Commit d2ccbccb authored Jan 02, 2020 by Steven Rostedt (VMware)

tracing: Define MCOUNT_INSN_SIZE when not defined without direct calls

In order to handle direct calls along side of function graph tracer, a check
is made to see if the address being traced by the function graph tracer is a
direct call or not. To get the address used by direct callers, the return
address is subtracted by MCOUNT_INSN_SIZE.

For some archs with certain configurations, MCOUNT_INSN_SIZE is undefined
here. But these should not be using direct calls anyway. Just define
MCOUNT_INSN_SIZE to zero in this case.

Link: https://lore.kernel.org/r/202001020219.zvE3vsty%lkp@intel.com

Reported-by: kbuild test robot <lkp@intel.com>
Fixes: ff205766 ("ftrace: Fix function_graph tracer interaction with BPF trampoline")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

parent 02f4e01c

kernel/trace/fgraph.c

+14 −0

Original line number	Diff line number	Diff line
		@@ -96,6 +96,20 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
		return 0;
		}

		/*
		* Not all archs define MCOUNT_INSN_SIZE which is used to look for direct
		* functions. But those archs currently don't support direct functions
		* anyway, and ftrace_find_rec_direct() is just a stub for them.
		* Define MCOUNT_INSN_SIZE to keep those archs compiling.
		*/
		#ifndef MCOUNT_INSN_SIZE
		/* Make sure this only works without direct calls */
		# ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
		# error MCOUNT_INSN_SIZE not defined with direct calls enabled
		# endif
		# define MCOUNT_INSN_SIZE 0
		#endif

		int function_graph_enter(unsigned long ret, unsigned long func,
		unsigned long frame_pointer, unsigned long *retp)
		{

Admin message