Commit aee16b3c authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Linus Torvalds
Browse files

Add apply_to_page_range() which applies a function to a pte range 



Add a new mm function apply_to_page_range() which applies a given function to
every pte in a given virtual address range in a given mm structure.  This is a
generic alternative to cut-and-pasting the Linux idiomatic pagetable walking
code in every place that a sequence of PTEs must be accessed.

Although this interface is intended to be useful in a wide range of
situations, it is currently used specifically by several Xen subsystems, for
example: to ensure that pagetables have been allocated for a virtual address
range, and to construct batched special pagetable update requests to map I/O
memory (in ioremap()).

[akpm@linux-foundation.org: fix warning, unpleasantly]
Signed-off-by: default avatarIan Pratt <ian.pratt@xensource.com>
Signed-off-by: default avatarChristian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: default avatarChris Wright <chrisw@sous-sol.org>
Signed-off-by: default avatarJeremy Fitzhardinge <jeremy@xensource.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Matt Mackall <mpm@waste.org>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent eb3a1e11

include/linux/mm.h

+5 −0
Original line number Diff line number Diff line
@@ -1130,6 +1130,11 @@ struct page *follow_page(struct vm_area_struct *, unsigned long address, 
#define FOLL_GET	0x04	/* do get_page on page */

#define FOLL_ANON	0x08	/* give ZERO_PAGE if no pgtable */



typedef int (*pte_fn_t)(pte_t *pte, struct page *pmd_page, unsigned long addr,

			void *data);

extern int apply_to_page_range(struct mm_struct *mm, unsigned long address,

			       unsigned long size, pte_fn_t fn, void *data);



#ifdef CONFIG_PROC_FS

void vm_stat_account(struct mm_struct *, unsigned long, struct file *, long);

#else

mm/memory.c

+94 −0
Original line number Diff line number Diff line
@@ -1448,6 +1448,100 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 
}

EXPORT_SYMBOL(remap_pfn_range);



static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,

				     unsigned long addr, unsigned long end,

				     pte_fn_t fn, void *data)

{

	pte_t *pte;

	int err;

	struct page *pmd_page;

	spinlock_t *ptl = ptl;		/* Suppress gcc warning */



	pte = (mm == &init_mm) ?

		pte_alloc_kernel(pmd, addr) :

		pte_alloc_map_lock(mm, pmd, addr, &ptl);

	if (!pte)

		return -ENOMEM;



	BUG_ON(pmd_huge(*pmd));



	pmd_page = pmd_page(*pmd);



	do {

		err = fn(pte, pmd_page, addr, data);

		if (err)

			break;

	} while (pte++, addr += PAGE_SIZE, addr != end);



	if (mm != &init_mm)

		pte_unmap_unlock(pte-1, ptl);

	return err;

}



static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,

				     unsigned long addr, unsigned long end,

				     pte_fn_t fn, void *data)

{

	pmd_t *pmd;

	unsigned long next;

	int err;



	pmd = pmd_alloc(mm, pud, addr);

	if (!pmd)

		return -ENOMEM;

	do {

		next = pmd_addr_end(addr, end);

		err = apply_to_pte_range(mm, pmd, addr, next, fn, data);

		if (err)

			break;

	} while (pmd++, addr = next, addr != end);

	return err;

}



static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,

				     unsigned long addr, unsigned long end,

				     pte_fn_t fn, void *data)

{

	pud_t *pud;

	unsigned long next;

	int err;



	pud = pud_alloc(mm, pgd, addr);

	if (!pud)

		return -ENOMEM;

	do {

		next = pud_addr_end(addr, end);

		err = apply_to_pmd_range(mm, pud, addr, next, fn, data);

		if (err)

			break;

	} while (pud++, addr = next, addr != end);

	return err;

}



/*

 * Scan a region of virtual memory, filling in page tables as necessary

 * and calling a provided function on each leaf page table.

 */

int apply_to_page_range(struct mm_struct *mm, unsigned long addr,

			unsigned long size, pte_fn_t fn, void *data)

{

	pgd_t *pgd;

	unsigned long next;

	unsigned long end = addr + size;

	int err;



	BUG_ON(addr >= end);

	pgd = pgd_offset(mm, addr);

	do {

		next = pgd_addr_end(addr, end);

		err = apply_to_pud_range(mm, pgd, addr, next, fn, data);

		if (err)

			break;

	} while (pgd++, addr = next, addr != end);

	return err;

}

EXPORT_SYMBOL_GPL(apply_to_page_range);



/*

 * handle_pte_fault chooses page fault handler according to an entry

 * which was read non-atomically.  Before making any commitment, on

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