From 8e4bff4cab0ddac6060645b0715210484d02ff40 Mon Sep 17 00:00:00 2001
From: Yuval Adam <_@yuv.al>
Date: Wed, 30 Aug 2017 08:25:59 +0000
Subject: Initial file dump from open source release

---
 arch/ia64/kernel/crash_dump.c | 50 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 arch/ia64/kernel/crash_dump.c

(limited to 'arch/ia64/kernel/crash_dump.c')

diff --git a/arch/ia64/kernel/crash_dump.c b/arch/ia64/kernel/crash_dump.c
new file mode 100644
index 00000000..c8c92986
--- /dev/null
+++ b/arch/ia64/kernel/crash_dump.c
@@ -0,0 +1,50 @@
+/*
+ *	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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