From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id E39853858431; Mon, 1 Apr 2024 14:03:49 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E39853858431 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1711980229; bh=uEfGtLp6HQTr6MYELXKvfCj4dbPDlXO3tFQE8pzsYLI=; h=From:To:Subject:Date:In-Reply-To:References:From; b=MkLA7Vnzl+Xo/xwH1LXMNi6wVSokty4O4n/LpjUGzYmWoIB1L+qvELMMiEJW124+t 2R8x+Kj9jCI+GaMfP7XGxTSJcfygGGXnrK6TocngGI8kF7Tzqv8PI+maGywA2ziuCs Re/+qvBuF50geQjYqmZLFNGpFkqx3mQ4JgRR0bx0= From: "giuliano.belinassi at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/112980] 64-bit powerpc ELFv2 does not allow nops to be generated before function global entry point Date: Mon, 01 Apr 2024 14:03:46 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: target X-Bugzilla-Version: 13.2.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: giuliano.belinassi at gmail dot com X-Bugzilla-Status: ASSIGNED X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: linkw at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 List-Id: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D112980 --- Comment #9 from Giuliano Belinassi --- Hello, Kewen. (In reply to Kewen Lin from comment #8) > Hi @Michael, @Martin, could you help to confirm/clarify what triggers you= to > be interested in this feature, is it for some user space usage or not? Yes, this is for userspace livepatching. Assume the following example: https://godbolt.org/z/b9M8nMbo1 As one can see, the sequence of 14 nops are generated after the global func= tion entry point. In such way we can't use the this space to place a trampoline = to the new function. We need this sequence of nops to be placed *before* the global function entry point. Thanks, Giuliano.=