From b5c88f21531c3457e3e202817556b68171484e00 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Fri, 13 Jan 2023 18:10:11 +0100 Subject: microblaze/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by stealing one bit from the type. Generic MM currently only uses 5 bits for the type (MAX_SWAPFILES_SHIFT), so the stolen bit is effectively unused. The shift by 2 when converting between PTE and arch-specific swap entry makes the swap PTE layout a little bit harder to decipher. While at it, drop the comment from paulus---copy-and-paste leftover from powerpc where we actually have _PAGE_HASHPTE---and mask the type in __swp_entry_to_pte() as well. Link: https://lkml.kernel.org/r/20230113171026.582290-12-david@redhat.com Signed-off-by: David Hildenbrand Cc: Michal Simek Signed-off-by: Andrew Morton --- arch/microblaze/include/asm/pgtable.h | 45 +++++++++++++++++++++++++++-------- 1 file changed, 35 insertions(+), 10 deletions(-) (limited to 'arch/microblaze/include/asm/pgtable.h') diff --git a/arch/microblaze/include/asm/pgtable.h b/arch/microblaze/include/asm/pgtable.h index 42f5988e998b..7e3de54bf426 100644 --- a/arch/microblaze/include/asm/pgtable.h +++ b/arch/microblaze/include/asm/pgtable.h @@ -131,10 +131,10 @@ extern pte_t *va_to_pte(unsigned long address); * of the 16 available. Bit 24-26 of the TLB are cleared in the TLB * miss handler. Bit 27 is PAGE_USER, thus selecting the correct * zone. - * - PRESENT *must* be in the bottom two bits because swap cache - * entries use the top 30 bits. Because 4xx doesn't support SMP - * anyway, M is irrelevant so we borrow it for PAGE_PRESENT. Bit 30 - * is cleared in the TLB miss handler before the TLB entry is loaded. + * - PRESENT *must* be in the bottom two bits because swap PTEs use the top + * 30 bits. Because 4xx doesn't support SMP anyway, M is irrelevant so we + * borrow it for PAGE_PRESENT. Bit 30 is cleared in the TLB miss handler + * before the TLB entry is loaded. * - All other bits of the PTE are loaded into TLBLO without * * modification, leaving us only the bits 20, 21, 24, 25, 26, 30 for * software PTE bits. We actually use bits 21, 24, 25, and @@ -155,6 +155,9 @@ extern pte_t *va_to_pte(unsigned long address); #define _PAGE_ACCESSED 0x400 /* software: R: page referenced */ #define _PMD_PRESENT PAGE_MASK +/* We borrow bit 24 to store the exclusive marker in swap PTEs. */ +#define _PAGE_SWP_EXCLUSIVE _PAGE_DIRTY + /* * Some bits are unused... */ @@ -393,18 +396,40 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd) extern pgd_t swapper_pg_dir[PTRS_PER_PGD]; /* - * 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(). + * + * 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 -------------------> E < type -> 0 0 + * + * E is the exclusive marker that is not stored in swap entries. */ -#define __swp_type(entry) ((entry).val & 0x3f) +#define __swp_type(entry) ((entry).val & 0x1f) #define __swp_offset(entry) ((entry).val >> 6) #define __swp_entry(type, offset) \ - ((swp_entry_t) { (type) | ((offset) << 6) }) + ((swp_entry_t) { ((type) & 0x1f) | ((offset) << 6) }) #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) >> 2 }) #define __swp_entry_to_pte(x) ((pte_t) { (x).val << 2 }) +#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; +} + extern unsigned long iopa(unsigned long addr); /* Values for nocacheflag and cmode */ -- cgit