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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /mm/mincore.c
downloadlinux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'mm/mincore.c')
-rw-r--r--mm/mincore.c191
1 files changed, 191 insertions, 0 deletions
diff --git a/mm/mincore.c b/mm/mincore.c
new file mode 100644
index 00000000000..07833dc5829
--- /dev/null
+++ b/mm/mincore.c
@@ -0,0 +1,191 @@
+/*
+ * 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;
+
+ if (start < FIRST_USER_PGD_NR * PGDIR_SIZE)
+ goto enomem;
+
+ 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(&current->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(&current->mm->mmap_sem);
+ return error;
+
+einval:
+ return -EINVAL;
+enomem:
+ return -ENOMEM;
+}