[PATCH 3.16 153/245] tracing: Have stack tracer compile when MCOUNT_INSN_SIZE is not defined

[Ben Hutchings]

3.16.83-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>

commit b8299d362d0837ae39e87e9019ebe6b736e0f035 upstream.

On some archs with some configurations, MCOUNT_INSN_SIZE is not defined, and
this makes the stack tracer fail to compile. Just define it to zero in this
case.

Link: https://lore.kernel.org/r/202001020219.zvE3vsty%lkp@xxxxxxxxx

Fixes: 4df297129f622 ("tracing: Remove most or all of stack tracer stack size from stack_max_size")
Reported-by: kbuild test robot <lkp@xxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 kernel/trace/trace_stack.c | 5 +++++
 1 file changed, 5 insertions(+)

--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -182,6 +182,11 @@ check_stack(unsigned long ip, unsigned l
 	local_irq_restore(flags);
 }
 
+/* Some archs may not define MCOUNT_INSN_SIZE */
+#ifndef MCOUNT_INSN_SIZE
+# define MCOUNT_INSN_SIZE 0
+#endif
+
 static void
 stack_trace_call(unsigned long ip, unsigned long parent_ip,
 		 struct ftrace_ops *op, struct pt_regs *pt_regs)