[deliverable/linux.git] / arch / mips / kernel / ftrace.c

/*
 * Code for replacing ftrace calls with jumps.
 *
 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
 * Copyright (C) 2009, 2010 DSLab, Lanzhou University, China
 * Author: Wu Zhangjin <wuzhangjin@gmail.com>
 *
 * Thanks goes to Steven Rostedt for writing the original x86 version.
 */

#include <linux/uaccess.h>
#include <linux/init.h>
#include <linux/ftrace.h>

#include <asm/asm.h>
#include <asm/asm-offsets.h>
#include <asm/cacheflush.h>
#include <asm/uasm.h>

#include <asm-generic/sections.h>

#ifdef CONFIG_DYNAMIC_FTRACE

#define JAL 0x0c000000		/* jump & link: ip --> ra, jump to target */
#define ADDR_MASK 0x03ffffff	/*  op_code|addr : 31...26|25 ....0 */
#define JUMP_RANGE_MASK ((1UL << 28) - 1)

#define INSN_NOP 0x00000000	/* nop */
#define INSN_JAL(addr)	\
	((unsigned int)(JAL | (((addr) >> 2) & ADDR_MASK)))

static unsigned int insn_jal_ftrace_caller __read_mostly;
static unsigned int insn_lui_v1_hi16_mcount __read_mostly;
static unsigned int insn_j_ftrace_graph_caller __maybe_unused __read_mostly;

static inline void ftrace_dyn_arch_init_insns(void)
{
	u32 *buf;
	unsigned int v1;

	/* lui v1, hi16_mcount */
	v1 = 3;
	buf = (u32 *)&insn_lui_v1_hi16_mcount;
	UASM_i_LA_mostly(&buf, v1, MCOUNT_ADDR);

	/* jal (ftrace_caller + 8), jump over the first two instruction */
	buf = (u32 *)&insn_jal_ftrace_caller;
	uasm_i_jal(&buf, (FTRACE_ADDR + 8) & JUMP_RANGE_MASK);

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	/* j ftrace_graph_caller */
	buf = (u32 *)&insn_j_ftrace_graph_caller;
	uasm_i_j(&buf, (unsigned long)ftrace_graph_caller & JUMP_RANGE_MASK);
#endif
}

/*
 * Check if the address is in kernel space
 *
 * Clone core_kernel_text() from kernel/extable.c, but doesn't call
 * init_kernel_text() for Ftrace doesn't trace functions in init sections.
 */
static inline int in_kernel_space(unsigned long ip)
{
	if (ip >= (unsigned long)_stext &&
	    ip <= (unsigned long)_etext)
		return 1;
	return 0;
}

static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
{
	int faulted;

	/* *(unsigned int *)ip = new_code; */
	safe_store_code(new_code, ip, faulted);

	if (unlikely(faulted))
		return -EFAULT;

	flush_icache_range(ip, ip + 8);

	return 0;
}

/*
 * The details about the calling site of mcount on MIPS
 *
 * 1. For kernel:
 *
 * move at, ra
 * jal _mcount		--> nop
 *
 * 2. For modules:
 *
 * 2.1 For KBUILD_MCOUNT_RA_ADDRESS and CONFIG_32BIT
 *
 * lui v1, hi_16bit_of_mcount        --> b 1f (0x10000005)
 * addiu v1, v1, low_16bit_of_mcount
 * move at, ra
 * move $12, ra_address
 * jalr v1
 *  sub sp, sp, 8
 *                                  1: offset = 5 instructions
 * 2.2 For the Other situations
 *
 * lui v1, hi_16bit_of_mcount        --> b 1f (0x10000004)
 * addiu v1, v1, low_16bit_of_mcount
 * move at, ra
 * jalr v1
 *  nop | move $12, ra_address | sub sp, sp, 8
 *                                  1: offset = 4 instructions
 */

#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
#define MCOUNT_OFFSET_INSNS 5
#else
#define MCOUNT_OFFSET_INSNS 4
#endif
#define INSN_B_1F (0x10000000 | MCOUNT_OFFSET_INSNS)

int ftrace_make_nop(struct module *mod,
		    struct dyn_ftrace *rec, unsigned long addr)
{
	unsigned int new;
	unsigned long ip = rec->ip;

