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- /*
- * kernel/crash_dump.c - Memory preserving reboot related code.
- *
- * Created by: Simon Horman <horms@verge.net.au>
- * Original code moved from kernel/crash.c
- * Original code comment copied from the i386 version of this file
- */
- #include <linux/errno.h>
- #include <linux/types.h>
- #include <linux/crash_dump.h>
- #include <asm/page.h>
- #include <asm/uaccess.h>
- /**
- * copy_oldmem_page - copy one page from "oldmem"
- * @pfn: page frame number to be copied
- * @buf: target memory address for the copy; this can be in kernel address
- * space or user address space (see @userbuf)
- * @csize: number of bytes to copy
- * @offset: offset in bytes into the page (based on pfn) to begin the copy
- * @userbuf: if set, @buf is in user address space, use copy_to_user(),
- * otherwise @buf is in kernel address space, use memcpy().
- *
- * Copy a page from "oldmem". For this page, there is no pte mapped
- * in the current kernel. We stitch up a pte, similar to kmap_atomic.
- *
- * Calling copy_to_user() in atomic context is not desirable. Hence first
- * copying the data to a pre-allocated kernel page and then copying to user
- * space in non-atomic context.
- */
- ssize_t
- copy_oldmem_page(unsigned long pfn, char *buf,
- size_t csize, unsigned long offset, int userbuf)
- {
- void *vaddr;
- if (!csize)
- return 0;
- vaddr = __va(pfn<<PAGE_SHIFT);
- if (userbuf) {
- if (copy_to_user(buf, (vaddr + offset), csize)) {
- return -EFAULT;
- }
- } else
- memcpy(buf, (vaddr + offset), csize);
- return csize;
- }
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