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microblaze/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE

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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 <david@redhat.com>
Cc: Michal Simek <monstr@monstr.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2023-01-13 18:10:11 +01:00 committed by Andrew Morton
parent ed4154067a
commit b5c88f2153
2 changed files with 37 additions and 12 deletions
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4
arch/m68k/include/asm/mcf_pgtable.h
View file

@ -46,8 +46,8 @@
#define _CACHEMASK040 (~0x060)
#define _PAGE_GLOBAL040 0x400 /* 68040 global bit, used for kva descs */
/* We borrow bit 7 to store the exclusive marker in swap PTEs. */
#define _PAGE_SWP_EXCLUSIVE 0x080
/* We borrow bit 24 to store the exclusive marker in swap PTEs. */
#define _PAGE_SWP_EXCLUSIVE CF_PAGE_NOCACHE
/*
* Externally used page protection values.

45
arch/microblaze/include/asm/pgtable.h
View file

@ -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 */