Commit fc49a3be authored by Wu Zhangjin's avatar Wu Zhangjin Committed by Ralf Baechle
Browse files

MIPS: Tracing: Reserve $12(t0) for mcount-ra-address of gcc 4.5 



A new option -mmcount-ra-address for gcc 4.5 have been sent by David
Daney <ddaney@caviumnetworks.com> in the thread "MIPS: Add option to
pass return address location to _mcount", which help to record the
location of the return address(ra) for the function graph tracer of MIPS
to hijack the return address easier and safer. that option used the
$12(t0) register by default, so, we reserve it for it, and use t1,t2,t3
instead of t0,t1,t2.

Signed-off-by: default avatarWu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/680/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 046199ca

arch/mips/kernel/mcount.S

+13 −13
Original line number Diff line number Diff line
@@ -65,8 +65,8 @@ NESTED(ftrace_caller, PT_SIZE, ra) 
_mcount:

	b	ftrace_stub

	 nop

	lw	t0, function_trace_stop

	bnez	t0, ftrace_stub

	lw	t1, function_trace_stop

	bnez	t1, ftrace_stub

	 nop



	MCOUNT_SAVE_REGS
@@ -93,21 +93,21 @@ ftrace_stub: 
#else	/* ! CONFIG_DYNAMIC_FTRACE */



NESTED(_mcount, PT_SIZE, ra)

	lw	t0, function_trace_stop

	bnez	t0, ftrace_stub

	lw	t1, function_trace_stop

	bnez	t1, ftrace_stub

	 nop

	PTR_LA	t0, ftrace_stub

	PTR_L	t1, ftrace_trace_function /* Prepare t1 for (1) */

	bne	t0, t1, static_trace

	PTR_LA	t1, ftrace_stub

	PTR_L	t2, ftrace_trace_function /* Prepare t2 for (1) */

	bne	t1, t2, static_trace

	 nop



#ifdef	CONFIG_FUNCTION_GRAPH_TRACER

	PTR_L	t2, ftrace_graph_return

	bne	t0, t2, ftrace_graph_caller

	PTR_L	t3, ftrace_graph_return

	bne	t1, t3, ftrace_graph_caller

	 nop

	PTR_LA	t0, ftrace_graph_entry_stub

	PTR_L	t2, ftrace_graph_entry

	bne	t0, t2, ftrace_graph_caller

	PTR_LA	t1, ftrace_graph_entry_stub

	PTR_L	t3, ftrace_graph_entry

	bne	t1, t3, ftrace_graph_caller

	 nop

#endif

	b	ftrace_stub
@@ -117,7 +117,7 @@ static_trace: 
	MCOUNT_SAVE_REGS



	move	a0, ra		/* arg1: next ip, selfaddr */

	jalr	t1	/* (1) call *ftrace_trace_function */

	jalr	t2		/* (1) call *ftrace_trace_function */

	 move	a1, AT		/* arg2: the caller's next ip, parent */



	MCOUNT_RESTORE_REGS

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