281.1658340462416; Wed, 20 Jul 2022 11:07:42 -0700 (PDT) MIME-Version: 1.0 References: <20220716230344.239749011@linutronix.de> <20220720125736.48164a14@gandalf.local.home> <20220720135016.3178ffc6@gandalf.local.home> In-Reply-To: <20220720135016.3178ffc6@gandalf.local.home> From: Linus Torvalds Date: Wed, 20 Jul 2022 11:07:26 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [patch 00/38] x86/retbleed: Call depth tracking mitigation To: Steven Rostedt Cc: Peter Zijlstra , Thomas Gleixner , LKML , "the arch/x86 maintainers" , Tim Chen , Josh Poimboeuf , Andrew Cooper , Pawan Gupta , Johannes Wikner , Alyssa Milburn , Jann Horn , "H.J. Lu" , Joao Moreira , Joseph Nuzman , Juergen Gross , Masami Hiramatsu , Alexei Starovoitov , Daniel Borkmann Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 20, 2022 at 10:50 AM Steven Rostedt wrote: > > [ 2.464117] missing return thunk: lkdtm_rodata_do_nothing+0x0/0x8-lkdtm_rodata_do_nothing+0x5/0x8: e9 00 00 00 00 Well, that looks like a "jmp" instruction that has never been relocated. The 'e9' is 'jmp', the four zeros after it are either "I'm jumping to the next instruction" or "I haven't been filled in". I'm assuming it's the second case. That lkdtm_rodata_do_nothing thing is odd, and does OBJCOPYFLAGS_rodata_objcopy.o := \ --rename-section .noinstr.text=.rodata,alloc,readonly,load,contents to put the code in an odd section. I'm assuming this hackery is related to it then not getting relocated. Linus