From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id A6BE5385828E for ; Wed, 21 Sep 2022 13:01:40 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org A6BE5385828E Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1663765300; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=urdGKqZnYGmpYIGNon409XAjH/2Or1S1Xsdbhe1wmTU=; b=iMnmCsFpsnVQduNFTRH9orw9BtG4xTglzHjwVhAt+UEaztlKhZw4iet9wnzSdI79XygTxN ICYgpGtw+YKGpaHXCh/oMtu9I/Gvy75hgUCH+0pmkZZgRSP29J9pW3QxKITttHEs/eRYsS VTWM7SVYXeNsofY6q9D+gQTYO7fHmMo= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-512-QvPtej1hOO-LskpX3iWEDw-1; Wed, 21 Sep 2022 09:01:37 -0400 X-MC-Unique: QvPtej1hOO-LskpX3iWEDw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id F02C9857FAC; Wed, 21 Sep 2022 13:01:36 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.54]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6EC5F40CA42A; Wed, 21 Sep 2022 13:01:36 +0000 (UTC) From: Florian Weimer To: Zack Weinberg via Libc-alpha Cc: Zack Weinberg Subject: Re: RFC PATCH: Don't use /proc/self/maps to calculate size of initial thread stack References: <79dae81f-8e33-4499-a47a-93cc0903be6a@www.fastmail.com> <87fsgvvbwq.fsf@oldenburg.str.redhat.com> <9d232b1b-f123-4189-bf09-dd29aab6486a@www.fastmail.com> <87y1uemebf.fsf@oldenburg.str.redhat.com> <354f7066-9b7d-47f2-944f-0512d1437627@www.fastmail.com> Date: Wed, 21 Sep 2022 15:01:35 +0200 In-Reply-To: <354f7066-9b7d-47f2-944f-0512d1437627@www.fastmail.com> (Zack Weinberg via Libc-alpha's message of "Wed, 21 Sep 2022 08:41:07 -0400") Message-ID: <87edw43mq8.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-5.0 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: * Zack Weinberg via Libc-alpha: > On Tue, Sep 20, 2022, at 8:16 AM, Florian Weimer via Libc-alpha wrote: >>>> Maybe we can get the kernel to pass the end of the stack in the >>>> auxiliary vector? >>> >>> Sure, but then what do we do on older kernels? I'm reluctant to say >>> "keep the old code" because we know this is breaking for people right >>> now (although honestly "mount /proc earlier" isn't a terrible >>> suggestion for a workaround). >> >> We can keep doing what we are doing on older kernels. I don't think we >> should add yet another fallback path for this in case /proc isn't >> available and the kernel doesn't provide the (future) AT_* entry. *Two* >> fallback paths instead of one seems a bit over the top. > > Fair enough. I have no experience writing kernel patches, do you know > anyone who can make the additional AT entry happen? Sorry, no idea. The easiest way to get people's attention seems to be, post a slightly broken patch to fs/binfmt_elf.c. Thanks, Florian