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Commit 65b1bfc1 authored by Russell King's avatar Russell King Committed by Russell King
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[ARM] pgtable: file pte layout documentation 



Document the layout of our file PTE entries.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent fb93a1c7

arch/arm/include/asm/pgtable.h

+14 −9
Original line number Diff line number Diff line
@@ -285,15 +285,6 @@ extern struct page *empty_zero_page; 
#define pte_young(pte)		(pte_val(pte) & L_PTE_YOUNG)

#define pte_special(pte)	(0)



/*

 * The following only works if pte_present() is not true.

 */

#define pte_file(pte)		(pte_val(pte) & L_PTE_FILE)

#define pte_to_pgoff(x)		(pte_val(x) >> 2)

#define pgoff_to_pte(x)		__pte(((x) << 2) | L_PTE_FILE)



#define PTE_FILE_MAX_BITS	30



#define PTE_BIT_FUNC(fn,op) \

static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; }
@@ -414,6 +405,20 @@ extern pgd_t swapper_pg_dir[PTRS_PER_PGD]; 
 */

#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > __SWP_TYPE_BITS)



/*

 * Encode and decode a file entry.  File entries are stored in the Linux

 * page tables as follows:

 *

 *   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 -------------------------> 1 0

 */

#define pte_file(pte)		(pte_val(pte) & L_PTE_FILE)

#define pte_to_pgoff(x)		(pte_val(x) >> 2)

#define pgoff_to_pte(x)		__pte(((x) << 2) | L_PTE_FILE)



#define PTE_FILE_MAX_BITS	30



/* Needs to be defined here and not in linux/mm.h, as it is arch dependent */

/* FIXME: this is not correct */

#define kern_addr_valid(addr)	(1)