kdump: sh: parse elfcorehdr command line argument

A quick cut and paste from other architectures to allow SH
to parse the elfcorehdr command line argument which is required
for both is_kdump_kernel() and vmcore to function.
(the former is as yet unused on SH).

Tested compilation only
Signed-off-by: NSimon Horman <horms@verge.net.au>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/sh/kernel/setup.c

@@ -25,6 +25,7 @@
 #include <linux/smp.h>
 #include <linux/err.h>
 #include <linux/debugfs.h>
+#include <linux/crash_dump.h>
 #include <asm/uaccess.h>
 #include <asm/io.h>
 #include <asm/page.h>
@@ -286,6 +287,25 @@ static void __init setup_memory(void)
 extern void __init setup_memory(void);
 #endif
 
+/*
+ * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by
+ * is_kdump_kernel() to determine if we are booting after a panic. Hence
+ * ifdef it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE.
+ */
+#ifdef CONFIG_CRASH_DUMP
+/* elfcorehdr= specifies the location of elf core header
+ * stored by the crashed kernel.
+ */
+static int __init parse_elfcorehdr(char *arg)
+{
+	if (!arg)
+		return -EINVAL;
+	elfcorehdr_addr = memparse(arg, &arg);
+	return 0;
+}
+early_param("elfcorehdr", parse_elfcorehdr);
+#endif
+
 void __init setup_arch(char **cmdline_p)
 {
 	enable_mmu();