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96d4f267e4
Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument of the user address range verification function since we got rid of the old racy i386-only code to walk page tables by hand. It existed because the original 80386 would not honor the write protect bit when in kernel mode, so you had to do COW by hand before doing any user access. But we haven't supported that in a long time, and these days the 'type' argument is a purely historical artifact. A discussion about extending 'user_access_begin()' to do the range checking resulted this patch, because there is no way we're going to move the old VERIFY_xyz interface to that model. And it's best done at the end of the merge window when I've done most of my merges, so let's just get this done once and for all. This patch was mostly done with a sed-script, with manual fix-ups for the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form. There were a couple of notable cases: - csky still had the old "verify_area()" name as an alias. - the iter_iov code had magical hardcoded knowledge of the actual values of VERIFY_{READ,WRITE} (not that they mattered, since nothing really used it) - microblaze used the type argument for a debug printout but other than those oddities this should be a total no-op patch. I tried to fix up all architectures, did fairly extensive grepping for access_ok() uses, and the changes are trivial, but I may have missed something. Any missed conversion should be trivially fixable, though. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
274 lines
6.7 KiB
C
274 lines
6.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/mm/mincore.c
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*
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* Copyright (C) 1994-2006 Linus Torvalds
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*/
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/*
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* The mincore() system call.
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*/
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#include <linux/pagemap.h>
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#include <linux/gfp.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/syscalls.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/shmem_fs.h>
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#include <linux/hugetlb.h>
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#include <linux/uaccess.h>
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#include <asm/pgtable.h>
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static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr,
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unsigned long end, struct mm_walk *walk)
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{
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#ifdef CONFIG_HUGETLB_PAGE
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unsigned char present;
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unsigned char *vec = walk->private;
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/*
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* Hugepages under user process are always in RAM and never
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* swapped out, but theoretically it needs to be checked.
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*/
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present = pte && !huge_pte_none(huge_ptep_get(pte));
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for (; addr != end; vec++, addr += PAGE_SIZE)
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*vec = present;
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walk->private = vec;
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#else
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BUG();
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#endif
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return 0;
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}
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/*
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* Later we can get more picky about what "in core" means precisely.
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* For now, simply check to see if the page is in the page cache,
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* and is up to date; i.e. that no page-in operation would be required
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* at this time if an application were to map and access this page.
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*/
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static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
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{
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unsigned char present = 0;
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struct page *page;
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/*
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* When tmpfs swaps out a page from a file, any process mapping that
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* file will not get a swp_entry_t in its pte, but rather it is like
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* any other file mapping (ie. marked !present and faulted in with
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* tmpfs's .fault). So swapped out tmpfs mappings are tested here.
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*/
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#ifdef CONFIG_SWAP
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if (shmem_mapping(mapping)) {
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page = find_get_entry(mapping, pgoff);
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/*
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* shmem/tmpfs may return swap: account for swapcache
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* page too.
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*/
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if (xa_is_value(page)) {
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swp_entry_t swp = radix_to_swp_entry(page);
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page = find_get_page(swap_address_space(swp),
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swp_offset(swp));
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}
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} else
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page = find_get_page(mapping, pgoff);
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#else
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page = find_get_page(mapping, pgoff);
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#endif
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if (page) {
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present = PageUptodate(page);
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put_page(page);
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}
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return present;
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}
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static int __mincore_unmapped_range(unsigned long addr, unsigned long end,
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struct vm_area_struct *vma, unsigned char *vec)
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{
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unsigned long nr = (end - addr) >> PAGE_SHIFT;
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int i;
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if (vma->vm_file) {
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pgoff_t pgoff;
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pgoff = linear_page_index(vma, addr);
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for (i = 0; i < nr; i++, pgoff++)
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vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
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} else {
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for (i = 0; i < nr; i++)
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vec[i] = 0;
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}
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return nr;
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}
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static int mincore_unmapped_range(unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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walk->private += __mincore_unmapped_range(addr, end,
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walk->vma, walk->private);
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return 0;
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}
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static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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spinlock_t *ptl;
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struct vm_area_struct *vma = walk->vma;
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pte_t *ptep;
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unsigned char *vec = walk->private;
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int nr = (end - addr) >> PAGE_SHIFT;
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ptl = pmd_trans_huge_lock(pmd, vma);
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if (ptl) {
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memset(vec, 1, nr);
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spin_unlock(ptl);
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goto out;
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}
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if (pmd_trans_unstable(pmd)) {
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__mincore_unmapped_range(addr, end, vma, vec);
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goto out;
