mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 01:10:04 +00:00
![Hugh Dickins](/assets/img/avatar_default.png)
Remove use of FIRST_USER_PGD_NR from sys_mincore: it's inconsistent (no other syscall refers to it), unnecessary (sys_mincore loops over vmas further down) and incorrect (misses user addresses in ARM's first pgd). Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
188 lines
4.4 KiB
C
188 lines
4.4 KiB
C
/*
|
|
* linux/mm/mincore.c
|
|
*
|
|
* Copyright (C) 1994-1999 Linus Torvalds
|
|
*/
|
|
|
|
/*
|
|
* The mincore() system call.
|
|
*/
|
|
#include <linux/slab.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/mman.h>
|
|
#include <linux/syscalls.h>
|
|
|
|
#include <asm/uaccess.h>
|
|
#include <asm/pgtable.h>
|
|
|
|
/*
|
|
* Later we can get more picky about what "in core" means precisely.
|
|
* For now, simply check to see if the page is in the page cache,
|
|
* and is up to date; i.e. that no page-in operation would be required
|
|
* at this time if an application were to map and access this page.
|
|
*/
|
|
static unsigned char mincore_page(struct vm_area_struct * vma,
|
|
unsigned long pgoff)
|
|
{
|
|
unsigned char present = 0;
|
|
struct address_space * as = vma->vm_file->f_mapping;
|
|
struct page * page;
|
|
|
|
page = find_get_page(as, pgoff);
|
|
if (page) {
|
|
present = PageUptodate(page);
|
|
page_cache_release(page);
|
|
}
|
|
|
|
return present;
|
|
}
|
|
|
|
static long mincore_vma(struct vm_area_struct * vma,
|
|
unsigned long start, unsigned long end, unsigned char __user * vec)
|
|
{
|
|
long error, i, remaining;
|
|
unsigned char * tmp;
|
|
|
|
error = -ENOMEM;
|
|
if (!vma->vm_file)
|
|
return error;
|
|
|
|
start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
|
|
if (end > vma->vm_end)
|
|
end = vma->vm_end;
|
|
end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
|
|
|
|
error = -EAGAIN;
|
|
tmp = (unsigned char *) __get_free_page(GFP_KERNEL);
|
|
if (!tmp)
|
|
return error;
|
|
|
|
/* (end - start) is # of pages, and also # of bytes in "vec */
|
|
remaining = (end - start),
|
|
|
|
error = 0;
|
|
for (i = 0; remaining > 0; remaining -= PAGE_SIZE, i++) {
|
|
int j = 0;
|
|
long thispiece = (remaining < PAGE_SIZE) ?
|
|
remaining : PAGE_SIZE;
|
|
|
|
while (j < thispiece)
|
|
tmp[j++] = mincore_page(vma, start++);
|
|
|
|
if (copy_to_user(vec + PAGE_SIZE * i, tmp, thispiece)) {
|
|
error = -EFAULT;
|
|
break;
|
|
}
|
|
}
|
|
|
|
free_page((unsigned long) tmp);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* The mincore(2) system call.
|
|
*
|
|
* mincore() returns the memory residency status of the pages in the
|
|
* current process's address space specified by [addr, addr + len).
|
|
* The status is returned in a vector of bytes. The least significant
|
|
* bit of each byte is 1 if the referenced page is in memory, otherwise
|
|
* it is zero.
|
|
*
|
|
* Because the status of a page can change after mincore() checks it
|
|
* but before it returns to the application, the returned vector may
|
|
* contain stale information. Only locked pages are guaranteed to
|
|
* remain in memory.
|
|
*
|
|
* return values:
|
|
* zero - success
|
|
* -EFAULT - vec points to an illegal address
|
|
* -EINVAL - addr is not a multiple of PAGE_CACHE_SIZE
|
|
* -ENOMEM - Addresses in the range [addr, addr + len] are
|
|
* invalid for the address space of this process, or
|
|
* specify one or more pages which are not currently
|
|
* mapped
|
|
* -EAGAIN - A kernel resource was temporarily unavailable.
|
|
*/
|
|
asmlinkage long sys_mincore(unsigned long start, size_t len,
|
|
unsigned char __user * vec)
|
|
{
|
|
int index = 0;
|
|
unsigned long end, limit;
|
|
struct vm_area_struct * vma;
|
|
size_t max;
|
|
int unmapped_error = 0;
|
|
long error;
|
|
|
|
/* check the arguments */
|
|
if (start & ~PAGE_CACHE_MASK)
|
|
goto einval;
|
|
|
|
limit = TASK_SIZE;
|
|
if (start >= limit)
|
|
goto enomem;
|
|
|
|
if (!len)
|
|
return 0;
|
|
|
|
max = limit - start;
|
|
len = PAGE_CACHE_ALIGN(len);
|
|
if (len > max || !len)
|
|
goto enomem;
|
|
|
|
end = start + len;
|
|
|
|
/* check the output buffer whilst holding the lock */
|
|
error = -EFAULT;
|
|
down_read(¤t->mm->mmap_sem);
|
|
|
|
if (!access_ok(VERIFY_WRITE, vec, len >> PAGE_SHIFT))
|
|
goto out;
|
|
|
|
/*
|
|
* If the interval [start,end) covers some unmapped address
|
|
* ranges, just ignore them, but return -ENOMEM at the end.
|
|
*/
|
|
error = 0;
|
|
|
|
vma = find_vma(current->mm, start);
|
|
while (vma) {
|
|
/* Here start < vma->vm_end. */
|
|
if (start < vma->vm_start) {
|
|
unmapped_error = -ENOMEM;
|
|
start = vma->vm_start;
|
|
}
|
|
|
|
/* Here vma->vm_start <= start < vma->vm_end. */
|
|
if (end <= vma->vm_end) {
|
|
if (start < end) {
|
|
error = mincore_vma(vma, start, end,
|
|
&vec[index]);
|
|
if (error)
|
|
goto out;
|
|
}
|
|
error = unmapped_error;
|
|
goto out;
|
|
}
|
|
|
|
/* Here vma->vm_start <= start < vma->vm_end < end. */
|
|
error = mincore_vma(vma, start, vma->vm_end, &vec[index]);
|
|
if (error)
|
|
goto out;
|
|
index += (vma->vm_end - start) >> PAGE_CACHE_SHIFT;
|
|
start = vma->vm_end;
|
|
vma = vma->vm_next;
|
|
}
|
|
|
|
/* we found a hole in the area queried if we arrive here */
|
|
error = -ENOMEM;
|
|
|
|
out:
|
|
up_read(¤t->mm->mmap_sem);
|
|
return error;
|
|
|
|
einval:
|
|
return -EINVAL;
|
|
enomem:
|
|
return -ENOMEM;
|
|
}
|