diff options
author | David Hildenbrand <david@redhat.com> | 2023-01-13 20:10:04 +0300 |
---|---|---|
committer | Andrew Morton <akpm@linux-foundation.org> | 2023-02-03 09:33:06 +0300 |
commit | 20aae9eff5acd8f50f72adca1176f9269a46b827 (patch) | |
tree | c1e6330fab2b77c927caa120574a19f69fc591e2 /arch/arm/include | |
parent | 4a446b3dd335d0bd14a5ca3e563688de3637be0c (diff) | |
download | linux-20aae9eff5acd8f50f72adca1176f9269a46b827.tar.xz |
arm/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by stealing one bit from the
offset. This reduces the maximum swap space per file to 64 GiB (was 128
GiB).
While at it drop the PTE_TYPE_FAULT from __swp_entry_to_pte() which is
defined to be 0 and is rather confusing because we should be dealing with
"Linux PTEs" not "hardware PTEs". Also, properly mask the type in
__swp_entry().
Link: https://lkml.kernel.org/r/20230113171026.582290-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'arch/arm/include')
-rw-r--r-- | arch/arm/include/asm/pgtable-2level.h | 3 | ||||
-rw-r--r-- | arch/arm/include/asm/pgtable-3level.h | 3 | ||||
-rw-r--r-- | arch/arm/include/asm/pgtable.h | 35 |
3 files changed, 34 insertions, 7 deletions
diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h index 92abd4cd8ca2..ce543cd9380c 100644 --- a/arch/arm/include/asm/pgtable-2level.h +++ b/arch/arm/include/asm/pgtable-2level.h @@ -126,6 +126,9 @@ #define L_PTE_SHARED (_AT(pteval_t, 1) << 10) /* shared(v6), coherent(xsc3) */ #define L_PTE_NONE (_AT(pteval_t, 1) << 11) +/* We borrow bit 7 to store the exclusive marker in swap PTEs. */ +#define L_PTE_SWP_EXCLUSIVE L_PTE_RDONLY + /* * These are the memory types, defined to be compatible with * pre-ARMv6 CPUs cacheable and bufferable bits: n/a,n/a,C,B diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h index eabe72ff7381..106049791500 100644 --- a/arch/arm/include/asm/pgtable-3level.h +++ b/arch/arm/include/asm/pgtable-3level.h @@ -76,6 +76,9 @@ #define L_PTE_NONE (_AT(pteval_t, 1) << 57) /* PROT_NONE */ #define L_PTE_RDONLY (_AT(pteval_t, 1) << 58) /* READ ONLY */ +/* We borrow bit 7 to store the exclusive marker in swap PTEs. */ +#define L_PTE_SWP_EXCLUSIVE (_AT(pteval_t, 1) << 7) + #define L_PMD_SECT_VALID (_AT(pmdval_t, 1) << 0) #define L_PMD_SECT_DIRTY (_AT(pmdval_t, 1) << 55) #define L_PMD_SECT_NONE (_AT(pmdval_t, 1) << 57) diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h index f049072b2e85..886c275995a2 100644 --- a/arch/arm/include/asm/pgtable.h +++ b/arch/arm/include/asm/pgtable.h @@ -271,27 +271,48 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) } /* - * Encode and decode a swap entry. Swap entries are stored in the Linux - * page tables as follows: + * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that + * are !pte_none() && !pte_present(). + * + * 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 + * <------------------- offset ------------------> E < type -> 0 0 + * + * E is the exclusive marker that is not stored in swap entries. * - * This gives us up to 31 swap files and 128GB per swap file. Note that + * This gives us up to 31 swap files and 64GB per swap file. Note that * the offset field is always non-zero. */ #define __SWP_TYPE_SHIFT 2 #define __SWP_TYPE_BITS 5 #define __SWP_TYPE_MASK ((1 << __SWP_TYPE_BITS) - 1) -#define __SWP_OFFSET_SHIFT (__SWP_TYPE_BITS + __SWP_TYPE_SHIFT) +#define __SWP_OFFSET_SHIFT (__SWP_TYPE_BITS + __SWP_TYPE_SHIFT + 1) #define __swp_type(x) (((x).val >> __SWP_TYPE_SHIFT) & __SWP_TYPE_MASK) #define __swp_offset(x) ((x).val >> __SWP_OFFSET_SHIFT) -#define __swp_entry(type,offset) ((swp_entry_t) { ((type) << __SWP_TYPE_SHIFT) | ((offset) << __SWP_OFFSET_SHIFT) }) +#define __swp_entry(type, offset) ((swp_entry_t) { (((type) & __SWP_TYPE_BITS) << __SWP_TYPE_SHIFT) | \ + ((offset) << __SWP_OFFSET_SHIFT) }) #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) }) -#define __swp_entry_to_pte(swp) __pte((swp).val | PTE_TYPE_FAULT) +#define __swp_entry_to_pte(swp) __pte((swp).val) + +#define __HAVE_ARCH_PTE_SWP_EXCLUSIVE +static inline int pte_swp_exclusive(pte_t pte) +{ + return pte_isset(pte, L_PTE_SWP_EXCLUSIVE); +} + +static inline pte_t pte_swp_mkexclusive(pte_t pte) +{ + return set_pte_bit(pte, __pgprot(L_PTE_SWP_EXCLUSIVE)); +} + +static inline pte_t pte_swp_clear_exclusive(pte_t pte) +{ + return clear_pte_bit(pte, __pgprot(L_PTE_SWP_EXCLUSIVE)); +} /* * It is an error for the kernel to have more swap files than we can |