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}
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ptep = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
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for (; addr != end; ptep++, addr += PAGE_SIZE) {
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pte_t pte = *ptep;
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if (pte_none(pte))
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__mincore_unmapped_range(addr, addr + PAGE_SIZE,
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vma, vec);
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else if (pte_present(pte))
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*vec = 1;
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else { /* pte is a swap entry */
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swp_entry_t entry = pte_to_swp_entry(pte);
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if (non_swap_entry(entry)) {
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/*
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* migration or hwpoison entries are always
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* uptodate
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*/
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*vec = 1;
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} else {
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#ifdef CONFIG_SWAP
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*vec = mincore_page(swap_address_space(entry),
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swp_offset(entry));
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#else
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WARN_ON(1);
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*vec = 1;
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#endif
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}
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}
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vec++;
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}
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pte_unmap_unlock(ptep - 1, ptl);
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out:
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walk->private += nr;
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cond_resched();
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return 0;
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}
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/*
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* Do a chunk of "sys_mincore()". We've already checked
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* all the arguments, we hold the mmap semaphore: we should
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* just return the amount of info we're asked for.
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*/
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static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)
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{
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struct vm_area_struct *vma;
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unsigned long end;
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int err;
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struct mm_walk mincore_walk = {
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.pmd_entry = mincore_pte_range,
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.pte_hole = mincore_unmapped_range,
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.hugetlb_entry = mincore_hugetlb,
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.private = vec,
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};
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vma = find_vma(current->mm, addr);
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if (!vma || addr < vma->vm_start)
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return -ENOMEM;
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mincore_walk.mm = vma->vm_mm;
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end = min(vma->vm_end, addr + (pages << PAGE_SHIFT));
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err = walk_page_range(addr, end, &mincore_walk);
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if (err < 0)
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return err;
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return (end - addr) >> PAGE_SHIFT;
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}
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/*
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* The mincore(2) system call.
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*
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* mincore() returns the memory residency status of the pages in the
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* current process's address space specified by [addr, addr + len).
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* The status is returned in a vector of bytes. The least significant
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* bit of each byte is 1 if the referenced page is in memory, otherwise
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* it is zero.
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*
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* Because the status of a page can change after mincore() checks it
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* but before it returns to the application, the returned vector may
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* contain stale information. Only locked pages are guaranteed to
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* remain in memory.
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*
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* return values:
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* zero - success
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* -EFAULT - vec points to an illegal address
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* -EINVAL - addr is not a multiple of PAGE_SIZE
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* -ENOMEM - Addresses in the range [addr, addr + len] are
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* invalid for the address space of this process, or
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* specify one or more pages which are not currently
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* mapped
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* -EAGAIN - A kernel resource was temporarily unavailable.
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*/
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SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
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unsigned char __user *, vec)
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{
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long retval;
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unsigned long pages;
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unsigned char *tmp;
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/* Check the start address: needs to be page-aligned.. */
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if (start & ~PAGE_MASK)
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return -EINVAL;
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/* ..and we need to be passed a valid user-space range */
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if (!access_ok((void __user *) start, len))
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return -ENOMEM;
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/* This also avoids any overflows on PAGE_ALIGN */
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pages = len >> PAGE_SHIFT;
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pages += (offset_in_page(len)) != 0;
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if (!access_ok(vec, pages))
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return -EFAULT;
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tmp = (void *) __get_free_page(GFP_USER);
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if (!tmp)
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return -EAGAIN;
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retval = 0;
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while (pages) {
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/*
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* Do at most PAGE_SIZE entries per iteration, due to
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* the temporary buffer size.
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*/
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down_read(¤t->mm->mmap_sem);
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retval = do_mincore(start, min(pages, PAGE_SIZE), tmp);
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up_read(¤t->mm->mmap_sem);
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if (retval <= 0)
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break;
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if (copy_to_user(vec, tmp, retval)) {
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retval = -EFAULT;
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break;
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}
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pages -= retval;
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vec += retval;
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start += retval << PAGE_SHIFT;
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retval = 0;
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}
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free_page((unsigned long) tmp);
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return retval;
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}
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