lkml.org 
[lkml]   [2022]   [Dec]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH mm-unstable RFC 23/26] um/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
    Date
    Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by using bit 10, which is
    yet unused for swap PTEs.

    The pte_mkuptodate() is a bit weird in __pte_to_swp_entry() for a swap PTE
    ... but it only messes with bit 1 and 2 and there is a comment in
    set_pte(), so leave these bits alone.

    While at it, mask the type in __swp_entry().

    Cc: Richard Weinberger <richard@nod.at>
    Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
    Cc: Johannes Berg <johannes@sipsolutions.net>
    Signed-off-by: David Hildenbrand <david@redhat.com>
    ---
    arch/um/include/asm/pgtable.h | 37 +++++++++++++++++++++++++++++++++--
    1 file changed, 35 insertions(+), 2 deletions(-)

    diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable.h
    index 4e3052f2671a..cedc5fd451ce 100644
    --- a/arch/um/include/asm/pgtable.h
    +++ b/arch/um/include/asm/pgtable.h
    @@ -21,6 +21,9 @@
    #define _PAGE_PROTNONE 0x010 /* if the user mapped it with PROT_NONE;
    pte_present gives true */

    +/* We borrow bit 10 to store the exclusive marker in swap PTEs. */
    +#define _PAGE_SWP_EXCLUSIVE 0x400
    +
    #ifdef CONFIG_3_LEVEL_PGTABLES
    #include <asm/pgtable-3level.h>
    #else
    @@ -288,16 +291,46 @@ extern pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr);

    #define update_mmu_cache(vma,address,ptep) do {} while (0)

    -/* 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:
    + *
    + * 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 ----------------> E < type -> 0 0 0 1 0
    + *
    + * E is the exclusive marker that is not stored in swap entries.
    + * _PAGE_NEWPAGE (bit 1) is always set to 1 in set_pte().
    + */
    #define __swp_type(x) (((x).val >> 5) & 0x1f)
    #define __swp_offset(x) ((x).val >> 11)

    #define __swp_entry(type, offset) \
    - ((swp_entry_t) { ((type) << 5) | ((offset) << 11) })
    + ((swp_entry_t) { (((type) & 0x1f) << 5) | ((offset) << 11) })
    #define __pte_to_swp_entry(pte) \
    ((swp_entry_t) { pte_val(pte_mkuptodate(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_get_bits(pte, _PAGE_SWP_EXCLUSIVE);
    +}
    +
    +static inline pte_t pte_swp_mkexclusive(pte_t pte)
    +{
    + pte_set_bits(pte, _PAGE_SWP_EXCLUSIVE);
    + return pte;
    +}
    +
    +static inline pte_t pte_swp_clear_exclusive(pte_t pte)
    +{
    + pte_clear_bits(pte, _PAGE_SWP_EXCLUSIVE);
    + return pte;
    +}
    +
    /* Clear a kernel PTE and flush it from the TLB */
    #define kpte_clear_flush(ptep, vaddr) \
    do { \
    --
    2.38.1
    \
     
     \ /
      Last update: 2022-12-06 15:58    [W:6.197 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site