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-rw-r--r--drivers/char/mem.c51
1 files changed, 15 insertions, 36 deletions
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 01b3c17ca85..b64108dd765 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -26,6 +26,7 @@
#include <linux/highmem.h>
#include <linux/crash_dump.h>
#include <linux/backing-dev.h>
+#include <linux/bootmem.h>
#include <asm/uaccess.h>
#include <asm/io.h>
@@ -278,55 +279,33 @@ static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
#ifdef CONFIG_CRASH_DUMP
/*
* Read memory corresponding to the old kernel.
- * If we are reading from the reserved section, which is
- * actually used by the current kernel, we just return zeroes.
- * Or if we are reading from the first 640k, we return from the
- * backed up area.
*/
-static ssize_t read_oldmem(struct file * file, char * buf,
+static ssize_t read_oldmem(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
- unsigned long pfn;
- unsigned backup_start, backup_end, relocate_start;
- size_t read=0, csize;
-
- backup_start = CRASH_BACKUP_BASE / PAGE_SIZE;
- backup_end = backup_start + (CRASH_BACKUP_SIZE / PAGE_SIZE);
- relocate_start = (CRASH_BACKUP_BASE + CRASH_BACKUP_SIZE) / PAGE_SIZE;
+ unsigned long pfn, offset;
+ size_t read = 0, csize;
+ int rc = 0;
while(count) {
pfn = *ppos / PAGE_SIZE;
+ if (pfn > saved_max_pfn)
+ return read;
- csize = (count > PAGE_SIZE) ? PAGE_SIZE : count;
-
- /* Perform translation (see comment above) */
- if ((pfn >= backup_start) && (pfn < backup_end)) {
- if (clear_user(buf, csize)) {
- read = -EFAULT;
- goto done;
- }
-
- goto copy_done;
- } else if (pfn < (CRASH_RELOCATE_SIZE / PAGE_SIZE))
- pfn += relocate_start;
-
- if (pfn > saved_max_pfn) {
- read = 0;
- goto done;
- }
-
- if (copy_oldmem_page(pfn, buf, csize, 1)) {
- read = -EFAULT;
- goto done;
- }
+ offset = (unsigned long)(*ppos % PAGE_SIZE);
+ if (count > PAGE_SIZE - offset)
+ csize = PAGE_SIZE - offset;
+ else
+ csize = count;
-copy_done:
+ rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
+ if (rc < 0)
+ return rc;
buf += csize;
*ppos += csize;
read += csize;
count -= csize;
}
-done:
return read;
}
#endif