From patchwork Tue Dec 6 14:47:24 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13065996 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 ABCB1C63703 for ; Tue, 6 Dec 2022 14:57:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235496AbiLFO5R (ORCPT ); Tue, 6 Dec 2022 09:57:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47674 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231220AbiLFO4I (ORCPT ); Tue, 6 Dec 2022 09:56:08 -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 C8D1E2FA55 for ; Tue, 6 Dec 2022 06:50:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1670338219; 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=t2dM4tcpRYTtx8QXJb/K6cGk7rDB2W5PELTjmuISuR8=; b=BSKtSzEDEfNwuj3draSR5oDsvVOVt/6aA0KEr60wLecvmQQViwRwiSHZIhFPnGzU4QG78s tKHgUac1qnkQIvuxyGp4ZhOHwi3fUs4ndIbaAADrGL1tbsOQeyQFht3mIwbXG6/2UUoCxA YdwmEiJ0bQTrKe/0TXfBo4gMirjumhg= 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-167-njC9THvHN7u9IC4K-UJ9ew-1; Tue, 06 Dec 2022 09:50:14 -0500 X-MC-Unique: njC9THvHN7u9IC4K-UJ9ew-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 89B66811E7A; Tue, 6 Dec 2022 14:50:14 +0000 (UTC) Received: from t480s.redhat.com (unknown [10.39.193.173]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5B352492B07; Tue, 6 Dec 2022 14:50:07 +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 , Yoshinori Sato , Rich Felker Subject: [PATCH mm-unstable RFC 20/26] sh/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE Date: Tue, 6 Dec 2022 15:47:24 +0100 Message-Id: <20221206144730.163732-21-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 using bit 6 in the PTE, reducing the swap type in the !CONFIG_X2TLB case to 5 bits. Generic MM currently only uses 5 bits for the type (MAX_SWAPFILES_SHIFT), so the stolen bit is effectively unused. Interrestingly, the swap type in the !CONFIG_X2TLB case could currently overlap with the _PAGE_PRESENT bit, because there is a sneaky shift by 1 in __pte_to_swp_entry() and __swp_entry_to_pte(). Bit 0-7 in the architecture specific swap PTE would get shifted to bit 1-8 in the PTE. As generic MM uses 5 bits only, this didn't matter so far. While at it, mask the type in __swp_entry(). Cc: Yoshinori Sato Cc: Rich Felker Signed-off-by: David Hildenbrand --- arch/sh/include/asm/pgtable_32.h | 54 +++++++++++++++++++++++++------- 1 file changed, 42 insertions(+), 12 deletions(-) diff --git a/arch/sh/include/asm/pgtable_32.h b/arch/sh/include/asm/pgtable_32.h index d0240decacca..090940aadbcc 100644 --- a/arch/sh/include/asm/pgtable_32.h +++ b/arch/sh/include/asm/pgtable_32.h @@ -423,40 +423,70 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd) #endif /* - * 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(). * * Constraints: * _PAGE_PRESENT at bit 8 * _PAGE_PROTNONE at bit 9 * - * For the normal case, we encode the swap type into bits 0:7 and the - * swap offset into bits 10:30. For the 64-bit PTE case, we keep the - * preserved bits in the low 32-bits and use the upper 32 as the swap - * offset (along with a 5-bit type), following the same approach as x86 - * PAE. This keeps the logic quite simple. + * For the normal case, we encode the swap type and offset into the swap PTE + * such that bits 8 and 9 stay zero. For the 64-bit PTE case, we use the + * upper 32 for the swap offset and swap type, following the same approach as + * x86 PAE. This keeps the logic quite simple. * * As is evident by the Alpha code, if we ever get a 64-bit unsigned * long (swp_entry_t) to match up with the 64-bit PTEs, this all becomes * much cleaner.. - * - * NOTE: We should set ZEROs at the position of _PAGE_PRESENT - * and _PAGE_PROTNONE bits */ + #ifdef CONFIG_X2TLB +/* + * Format of swap PTEs: + * + * 6 6 6 6 5 5 5 5 5 5 5 5 5 5 4 4 4 4 4 4 4 4 4 4 3 3 3 3 3 3 3 3 + * 3 2 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 + * <--------------------- offset ----------------------> < type -> + * + * 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 + * <------------------- zeroes --------------------> E 0 0 0 0 0 0 + */ #define __swp_type(x) ((x).val & 0x1f) #define __swp_offset(x) ((x).val >> 5) -#define __swp_entry(type, offset) ((swp_entry_t){ (type) | (offset) << 5}) +#define __swp_entry(type, offset) ((swp_entry_t){ ((type) & 0x1f) | (offset) << 5}) #define __pte_to_swp_entry(pte) ((swp_entry_t){ (pte).pte_high }) #define __swp_entry_to_pte(x) ((pte_t){ 0, (x).val }) #else -#define __swp_type(x) ((x).val & 0xff) +/* + * 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 ----------------> 0 0 0 0 E < type -> 0 + * + * E is the exclusive marker that is not stored in swap entries. + */ +#define __swp_type(x) ((x).val & 0x1f) #define __swp_offset(x) ((x).val >> 10) -#define __swp_entry(type, offset) ((swp_entry_t){(type) | (offset) <<10}) +#define __swp_entry(type, offset) ((swp_entry_t){((type) & 0x1f) | (offset) <<10}) #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) >> 1 }) #define __swp_entry_to_pte(x) ((pte_t) { (x).val << 1 }) #endif +/* In both cases, we borrow bit 6 to store the exclusive marker in swap PTEs. */ +#define _PAGE_SWP_EXCLUSIVE _PAGE_USER + +#define __HAVE_ARCH_PTE_SWP_EXCLUSIVE +static inline int pte_swp_exclusive(pte_t pte) +{ + return pte.pte_low & _PAGE_SWP_EXCLUSIVE; +} + +PTE_BIT_FUNC(low, swp_mkexclusive, |= _PAGE_SWP_EXCLUSIVE); +PTE_BIT_FUNC(low, swp_clear_exclusive, &= ~_PAGE_SWP_EXCLUSIVE); + #endif /* __ASSEMBLY__ */ #endif /* __ASM_SH_PGTABLE_32_H */