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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: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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1 changed files with 15 additions and 36 deletions
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@ -26,6 +26,7 @@
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#include <linux/highmem.h>
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#include <linux/crash_dump.h>
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#include <linux/backing-dev.h>
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#include <linux/bootmem.h>
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#include <asm/uaccess.h>
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#include <asm/io.h>
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@ -278,55 +279,33 @@ static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
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#ifdef CONFIG_CRASH_DUMP
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/*
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* Read memory corresponding to the old kernel.
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* If we are reading from the reserved section, which is
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* actually used by the current kernel, we just return zeroes.
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* Or if we are reading from the first 640k, we return from the
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* backed up area.
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*/
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static ssize_t read_oldmem(struct file * file, char * buf,
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static ssize_t read_oldmem(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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unsigned long pfn;
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unsigned backup_start, backup_end, relocate_start;
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size_t read=0, csize;
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backup_start = CRASH_BACKUP_BASE / PAGE_SIZE;
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backup_end = backup_start + (CRASH_BACKUP_SIZE / PAGE_SIZE);
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relocate_start = (CRASH_BACKUP_BASE + CRASH_BACKUP_SIZE) / PAGE_SIZE;
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unsigned long pfn, offset;
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size_t read = 0, csize;
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int rc = 0;
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while(count) {
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pfn = *ppos / PAGE_SIZE;
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if (pfn > saved_max_pfn)
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return read;
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csize = (count > PAGE_SIZE) ? PAGE_SIZE : count;
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offset = (unsigned long)(*ppos % PAGE_SIZE);
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if (count > PAGE_SIZE - offset)
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csize = PAGE_SIZE - offset;
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else
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csize = count;
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/* Perform translation (see comment above) */
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if ((pfn >= backup_start) && (pfn < backup_end)) {
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if (clear_user(buf, csize)) {
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read = -EFAULT;
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goto done;
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}
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goto copy_done;
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} else if (pfn < (CRASH_RELOCATE_SIZE / PAGE_SIZE))
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pfn += relocate_start;
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if (pfn > saved_max_pfn) {
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read = 0;
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goto done;
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}
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if (copy_oldmem_page(pfn, buf, csize, 1)) {
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read = -EFAULT;
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goto done;
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}
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copy_done:
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rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
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if (rc < 0)
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return rc;
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buf += csize;
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*ppos += csize;
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read += csize;
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count -= csize;
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}
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done:
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return read;
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}
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#endif
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