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[23.128.96.35]) by mx.google.com with ESMTPS id n12-20020a170902d2cc00b001b69ede5b79si2712131plc.470.2023.09.21.16.36.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Sep 2023 16:36:44 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.35 as permitted sender) client-ip=23.128.96.35; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=casper.20170209 header.b=GGxYiouD; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.35 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by groat.vger.email (Postfix) with ESMTP id 904E28373A06; Thu, 21 Sep 2023 16:25:41 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at groat.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230156AbjIUXZ1 (ORCPT + 29 others); Thu, 21 Sep 2023 19:25:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48094 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230050AbjIUXZW (ORCPT ); Thu, 21 Sep 2023 19:25:22 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E46F4F9; Thu, 21 Sep 2023 11:10:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-Id:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=9OUktNkwNXjB5runbwWnUkYaH4gkQXyoyA8wphj6CxQ=; b=GGxYiouDxwMhpCaPcVH40k98P/ XAfPr7EX2gzP8TckrBbk0itBDqh1K7L47qzj5ufg0WUG7Olk8Cby/mGQk/MfSUHpFcAoHFbPrC9vs EjyJVceNWZaOGslnAhpSgFyQciPs7Zl7wH+N2XntEXFqDsPfCoE6LiaK/AnohyGjrKsGsSQ089gs3 hlcFVZvN0eJHab3vYggwHl9ShJvSk4C58uCtLGwBHhEyqjaQe2iX2kH0aoMJkbcnplJDonkvdIIhK hXDu6aGgekrKWj5LYF6dmt9W2ciUrqRrAGk+jg2tMV2PEMXwjpNtLXqPV9S9yK+8ASFpo1IaN/Y4q uQIXkbmg==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1qjHQO-00BTom-U1; Thu, 21 Sep 2023 11:00:49 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 0) id 26D833008D6; Thu, 21 Sep 2023 13:00:43 +0200 (CEST) Message-Id: <20230921105249.108410391@noisy.programming.kicks-ass.net> User-Agent: quilt/0.65 Date: Thu, 21 Sep 2023 12:45:19 +0200 From: peterz@infradead.org To: tglx@linutronix.de, axboe@kernel.dk Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@redhat.com, dvhart@infradead.org, dave@stgolabs.net, andrealmeid@igalia.com, Andrew Morton , urezki@gmail.com, hch@infradead.org, lstoakes@gmail.com, Arnd Bergmann , linux-api@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, malteskarupke@web.de Subject: [PATCH v3 14/15] futex: Enable FUTEX2_{8,16} References: <20230921104505.717750284@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Disposition: inline; filename=peterz-futex2-small.patch X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on groat.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (groat.vger.email [0.0.0.0]); Thu, 21 Sep 2023 16:25:41 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1777692211391856897 X-GMAIL-MSGID: 1777692211391856897 When futexes are no longer u32 aligned, the lower offset bits are no longer available to put type info in. However, since offset is the offset within a page, there are plenty bits available on the top end. After that, pass flags into futex_get_value_locked() for WAIT and disallow FUTEX2_SIZE_U64 instead of mandating FUTEX2_SIZE_U32. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Thomas Gleixner --- include/linux/futex.h | 11 ++++++----- kernel/futex/core.c | 9 +++++++++ kernel/futex/futex.h | 4 ++-- kernel/futex/waitwake.c | 5 +++-- 4 files changed, 20 insertions(+), 9 deletions(-) Index: linux-2.6/include/linux/futex.h =================================================================== --- linux-2.6.orig/include/linux/futex.h +++ linux-2.6/include/linux/futex.h @@ -16,18 +16,19 @@ struct task_struct; * The key type depends on whether it's a shared or private mapping. * Don't rearrange members without looking at hash_futex(). * - * offset is aligned to a multiple of sizeof(u32) (== 4) by definition. - * We use the two low order bits of offset to tell what is the kind of key : + * offset is the position within a page and is in the range [0, PAGE_SIZE). + * The high bits of the offset indicate what kind of key this is: * 00 : Private process futex (PTHREAD_PROCESS_PRIVATE) * (no reference on an inode or mm) * 01 : Shared futex (PTHREAD_PROCESS_SHARED) * mapped on a file (reference on the underlying inode) * 10 : Shared futex (PTHREAD_PROCESS_SHARED) * (but private mapping on an mm, and reference taken on it) -*/ + */ -#define FUT_OFF_INODE 1 /* We set bit 0 if key has a reference on inode */ -#define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */ +#define FUT_OFF_INODE (PAGE_SIZE << 0) +#define FUT_OFF_MMSHARED (PAGE_SIZE << 1) +#define FUT_OFF_SIZE (PAGE_SIZE << 2) union futex_key { struct { Index: linux-2.6/kernel/futex/core.c =================================================================== --- linux-2.6.orig/kernel/futex/core.c +++ linux-2.6/kernel/futex/core.c @@ -311,6 +311,15 @@ int get_futex_key(void __user *uaddr, un } /* + * Encode the futex size in the offset. This makes cross-size + * wake-wait fail -- see futex_match(). + * + * NOTE that cross-size wake-wait is fundamentally broken wrt + * FLAGS_NUMA. + */ + key->both.offset |= FUT_OFF_SIZE * (flags & FLAGS_SIZE_MASK); + + /* * PROCESS_PRIVATE futexes are fast. * As the mm cannot disappear under us and the 'key' only needs * virtual address, we dont even have to find the underlying vma. Index: linux-2.6/kernel/futex/futex.h =================================================================== --- linux-2.6.orig/kernel/futex/futex.h +++ linux-2.6/kernel/futex/futex.h @@ -79,8 +79,8 @@ static inline bool futex_flags_valid(uns return false; } - /* Only 32bit futexes are implemented -- for now */ - if ((flags & FLAGS_SIZE_MASK) != FLAGS_SIZE_32) + /* 64bit futexes aren't implemented -- yet */ + if ((flags & FLAGS_SIZE_MASK) == FLAGS_SIZE_64) return false; /* Index: linux-2.6/kernel/futex/waitwake.c =================================================================== --- linux-2.6.orig/kernel/futex/waitwake.c +++ linux-2.6/kernel/futex/waitwake.c @@ -437,11 +437,12 @@ retry: for (i = 0; i < count; i++) { u32 __user *uaddr = (u32 __user *)(unsigned long)vs[i].w.uaddr; + unsigned int flags = vs[i].w.flags; struct futex_q *q = &vs[i].q; u32 val = vs[i].w.val; hb = futex_q_lock(q); - ret = futex_get_value_locked(&uval, uaddr, FLAGS_SIZE_32); + ret = futex_get_value_locked(&uval, uaddr, flags); if (!ret && uval == val) { /* @@ -609,7 +610,7 @@ retry: retry_private: *hb = futex_q_lock(q); - ret = futex_get_value_locked(&uval, uaddr, FLAGS_SIZE_32); + ret = futex_get_value_locked(&uval, uaddr, flags); if (ret) { futex_q_unlock(*hb);