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pagemap: introduce data structure for pagemap entry
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Currently a local variable of pagemap entry in pagemap_pte_range() is
named pfn and typed with u64, but it's not correct (pfn should be unsigned
long.)

This patch introduces special type for pagemap entries and replaces code
with it.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Naoya Horiguchi authored and Linus Torvalds committed Mar 22, 2012
1 parent 807f0cc commit 092b50b
Showing 1 changed file with 38 additions and 31 deletions.
69 changes: 38 additions & 31 deletions fs/proc/task_mmu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -594,9 +594,13 @@ const struct file_operations proc_clear_refs_operations = {
.llseek = noop_llseek,
};

typedef struct {
u64 pme;
} pagemap_entry_t;

struct pagemapread {
int pos, len;
u64 *buffer;
pagemap_entry_t *buffer;
};

#define PAGEMAP_WALK_SIZE (PMD_SIZE)
Expand All @@ -619,10 +623,15 @@ struct pagemapread {
#define PM_NOT_PRESENT PM_PSHIFT(PAGE_SHIFT)
#define PM_END_OF_BUFFER 1

static int add_to_pagemap(unsigned long addr, u64 pfn,
static inline pagemap_entry_t make_pme(u64 val)
{
return (pagemap_entry_t) { .pme = val };
}

static int add_to_pagemap(unsigned long addr, pagemap_entry_t *pme,
struct pagemapread *pm)
{
pm->buffer[pm->pos++] = pfn;
pm->buffer[pm->pos++] = *pme;
if (pm->pos >= pm->len)
return PM_END_OF_BUFFER;
return 0;
Expand All @@ -634,8 +643,10 @@ static int pagemap_pte_hole(unsigned long start, unsigned long end,
struct pagemapread *pm = walk->private;
unsigned long addr;
int err = 0;
pagemap_entry_t pme = make_pme(PM_NOT_PRESENT);

for (addr = start; addr < end; addr += PAGE_SIZE) {
err = add_to_pagemap(addr, PM_NOT_PRESENT, pm);
err = add_to_pagemap(addr, &pme, pm);
if (err)
break;
}
Expand All @@ -648,36 +659,33 @@ static u64 swap_pte_to_pagemap_entry(pte_t pte)
return swp_type(e) | (swp_offset(e) << MAX_SWAPFILES_SHIFT);
}

static u64 pte_to_pagemap_entry(pte_t pte)
static void pte_to_pagemap_entry(pagemap_entry_t *pme, pte_t pte)
{
u64 pme = 0;
if (is_swap_pte(pte))
pme = PM_PFRAME(swap_pte_to_pagemap_entry(pte))
| PM_PSHIFT(PAGE_SHIFT) | PM_SWAP;
*pme = make_pme(PM_PFRAME(swap_pte_to_pagemap_entry(pte))
| PM_PSHIFT(PAGE_SHIFT) | PM_SWAP);
else if (pte_present(pte))
pme = PM_PFRAME(pte_pfn(pte))
| PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT;
return pme;
*pme = make_pme(PM_PFRAME(pte_pfn(pte))
| PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT);
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static u64 thp_pmd_to_pagemap_entry(pmd_t pmd, int offset)
static void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme,
pmd_t pmd, int offset)
{
u64 pme = 0;
/*
* Currently pmd for thp is always present because thp can not be
* swapped-out, migrated, or HWPOISONed (split in such cases instead.)
* This if-check is just to prepare for future implementation.
*/
if (pmd_present(pmd))
pme = PM_PFRAME(pmd_pfn(pmd) + offset)
| PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT;
return pme;
*pme = make_pme(PM_PFRAME(pmd_pfn(pmd) + offset)
| PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT);
}
#else
static inline u64 thp_pmd_to_pagemap_entry(pmd_t pmd, int offset)
static inline void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme,
pmd_t pmd, int offset)
{
return 0;
}
#endif

Expand All @@ -688,7 +696,7 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
struct pagemapread *pm = walk->private;
pte_t *pte;
int err = 0;
u64 pfn = PM_NOT_PRESENT;
pagemap_entry_t pme = make_pme(PM_NOT_PRESENT);

if (pmd_trans_unstable(pmd))
return 0;
Expand All @@ -702,8 +710,8 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,

offset = (addr & ~PAGEMAP_WALK_MASK) >>
PAGE_SHIFT;
pfn = thp_pmd_to_pagemap_entry(*pmd, offset);
err = add_to_pagemap(addr, pfn, pm);
thp_pmd_to_pagemap_entry(&pme, *pmd, offset);
err = add_to_pagemap(addr, &pme, pm);
if (err)
break;
}
Expand All @@ -723,11 +731,11 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
if (vma && (vma->vm_start <= addr) &&
!is_vm_hugetlb_page(vma)) {
pte = pte_offset_map(pmd, addr);
pfn = pte_to_pagemap_entry(*pte);
pte_to_pagemap_entry(&pme, *pte);
/* unmap before userspace copy */
pte_unmap(pte);
}
err = add_to_pagemap(addr, pfn, pm);
err = add_to_pagemap(addr, &pme, pm);
if (err)
return err;
}
Expand All @@ -738,13 +746,12 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
}

#ifdef CONFIG_HUGETLB_PAGE
static u64 huge_pte_to_pagemap_entry(pte_t pte, int offset)
static void huge_pte_to_pagemap_entry(pagemap_entry_t *pme,
pte_t pte, int offset)
{
u64 pme = 0;
if (pte_present(pte))
pme = PM_PFRAME(pte_pfn(pte) + offset)
| PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT;
return pme;
*pme = make_pme(PM_PFRAME(pte_pfn(pte) + offset)
| PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT);
}

/* This function walks within one hugetlb entry in the single call */
Expand All @@ -754,12 +761,12 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
{
struct pagemapread *pm = walk->private;
int err = 0;
u64 pfn;
pagemap_entry_t pme = make_pme(PM_NOT_PRESENT);

for (; addr != end; addr += PAGE_SIZE) {
int offset = (addr & ~hmask) >> PAGE_SHIFT;
pfn = huge_pte_to_pagemap_entry(*pte, offset);
err = add_to_pagemap(addr, pfn, pm);
huge_pte_to_pagemap_entry(&pme, *pte, offset);
err = add_to_pagemap(addr, &pme, pm);
if (err)
return err;
}
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