fgraph: Add comment to describe ftrace_graph_get_ret_stack (45fe439b) · Commits · 戴 / test

The ret_stack should not be accessed directly via the curr_ret_stack variable on the task_struct. This is because the ret_stack is going to be converted into a series of longs and not an array of ret_stack structures. The way that a ret_stack should be retrieved is via the ftrace_graph_get_ret_stack structure, but it needs to be documented on how to use it. Signed-off-by:

Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/fgraph.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -232,6 +232,17 @@ unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
		return ret;
		}

		/**
		* ftrace_graph_get_ret_stack - return the entry of the shadow stack
		* @task: The task to read the shadow stack from
		* @idx: Index down the shadow stack
		*
		* Return the ret_struct on the shadow stack of the @task at the
		* call graph at @idx starting with zero. If @idx is zero, it
		* will return the last saved ret_stack entry. If it is greater than
		* zero, it will return the corresponding ret_stack for the depth
		* of saved return addresses.
		*/
		struct ftrace_ret_stack *
		ftrace_graph_get_ret_stack(struct task_struct *task, int idx)
		{

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