Messages in this thread Patch in this message | | | Date | Mon, 10 Dec 2018 14:30:08 -0500 | From | Steven Rostedt <> | Subject | [PATCH 1/6] fgraph: Add comment to describe ftrace_graph_get_ret_stack |
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From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
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 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index a3704ec8b599..d4f04f0ca646 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -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) { -- 2.19.1
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