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Commit 8712b27c authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
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MIPS: 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 MIPS 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: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@linux-mips.org
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 556763e5

arch/mips/kernel/ftrace.c

+2 −12
Original line number Diff line number Diff line
@@ -322,7 +322,6 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra, 
			   unsigned long fp)

{

	unsigned long old_parent_ra;

	struct ftrace_graph_ent trace;

	unsigned long return_hooker = (unsigned long)

	    &return_to_handler;

	int faulted, insns;
@@ -369,12 +368,6 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra, 
	if (unlikely(faulted))

		goto out;



	if (ftrace_push_return_trace(old_parent_ra, self_ra, &trace.depth, fp,

				     NULL) == -EBUSY) {

		*parent_ra_addr = old_parent_ra;

		return;

	}



	/*

	 * Get the recorded ip of the current mcount calling site in the

	 * __mcount_loc section, which will be used to filter the function
@@ -382,13 +375,10 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra, 
	 */



	insns = core_kernel_text(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1;

	trace.func = self_ra - (MCOUNT_INSN_SIZE * insns);

	self_ra -= (MCOUNT_INSN_SIZE * insns);



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

	if (!ftrace_graph_entry(&trace)) {

		current->curr_ret_stack--;

	if (function_graph_enter(old_parent_ra, self_ra, fp, NULL))

		*parent_ra_addr = old_parent_ra;

	}

	return;

out:

	ftrace_graph_stop();