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Commit 8114865f authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
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function_graph: Create function_graph_enter() to consolidate architecture code 



Currently all the architectures do basically the same thing in preparing the
function graph tracer on entry to a function. This code can be pulled into a
generic location and then this will allow the function graph tracer to be
fixed, as well as extended.

Create a new function graph helper function_graph_enter() that will call the
hook function (ftrace_graph_entry) and the shadow stack operation
(ftrace_push_return_trace), and remove the need of the architecture code to
manage the shadow stack.

This is needed to prepare for a fix of a design bug on how the curr_ret_stack
is used.

Cc: stable@kernel.org
Fixes: 03274a3f ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Reviewed-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 9ff01193

include/linux/ftrace.h

+3 −0
Original line number Diff line number Diff line
@@ -779,6 +779,9 @@ extern void return_to_handler(void); 
extern int

ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,

			 unsigned long frame_pointer, unsigned long *retp);

extern int

function_graph_enter(unsigned long ret, unsigned long func,

		     unsigned long frame_pointer, unsigned long *retp);



unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,

				    unsigned long ret, unsigned long *retp);

kernel/trace/trace_functions_graph.c

+16 −0
Original line number Diff line number Diff line
@@ -182,6 +182,22 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth, 
	return 0;

}



int function_graph_enter(unsigned long ret, unsigned long func,

			 unsigned long frame_pointer, unsigned long *retp)

{

	struct ftrace_graph_ent trace;



	trace.func = func;

	trace.depth = current->curr_ret_stack + 1;



	/* Only trace if the calling function expects to */

	if (!ftrace_graph_entry(&trace))

		return -EBUSY;



	return ftrace_push_return_trace(ret, func, &trace.depth,

					frame_pointer, retp);

}



/* Retrieve a function return address to the trace stack on thread info.*/

static void

ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,