tracing: Allow arch-specific stack tracer

A stack frame may be used in a different way depending on cpu architecture.
Thus it is not always appropriate to slurp the stack contents, as current
check_stack() does, in order to calcurate a stack index (height) at a given
function call. At least not on arm64.
In addition, there is a possibility that we will mistakenly detect a stale
stack frame which has not been overwritten.

This patch makes check_stack() a weak function so as to later implement
arch-specific version.

Link: http://lkml.kernel.org/r/1446182741-31019-5-git-send-email-takahiro.akashi@linaro.org

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 6cd8c0ee4b6f..b4c92ab9e08b 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -263,7 +263,18 @@ static inline void ftrace_kill(void) { }
 #endif /* CONFIG_FUNCTION_TRACER */
 
 #ifdef CONFIG_STACK_TRACER
+
+#define STACK_TRACE_ENTRIES 500
+
+struct stack_trace;
+
+extern unsigned stack_trace_index[];
+extern struct stack_trace stack_trace_max;
+extern unsigned long stack_trace_max_size;
+extern arch_spinlock_t max_stack_lock;
+
 extern int stack_tracer_enabled;
+void stack_trace_print(void);
 int
 stack_trace_sysctl(struct ctl_table *table, int write,
                    void __user *buffer, size_t *lenp,