1 files changed, 77 insertions, 0 deletions

diff --git a/arch/mips/kernel/crash_dump.c b/arch/mips/kernel/crash_dump.c
new file mode 100644
index 000000000000..d9ec3898f9fa
--- /dev/null
+++ b/arch/mips/kernel/crash_dump.c
@@ -0,0 +1,77 @@
+#include <linux/highmem.h>
+#include <linux/bootmem.h>
+#include <linux/crash_dump.h>
+#include <asm/uaccess.h>
+
+unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
+
+static int __init parse_savemaxmem(char *p)
+{
+        if (p)
+                saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;
+
+        return 1;
+}
+__setup("savemaxmem=", parse_savemaxmem);
+
+
+static void *kdump_buf_page;
+
+/**
+ * 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.
+ *
+ * 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 = kmap_atomic_pfn(pfn);
+
+        if (!userbuf) {
+                memcpy(buf, (vaddr + offset), csize);
+                kunmap_atomic(vaddr);
+        } else {
+                if (!kdump_buf_page) {
+                        pr_warning("Kdump: Kdump buffer page not allocated\n");
+
+                        return -EFAULT;
+                }
+                copy_page(kdump_buf_page, vaddr);
+                kunmap_atomic(vaddr);
+                if (copy_to_user(buf, (kdump_buf_page + offset), csize))
+                        return -EFAULT;
+        }
+
+        return csize;
+}
+
+static int __init kdump_buf_page_init(void)
+{
+        int ret = 0;
+
+        kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL);
+        if (!kdump_buf_page) {
+                pr_warning("Kdump: Failed to allocate kdump buffer page\n");
+                ret = -ENOMEM;
+        }
+
+        return ret;
+}
+arch_initcall(kdump_buf_page_init);