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Fri, 13 Jan 2023 12:13:10 -0500 X-MC-Unique: tcQ5phS1Ng-WmjPesDZNfg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E6769100F902; Fri, 13 Jan 2023 17:13:08 +0000 (UTC) Received: from t480s.fritz.box (unknown [10.39.193.196]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8CFF640C2064; Fri, 13 Jan 2023 17:13:02 +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 v1 20/26] sh/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE Date: Fri, 13 Jan 2023 18:10:20 +0100 Message-Id: <20230113171026.582290-21-david@redhat.com> In-Reply-To: <20230113171026.582290-1-david@redhat.com> References: <20230113171026.582290-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230113_091312_745993_A160C873 X-CRM114-Status: GOOD ( 18.07 ) X-Spam-Score: -0.4 (/) X-Spam-Report: Spam detection software, running on the system "bombadil.infradead.org", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: 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_SHI [...] Content analysis details: (-0.4 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_MSPIKE_H2 RBL: Average reputation (+2) [170.10.133.124 listed in wl.mailspike.net] -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [170.10.133.124 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.0 SPF_NONE SPF: sender does not publish an SPF Record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.2 DKIMWL_WL_HIGH DKIMwl.org - High trust sender 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: , Sender: "linux-um" Errors-To: linux-um-bounces+incoming=patchwork.ozlabs.org@lists.infradead.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..c34aa795a9d2 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 */