	/*
	 * If ip is in kernel space, no long call, otherwise, long call is
	 * needed.
	 */
	new = in_kernel_space(ip) ? INSN_NOP : INSN_B_1F;

	return ftrace_modify_code(ip, new);
}

int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
	unsigned int new;
	unsigned long ip = rec->ip;

	new = in_kernel_space(ip) ? insn_jal_ftrace_caller :
		insn_lui_v1_hi16_mcount;

	return ftrace_modify_code(ip, new);
}

#define FTRACE_CALL_IP ((unsigned long)(&ftrace_call))

int ftrace_update_ftrace_func(ftrace_func_t func)
{
	unsigned int new;

	new = INSN_JAL((unsigned long)func);

	return ftrace_modify_code(FTRACE_CALL_IP, new);
}

int __init ftrace_dyn_arch_init(void *data)
{
	/* Encode the instructions when booting */
	ftrace_dyn_arch_init_insns();

	/* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */
	ftrace_modify_code(MCOUNT_ADDR, INSN_NOP);

	/* The return code is retured via data */
	*(unsigned long *)data = 0;

	return 0;
}
#endif	/* CONFIG_DYNAMIC_FTRACE */

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

#ifdef CONFIG_DYNAMIC_FTRACE

extern void ftrace_graph_call(void);
#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,
			insn_j_ftrace_graph_caller);
}

int ftrace_disable_ftrace_graph_caller(void)
{
	return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, INSN_NOP);
}

#endif	/* CONFIG_DYNAMIC_FTRACE */

#ifndef KBUILD_MCOUNT_RA_ADDRESS

#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 */

unsigned long ftrace_get_parent_ra_addr(unsigned long self_ra, unsigned long
		old_parent_ra, unsigned long parent_ra_addr, unsigned long fp)
{
	unsigned long sp, ip, tmp;
	unsigned int code;
	int faulted;

	/*
	 * For module, move the ip from the return address after the
	 * instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for
	 * kernel, move after the instruction "move ra, at"(offset is 16)
	 */
	ip = self_ra - (in_kernel_space(self_ra) ? 16 : 24);

	/*
	 * search the text until finding the non-store instruction or "s{d,w}
	 * ra, offset(sp)" instruction
	 */
	do {
		/* get the code at "ip": code = *(unsigned int *)ip; */
		safe_load_code(code, ip, faulted);

		if (unlikely(faulted))
			return 0;
		/*
		 * If we hit the non-store instruction before finding where the
		 * ra is stored, then this is a leaf function and it does not
		 * store the ra on the stack
		 */
		if ((code & S_R_SP) != S_R_SP)
			return parent_ra_addr;

		/* Move to the next instruction */
		ip -= 4;
	} while ((code & S_RA_SP) != S_RA_SP);

	sp = fp + (code & OFFSET_MASK);

	/* tmp = *(unsigned long *)sp; */
	safe_load_stack(tmp, sp, faulted);
	if (unlikely(faulted))
		return 0;

	if (tmp == old_parent_ra)
		return sp;
	return 0;
}

#endif	/* !KBUILD_MCOUNT_RA_ADDRESS */

/*
 * Hook the return address and push it in the stack of return addrs
 * in current thread info.
 */
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;

	if (unlikely(atomic_read(&current->tracing_graph_pause)))
		return;

	/*
	 * "parent_ra_addr" is the stack address saved the return address of
	 * the caller of _mcount.
	 *
	 * if the gcc < 4.5, a leaf function does not save the return address
	 * in the stack address, so, we "emulate" one in _mcount's stack space,
	 * and hijack it directly, but for a non-leaf function, it save the
	 * return address to the its own stack space, we can not hijack it
	 * directly, but need to find the real stack address,
	 * ftrace_get_parent_addr() does it!
	 *
	 * if gcc>= 4.5, with the new -mmcount-ra-address option, for a
	 * non-leaf function, the location of the return address will be saved
	 * to $12 for us, and for a leaf function, only put a zero into $12. we
	 * do it in ftrace_graph_caller of mcount.S.
	 */

