[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 <linux/syscalls.h>

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

#include <asm-generic/sections.h>

#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
#define MCOUNT_OFFSET_INSNS 5
#else
#define MCOUNT_OFFSET_INSNS 4
#endif

#ifdef CONFIG_DYNAMIC_FTRACE

/* Arch override because MIPS doesn't need to run this from stop_machine() */
void arch_ftrace_update_code(int command)
{
	ftrace_modify_all_code(command);
}

#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;
}

#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
}

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;
}

#ifndef CONFIG_64BIT
static int ftrace_modify_code_2(unsigned long ip, unsigned int new_code1,
				unsigned int new_code2)
{
	int faulted;

	safe_store_code(new_code1, ip, faulted);
	if (unlikely(faulted))
		return -EFAULT;
	safe_store_code(new_code2, ip + 4, faulted);
	if (unlikely(faulted))
		return -EFAULT;
	flush_icache_range(ip, ip + 8);
	return 0;
}
#endif

/*
 * 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
 */

#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;
#ifdef CONFIG_64BIT
	return ftrace_modify_code(ip, new);
#else
	/*
	 * On 32 bit MIPS platforms, gcc adds a stack adjust
	 * instruction in the delay slot after the branch to
	 * mcount and expects mcount to restore the sp on return.
	 * This is based on a legacy API and does nothing but
	 * waste instructions so it's being removed at runtime.
	 */
	return ftrace_modify_code_2(ip, new, INSN_NOP);
#endif
}

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 */

#ifdef CONFIG_FTRACE_SYSCALLS

#ifdef CONFIG_32BIT
unsigned long __init arch_syscall_addr(int nr)
{
	return (unsigned long)sys_call_table[nr - __NR_O32_Linux];
}
#endif

#ifdef CONFIG_64BIT

unsigned long __init arch_syscall_addr(int nr)
{
#ifdef CONFIG_MIPS32_N32
	if (nr >= __NR_N32_Linux && nr <= __NR_N32_Linux + __NR_N32_Linux_syscalls)
		return (unsigned long)sysn32_call_table[nr - __NR_N32_Linux];
#endif
	if (nr >= __NR_64_Linux  && nr <= __NR_64_Linux + __NR_64_Linux_syscalls)
		return (unsigned long)sys_call_table[nr - __NR_64_Linux];
#ifdef CONFIG_MIPS32_O32
	if (nr >= __NR_O32_Linux && nr <= __NR_O32_Linux + __NR_O32_Linux_syscalls)
		return (unsigned long)sys32_call_table[nr - __NR_O32_Linux];
#endif

