From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id KlpxOtKrGVs9MgAAmS7hNA ; Thu, 07 Jun 2018 22:04:03 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id D4C0F6063F; Thu, 7 Jun 2018 22:04:02 +0000 (UTC) Authentication-Results: smtp.codeaurora.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="q3XFwavH" X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,MAILING_LIST_MULTI autolearn=unavailable autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 635D360452; Thu, 7 Jun 2018 22:04:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 635D360452 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752201AbeFGWEA (ORCPT + 25 others); Thu, 7 Jun 2018 18:04:00 -0400 Received: from mail-ot0-f196.google.com ([74.125.82.196]:35938 "EHLO mail-ot0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751631AbeFGWD6 (ORCPT ); Thu, 7 Jun 2018 18:03:58 -0400 Received: by mail-ot0-f196.google.com with SMTP id c15-v6so3538532otl.3; Thu, 07 Jun 2018 15:03:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=LHwiXGTDOH7nVeZGDgYlZpmSyJin1x2ftVwUJU2VzVg=; b=q3XFwavHeM6SJYSXvPL3UHVuY97vTLNFEMRNEV0sXVs6ENomnjGxEHgYOgWltnmqbK dC/pxq/OVUu9Q9wTei3ywAxVeODQE0Pt9a22e3Jr4LpRnpd2bcfdV8uxrdlsXrzVYKcR 7q3+KiRQu3cQSFhdK6OJvQE/MEN3RJw85prAE9x7MSautljg0iYpaQuc0oSokSvRT1f4 1IqAkxGBm7iiAsfZvUTUWRvTrIs2mDUGzyP/8WfszIy3MY8zkheLqeCb8hUznq9KtAiz y+3uHg9E/qltXf0OwdNVEf031a6levHt19ESImzJCA4/U9xrWmvuJD/o1xXhwohhBShi RcTg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=LHwiXGTDOH7nVeZGDgYlZpmSyJin1x2ftVwUJU2VzVg=; b=BAx3wzmio49/CfrnNvB0TeCZteIX1S0CqzmG/9V+b6QUwn7cALiUKsmcF945b7yqoU J6hjHd6XGjastEXnc2nFYc8qhuCFMnXp9wpTr9zMLreN0HV6hQYJC36R7xeGvNY7hEw7 jGLnkwUej8WL/7k9MCaIf1Ls41nHmk3e4J8jWuoZnZ3oiq3lbiWk6QxlXI/S5jXxyoOm IB0Jqpx4qoUqFyVpfXOOF2ixgtm9tjmkFXlRZTyhuogxzL0pQBpqSLurqy5C/OqV8R2C 3oIZr7lLNbEzWSgAXVMQg9lWjFHwVuWtlHD59MqyDcEhowb7lvAC7Yp92CejG8G5xjIE XIiQ== X-Gm-Message-State: APt69E1fwe2tM/dKuz9bem9P1dVm1RZ5tSPnL24+9c2/tY1TcYrRRBr+ +7Yy/ZF//52w3ySq4VMM/ajfcTyQVa1jvAcAG/k= X-Google-Smtp-Source: ADUXVKJfeU5EuGLm/7AfID5ohBIuBJWshdSAf43jy7EKKHvmZsmEOuUHlAU8Q8Zp231QnH3YZ1GrKrb/15Xn4ycBJYM= X-Received: by 2002:a9d:322f:: with SMTP id t47-v6mr2314232otc.7.1528409037712; Thu, 07 Jun 2018 15:03:57 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a4a:7019:0:0:0:0:0 with HTTP; Thu, 7 Jun 2018 15:03:56 -0700 (PDT) In-Reply-To: References: <20180607143855.3681-1-yu-cheng.yu@intel.com> <20180607143855.3681-6-yu-cheng.yu@intel.com> From: "H.J. Lu" Date: Thu, 7 Jun 2018 15:03:56 -0700 Message-ID: Subject: Re: [PATCH 5/7] x86: Insert endbr32/endbr64 to vDSO To: Andy Lutomirski Cc: Yu-cheng Yu , LKML , linux-doc@vger.kernel.org, Linux-MM , linux-arch , X86 ML , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , "Shanbhogue, Vedvyas" , "Ravi V. Shankar" , Dave Hansen , Jonathan Corbet , Oleg Nesterov , Arnd Bergmann , mike.kravetz@oracle.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 7, 2018 at 1:50 PM, Andy Lutomirski wrote: > On Thu, Jun 7, 2018 at 7:42 AM Yu-cheng Yu wrote: >> >> From: "H.J. Lu" >> >> When Intel indirect branch tracking is enabled, functions in vDSO which >> may be called indirectly should have endbr32 or endbr64 as the first >> instruction. We try to compile vDSO with -fcf-protection=branch -mibt >> if possible. Otherwise, we insert endbr32 or endbr64 by hand to assembly >> codes generated by the compiler. > > Wow, that's... a genuine abomination. Do we really need to support > CET on kernels built with old toolchains? > Yes. GCC 7 should be able to build CET kernel. -- H.J. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.4 required=5.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, T_DKIM_INVALID autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 0FDBC7D062 for ; Thu, 7 Jun 2018 22:04:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751752AbeFGWD7 (ORCPT ); Thu, 7 Jun 2018 18:03:59 -0400 Received: from mail-ot0-f196.google.com ([74.125.82.196]:35938 "EHLO mail-ot0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751631AbeFGWD6 (ORCPT ); Thu, 7 Jun 2018 18:03:58 -0400 Received: by mail-ot0-f196.google.com with SMTP id c15-v6so3538532otl.3; Thu, 07 Jun 2018 15:03:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=LHwiXGTDOH7nVeZGDgYlZpmSyJin1x2ftVwUJU2VzVg=; b=q3XFwavHeM6SJYSXvPL3UHVuY97vTLNFEMRNEV0sXVs6ENomnjGxEHgYOgWltnmqbK dC/pxq/OVUu9Q9wTei3ywAxVeODQE0Pt9a22e3Jr4LpRnpd2bcfdV8uxrdlsXrzVYKcR 7q3+KiRQu3cQSFhdK6OJvQE/MEN3RJw85prAE9x7MSautljg0iYpaQuc0oSokSvRT1f4 1IqAkxGBm7iiAsfZvUTUWRvTrIs2mDUGzyP/8WfszIy3MY8zkheLqeCb8hUznq9KtAiz y+3uHg9E/qltXf0OwdNVEf031a6levHt19ESImzJCA4/U9xrWmvuJD/o1xXhwohhBShi RcTg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=LHwiXGTDOH7nVeZGDgYlZpmSyJin1x2ftVwUJU2VzVg=; b=BAx3wzmio49/CfrnNvB0TeCZteIX1S0CqzmG/9V+b6QUwn7cALiUKsmcF945b7yqoU J6hjHd6XGjastEXnc2nFYc8qhuCFMnXp9wpTr9zMLreN0HV6hQYJC36R7xeGvNY7hEw7 jGLnkwUej8WL/7k9MCaIf1Ls41nHmk3e4J8jWuoZnZ3oiq3lbiWk6QxlXI/S5jXxyoOm IB0Jqpx4qoUqFyVpfXOOF2ixgtm9tjmkFXlRZTyhuogxzL0pQBpqSLurqy5C/OqV8R2C 3oIZr7lLNbEzWSgAXVMQg9lWjFHwVuWtlHD59MqyDcEhowb7lvAC7Yp92CejG8G5xjIE XIiQ== X-Gm-Message-State: APt69E1fwe2tM/dKuz9bem9P1dVm1RZ5tSPnL24+9c2/tY1TcYrRRBr+ +7Yy/ZF//52w3ySq4VMM/ajfcTyQVa1jvAcAG/k= X-Google-Smtp-Source: ADUXVKJfeU5EuGLm/7AfID5ohBIuBJWshdSAf43jy7EKKHvmZsmEOuUHlAU8Q8Zp231QnH3YZ1GrKrb/15Xn4ycBJYM= X-Received: by 2002:a9d:322f:: with SMTP id t47-v6mr2314232otc.7.1528409037712; Thu, 07 Jun 2018 15:03:57 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a4a:7019:0:0:0:0:0 with HTTP; Thu, 7 Jun 2018 15:03:56 -0700 (PDT) In-Reply-To: References: <20180607143855.3681-1-yu-cheng.yu@intel.com> <20180607143855.3681-6-yu-cheng.yu@intel.com> From: "H.J. Lu" Date: Thu, 7 Jun 2018 15:03:56 -0700 Message-ID: Subject: Re: [PATCH 5/7] x86: Insert endbr32/endbr64 to vDSO To: Andy Lutomirski Cc: Yu-cheng Yu , LKML , linux-doc@vger.kernel.org, Linux-MM , linux-arch , X86 ML , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , "Shanbhogue, Vedvyas" , "Ravi V. Shankar" , Dave Hansen , Jonathan Corbet , Oleg Nesterov , Arnd Bergmann , mike.kravetz@oracle.com Content-Type: text/plain; charset="UTF-8" Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Thu, Jun 7, 2018 at 1:50 PM, Andy Lutomirski wrote: > On Thu, Jun 7, 2018 at 7:42 AM Yu-cheng Yu wrote: >> >> From: "H.J. Lu" >> >> When Intel indirect branch tracking is enabled, functions in vDSO which >> may be called indirectly should have endbr32 or endbr64 as the first >> instruction. We try to compile vDSO with -fcf-protection=branch -mibt >> if possible. Otherwise, we insert endbr32 or endbr64 by hand to assembly >> codes generated by the compiler. > > Wow, that's... a genuine abomination. Do we really need to support > CET on kernels built with old toolchains? > Yes. GCC 7 should be able to build CET kernel. -- H.J. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html