[POWERPC] Stacktrace support for lockdep
This adds stacktrace support for powerpc, which will be needed for
lockdep.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c
new file mode 100644
index 0000000..e3638ee
--- /dev/null
+++ b/arch/powerpc/kernel/stacktrace.c
@@ -0,0 +1,47 @@
+/*
+ * Stack trace utility
+ *
+ * Copyright 2008 Christoph Hellwig, IBM Corp.
+ *
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/sched.h>
+#include <linux/stacktrace.h>
+#include <asm/ptrace.h>
+#include <asm/asm-offsets.h>
+
+/*
+ * Save stack-backtrace addresses into a stack_trace buffer.
+ */
+void save_stack_trace(struct stack_trace *trace)
+{
+ unsigned long sp;
+
+ asm("mr %0,1" : "=r" (sp));
+
+ for (;;) {
+ unsigned long *stack = (unsigned long *) sp;
+ unsigned long newsp, ip;
+
+ if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
+ return;
+
+ newsp = stack[0];
+ ip = stack[STACK_FRAME_LR_SAVE];
+
+ if (!trace->skip)
+ trace->entries[trace->nr_entries++] = ip;
+ else
+ trace->skip--;
+
+ if (trace->nr_entries >= trace->max_entries)
+ return;
+
+ sp = newsp;
+ }
+}