	/* old_parent_ra = *parent_ra_addr; */
	safe_load_stack(old_parent_ra, parent_ra_addr, faulted);
	if (unlikely(faulted))
		goto out;
#ifndef KBUILD_MCOUNT_RA_ADDRESS
	parent_ra_addr = (unsigned long *)ftrace_get_parent_ra_addr(self_ra,
			old_parent_ra, (unsigned long)parent_ra_addr, fp);
	/*
	 * If fails when getting the stack address of the non-leaf function's
	 * ra, stop function graph tracer and return
	 */
	if (parent_ra_addr == 0)
		goto out;
#endif
	/* *parent_ra_addr = return_hooker; */
	safe_store_stack(return_hooker, parent_ra_addr, faulted);
	if (unlikely(faulted))
		goto out;

	if (ftrace_push_return_trace(old_parent_ra, self_ra, &trace.depth, fp)
	    == -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
	 * 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)) {
		current->curr_ret_stack--;
		*parent_ra_addr = old_parent_ra;
	}
	return;
out:
	ftrace_graph_stop();
	WARN_ON(1);
}
#endif	/* CONFIG_FUNCTION_GRAPH_TRACER */
Commit	Line	Data
538f1952 WZ	1	/*
	2	* Code for replacing ftrace calls with jumps.
	3	*
	4	* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
e4240540	5	* Copyright (C) 2009, 2010 DSLab, Lanzhou University, China
f7a904df	6	* Author: Wu Zhangjin <wuzhangjin@gmail.com>
538f1952 WZ	7	*
	8	* Thanks goes to Steven Rostedt for writing the original x86 version.
	9	*/
	10
	11	#include <linux/uaccess.h>
	12	#include <linux/init.h>
	13	#include <linux/ftrace.h>
	14
29c5d346 WZ	15	#include <asm/asm.h>
29c5d346 WZ	16	#include <asm/asm-offsets.h>
e4240540 WZ	17	#include <asm/cacheflush.h>
e4240540 WZ	18	#include <asm/uasm.h>
538f1952	19
d9cdb2f1	20	#include <asm-generic/sections.h>
c9f84873	21
538f1952 WZ	22	#ifdef CONFIG_DYNAMIC_FTRACE
	23
	24	#define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */
	25	#define ADDR_MASK 0x03ffffff /* op_code\|addr : 31...26\|25 ....0 */
c54794d1	26	#define JUMP_RANGE_MASK ((1UL << 28) - 1)
538f1952	27
4d6829f9	28	#define INSN_NOP 0x00000000 /* nop */
e4240540 WZ	29	#define INSN_JAL(addr) \
	30	((unsigned int)(JAL \| (((addr) >> 2) & ADDR_MASK)))
	31
	32	static unsigned int insn_jal_ftrace_caller __read_mostly;
	33	static unsigned int insn_lui_v1_hi16_mcount __read_mostly;
	34	static unsigned int insn_j_ftrace_graph_caller __maybe_unused __read_mostly;
	35
	36	static inline void ftrace_dyn_arch_init_insns(void)
	37	{
	38	u32 *buf;
	39	unsigned int v1;
	40
	41	/* lui v1, hi16_mcount */
	42	v1 = 3;
	43	buf = (u32 *)&insn_lui_v1_hi16_mcount;
	44	UASM_i_LA_mostly(&buf, v1, MCOUNT_ADDR);
	45
	46	/* jal (ftrace_caller + 8), jump over the first two instruction */
	47	buf = (u32 *)&insn_jal_ftrace_caller;
c54794d1	48	uasm_i_jal(&buf, (FTRACE_ADDR + 8) & JUMP_RANGE_MASK);
e4240540 WZ	49
	50	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	51	/* j ftrace_graph_caller */
	52	buf = (u32 *)&insn_j_ftrace_graph_caller;
c54794d1	53	uasm_i_j(&buf, (unsigned long)ftrace_graph_caller & JUMP_RANGE_MASK);
e4240540 WZ	54	#endif
e4240540 WZ	55	}
538f1952	56
d9cdb2f1 WZ	57	/*
	58	* Check if the address is in kernel space
