Commit 315c215c authored by Vivek Goyal's avatar Vivek Goyal Committed by Linus Torvalds
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[PATCH] kdump: cleanups for dump file access in linear raw format 



Removed the dependency on backup region.  Now all the information is encoded
in ELF format.  /dev/oldmem is a dummy interface.  User space tool need to be
intelligent enough to parse the elf headers and read the relevant memory areas
with the help of /dev/oldmem.

Signed-off-by: default avatarVivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 50b1fdbd

drivers/char/mem.c

+15 −36
Original line number Diff line number Diff line
@@ -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;

	unsigned long pfn, offset;

	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;

	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