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Bottomley" , Helge Deller Subject: [PATCH mm-unstable RFC 16/26] parisc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE Date: Tue, 6 Dec 2022 15:47:20 +0100 Message-Id: <20221206144730.163732-17-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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221206_064951_890967_699EE8AD X-CRM114-Status: GOOD ( 14.32 ) 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 the yet-unused _PAGE_ACCESSED location in the swap PTE. Looking at pte_present() and pte_none() checks, there seems to be no actual reason why we c [...] Content analysis details: (-0.4 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_MSPIKE_H2 RBL: Average reputation (+2) [170.10.129.124 listed in wl.mailspike.net] -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [170.10.129.124 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-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux on Synopsys ARC Processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by using the yet-unused _PAGE_ACCESSED location in the swap PTE. Looking at pte_present() and pte_none() checks, there seems to be no actual reason why we cannot use it: we only have to make sure we're not using _PAGE_PRESENT. Reusing this bit avoids having to steal one bit from the swap offset. Cc: "James E.J. Bottomley" Cc: Helge Deller Signed-off-by: David Hildenbrand --- arch/parisc/include/asm/pgtable.h | 41 ++++++++++++++++++++++++++++--- 1 file changed, 38 insertions(+), 3 deletions(-) diff --git a/arch/parisc/include/asm/pgtable.h b/arch/parisc/include/asm/pgtable.h index bd09a44cfb2d..75115c8bf888 100644 --- a/arch/parisc/include/asm/pgtable.h +++ b/arch/parisc/include/asm/pgtable.h @@ -218,6 +218,9 @@ extern void __update_cache(pte_t pte); #define _PAGE_KERNEL_RWX (_PAGE_KERNEL_EXEC | _PAGE_WRITE) #define _PAGE_KERNEL (_PAGE_KERNEL_RO | _PAGE_WRITE) +/* We borrow bit 23 to store the exclusive marker in swap PTEs. */ +#define _PAGE_SWP_EXCLUSIVE _PAGE_ACCESSED + /* The pgd/pmd contains a ptr (in phys addr space); since all pgds/pmds * are page-aligned, we don't care about the PAGE_OFFSET bits, except * for a few meta-information bits, so we shift the address to be @@ -394,17 +397,49 @@ extern void paging_init (void); #define update_mmu_cache(vms,addr,ptep) __update_cache(*ptep) -/* 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 (32bit): + * + * 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 -----------------> P E < type -> + * + * E is the exclusive marker that is not stored in swap entries. + * _PAGE_PRESENT (P) must be 0. + * + * For the 64bit version, the offset is extended by 32bit. + */ #define __swp_type(x) ((x).val & 0x1f) #define __swp_offset(x) ( (((x).val >> 6) & 0x7) | \ (((x).val >> 8) & ~0x7) ) -#define __swp_entry(type, offset) ((swp_entry_t) { (type) | \ +#define __swp_entry(type, offset) ((swp_entry_t) { \ + ((type) & 0x1f) | \ ((offset & 0x7) << 6) | \ ((offset & ~0x7) << 8) }) #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) & _PAGE_SWP_EXCLUSIVE; +} + +static inline pte_t pte_swp_mkexclusive(pte_t pte) +{ + pte_val(pte) |= _PAGE_SWP_EXCLUSIVE; + return pte; +} + +static inline pte_t pte_swp_clear_exclusive(pte_t pte) +{ + pte_val(pte) &= ~_PAGE_SWP_EXCLUSIVE; + return pte; +} + static inline int ptep_test_and_clear_young(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) { pte_t pte;