	59	*
	60	* Clone core_kernel_text() from kernel/extable.c, but doesn't call
	61	* init_kernel_text() for Ftrace doesn't trace functions in init sections.
	62	*/
	63	static inline int in_kernel_space(unsigned long ip)
	64	{
	65	if (ip >= (unsigned long)_stext &&
	66	ip <= (unsigned long)_etext)
	67	return 1;
	68	return 0;
	69	}
	70
538f1952 WZ	71	static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
538f1952 WZ	72	{
046199ca WZ	73	int faulted;
	74
	75	/* (unsigned int )ip = new_code; */
	76	safe_store_code(new_code, ip, faulted);
	77
	78	if (unlikely(faulted))
	79	return -EFAULT;
538f1952 WZ	80
	81	flush_icache_range(ip, ip + 8);
	82
	83	return 0;
	84	}
	85
7f21a609 WZ	86	/*
	87	* The details about the calling site of mcount on MIPS
	88	*
	89	* 1. For kernel:
	90	*
	91	* move at, ra
	92	* jal _mcount --> nop
	93	*
	94	* 2. For modules:
	95	*
	96	* 2.1 For KBUILD_MCOUNT_RA_ADDRESS and CONFIG_32BIT
	97	*
	98	* lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
	99	* addiu v1, v1, low_16bit_of_mcount
	100	* move at, ra
	101	* move $12, ra_address
	102	* jalr v1
	103	* sub sp, sp, 8
	104	* 1: offset = 5 instructions
	105	* 2.2 For the Other situations
	106	*
	107	* lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
	108	* addiu v1, v1, low_16bit_of_mcount
	109	* move at, ra
	110	* jalr v1
	111	* nop \| move $12, ra_address \| sub sp, sp, 8
	112	* 1: offset = 4 instructions
	113	*/
	114
	115	#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
	116	#define MCOUNT_OFFSET_INSNS 5
	117	#else
	118	#define MCOUNT_OFFSET_INSNS 4
	119	#endif
	120	#define INSN_B_1F (0x10000000 \| MCOUNT_OFFSET_INSNS)
	121
538f1952 WZ	122	int ftrace_make_nop(struct module *mod,
	123	struct dyn_ftrace *rec, unsigned long addr)
	124	{
	125	unsigned int new;
	126	unsigned long ip = rec->ip;
	127
e4240540	128	/*
d9cdb2f1 WZ	129	* If ip is in kernel space, no long call, otherwise, long call is
d9cdb2f1 WZ	130	* needed.
e4240540	131	*/
7f21a609 WZ	132	new = in_kernel_space(ip) ? INSN_NOP : INSN_B_1F;
7f21a609 WZ	133
538f1952 WZ	134	return ftrace_modify_code(ip, new);
	135	}
	136
538f1952 WZ	137	int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
	138	{
	139	unsigned int new;
	140	unsigned long ip = rec->ip;
	141
d9cdb2f1 WZ	142	new = in_kernel_space(ip) ? insn_jal_ftrace_caller :
d9cdb2f1 WZ	143	insn_lui_v1_hi16_mcount;
538f1952 WZ	144
	145	return ftrace_modify_code(ip, new);
	146	}
	147
	148	#define FTRACE_CALL_IP ((unsigned long)(&ftrace_call))
	149
	150	int ftrace_update_ftrace_func(ftrace_func_t func)
	151	{
	152	unsigned int new;
	153
4d6829f9	154	new = INSN_JAL((unsigned long)func);
538f1952 WZ	155
	156	return ftrace_modify_code(FTRACE_CALL_IP, new);
	157	}
	158
	159	int __init ftrace_dyn_arch_init(void *data)
	160	{
e4240540 WZ	161	/* Encode the instructions when booting */
	162	ftrace_dyn_arch_init_insns();
	163
	164	/* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */
	165	ftrace_modify_code(MCOUNT_ADDR, INSN_NOP);
	166
538f1952 WZ	167	/* The return code is retured via data */
