Commit e17ff5fe authored by Wu Zhangjin's avatar Wu Zhangjin Committed by Ralf Baechle
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MIPS: Tracing: Add dynamic function graph tracer for MIPS 



This patch make function graph tracer work with dynamic function tracer.

To share the source code of dynamic function tracer(MCOUNT_SAVE_REGS),
and avoid restoring the whole saved registers, we need to restore the ra
register from the stack.

(NOTE: This not work with 32bit! need to ensure why!)

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/678/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 29c5d346

arch/mips/kernel/ftrace.c

+21 −0
Original line number Diff line number Diff line
@@ -115,6 +115,27 @@ int __init ftrace_dyn_arch_init(void *data) 


#ifdef CONFIG_FUNCTION_GRAPH_TRACER



#ifdef CONFIG_DYNAMIC_FTRACE



extern void ftrace_graph_call(void);

#define JMP	0x08000000	/* jump to target directly */

#define CALL_FTRACE_GRAPH_CALLER \

	jump_insn_encode(JMP, (unsigned long)(&ftrace_graph_caller))

#define FTRACE_GRAPH_CALL_IP	((unsigned long)(&ftrace_graph_call))



int ftrace_enable_ftrace_graph_caller(void)

{

	return ftrace_modify_code(FTRACE_GRAPH_CALL_IP,

				  CALL_FTRACE_GRAPH_CALLER);

}



int ftrace_disable_ftrace_graph_caller(void)

{

	return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, ftrace_nop);

}



#endif				/* !CONFIG_DYNAMIC_FTRACE */



#define S_RA_SP	(0xafbf << 16)	/* s{d,w} ra, offset(sp) */

#define S_R_SP	(0xafb0 << 16)  /* s{d,w} R, offset(sp) */

#define OFFSET_MASK	0xffff	/* stack offset range: 0 ~ PT_SIZE */

arch/mips/kernel/mcount.S

+12 −2
Original line number Diff line number Diff line
@@ -77,6 +77,13 @@ ftrace_call: 
	nop	/* a placeholder for the call to a real tracing function */

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



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	.globl ftrace_graph_call

ftrace_graph_call:

	nop

	 nop

#endif



	MCOUNT_RESTORE_REGS

	.globl ftrace_stub

ftrace_stub:
@@ -124,10 +131,13 @@ ftrace_stub: 
#ifdef CONFIG_FUNCTION_GRAPH_TRACER



NESTED(ftrace_graph_caller, PT_SIZE, ra)

#ifdef CONFIG_DYNAMIC_FTRACE

	PTR_L	a1, PT_R31(sp)	/* load the original ra from the stack */

#else

	MCOUNT_SAVE_REGS



	PTR_LA	a0, PT_R1(sp)	/* arg1: &AT -> a0 */

	move	a1, ra		/* arg2: next ip, selfaddr */

#endif

	PTR_LA	a0, PT_R1(sp)	/* arg1: &AT -> a0 */

	jal	prepare_ftrace_return

	 move	a2, fp		/* arg3: frame pointer */

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