From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id D53053858C2F; Fri, 27 Jan 2023 15:20:19 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org D53053858C2F
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1674832819;
	bh=LEI+uh2bp1skRyRnXUi4cUTCX2CpWTrhLMQNiF4hdTk=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=Zq8jzQacO1r5dDh7chDS3lWPqt7SCg26Cx8W2oAY/KCs3Glp0DAQ6vw3RseC/L2t/
	 IatxAeTy0vFL0BJT+tPvhRUUA1v1iRW9EPnp2E0yBLJe4EWCigKZV1wpwa79h7VUxU
	 IX8zK55VtuaJgKyswrpA4d63rou3T72+difkpMqs=
From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/108552] Linux i386 kernel 5.14 memory
 corruption for pre_compound_page() when gcov is enabled
Date: Fri, 27 Jan 2023 15:20:19 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 11.3.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jakub at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-108552-4-j7im5TagUf@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-108552-4@http.gcc.gnu.org/bugzilla/>
References: <bug-108552-4@http.gcc.gnu.org/bugzilla/>
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: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108552

--- Comment #29 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #27)
> Well, we could in -fprofile-update=3Dsingle (or perhaps in a new single-l=
ike
> mode) mark the gcov artificial vars volatile or with some flag that would=
 at
> least cause reload not to reread values from memory.  The profiling would=
 be
> still racy, but at the expense of somewhat slower code (with volatile mor=
e,
> with special flag less so) slightly less so (as it would e.g. prevent the
> compiler from avoiding the rereads).

Though, e.g. volatile would then prevent say on x86 using inc directly on t=
he
memory
location, which is used in the -fprofile-update=3Datomic mode (with additio=
nal
lock).=