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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: Hans Rosenfeld <hans.rosenfeld@amd.com>
Signed-off-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hans Rosenfeld 2008-03-21 18:46:59 -05:00 committed by Linus Torvalds
parent 51ec92e295
commit f16278c679
1 changed files with 34 additions and 16 deletions
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50
fs/proc/task_mmu.c
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@ -527,13 +527,21 @@ struct pagemapread {
char __user *out, *end;
};
#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_ENTRY_BYTES sizeof(u64)
#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.
*