From mboxrd@z Thu Jan 1 00:00:00 1970 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E884BC636CD for ; Fri, 10 Feb 2023 05:08:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:References :In-Reply-To:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=2aG2j4k9IiqQumF99X4HrRah3a1glvu5TQqMD5P4mYk=; b=YIVRwQqKZBabWl gkdixyAk0zteeATukpc1j3p96TK5E93YhPAq8D3FaLwukGPaY68t0hYvVnIh0WKcIiB0bSUL0N4s4 7eEkiQ2MGu6dJAaTkpUV9AVPMQ9QJL0RS06Tbl1xh3u168iPxEZfINY1olQCY9Ych8Xtyuez5OcDE Sy9JZSPXYgWQ+6C2VOZ7SwPhYg97fKf2bFrJVw4HDecivePfy2qIpu95KfGrRPRKpzehepC5JrqBH WL/9xA4Cizns2p8nItO7O/kumjZfIyb8zziH4ZPJY31a6CDwC4BnZc0ptya5wEb1N3N/t9Ra+qLfB iRGy6VF3I9XAvYFl8qLw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pQLeF-004FyY-00; Fri, 10 Feb 2023 05:08:35 +0000 Received: from gandalf.ozlabs.org ([150.107.74.76]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1pQLe2-004FvL-PB; Fri, 10 Feb 2023 05:08:24 +0000 Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4PChZj6hzVz4xwy; Fri, 10 Feb 2023 16:08:13 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1676005696; bh=gjOEhpmQ4QzYiJxNRSCplO6mzBIo8CgdHMudas4f4m4=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=VzBHDakF5oapgbqSwyCXW4NlOxuhWIXgHT5bnjksmwxnwzB2j77QlwtNy9auFKO5k R5zuzvTLv5v6JR0g4zAQSDALbGO0+HtyCcaxIv+XCmtUOUNdsZXpr/60HJ8m0se9Ac HCqPfRmHl1K9cRm2zGL0JLt1dLbvDoohuA4JmvWcFN0J1XTPyIZXfr0n3q8zPBgbwM 2KTETWI8PkOX6ZP5se3LmuOaFIoUbfwmRFq7s/gffXRM+ntl6Tsz8s7uIuoBncovYH 169scsrJUZSYlGwI60JQl2lk38JbvV/eRPo8tLjsBgWQeltv5kZiHwGm5Gqurl9z/4 hTaeq+aYRbc4A== From: Michael Ellerman To: David Hildenbrand , 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 , Nicholas Piggin , Christophe Leroy Subject: Re: [PATCH mm-unstable v1 17/26] powerpc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on 32bit book3s In-Reply-To: <20230113171026.582290-18-david@redhat.com> References: <20230113171026.582290-1-david@redhat.com> <20230113171026.582290-18-david@redhat.com> Date: Fri, 10 Feb 2023 16:08:07 +1100 Message-ID: <87cz6iw1jc.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230209_210823_230868_E61C58F8 X-CRM114-Status: GOOD ( 24.58 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org David Hildenbrand writes: > We already implemented support for 64bit book3s in commit bff9beaa2e80 > ("powerpc/pgtable: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE for book3s") > > Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE also in 32bit by reusing yet > unused LSB 2 / MSB 29. There seems to be no real reason why that bit cannot > be used, and reusing it avoids having to steal one bit from the swap > offset. > > While at it, mask the type in __swp_entry(). > > Cc: Michael Ellerman > Cc: Nicholas Piggin > Cc: Christophe Leroy > Signed-off-by: David Hildenbrand > --- > arch/powerpc/include/asm/book3s/32/pgtable.h | 38 +++++++++++++++++--- > 1 file changed, 33 insertions(+), 5 deletions(-) I gave this a quick test on a ppc32 machine, everything seems fine. Your test_swp_exclusive.c passes, and an LTP run looks normal. Acked-by: Michael Ellerman (powerpc) cheers > diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h > index 75823f39e042..0ecb3a58f23f 100644 > --- a/arch/powerpc/include/asm/book3s/32/pgtable.h > +++ b/arch/powerpc/include/asm/book3s/32/pgtable.h > @@ -42,6 +42,9 @@ > #define _PMD_PRESENT_MASK (PAGE_MASK) > #define _PMD_BAD (~PAGE_MASK) > > +/* We borrow the _PAGE_USER bit to store the exclusive marker in swap PTEs. */ > +#define _PAGE_SWP_EXCLUSIVE _PAGE_USER > + > /* And here we include common definitions */ > > #define _PAGE_KERNEL_RO 0 > @@ -363,17 +366,42 @@ static inline void __ptep_set_access_flags(struct vm_area_struct *vma, > #define pmd_page(pmd) pfn_to_page(pmd_pfn(pmd)) > > /* > - * Encode and decode a swap entry. > - * Note that the bits we use in a PTE for representing a swap entry > - * must not include the _PAGE_PRESENT bit or the _PAGE_HASHPTE bit (if used). > - * -- paulus > + * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that > + * are !pte_none() && !pte_present(). > + * > + * Format of swap PTEs (32bit PTEs): > + * > + * 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 > + * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 > + * <----------------- offset --------------------> < type -> E H P > + * > + * E is the exclusive marker that is not stored in swap entries. > + * _PAGE_PRESENT (P) and __PAGE_HASHPTE (H) must be 0. > + * > + * For 64bit PTEs, the offset is extended by 32bit. > */ > #define __swp_type(entry) ((entry).val & 0x1f) > #define __swp_offset(entry) ((entry).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_val(pte) >> 3 }) > #define __swp_entry_to_pte(x) ((pte_t) { (x).val << 3 }) > > +#define __HAVE_ARCH_PTE_SWP_EXCLUSIVE > +static inline int pte_swp_exclusive(pte_t pte) > +{ > + return pte_val(pte) & _PAGE_SWP_EXCLUSIVE; > +} > + > +static inline pte_t pte_swp_mkexclusive(pte_t pte) > +{ > + return __pte(pte_val(pte) | _PAGE_SWP_EXCLUSIVE); > +} > + > +static inline pte_t pte_swp_clear_exclusive(pte_t pte) > +{ > + return __pte(pte_val(pte) & ~_PAGE_SWP_EXCLUSIVE); > +} > + > /* Generic accessors to PTE bits */ > static inline int pte_write(pte_t pte) { return !!(pte_val(pte) & _PAGE_RW);} > static inline int pte_read(pte_t pte) { return 1; } > -- > 2.39.0 > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um