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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-Spamd-Result: default: False [-0.90 / 9.00]; BAYES_HAM(-6.00)[100.00%]; R_MISSING_CHARSET(2.50)[]; SUSPICIOUS_RECIPS(1.50)[]; SUBJECT_HAS_UNDERSCORES(1.00)[]; MID_CONTAINS_FROM(1.00)[]; DMARC_POLICY_ALLOW(-0.50)[redhat.com,none]; R_SPF_ALLOW(-0.20)[+ip4:170.10.129.0/24]; R_DKIM_ALLOW(-0.20)[redhat.com:s=mimecast20190719]; RCVD_NO_TLS_LAST(0.10)[]; MIME_GOOD(-0.10)[text/plain]; MIME_TRACE(0.00)[0:+]; FROM_EQ_ENVFROM(0.00)[]; RCPT_COUNT_TWELVE(0.00)[34]; RCVD_COUNT_THREE(0.00)[4]; TO_MATCH_ENVRCPT_SOME(0.00)[]; FROM_HAS_DN(0.00)[]; DKIM_TRACE(0.00)[redhat.com:+]; TO_DN_SOME(0.00)[]; ARC_SIGNED(0.00)[hostedemail.com:s=arc-20220608:i=1]; ARC_NA(0.00)[] X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 9F7AD40004 X-Stat-Signature: nwyxmjs79h47cswnbuk9ojypxu7tziwe X-HE-Tag: 1670338190-666491 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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;