diff options
Diffstat (limited to 'mm/pagewalk.c')
| -rw-r--r-- | mm/pagewalk.c | 246 |
1 files changed, 246 insertions, 0 deletions
diff --git a/mm/pagewalk.c b/mm/pagewalk.c new file mode 100644 index 00000000..35aa2946 --- /dev/null +++ b/mm/pagewalk.c @@ -0,0 +1,246 @@ +#include <linux/mm.h> +#include <linux/highmem.h> +#include <linux/sched.h> +#include <linux/hugetlb.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 { +again: + next = pmd_addr_end(addr, end); + if (pmd_none(*pmd)) { + if (walk->pte_hole) + err = walk->pte_hole(addr, next, walk); + if (err) + break; + continue; + } + /* + * This implies that each ->pmd_entry() handler + * needs to know about pmd_trans_huge() pmds + */ + if (walk->pmd_entry) + err = walk->pmd_entry(pmd, addr, next, walk); + if (err) + break; + + /* + * Check this here so we only break down trans_huge + * pages when we _need_ to + */ + if (!walk->pte_entry) + continue; + + split_huge_page_pmd_mm(walk->mm, addr, pmd); + if (pmd_none_or_trans_huge_or_clear_bad(pmd)) + goto again; + 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; +} + +#ifdef CONFIG_HUGETLB_PAGE +static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr, + unsigned long end) +{ + unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h); + return boundary < end ? boundary : end; +} + +static int walk_hugetlb_range(struct vm_area_struct *vma, + unsigned long addr, unsigned long end, + struct mm_walk *walk) +{ + struct hstate *h = hstate_vma(vma); + unsigned long next; + unsigned long hmask = huge_page_mask(h); + pte_t *pte; + int err = 0; + + do { + next = hugetlb_entry_end(h, addr, end); + pte = huge_pte_offset(walk->mm, addr & hmask); + if (pte && walk->hugetlb_entry) + err = walk->hugetlb_entry(pte, hmask, addr, next, walk); + if (err) + return err; + } while (addr = next, addr != end); + + return 0; +} + +static struct vm_area_struct* hugetlb_vma(unsigned long addr, struct mm_walk *walk) +{ + struct vm_area_struct *vma; + + /* We don't need vma lookup at all. */ + if (!walk->hugetlb_entry) + return NULL; + + VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem)); + vma = find_vma(walk->mm, addr); + if (vma && vma->vm_start <= addr && is_vm_hugetlb_page(vma)) + return vma; + + return NULL; +} + +#else /* CONFIG_HUGETLB_PAGE */ +static struct vm_area_struct* hugetlb_vma(unsigned long addr, struct mm_walk *walk) +{ + return NULL; +} + +static int walk_hugetlb_range(struct vm_area_struct *vma, + unsigned long addr, unsigned long end, + struct mm_walk *walk) +{ + return 0; +} + +#endif /* CONFIG_HUGETLB_PAGE */ + + + +/** + * walk_page_range - walk a memory map's page tables with a callback + * @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. + * + * Usually no locks are taken, but splitting transparent huge page may + * take page table lock. And 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. + * + * walk->mm->mmap_sem must be held for at least read if walk->hugetlb_entry + * is !NULL. + */ +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 { + struct vm_area_struct *vma; + + next = pgd_addr_end(addr, end); + + /* + * handle hugetlb vma individually because pagetable walk for + * the hugetlb page is dependent on the architecture and + * we can't handled it in the same manner as non-huge pages. + */ + vma = hugetlb_vma(addr, walk); + if (vma) { + if (vma->vm_end < next) + next = vma->vm_end; + /* + * Hugepage is very tightly coupled with vma, so + * walk through hugetlb entries within a given vma. + */ + err = walk_hugetlb_range(vma, addr, next, walk); + if (err) + break; + pgd = pgd_offset(walk->mm, next); + continue; + } + + if (pgd_none_or_clear_bad(pgd)) { + if (walk->pte_hole) + err = walk->pte_hole(addr, next, walk); + if (err) + break; + pgd++; + 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; + pgd++; + } while (addr = next, addr != end); + + return err; +} |