Commit e949b6db authored Nov 18, 2018 by Steven Rostedt (VMware)

riscv/function_graph: Simplify with function_graph_enter()



The function_graph_enter() function does the work of calling the function
graph hook function and the management of the shadow stack, simplifying the
work done in the architecture dependent prepare_ftrace_return().

Have riscv use the new code, and remove the shadow stack management as well as
having to set up the trace structure.

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

Cc: Greentime Hu <greentime@andestech.com>
Cc: Alan Kao <alankao@andestech.com>
Cc: stable@kernel.org
Fixes: 03274a3f ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

parent fe60522e

arch/riscv/kernel/ftrace.c

+2 −12

Original line number	Diff line number	Diff line
		@@ -132,7 +132,6 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
		{
		unsigned long return_hooker = (unsigned long)&return_to_handler;
		unsigned long old;
		struct ftrace_graph_ent trace;
		int err;

		if (unlikely(atomic_read(&current->tracing_graph_pause)))
		@@ -144,16 +143,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
		*/
		old = *parent;

		trace.func = self_addr;
		trace.depth = current->curr_ret_stack + 1;

		if (!ftrace_graph_entry(&trace))
		return;

		err = ftrace_push_return_trace(old, self_addr, &trace.depth,
		frame_pointer, parent);
		if (err == -EBUSY)
		return;
		if (function_graph_enter(old, self_addr, frame_pointer, parent))
		*parent = return_hooker;
		}