Commit 3151cc26 authored by David Hildenbrand's avatar David Hildenbrand Committed by Andrew Morton
Browse files

ia64/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE 

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.

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

Link: https://lkml.kernel.org/r/20230113171026.582290-8-david@redhat.com


Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 61f4a896

arch/ia64/include/asm/pgtable.h

+29 −3
Original line number Diff line number Diff line
@@ -58,6 +58,9 @@ 
#define _PAGE_ED		(__IA64_UL(1) << 52)	/* exception deferral */

#define _PAGE_PROTNONE		(__IA64_UL(1) << 63)



/* We borrow bit 7 to store the exclusive marker in swap PTEs. */

#define _PAGE_SWP_EXCLUSIVE	(1 << 7)



#define _PFN_MASK		_PAGE_PPN_MASK

/* Mask of bits which may be changed by pte_modify(); the odd bits are there for _PAGE_PROTNONE */

#define _PAGE_CHG_MASK	(_PAGE_P | _PAGE_PROTNONE | _PAGE_PL_MASK | _PAGE_AR_MASK | _PAGE_ED)
@@ -399,6 +402,9 @@ extern pgd_t swapper_pg_dir[PTRS_PER_PGD]; 
extern void paging_init (void);



/*

 * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that

 * are !pte_none() && !pte_present().

 *

 * Note: The macros below rely on the fact that MAX_SWAPFILES_SHIFT <= number of

 *	 bits in the swap-type field of the swap pte.  It would be nice to

 *	 enforce that, but we can't easily include <linux/swap.h> here.
@@ -406,16 +412,36 @@ extern void paging_init (void); 
 *

 * Format of swap pte:

 *	bit   0   : present bit (must be zero)

 *	bits  1- 7: swap-type

 *	bits  1- 6: swap type

 *	bit   7   : exclusive marker

 *	bits  8-62: swap offset

 *	bit  63   : _PAGE_PROTNONE bit

 */

#define __swp_type(entry)		(((entry).val >> 1) & 0x7f)

#define __swp_type(entry)		(((entry).val >> 1) & 0x3f)

#define __swp_offset(entry)		(((entry).val << 1) >> 9)

#define __swp_entry(type,offset)	((swp_entry_t) { ((type) << 1) | ((long) (offset) << 8) })

#define __swp_entry(type, offset)	((swp_entry_t) { ((type & 0x3f) << 1) | \

							 ((long) (offset) << 8) })

#define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val(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_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;

}



/*

 * ZERO_PAGE is a global shared page that is always zero: used

 * for zero-mapped memory areas etc..