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 [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 30A7C3858D39 for ; Sat, 4 Dec 2021 18:10:41 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 30A7C3858D39 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-473-XJmfDvzLOOeFiZh0xSdVZQ-1; Sat, 04 Dec 2021 13:10:37 -0500 X-MC-Unique: XJmfDvzLOOeFiZh0xSdVZQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 14163835B47; Sat, 4 Dec 2021 18:10:36 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.193.123]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D197B604CC; Sat, 4 Dec 2021 18:10:34 +0000 (UTC) From: Florian Weimer To: Rongwei Wang via Libc-alpha Cc: Rongwei Wang , xuyu@linux.alibaba.com, gavin.dg@linux.alibaba.com Subject: Re: [PATCH RFC 1/1] elf: align the mapping address of LOAD segments with p_align References: <20211204045848.71105-1-rongwei.wang@linux.alibaba.com> <20211204045848.71105-2-rongwei.wang@linux.alibaba.com> Date: Sat, 04 Dec 2021 19:10:32 +0100 In-Reply-To: <20211204045848.71105-2-rongwei.wang@linux.alibaba.com> (Rongwei Wang via Libc-alpha's message of "Sat, 4 Dec 2021 12:58:48 +0800") Message-ID: <87wnkktf53.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 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.6 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 04 Dec 2021 18:10:42 -0000 * Rongwei Wang via Libc-alpha: > Now, ld.so always map the LOAD segments and aligned by base > page size (e.g. 4k in x86 or 4k, 16k and 64k in arm64). And > this patch improve the scheme here. In this patch, ld.so > can align the mapping address of the first LOAD segment with > p_align when p_align is greater than the current base page > size. > > And this change makes code segments using huge pages become > simple and available. I feel like we should be able to tell the kernel that we want an aligned mapping. munmap is not actually cheap. Do you know if there are some ideas in this area? Perhaps with another MAP_ flag and encoding the requested alignment in the lower bits of the hints address? Thanks, Florian