[PATCH] kdump: Routines for copying dump pages

[mirror_ubuntu-zesty-kernel.git] / kernel / crash_dump.c

diff --git a/kernel/crash_dump.c b/kernel/crash_dump.c
new file mode 100644 (file)
index 0000000..5a1e6d5
--- /dev/null
+++ b/kernel/crash_dump.c
@@ -0,0 +1,49 @@
+/*
+ *     kernel/crash_dump.c - Memory preserving reboot related code.
+ *
+ *     Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
+ *     Copyright (C) IBM Corporation, 2004. All rights reserved
+ */
+
+#include <linux/smp_lock.h>
+#include <linux/errno.h>
+#include <linux/proc_fs.h>
+#include <linux/bootmem.h>
+#include <linux/highmem.h>
+#include <linux/crash_dump.h>
+
+#include <asm/io.h>
+#include <asm/uaccess.h>
+
+/*
+ * 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.
+ */
+ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
+                               size_t csize, unsigned long offset, int userbuf)
+{
+       void *page, *vaddr;
+
+       if (!csize)
+               return 0;
+
+       page = kmalloc(PAGE_SIZE, GFP_KERNEL);
+       if (!page)
+               return -ENOMEM;
+
+       vaddr = kmap_atomic_pfn(pfn, KM_PTE0);
+       copy_page(page, vaddr);
+       kunmap_atomic(vaddr, KM_PTE0);
+
+       if (userbuf) {
+               if (copy_to_user(buf, (page + offset), csize)) {
+                       kfree(page);
+                       return -EFAULT;
+               }
+       } else {
+               memcpy(buf, (page + offset), csize);
+       }
+
+       kfree(page);
+       return csize;
+}