x86/ftrace: Do not call function graph from dynamic trampolines
[ Upstream commit d2a68c4effd821f0871d20368f76b609349c8a3b ] Since commit 79922b80 ("ftrace: Optimize function graph to be called directly"), dynamic trampolines should not be calling the function graph tracer at the end. If they do, it could cause the function graph tracer to trace functions that it filtered out. Right now it does not cause a problem because there's a test to check if the function graph tracer is attached to the same function as the function tracer, which for now is true. But the function graph tracer is undergoing changes that can make this no longer true which will cause the function graph tracer to trace other functions. For example: # cd /sys/kernel/tracing/ # echo do_IRQ > set_ftrace_filter # mkdir instances/foo # echo ip_rcv > instances/foo/set_ftrace_filter # echo function_graph > current_tracer # echo function > instances/foo/current_tracer Would cause the function graph tracer to trace both do_IRQ and ip_rcv, if the current tests change. As the current tests prevent this from being a problem, this code does not need to be backported. But it does make the code cleaner. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: NSasha Levin <sashal@kernel.org>
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