maps4: introduce a generic page walker

Introduce a general page table walker

Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matt Mackall 2008-02-04 22:29:01 -08:00 committed by Linus Torvalds
parent 698dd4ba6b
commit e6473092bd
3 changed files with 154 additions and 1 deletions

View File

@ -718,6 +718,28 @@ unsigned long unmap_vmas(struct mmu_gather **tlb,
struct vm_area_struct *start_vma, unsigned long start_addr,
unsigned long end_addr, unsigned long *nr_accounted,
struct zap_details *);
/**
* mm_walk - callbacks for walk_page_range
* @pgd_entry: if set, called for each non-empty PGD (top-level) entry
* @pud_entry: if set, called for each non-empty PUD (2nd-level) entry
* @pmd_entry: if set, called for each non-empty PMD (3rd-level) entry
* @pte_entry: if set, called for each non-empty PTE (4th-level) entry
* @pte_hole: if set, called for each hole at all levels
*
* (see walk_page_range for more details)
*/
struct mm_walk {
int (*pgd_entry)(pgd_t *, unsigned long, unsigned long, void *);
int (*pud_entry)(pud_t *, unsigned long, unsigned long, void *);
int (*pmd_entry)(pmd_t *, unsigned long, unsigned long, void *);
int (*pte_entry)(pte_t *, unsigned long, unsigned long, void *);
int (*pte_hole)(unsigned long, unsigned long, void *);
};
int walk_page_range(const struct mm_struct *, unsigned long addr,
unsigned long end, const struct mm_walk *walk,
void *private);
void free_pgd_range(struct mmu_gather **tlb, unsigned long addr,
unsigned long end, unsigned long floor, unsigned long ceiling);
void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *start_vma,

View File

@ -5,7 +5,7 @@
mmu-y := nommu.o
mmu-$(CONFIG_MMU) := fremap.o highmem.o madvise.o memory.o mincore.o \
mlock.o mmap.o mprotect.o mremap.o msync.o rmap.o \
vmalloc.o
vmalloc.o pagewalk.o
obj-y := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
page_alloc.o page-writeback.o pdflush.o \

131
mm/pagewalk.c Normal file
View File

@ -0,0 +1,131 @@
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/sched.h>
static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
const struct mm_walk *walk, void *private)
{
pte_t *pte;
int err = 0;
pte = pte_offset_map(pmd, addr);
do {
err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, private);
if (err)
break;
} while (pte++, addr += PAGE_SIZE, addr != end);
pte_unmap(pte);
return err;
}
static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
const struct mm_walk *walk, void *private)
{
pmd_t *pmd;
unsigned long next;
int err = 0;
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd)) {
if (walk->pte_hole)
err = walk->pte_hole(addr, next, private);
if (err)
break;
continue;
}
if (walk->pmd_entry)
err = walk->pmd_entry(pmd, addr, next, private);
if (!err && walk->pte_entry)
err = walk_pte_range(pmd, addr, next, walk, private);
if (err)
break;
} while (pmd++, addr = next, addr != end);
return err;
}
static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
const struct mm_walk *walk, void *private)
{
pud_t *pud;
unsigned long next;
int err = 0;
pud = pud_offset(pgd, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud)) {
if (walk->pte_hole)
err = walk->pte_hole(addr, next, private);
if (err)
break;
continue;
}
if (walk->pud_entry)
err = walk->pud_entry(pud, addr, next, private);
if (!err && (walk->pmd_entry || walk->pte_entry))
err = walk_pmd_range(pud, addr, next, walk, private);
if (err)
break;
} while (pud++, addr = next, addr != end);
return err;
}
/**
* walk_page_range - walk a memory map's page tables with a callback
* @mm - memory map to walk
* @addr - starting address
* @end - ending address
* @walk - set of callbacks to invoke for each level of the tree
* @private - private data passed to the callback function
*
* Recursively walk the page table for the memory area in a VMA,
* calling supplied callbacks. Callbacks are called in-order (first
* PGD, first PUD, first PMD, first PTE, second PTE... second PMD,
* etc.). If lower-level callbacks are omitted, walking depth is reduced.
*
* Each callback receives an entry pointer, the start and end of the
* associated range, and a caller-supplied private data pointer.
*
* No locks are taken, but the bottom level iterator will map PTE
* directories from highmem if necessary.
*
* If any callback returns a non-zero value, the walk is aborted and
* the return value is propagated back to the caller. Otherwise 0 is returned.
*/
int walk_page_range(const struct mm_struct *mm,
unsigned long addr, unsigned long end,
const struct mm_walk *walk, void *private)
{
pgd_t *pgd;
unsigned long next;
int err = 0;
if (addr >= end)
return err;
pgd = pgd_offset(mm, addr);
do {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd)) {
if (walk->pte_hole)
err = walk->pte_hole(addr, next, private);
if (err)
break;
continue;
}
if (walk->pgd_entry)
err = walk->pgd_entry(pgd, addr, next, private);
if (!err &&
(walk->pud_entry || walk->pmd_entry || walk->pte_entry))
err = walk_pud_range(pgd, addr, next, walk, private);
if (err)
break;
} while (pgd++, addr = next, addr != end);
return err;
}