MIPS: kdump: Add support

[ralf@linux-mips.org: Original patch by Maxim Uvarov <muvarov@gmail.com>
with plenty of further shining, polishing, debugging and testing by me.]

Signed-off-by: Maxim Uvarov <muvarov@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: kexec@lists.infradead.org
Cc: horms@verge.net.au
Patchwork: https://patchwork.linux-mips.org/patch/1025/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 9005bf9..2e6374a 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -386,3 +386,20 @@
 
 EXPORT_SYMBOL(flush_tlb_page);
 EXPORT_SYMBOL(flush_tlb_one);
+
+#if defined(CONFIG_KEXEC)
+void (*dump_ipi_function_ptr)(void *) = NULL;
+void dump_send_ipi(void (*dump_ipi_callback)(void *))
+{
+	int i;
+	int cpu = smp_processor_id();
+
+	dump_ipi_function_ptr = dump_ipi_callback;
+	smp_mb();
+	for_each_online_cpu(i)
+		if (i != cpu)
+			mp_ops->send_ipi_single(i, SMP_DUMP);
+
+}
+EXPORT_SYMBOL(dump_send_ipi);
+#endif