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[2620:137:e000::1:20]) by mx.google.com with ESMTP id x11-20020a17090a970b00b002498408b1c5si719396pjo.39.2023.05.16.19.51.54; Tue, 16 May 2023 19:52:05 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20221208 header.b=nS7ih6tl; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231924AbjEQCVm (ORCPT + 99 others); Tue, 16 May 2023 22:21:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43664 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231913AbjEQCVd (ORCPT ); Tue, 16 May 2023 22:21:33 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 17465468E for ; Tue, 16 May 2023 19:21:30 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-5611211f767so2888547b3.0 for ; Tue, 16 May 2023 19:21:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1684290090; x=1686882090; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=rrlZpn5lxQz0wYWidXhNS5k4qYdBDD7AOOGwfPiDsdQ=; b=nS7ih6tlhFuvsMZlYwq74HbaDFXcOaTcEpDv9JgzLfbOcJeYHe55FxK9/JT/+cQbri Mn6JAGOT1VNNKqihdxteunOmx5PruJg2/fGmmxtN3oJJTqr4S4WMMQ0nGGzH9yNCitD0 Kqebqjin+DuMmuu1ErU226+1fL8do4fC3XsOIDYwtzvXNYfy2fVo4kDBR9Dx2K31khL6 UbHaRwmvEWWPO7TJUQ+CmLPQ8R7iMGPQ8aPuRy4ci2qpyyMDXCg6i23WhA35RidSAMDh 2IbzmeSuiKtMSP2SW/XYy9SByGadBaD56U2heVCkkevaE6uaQskw46S6Abvm/vT+UB+O 0DLg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684290090; x=1686882090; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=rrlZpn5lxQz0wYWidXhNS5k4qYdBDD7AOOGwfPiDsdQ=; b=MYB5QbFGczcaptYxK/3BpkyT4YbBgDlt3dmpy6Cfxb5irAakUpuovuX51GgMn2+r+b 2ycx1F1x9fwUN3U1bUFp7wG3XOeilE88F4pSaAdC7Kfmjp1fkWWfQZDZ5zMHWAXbPOSR mIgAMZ2//G+nUMw2IykR/2EBToDRYPGokILg4eWCOOx0oVJqIx4liEBaqGQKmNc6UzTw 0LgF3ZN796DZpowfc9O34UB8Wde9Jp+6VcsaR0LXU1BW9P1WgIOA8S/mcCCd2Y1EGKRm zmRGakWw1DCIjfOD5F43GVL0l7aGs8MSnYD/3B4sHWgJ8a4lELwmdylhKiYc6H7x1OVs spPw== X-Gm-Message-State: AC+VfDzqCx81MCvv5/h8deGnK/akP5vXKQpo6uCVLe+M3DtnxRiFgKBw ncwQFGVwAfk/sw8QjxUX7ygcXeQ= X-Received: from pcc-desktop.svl.corp.google.com ([2620:15c:2d3:205:b3a7:7c59:b96b:adaa]) (user=pcc job=sendgmr) by 2002:a81:ae54:0:b0:559:f89f:bc81 with SMTP id g20-20020a81ae54000000b00559f89fbc81mr23166501ywk.6.1684290089941; Tue, 16 May 2023 19:21:29 -0700 (PDT) Date: Tue, 16 May 2023 19:21:13 -0700 In-Reply-To: <20230517022115.3033604-1-pcc@google.com> Message-Id: <20230517022115.3033604-4-pcc@google.com> Mime-Version: 1.0 References: <20230517022115.3033604-1-pcc@google.com> X-Mailer: git-send-email 2.40.1.606.ga4b1b128d6-goog Subject: [PATCH v3 3/3] arm64: mte: Simplify swap tag restoration logic From: Peter Collingbourne To: Catalin Marinas Cc: Peter Collingbourne , " =?utf-8?b?UXVuLXdlaSBMaW4gKA==?= =?utf-8?b?5p6X576k5bS0KQ==?= " , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "surenb@google.com" , "david@redhat.com" , " =?utf-8?b?Q2hpbndlbiBDaGFuZyAo5by1?= =?utf-8?b?6Yym5paHKQ==?= " , "kasan-dev@googlegroups.com" , " =?utf-8?b?S3Vh?= =?utf-8?b?bi1ZaW5nIExlZSAo5p2O5Yag56mOKQ==?= " , " =?utf-8?b?Q2FzcGVyIExpICjmnY7kuK3mpq4p?= " , "gregkh@linuxfoundation.org" , vincenzo.frascino@arm.com, Alexandru Elisei , will@kernel.org, eugenis@google.com, Steven Price X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1766108090248613844?= X-GMAIL-MSGID: =?utf-8?q?1766108090248613844?= As a result of the previous two patches, there are no circumstances in which a swapped-in page is installed in a page table without first having arch_swap_restore() called on it. Therefore, we no longer need the logic in set_pte_at() that restores the tags, so remove it. Because we can now rely on the page being locked, we no longer need to handle the case where a page is having its tags restored by multiple tasks concurrently, so we can slightly simplify the logic in mte_restore_tags(). Signed-off-by: Peter Collingbourne Link: https://linux-review.googlesource.com/id/I8ad54476f3b2d0144ccd8ce0c1d7a2963e5ff6f3 Reviewed-by: Steven Price Reviewed-by: Catalin Marinas --- v3: - Rebased onto arm64/for-next/fixes, which already has a fix for