Commit e2858d77 authored by David Hildenbrand's avatar David Hildenbrand Committed by Andrew Morton
Browse files

um/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE 

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().

Link: https://lkml.kernel.org/r/20230113171026.582290-24-david@redhat.com


Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent adf8e329

arch/um/include/asm/pgtable.h

+35 −2
Original line number Diff line number Diff line
@@ -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 {						\