root/mm/pagewalk.c

DEFINITIONS

1. walk_pte_range
2. walk_pmd_range
3. walk_pud_range
4. walk_page_range

#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,
                          struct mm_walk *walk)
{
        pte_t *pte;
        int err = 0;

        pte = pte_offset_map(pmd, addr);
        for (;;) {
                err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
                if (err)
                       break;
                addr += PAGE_SIZE;
                if (addr == end)
                        break;
                pte++;
        }

        pte_unmap(pte);
        return err;
}

static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
                          struct mm_walk *walk)
{
        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, walk);
                        if (err)
                                break;
                        continue;
                }
                if (walk->pmd_entry)
                        err = walk->pmd_entry(pmd, addr, next, walk);
                if (!err && walk->pte_entry)
                        err = walk_pte_range(pmd, addr, next, walk);
                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,
                          struct mm_walk *walk)
{
        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, walk);
                        if (err)
                                break;
                        continue;
                }
                if (walk->pud_entry)
                        err = walk->pud_entry(pud, addr, next, walk);
                if (!err && (walk->pmd_entry || walk->pte_entry))
                        err = walk_pmd_range(pud, addr, next, walk);
                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
 *
 * 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 and the start and end of the
 * associated range, and a copy of the original mm_walk for access to
 * the ->private or ->mm fields.
 *
 * 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(unsigned long addr, unsigned long end,
                    struct mm_walk *walk)
{
        pgd_t *pgd;
        unsigned long next;
        int err = 0;

        if (addr >= end)
                return err;

        if (!walk->mm)
                return -EINVAL;

        pgd = pgd_offset(walk->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, walk);
                        if (err)
                                break;
                        continue;
                }
                if (walk->pgd_entry)
                        err = walk->pgd_entry(pgd, addr, next, walk);
                if (!err &&
                    (walk->pud_entry || walk->pmd_entry || walk->pte_entry))
                        err = walk_pud_range(pgd, addr, next, walk);
                if (err)
                        break;
        } while (pgd++, addr = next, addr != end);

        return err;
}