Commit b9f07eb2 authored Jan 22, 2011 by Wu Zhangjin Committed by Ralf Baechle Mar 14, 2011

MIPS, Tracing: Fix set_graph_function of function graph tracer



trace.func should be set to the recorded ip of the mcount calling site
in the __mcount_loc section to filter the function entries configured
through the tracing/set_graph_function interface, but before, this is
set to the self_ra(the return address of mcount), which has made
set_graph_function not work as expected.

This fixes it via calculating the right recorded ip in the __mcount_loc
section and assign it to trace.func.

Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Sergei Shtylyov <sshtylyov@mvista.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2017/


Signed-off-by: Ralf Baechle <ralf@duck.linux-mips.net>

parent 7f21a609

arch/mips/kernel/ftrace.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -257,7 +257,7 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra,
		struct ftrace_graph_ent trace;
		unsigned long return_hooker = (unsigned long)
		&return_to_handler;
		int faulted;
		int faulted, insns;

		if (unlikely(atomic_read(&current->tracing_graph_pause)))
		return;
		@@ -304,7 +304,14 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra,
		return;
		}

		trace.func = self_ra;
		/*
		* Get the recorded ip of the current mcount calling site in the
		* __mcount_loc section, which will be used to filter the function
		* entries configured through the tracing/set_graph_function interface.
		*/

		insns = in_kernel_space(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1;
		trace.func = self_ra - (MCOUNT_INSN_SIZE * insns);

		/* Only trace if the calling function expects to */
		if (!ftrace_graph_entry(&trace)) {