From 83d3b2b46ea3f8fa542fb7528b3bca6f476d0fab Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Fri, 13 Jan 2023 18:10:12 +0100 Subject: [PATCH] mips/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE. On 64bit, steal 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. On 32bit we're able to locate unused bits. As the PTE layout for 32 bit is very confusing, document it a bit better. While at it, mask the type in __swp_entry()/mk_swap_pte(). Link: https://lkml.kernel.org/r/20230113171026.582290-13-david@redhat.com Signed-off-by: David Hildenbrand Cc: Thomas Bogendoerfer Signed-off-by: Andrew Morton --- arch/mips/include/asm/pgtable-32.h | 88 ++++++++++++++++++++++++++++++++------ arch/mips/include/asm/pgtable-64.h | 23 ++++++++-- arch/mips/include/asm/pgtable.h | 36 ++++++++++++++++ 3 files changed, 131 insertions(+), 16 deletions(-) diff --git a/arch/mips/include/asm/pgtable-32.h b/arch/mips/include/asm/pgtable-32.h index b40a0e6..ba00167 100644 --- a/arch/mips/include/asm/pgtable-32.h +++ b/arch/mips/include/asm/pgtable-32.h @@ -191,49 +191,113 @@ static inline pte_t pfn_pte(unsigned long pfn, pgprot_t prot) #define pte_page(x) pfn_to_page(pte_pfn(x)) +/* + * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that + * are !pte_none() && !pte_present(). + */ #if defined(CONFIG_CPU_R3K_TLB) -/* Swap entries must have VALID bit cleared. */ +/* + * 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 ------------> < type -> V G E 0 0 0 0 0 0 P + * + * E is the exclusive marker that is not stored in swap entries. + * _PAGE_PRESENT (P), _PAGE_VALID (V) and_PAGE_GLOBAL (G) have to remain + * unused. + */ #define __swp_type(x) (((x).val >> 10) & 0x1f) #define __swp_offset(x) ((x).val >> 15) -#define __swp_entry(type,offset) ((swp_entry_t) { ((type) << 10) | ((offset) << 15) }) +#define __swp_entry(type, offset) ((swp_entry_t) { (((type) & 0x1f) << 10) | ((offset) << 15) }) #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) }) #define __swp_entry_to_pte(x) ((pte_t) { (x).val }) +/* We borrow bit 7 to store the exclusive marker in swap PTEs. */ +#define _PAGE_SWP_EXCLUSIVE (1 << 7) + #else #if defined(CONFIG_XPA) -/* Swap entries must have VALID and GLOBAL bits cleared. */ +/* + * 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 + * 0 0 0 0 0 0 E P <------------------ zeroes -------------------> + * + * 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 ------------------> < type -> V G 0 0 + * + * E is the exclusive marker that is not stored in swap entries. + * _PAGE_PRESENT (P), _PAGE_VALID (V) and_PAGE_GLOBAL (G) have to remain + * unused. + */ #define __swp_type(x) (((x).val >> 4) & 0x1f) #define __swp_offset(x) ((x).val >> 9) -#define __swp_entry(type,offset) ((swp_entry_t) { ((type) << 4) | ((offset) << 9) }) +#define __swp_entry(type, offset) ((swp_entry_t) { (((type) & 0x1f) << 4) | ((offset) << 9) }) #define __pte_to_swp_entry(pte) ((swp_entry_t) { (pte).pte_high }) #define __swp_entry_to_pte(x) ((pte_t) { 0, (x).val }) +/* + * We borrow bit 57 (bit 25 in the low PTE) to store the exclusive marker in + * swap PTEs. + */ +#define _PAGE_SWP_EXCLUSIVE (1 << 25) + #elif defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32) -/* Swap entries must have VALID and GLOBAL bits cleared. */ +/* + * 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 + * <------------------ zeroes -------------------> E P 0 0 0 0 0 0 + * + * 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 --------------------> < type -> V G + * + * E is the exclusive marker that is not stored in swap entries. + * _PAGE_PRESENT (P), _PAGE_VALID (V) and_PAGE_GLOBAL (G) have to remain + * unused. + */ #define __swp_type(x) (((x).val >> 2) & 0x1f) #define __swp_offset(x) ((x).val >> 7) -#define __swp_entry(type, offset) ((swp_entry_t) { ((type) << 2) | ((offset) << 7) }) +#define __swp_entry(type, offset) ((swp_entry_t) { (((type) & 0x1f) << 2) | ((offset) << 7) }) #define __pte_to_swp_entry(pte) ((swp_entry_t) { (pte).pte_high }) #define __swp_entry_to_pte(x) ((pte_t) { 0, (x).val }) +/* + * We borrow bit 39 (bit 7 in the low PTE) to store the exclusive marker in swap + * PTEs. + */ +#define _PAGE_SWP_EXCLUSIVE (1 << 7) + #else /* - * Constraints: - * _PAGE_PRESENT at bit 0 - * _PAGE_MODIFIED at bit 4 - * _PAGE_GLOBAL at bit 6 - * _PAGE_VALID at bit 7 + * 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 --------------> < type -> 0 0 0 0 0 0 E P + * + * E is the exclusive marker that is not stored in swap entries. + * _PAGE_PRESENT (P), _PAGE_VALID (V) and_PAGE_GLOBAL (G) have to remain + * unused. The location of V and G varies. */ #define __swp_type(x) (((x).val >> 8) & 0x1f) #define __swp_offset(x) ((x).val >> 13) -#define __swp_entry(type,offset) ((swp_entry_t) { ((type) << 8) | ((offset) << 13) }) +#define __swp_entry(type, offset) ((swp_entry_t) { ((type) << 8) | ((offset) << 13) }) #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) }) #define __swp_entry_to_pte(x) ((pte_t) { (x).val }) +/* We borrow bit 1 to store the exclusive marker in swap PTEs. */ +#define _PAGE_SWP_EXCLUSIVE (1 << 1) + #endif /* defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32) */ #endif /* defined(CONFIG_CPU_R3K_TLB) */ diff --git a/arch/mips/include/asm/pgtable-64.h b/arch/mips/include/asm/pgtable-64.h index c631019..98e24e3 100644 --- a/arch/mips/include/asm/pgtable-64.h +++ b/arch/mips/include/asm/pgtable-64.h @@ -320,16 +320,31 @@ extern void pud_init(void *addr); extern void pmd_init(void *addr); /* - * Non-present pages: high 40 bits are offset, next 8 bits type, - * low 16 bits zero. + * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that + * are !pte_none() && !pte_present(). + * + * 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 --------------------------- + * + * 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 + * --------------> E <-- type ---> <---------- zeroes -----------> + * + * E is the exclusive marker that is not stored in swap entries. */ static inline pte_t mk_swap_pte(unsigned long type, unsigned long offset) -{ pte_t pte; pte_val(pte) = (type << 16) | (offset << 24); return pte; } +{ pte_t pte; pte_val(pte) = ((type & 0x7f) << 16) | (offset << 24); return pte; } -#define __swp_type(x) (((x).val >> 16) & 0xff) +#define __swp_type(x) (((x).val >> 16) & 0x7f) #define __swp_offset(x) ((x).val >> 24) #define __swp_entry(type, offset) ((swp_entry_t) { pte_val(mk_swap_pte((type), (offset))) }) #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) }) #define __swp_entry_to_pte(x) ((pte_t) { (x).val }) +/* We borrow bit 23 to store the exclusive marker in swap PTEs. */ +#define _PAGE_SWP_EXCLUSIVE (1 << 23) + #endif /* _ASM_PGTABLE_64_H */ diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h index a68c0b0..711874c 100644 --- a/arch/mips/include/asm/pgtable.h +++ b/arch/mips/include/asm/pgtable.h @@ -528,6 +528,42 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) } #endif +#define __HAVE_ARCH_PTE_SWP_EXCLUSIVE +#if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32) +static inline int pte_swp_exclusive(pte_t pte) +{ + return pte.pte_low & _PAGE_SWP_EXCLUSIVE; +} + +static inline pte_t pte_swp_mkexclusive(pte_t pte) +{ + pte.pte_low |= _PAGE_SWP_EXCLUSIVE; + return pte; +} + +static inline pte_t pte_swp_clear_exclusive(pte_t pte) +{ + pte.pte_low &= ~_PAGE_SWP_EXCLUSIVE; + return pte; +} +#else +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; +} +#endif extern void __update_tlb(struct vm_area_struct *vma, unsigned long address, pte_t pte); -- 2.7.4