	168	(unsigned long )data = 0;
	169
	170	return 0;
	171	}
68ccf752	172	#endif /* CONFIG_DYNAMIC_FTRACE */
29c5d346 WZ	173
	174	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	175
e17ff5fe WZ	176	#ifdef CONFIG_DYNAMIC_FTRACE
	177
	178	extern void ftrace_graph_call(void);
e17ff5fe WZ	179	#define FTRACE_GRAPH_CALL_IP ((unsigned long)(&ftrace_graph_call))
	180
	181	int ftrace_enable_ftrace_graph_caller(void)
	182	{
	183	return ftrace_modify_code(FTRACE_GRAPH_CALL_IP,
e4240540	184	insn_j_ftrace_graph_caller);
e17ff5fe WZ	185	}
	186
	187	int ftrace_disable_ftrace_graph_caller(void)
	188	{
4d6829f9	189	return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, INSN_NOP);
e17ff5fe WZ	190	}
e17ff5fe WZ	191
68ccf752	192	#endif /* CONFIG_DYNAMIC_FTRACE */
e17ff5fe	193
7326c4e5	194	#ifndef KBUILD_MCOUNT_RA_ADDRESS
68ccf752	195
29c5d346 WZ	196	#define S_RA_SP (0xafbf << 16) /* s{d,w} ra, offset(sp) */
	197	#define S_R_SP (0xafb0 << 16) /* s{d,w} R, offset(sp) */
	198	#define OFFSET_MASK 0xffff /* stack offset range: 0 ~ PT_SIZE */
	199
2816e325 WZ	200	unsigned long ftrace_get_parent_ra_addr(unsigned long self_ra, unsigned long
2816e325 WZ	201	old_parent_ra, unsigned long parent_ra_addr, unsigned long fp)
29c5d346	202	{
2816e325	203	unsigned long sp, ip, tmp;
29c5d346	204	unsigned int code;
046199ca	205	int faulted;
29c5d346	206
68ccf752	207	/*
2816e325	208	* For module, move the ip from the return address after the
9a620a55 WZ	209	* instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for
9a620a55 WZ	210	* kernel, move after the instruction "move ra, at"(offset is 16)
68ccf752	211	*/
2816e325	212	ip = self_ra - (in_kernel_space(self_ra) ? 16 : 24);
29c5d346	213
68ccf752 WZ	214	/*
	215	* search the text until finding the non-store instruction or "s{d,w}
	216	* ra, offset(sp)" instruction
	217	*/
29c5d346	218	do {
046199ca WZ	219	/* get the code at "ip": code = (unsigned int )ip; */
	220	safe_load_code(code, ip, faulted);
	221
	222	if (unlikely(faulted))
	223	return 0;
68ccf752 WZ	224	/*
68ccf752 WZ	225	* If we hit the non-store instruction before finding where the
29c5d346	226	* ra is stored, then this is a leaf function and it does not
68ccf752 WZ	227	* store the ra on the stack
68ccf752 WZ	228	*/
29c5d346	229	if ((code & S_R_SP) != S_R_SP)
2816e325	230	return parent_ra_addr;
29c5d346	231
9a620a55 WZ	232	/* Move to the next instruction */
	233	ip -= 4;
	234	} while ((code & S_RA_SP) != S_RA_SP);
29c5d346 WZ	235
29c5d346 WZ	236	sp = fp + (code & OFFSET_MASK);
046199ca	237
2816e325 WZ	238	/* tmp = (unsigned long )sp; */
2816e325 WZ	239	safe_load_stack(tmp, sp, faulted);
046199ca WZ	240	if (unlikely(faulted))
046199ca WZ	241	return 0;
29c5d346	242
2816e325	243	if (tmp == old_parent_ra)
29c5d346	244	return sp;
29c5d346 WZ	245	return 0;
	246	}
	247
68ccf752	248	#endif /* !KBUILD_MCOUNT_RA_ADDRESS */
7326c4e5	249
29c5d346 WZ	250	/*
	251	* Hook the return address and push it in the stack of return addrs
	252	* in current thread info.
	253	*/
