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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2018-12-07 12:25:52 -0500
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2018-12-10 12:22:45 -0500
commit45fe439bc3699851802062c05acf4cbac4d672bc (patch)
treec8017bddbd42a2b0ec84e1cfcc3e4e13bcbcc98c /kernel/trace
parente4c07bf9867aeaec14bac042fbbd50d885f6ed3a (diff)
downloadblackbird-op-linux-45fe439bc3699851802062c05acf4cbac4d672bc.tar.gz
blackbird-op-linux-45fe439bc3699851802062c05acf4cbac4d672bc.zip
fgraph: Add comment to describe ftrace_graph_get_ret_stack
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>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/fgraph.c11
1 files changed, 11 insertions, 0 deletions
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)
{
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