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Commit e6473092 authored by Matt Mackall's avatar Matt Mackall Committed by Linus Torvalds
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maps4: introduce a generic page walker 



Introduce a general page table walker

Signed-off-by: default avatarMatt Mackall <mpm@selenic.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 698dd4ba

include/linux/mm.h

+22 −0
Original line number Diff line number Diff line
@@ -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,

mm/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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 \

mm/pagewalk.c

0 → 100644
+131 −0
Original line number Diff line number Diff line 
#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;

}