From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 2830 invoked by alias); 10 Feb 2014 08:54:17 -0000 Mailing-List: contact libc-ports-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: libc-ports-owner@sourceware.org Received: (qmail 2819 invoked by uid 89); 10 Feb 2014 08:54:16 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.4 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-yk0-f173.google.com Received: from mail-yk0-f173.google.com (HELO mail-yk0-f173.google.com) (209.85.160.173) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-SHA encrypted) ESMTPS; Mon, 10 Feb 2014 08:54:15 +0000 Received: by mail-yk0-f173.google.com with SMTP id 10so6312061ykt.4 for ; Mon, 10 Feb 2014 00:54:13 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=A38dyXqjCkPGBEeUTNgzE1MdlD+0/RjRaz02oL/sh44=; b=UQ8tFxWZ+ljP5sJo36kb2tSXpKX6IOunGdIzfWzG1Oudlc1D52bscSFV0AT7PmlXD5 hAsRJak750lIAcqmsaJK41PChO2K/NgZfupH8Wb3B5WGX1ZZZFbLRlL+MW+M4PmUo3Lm Fz3f7uoiF55cN3XFkT1TrobV5qaJeIr1MlOHvxg2mZt6TzvFZjIUoza+n0D+oaZHBK+a Tb3AaRjxhJeIVJXhfOzVz+ACXVN5sVOz/oBzrfLXKYhfSD7ozCCVISIXg8AsfGeDk5CH QqJRRfPGV+kdLtxDa0KEnsWGf6AmIA46SrOH0/TuFngy4Zbg++ynmJBCl2wCsXDxIMg3 jn2w== X-Gm-Message-State: ALoCoQlhPsMPYNzTqshT5nipwSLT6+IMhI7dnOGq4vQpxhsmWU5ds12hAKSho/qXULaZgFDHzi6W MIME-Version: 1.0 X-Received: by 10.236.31.138 with SMTP id m10mr12493192yha.55.1392022453258; Mon, 10 Feb 2014 00:54:13 -0800 (PST) Received: by 10.170.127.79 with HTTP; Mon, 10 Feb 2014 00:54:13 -0800 (PST) In-Reply-To: References: <1391594162-22269-1-git-send-email-will.newton@linaro.org> <20140206221127.6E28974443@topped-with-meat.com> <8761orknyz.fsf@igel.home> Date: Mon, 10 Feb 2014 08:54:00 -0000 Message-ID: Subject: Re: [PATCH v2] ARM: Add SystemTap probes to longjmp and setjmp. From: Will Newton To: "Jonathan S. Shapiro" Cc: Andreas Schwab , Roland McGrath , "libc-ports@sourceware.org" , Patch Tracking Content-Type: text/plain; charset=ISO-8859-1 X-IsSubscribed: yes X-SW-Source: 2014-02/txt/msg00019.txt.bz2 On 7 February 2014 15:27, Jonathan S. Shapiro wrote: > Yes. The layout of jmp_buf is part of the ABI. And not just the libc ABI, > but for some platforms it's part of the platform standard (e.g. SVID > specifies it). In consequence, changing the structure layout isn't an option > in either the current libc release or any foreseeable future libc release. > The patch point needs to be reworked so as to operate given the current > structure layout. The layout has changed in previous releases so I am not convinced this is true. > On the bright side, reworking the code to fit the current layout means that > (a) this can be integrated sooner, and (b) we don't have to accept a small > regression in GDB functionality in order to implement encrypted pointers. The GDB functionality regression is orthogonal to the layout change. The gdb issue is caused by the fact that the saved lr in the jmp_buf is now no longer a straightforward code pointer. The longjmp SystemTap probe added by this patch unencrypts lr and hands it to gdb so gdb can set a break there. -- Will Newton Toolchain Working Group, Linaro