the issue previously tagged, therefore removed Fixes: tag arch/arm64/include/asm/mte.h | 4 ++-- arch/arm64/include/asm/pgtable.h | 14 ++---------- arch/arm64/kernel/mte.c | 37 ++++++-------------------------- arch/arm64/mm/mteswap.c | 7 +++--- 4 files changed, 14 insertions(+), 48 deletions(-) diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h index c028afb1cd0b..4cedbaa16f41 100644 --- a/arch/arm64/include/asm/mte.h +++ b/arch/arm64/include/asm/mte.h @@ -90,7 +90,7 @@ static inline bool try_page_mte_tagging(struct page *page) } void mte_zero_clear_page_tags(void *addr); -void mte_sync_tags(pte_t old_pte, pte_t pte); +void mte_sync_tags(pte_t pte); void mte_copy_page_tags(void *kto, const void *kfrom); void mte_thread_init_user(void); void mte_thread_switch(struct task_struct *next); @@ -122,7 +122,7 @@ static inline bool try_page_mte_tagging(struct page *page) static inline void mte_zero_clear_page_tags(void *addr) { } -static inline void mte_sync_tags(pte_t old_pte, pte_t pte) +static inline void mte_sync_tags(pte_t pte) { } static inline void mte_copy_page_tags(void *kto, const void *kfrom) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 0bd18de9fd97..e8a252e62b12 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -337,18 +337,8 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr, * don't expose tags (instruction fetches don't check tags). */ if (system_supports_mte() && pte_access_permitted(pte, false) && - !pte_special(pte)) { - pte_t old_pte = READ_ONCE(*ptep); - /* - * We only need to synchronise if the new PTE has tags enabled - * or if swapping in (in which case another mapping may have - * set tags in the past even if this PTE isn't tagged). - * (!pte_none() && !pte_present()) is an open coded version of - * is_swap_pte() - */ - if (pte_tagged(pte) || (!pte_none(old_pte) && !pte_present(old_pte))) - mte_sync_tags(old_pte, pte); - } + !pte_special(pte) && pte_tagged(pte)) + mte_sync_tags(pte); __check_safe_pte_update(mm, ptep, pte); diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index 7e89968bd282..c40728046fed 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -35,41 +35,18 @@ DEFINE_STATIC_KEY_FALSE(mte_async_or_asymm_mode); EXPORT_SYMBOL_GPL(mte_async_or_asymm_mode); #endif -static void mte_sync_page_tags(struct page *page, pte_t old_pte, - bool check_swap, bool pte_is_tagged) -{ - if (check_swap && is_swap_pte(old_pte)) { - swp_entry_t entry = pte_to_swp_entry(old_pte); - - if (!non_swap_entry(entry)) - mte_restore_tags(entry, page); - } - - if (!pte_is_tagged) - return; - - if (try_page_mte_tagging(page)) { - mte_clear_page_tags(page_address(page)); - set_page_mte_tagged(page); - } -} - -void mte_sync_tags(pte_t old_pte, pte_t pte) +void mte_sync_tags(pte_t pte) { struct page *page = pte_page(pte); long i, nr_pages = compound_nr(page); - bool check_swap = nr_pages == 1; - bool pte_is_tagged = pte_tagged(pte); - - /* Early out if there's nothing to do */ - if (!check_swap && !pte_is_tagged) - return; /* if PG_mte_tagged is set, tags have already been initialised */ - for (i = 0; i < nr_pages; i++, page++) - if (!page_mte_tagged(page)) - mte_sync_page_tags(page, old_pte, check_swap, - pte_is_tagged); + for (i = 0; i < nr_pages; i++, page++) { + if (try_page_mte_tagging(page)) { + mte_clear_page_tags(page_address(page)); + set_page_mte_tagged(page); + } + } /* ensure the tags are visible before the PTE is set */ smp_wmb(); diff --git a/arch/arm64/mm/mteswap.c b/arch/arm64/mm/mteswap.c index cd508ba80ab1..3a78bf1b1364 100644 --- a/arch/arm64/mm/mteswap.c +++ b/arch/arm64/mm/mteswap.c @@ -53,10 +53,9 @@ void mte_restore_tags(swp_entry_t entry, struct page *page) if (!tags) return; - if (try_page_mte_tagging(page)) { - mte_restore_page_tags(page_address(page), tags); - set_page_mte_tagged(page); - } + WARN_ON_ONCE(!try_page_mte_tagging(page)); + mte_restore_page_tags(page_address(page), tags); + set_page_mte_tagged(page); } void mte_invalidate_tags(int type, pgoff_t offset)