From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by sourceware.org (Postfix) with ESMTP id E866738493CB for ; Thu, 12 Jan 2023 12:05:53 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org E866738493CB Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A349C1063; Thu, 12 Jan 2023 04:06:35 -0800 (PST) Received: from localhost (e121540-lin.manchester.arm.com [10.32.99.50]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9F9193F67D; Thu, 12 Jan 2023 04:05:52 -0800 (PST) From: Richard Sandiford To: Jakub Jelinek Mail-Followup-To: Jakub Jelinek ,Wilco Dijkstra , Martin =?utf-8?Q?Li=C5=A1ka?= , Kyrylo Tkachov , Szabolcs Nagy , GCC Patches , richard.sandiford@arm.com Cc: Wilco Dijkstra , Martin =?utf-8?Q?Li=C5=A1ka?= , Kyrylo Tkachov , Szabolcs Nagy , GCC Patches Subject: Re: [PATCH] libgcc: Fix uninitialized RA signing on AArch64 [PR107678] In-Reply-To: (Jakub Jelinek's message of "Thu, 12 Jan 2023 11:49:46 +0100") References: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) Date: Thu, 12 Jan 2023 12:05:45 +0000 Message-ID: MIME-Version: 1.0 Content-Type: text/plain X-Spam-Status: No, score=-32.0 required=5.0 tests=BAYES_00,KAM_DMARC_NONE,KAM_DMARC_STATUS,KAM_LAZY_DOMAIN_SECURITY,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Jakub Jelinek writes: > On Wed, Jan 11, 2023 at 11:59:27AM +0000, Wilco Dijkstra wrote: >> Hi, >> >> > On 1/10/23 19:12, Jakub Jelinek via Gcc-patches wrote: >> >> Anyway, the sooner this makes it into gcc trunk, the better, it breaks quite >> >> a lot of stuff. >> > >> > Yep, please, we're also waiting for this patch for pushing to our gcc13 package. >> >> Well I'm waiting for an OK from a maintainer... I believe Jakub can approve it as well. > > Yes, I can, but am not sure it is appropriate. While I'm familiar with the > unwinder, I'm not familiar with the pointer signing, and AArch64 has active > maintainers, so I'd prefer to defer the review to them. I think my main question is: how clean vs hacky is it to use REG_UNDEFINED as effectively a toggle bit, rather than using REG_UNDEFINED for its intended purpose? In the review for earlier (May) patch, I'd asked whether it would make sense to add a new enum. Would that be OK from a target-independent point of view? E.g. maybe REG_TOGGLE_ON. Although we don't AFAIK support using DW_CFA_undefined with RA signing, the failure mode would be non-obvious: it would effectively toggle the bit on. It would be good to remove the definition of RA_SIGNED_BIT as well, so that people don't accidentally use it in future. Thanks, Richard