From patchwork Tue Dec 6 14:47:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13065997 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 32A27C4708E for ; Tue, 6 Dec 2022 14:57:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232490AbiLFO5S (ORCPT ); Tue, 6 Dec 2022 09:57:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52490 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234552AbiLFO4m (ORCPT ); Tue, 6 Dec 2022 09:56:42 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 426E82FA71 for ; Tue, 6 Dec 2022 06:50:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1670338225; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=o58ZygDWZUVUa0aPclLuAuKtIdtSgpg5ZeaH/mRAX58=; b=T42vZuioPRbD3gQp02yXVU3T19Tr08wDgaNulRllJD1ZxYfG6wsfm/AnHbw95bBNCHFjL6 wr0JCdl1OsWCdY6BEunS1hE7fJ3kawaCEML6Iq/gi35e3wRBbBUbBqCq3b+M0SlIylpM9z UlCpmm0tSvfzLmvw/XTbMvmThGo4do4= 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-637-pN_-CD0VOWunzWbGG_vvRA-1; Tue, 06 Dec 2022 09:50:21 -0500 X-MC-Unique: pN_-CD0VOWunzWbGG_vvRA-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B62C2185A7AB; Tue, 6 Dec 2022 14:50:19 +0000 (UTC) Received: from t480s.redhat.com (unknown [10.39.193.173]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7C336492B07; Tue, 6 Dec 2022 14:50:13 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Hugh Dickins , John Hubbard , Jason Gunthorpe , Mike Rapoport , Yang Shi , Vlastimil Babka , Nadav Amit , Andrea Arcangeli , Peter Xu , linux-mm@kvack.org, x86@kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org, David Hildenbrand , "David S. Miller" Subject: [PATCH mm-unstable RFC 21/26] sparc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on 32bit Date: Tue, 6 Dec 2022 15:47:25 +0100 Message-Id: <20221206144730.163732-22-david@redhat.com> In-Reply-To: <20221206144730.163732-1-david@redhat.com> References: <20221206144730.163732-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by reusing the SRMMU_DIRTY bit as that seems to be safe to reuse inside a swap PTE. This avoids having to steal one bit from the swap offset. While at it, relocate the swap PTE layout documentation and use the same style now used for most other archs. Note that the old documentation was wrong: we use 20 bit for the offset and the reserved bits were 8 instead of 7 bits in the ascii art. Cc: "David S. Miller" Signed-off-by: David Hildenbrand --- arch/sparc/include/asm/pgtable_32.h | 27 ++++++++++++++++++++++++++- arch/sparc/include/asm/pgtsrmmu.h | 14 +++----------- 2 files changed, 29 insertions(+), 12 deletions(-) diff --git a/arch/sparc/include/asm/pgtable_32.h b/arch/sparc/include/asm/pgtable_32.h index 5acc05b572e6..abf7a2601209 100644 --- a/arch/sparc/include/asm/pgtable_32.h +++ b/arch/sparc/include/asm/pgtable_32.h @@ -323,7 +323,16 @@ void srmmu_mapiorange(unsigned int bus, unsigned long xpa, unsigned long xva, unsigned int len); void srmmu_unmapiorange(unsigned long virt_addr, unsigned int len); -/* Encode and de-code a swap entry */ +/* + * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that + * are !pte_none() && !pte_present(). + * + * Format of swap PTEs: + * + * 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 + * 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 + * <-------------- offset ---------------> < type -> E 0 0 0 0 0 0 + */ static inline unsigned long __swp_type(swp_entry_t entry) { return (entry.val >> SRMMU_SWP_TYPE_SHIFT) & SRMMU_SWP_TYPE_MASK; @@ -344,6 +353,22 @@ static inline swp_entry_t __swp_entry(unsigned long type, unsigned long offset) #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) }) #define __swp_entry_to_pte(x) ((pte_t) { (x).val }) +#define __HAVE_ARCH_PTE_SWP_EXCLUSIVE +static inline int pte_swp_exclusive(pte_t pte) +{ + return pte_val(pte) & SRMMU_SWP_EXCLUSIVE; +} + +static inline pte_t pte_swp_mkexclusive(pte_t pte) +{ + return __pte(pte_val(pte) | SRMMU_SWP_EXCLUSIVE); +} + +static inline pte_t pte_swp_clear_exclusive(pte_t pte) +{ + return __pte(pte_val(pte) & ~SRMMU_SWP_EXCLUSIVE); +} + static inline unsigned long __get_phys (unsigned long addr) { diff --git a/arch/sparc/include/asm/pgtsrmmu.h b/arch/sparc/include/asm/pgtsrmmu.h index 6067925972d9..18e68d43f036 100644 --- a/arch/sparc/include/asm/pgtsrmmu.h +++ b/arch/sparc/include/asm/pgtsrmmu.h @@ -53,21 +53,13 @@ #define SRMMU_CHG_MASK (0xffffff00 | SRMMU_REF | SRMMU_DIRTY) -/* SRMMU swap entry encoding - * - * We use 5 bits for the type and 19 for the offset. This gives us - * 32 swapfiles of 4GB each. Encoding looks like: - * - * oooooooooooooooooootttttRRRRRRRR - * fedcba9876543210fedcba9876543210 - * - * The bottom 7 bits are reserved for protection and status bits, especially - * PRESENT. - */ +/* SRMMU swap entry encoding */ #define SRMMU_SWP_TYPE_MASK 0x1f #define SRMMU_SWP_TYPE_SHIFT 7 #define SRMMU_SWP_OFF_MASK 0xfffff #define SRMMU_SWP_OFF_SHIFT (SRMMU_SWP_TYPE_SHIFT + 5) +/* We borrow bit 6 to store the exclusive marker in swap PTEs. */ +#define SRMMU_SWP_EXCLUSIVE SRMMU_DIRTY /* Some day I will implement true fine grained access bits for * user pages because the SRMMU gives us the capabilities to