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 16D783858D28 for ; Tue, 20 Sep 2022 12:16:11 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 16D783858D28 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=1663676170; 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=DgIDwtWEZeGQ9zSTxjFfkXNt8f9wSI+w0JOHB+sDdFw=; b=O7bnYO81YcLfSX8lQdF7oiaUhDgQINgvEubWEkM+8b0Zct4R4EC408/8RJUsYdYCOWe7hG i6PRDxDueccbvxTR7r4nXiJTM14Js00uO+RNJyGjNWpDJWva2CieGlu94/D3fu2vz7xB07 Ap+hkGFHjnCeG6LoSon7OtX1wMEw32U= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-556-KbEHFmxFOt6NYcRH5pafLQ-1; Tue, 20 Sep 2022 08:16:07 -0400 X-MC-Unique: KbEHFmxFOt6NYcRH5pafLQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 266111C0513E; Tue, 20 Sep 2022 12:16:07 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.195.39]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7A32E40E42E5; Tue, 20 Sep 2022 12:16:06 +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> Date: Tue, 20 Sep 2022 14:16:04 +0200 In-Reply-To: <9d232b1b-f123-4189-bf09-dd29aab6486a@www.fastmail.com> (Zack Weinberg via Libc-alpha's message of "Thu, 15 Sep 2022 12:09:36 -0400") Message-ID: <87y1uemebf.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 10.11.54.2 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-5.5 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: >> process_vm_readv seems quite likely to get blocked by seccomp filters. > > I was worried about that too :-/ I think we see that in the pre-commit CI builder. >> 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. Thanks, Florian