sparc64: Fix stack dumping and tracing when function graph is enabled.

Like x86, when the function graph tracer is enabled, emit the ftrace
stub as well as the program counter it will be transformed back into.

We duplicate a lot of similar stack walking logic in 3 or 4 spots, so
eventually we should consolidate things like x86 does.

Thanks to Frederic Weisbecker for pointing this out.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 22 insertions, 1 deletions

diff --git a/arch/sparc/kernel/stacktrace.c b/arch/sparc/kernel/stacktrace.c
index acb12f673757..3e0815349630 100644
--- a/arch/sparc/kernel/stacktrace.c
+++ b/arch/sparc/kernel/stacktrace.c
@@ -1,6 +1,7 @@
 #include <linux/sched.h>
 #include <linux/stacktrace.h>
 #include <linux/thread_info.h>
+#include <linux/ftrace.h>
 #include <linux/module.h>
 #include <asm/ptrace.h>
 #include <asm/stacktrace.h>
@@ -12,6 +13,10 @@ static void __save_stack_trace(struct thread_info *tp,
 			       bool skip_sched)
 {
 	unsigned long ksp, fp;
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	struct task_struct *t;
+	int graph = 0;
+#endif
 
 	if (tp == current_thread_info()) {
 		stack_trace_flush();
@@ -21,6 +26,9 @@ static void __save_stack_trace(struct thread_info *tp,
 	}
 
 	fp = ksp + STACK_BIAS;
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	t = tp->task;
+#endif
 	do {
 		struct sparc_stackf *sf;
 		struct pt_regs *regs;
@@ -44,8 +52,21 @@ static void __save_stack_trace(struct thread_info *tp,
 
 		if (trace->skip > 0)
 			trace->skip--;
-		else if (!skip_sched || !in_sched_functions(pc))
+		else if (!skip_sched || !in_sched_functions(pc)) {
 			trace->entries[trace->nr_entries++] = pc;
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+			if ((pc + 8UL) == (unsigned long) &return_to_handler) {
+				int index = t->curr_ret_stack;
+				if (t->ret_stack && index >= graph) {
+					pc = t->ret_stack[index - graph].ret;
+					if (trace->nr_entries <
+					    trace->max_entries)
+						trace->entries[trace->nr_entries++] = pc;
+					graph++;
+				}
+			}
+#endif
+		}
 	} while (trace->nr_entries < trace->max_entries);
 }