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Commit f16278c6 authored by Hans Rosenfeld's avatar Hans Rosenfeld Committed by Linus Torvalds
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Change pagemap output format to allow for future reporting of huge pages 



Change pagemap output format to allow for future reporting of huge pages.

(Format comment and minor cleanups: mpm@selenic.com)

Signed-off-by: default avatarHans Rosenfeld <hans.rosenfeld@amd.com>
Signed-off-by: default avatarMatt Mackall <mpm@selenic.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 51ec92e2

fs/proc/task_mmu.c

+34 −16
Original line number Diff line number Diff line
@@ -528,12 +528,20 @@ struct pagemapread { 
};



#define PM_ENTRY_BYTES      sizeof(u64)

#define PM_RESERVED_BITS    3

#define PM_RESERVED_OFFSET  (64 - PM_RESERVED_BITS)

#define PM_RESERVED_MASK    (((1LL<<PM_RESERVED_BITS)-1) << PM_RESERVED_OFFSET)

#define PM_SPECIAL(nr)      (((nr) << PM_RESERVED_OFFSET) & PM_RESERVED_MASK)

#define PM_NOT_PRESENT      PM_SPECIAL(1LL)

#define PM_SWAP             PM_SPECIAL(2LL)

#define PM_STATUS_BITS      3

#define PM_STATUS_OFFSET    (64 - PM_STATUS_BITS)

#define PM_STATUS_MASK      (((1LL << PM_STATUS_BITS) - 1) << PM_STATUS_OFFSET)

#define PM_STATUS(nr)       (((nr) << PM_STATUS_OFFSET) & PM_STATUS_MASK)

#define PM_PSHIFT_BITS      6

#define PM_PSHIFT_OFFSET    (PM_STATUS_OFFSET - PM_PSHIFT_BITS)

#define PM_PSHIFT_MASK      (((1LL << PM_PSHIFT_BITS) - 1) << PM_PSHIFT_OFFSET)

#define PM_PSHIFT(x)        (((u64) (x) << PM_PSHIFT_OFFSET) & PM_PSHIFT_MASK)

#define PM_PFRAME_MASK      ((1LL << PM_PSHIFT_OFFSET) - 1)

#define PM_PFRAME(x)        ((x) & PM_PFRAME_MASK)



#define PM_PRESENT          PM_STATUS(4LL)

#define PM_SWAP             PM_STATUS(2LL)

#define PM_NOT_PRESENT      PM_PSHIFT(PAGE_SHIFT)

#define PM_END_OF_BUFFER    1



static int add_to_pagemap(unsigned long addr, u64 pfn,
@@ -574,7 +582,7 @@ static int pagemap_pte_hole(unsigned long start, unsigned long end, 
u64 swap_pte_to_pagemap_entry(pte_t pte)

{

	swp_entry_t e = pte_to_swp_entry(pte);

	return PM_SWAP | swp_type(e) | (swp_offset(e) << MAX_SWAPFILES_SHIFT);

	return swp_type(e) | (swp_offset(e) << MAX_SWAPFILES_SHIFT);

}



static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
@@ -588,9 +596,11 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, 
		u64 pfn = PM_NOT_PRESENT;

		pte = pte_offset_map(pmd, addr);

		if (is_swap_pte(*pte))

			pfn = swap_pte_to_pagemap_entry(*pte);

			pfn = PM_PFRAME(swap_pte_to_pagemap_entry(*pte))

				| PM_PSHIFT(PAGE_SHIFT) | PM_SWAP;

		else if (pte_present(*pte))

			pfn = pte_pfn(*pte);

			pfn = PM_PFRAME(pte_pfn(*pte))

				| PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT;

		/* unmap so we're not in atomic when we copy to userspace */

		pte_unmap(pte);

		err = add_to_pagemap(addr, pfn, pm);
@@ -611,12 +621,20 @@ static struct mm_walk pagemap_walk = { 
/*

 * /proc/pid/pagemap - an array mapping virtual pages to pfns

 *

 * For each page in the address space, this file contains one 64-bit

 * entry representing the corresponding physical page frame number

 * (PFN) if the page is present. If there is a swap entry for the

 * physical page, then an encoding of the swap file number and the

 * page's offset into the swap file are returned. If no page is

 * present at all, PM_NOT_PRESENT is returned. This allows determining

 * For each page in the address space, this file contains one 64-bit entry

 * consisting of the following:

 *

 * Bits 0-55  page frame number (PFN) if present

 * Bits 0-4   swap type if swapped

 * Bits 5-55  swap offset if swapped

 * Bits 55-60 page shift (page size = 1<<page shift)

 * Bit  61    reserved for future use

 * Bit  62    page swapped

 * Bit  63    page present

 *

 * If the page is not present but in swap, then the PFN contains an

 * encoding of the swap file number and the page's offset into the

 * swap. Unmapped pages return a null PFN. This allows determining

 * precisely which pages are mapped (or in swap) and comparing mapped

 * pages between processes.

 *