2816e325	254	void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra,
29c5d346 WZ	255	unsigned long fp)
29c5d346 WZ	256	{
2816e325	257	unsigned long old_parent_ra;
29c5d346 WZ	258	struct ftrace_graph_ent trace;
	259	unsigned long return_hooker = (unsigned long)
	260	&return_to_handler;
b9f07eb2	261	int faulted, insns;
29c5d346 WZ	262
	263	if (unlikely(atomic_read(&current->tracing_graph_pause)))
	264	return;
	265
68ccf752	266	/*
2816e325 WZ	267	* "parent_ra_addr" is the stack address saved the return address of
2816e325 WZ	268	* the caller of _mcount.
7326c4e5 WZ	269	*
	270	* if the gcc < 4.5, a leaf function does not save the return address
	271	* in the stack address, so, we "emulate" one in _mcount's stack space,
	272	* and hijack it directly, but for a non-leaf function, it save the
	273	* return address to the its own stack space, we can not hijack it
	274	* directly, but need to find the real stack address,
29c5d346	275	* ftrace_get_parent_addr() does it!
7326c4e5 WZ	276	*
	277	* if gcc>= 4.5, with the new -mmcount-ra-address option, for a
	278	* non-leaf function, the location of the return address will be saved
	279	* to $12 for us, and for a leaf function, only put a zero into $12. we
	280	* do it in ftrace_graph_caller of mcount.S.
29c5d346 WZ	281	*/
29c5d346 WZ	282
2816e325 WZ	283	/* old_parent_ra = parent_ra_addr; /
2816e325 WZ	284	safe_load_stack(old_parent_ra, parent_ra_addr, faulted);
046199ca WZ	285	if (unlikely(faulted))
046199ca WZ	286	goto out;
7326c4e5	287	#ifndef KBUILD_MCOUNT_RA_ADDRESS
2816e325 WZ	288	parent_ra_addr = (unsigned long *)ftrace_get_parent_ra_addr(self_ra,
2816e325 WZ	289	old_parent_ra, (unsigned long)parent_ra_addr, fp);
68ccf752 WZ	290	/*
	291	* If fails when getting the stack address of the non-leaf function's
	292	* ra, stop function graph tracer and return
	293	*/
2816e325	294	if (parent_ra_addr == 0)
046199ca	295	goto out;
7326c4e5	296	#endif
2816e325 WZ	297	/* parent_ra_addr = return_hooker; /
2816e325 WZ	298	safe_store_stack(return_hooker, parent_ra_addr, faulted);
046199ca WZ	299	if (unlikely(faulted))
046199ca WZ	300	goto out;
29c5d346	301
2816e325 WZ	302	if (ftrace_push_return_trace(old_parent_ra, self_ra, &trace.depth, fp)
	303	== -EBUSY) {
	304	*parent_ra_addr = old_parent_ra;
29c5d346 WZ	305	return;
	306	}
	307
b9f07eb2 WZ	308	/*
	309	* Get the recorded ip of the current mcount calling site in the
	310	* __mcount_loc section, which will be used to filter the function
	311	* entries configured through the tracing/set_graph_function interface.
	312	*/
	313
	314	insns = in_kernel_space(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1;
	315	trace.func = self_ra - (MCOUNT_INSN_SIZE * insns);
29c5d346 WZ	316
	317	/* Only trace if the calling function expects to */
	318	if (!ftrace_graph_entry(&trace)) {
	319	current->curr_ret_stack--;
2816e325	320	*parent_ra_addr = old_parent_ra;
29c5d346	321	}
046199ca WZ	322	return;
	323	out:
	324	ftrace_graph_stop();
	325	WARN_ON(1);
29c5d346	326	}
68ccf752	327	#endif /* CONFIG_FUNCTION_GRAPH_TRACER */