	return (unsigned long) &sys_ni_syscall;
}
#endif

#endif /* CONFIG_FTRACE_SYSCALLS */
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>
19e2e172	14	#include <linux/syscalls.h>
538f1952	15
29c5d346 WZ	16	#include <asm/asm.h>
29c5d346 WZ	17	#include <asm/asm-offsets.h>
e4240540	18	#include <asm/cacheflush.h>
19e2e172	19	#include <asm/syscall.h>
e4240540	20	#include <asm/uasm.h>
19e2e172	21	#include <asm/unistd.h>
538f1952	22
d9cdb2f1	23	#include <asm-generic/sections.h>
c9f84873	24
49de830a TG	25	#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
	26	#define MCOUNT_OFFSET_INSNS 5
	27	#else
	28	#define MCOUNT_OFFSET_INSNS 4
	29	#endif
	30
cb2f9938 MC	31	#ifdef CONFIG_DYNAMIC_FTRACE
cb2f9938 MC	32
58b69401 AC	33	/* Arch override because MIPS doesn't need to run this from stop_machine() */
	34	void arch_ftrace_update_code(int command)
	35	{
	36	ftrace_modify_all_code(command);
	37	}
	38
cb2f9938 MC	39	#endif
cb2f9938 MC	40
49de830a TG	41	/*
	42	* Check if the address is in kernel space
	43	*
	44	* Clone core_kernel_text() from kernel/extable.c, but doesn't call
	45	* init_kernel_text() for Ftrace doesn't trace functions in init sections.
	46	*/
	47	static inline int in_kernel_space(unsigned long ip)
	48	{
	49	if (ip >= (unsigned long)_stext &&
	50	ip <= (unsigned long)_etext)
	51	return 1;
	52	return 0;
	53	}
	54
538f1952 WZ	55	#ifdef CONFIG_DYNAMIC_FTRACE
	56
	57	#define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */
	58	#define ADDR_MASK 0x03ffffff /* op_code\|addr : 31...26\|25 ....0 */
c54794d1	59	#define JUMP_RANGE_MASK ((1UL << 28) - 1)
538f1952	60
4d6829f9	61	#define INSN_NOP 0x00000000 /* nop */
e4240540 WZ	62	#define INSN_JAL(addr) \
	63	((unsigned int)(JAL \| (((addr) >> 2) & ADDR_MASK)))
	64
	65	static unsigned int insn_jal_ftrace_caller __read_mostly;
	66	static unsigned int insn_lui_v1_hi16_mcount __read_mostly;
	67	static unsigned int insn_j_ftrace_graph_caller __maybe_unused __read_mostly;
	68
	69	static inline void ftrace_dyn_arch_init_insns(void)
	70	{
	71	u32 *buf;
	72	unsigned int v1;
	73
	74	/* lui v1, hi16_mcount */
	75	v1 = 3;
	76	buf = (u32 *)&insn_lui_v1_hi16_mcount;
	77	UASM_i_LA_mostly(&buf, v1, MCOUNT_ADDR);
	78
	79	/* jal (ftrace_caller + 8), jump over the first two instruction */
	80	buf = (u32 *)&insn_jal_ftrace_caller;
c54794d1	81	uasm_i_jal(&buf, (FTRACE_ADDR + 8) & JUMP_RANGE_MASK);
e4240540 WZ	82
	83	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	84	/* j ftrace_graph_caller */
	85	buf = (u32 *)&insn_j_ftrace_graph_caller;
c54794d1	86	uasm_i_j(&buf, (unsigned long)ftrace_graph_caller & JUMP_RANGE_MASK);
e4240540 WZ	87	#endif
e4240540 WZ	88	}
538f1952 WZ	89
	90	static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
	91	{
046199ca WZ	92	int faulted;
	93
	94	/* (unsigned int )ip = new_code; */
	95	safe_store_code(new_code, ip, faulted);
	96
	97	if (unlikely(faulted))
	98	return -EFAULT;
538f1952 WZ	99
	100	flush_icache_range(ip, ip + 8);
	101
	102	return 0;
	103	}
	104
58b69401 AC	105	#ifndef CONFIG_64BIT
	106	static int ftrace_modify_code_2(unsigned long ip, unsigned int new_code1,
	107	unsigned int new_code2)
	108	{
	109	int faulted;
	110
	111	safe_store_code(new_code1, ip, faulted);
	112	if (unlikely(faulted))
	113	return -EFAULT;
a4671094	114	safe_store_code(new_code2, ip + 4, faulted);
58b69401 AC	115	if (unlikely(faulted))
58b69401 AC	116	return -EFAULT;
a4671094	117	flush_icache_range(ip, ip + 8);
58b69401 AC	118	return 0;
	119	}
	120	#endif
	121
7f21a609 WZ	122	/*
	123	* The details about the calling site of mcount on MIPS
	124	*
	125	* 1. For kernel:
	126	*
	127	* move at, ra
	128	* jal _mcount --> nop
	129	*
	130	* 2. For modules:
	131	*
	132	* 2.1 For KBUILD_MCOUNT_RA_ADDRESS and CONFIG_32BIT
	133	*
70342287	134	* lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
7f21a609 WZ	135	* addiu v1, v1, low_16bit_of_mcount
	136	* move at, ra
	137	* move $12, ra_address
	138	* jalr v1
	139	* sub sp, sp, 8
70342287	140	* 1: offset = 5 instructions
7f21a609 WZ	141	* 2.2 For the Other situations
7f21a609 WZ	142	*
70342287	143	* lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
7f21a609 WZ	144	* addiu v1, v1, low_16bit_of_mcount
	145	* move at, ra
	146	* jalr v1
	147	* nop \| move $12, ra_address \| sub sp, sp, 8
70342287	148	* 1: offset = 4 instructions
7f21a609 WZ	149	*/
7f21a609 WZ	150
7f21a609 WZ	151	#define INSN_B_1F (0x10000000 \| MCOUNT_OFFSET_INSNS)
7f21a609 WZ	152
538f1952 WZ	153	int ftrace_make_nop(struct module *mod,
	154	struct dyn_ftrace *rec, unsigned long addr)
	155	{
	156	unsigned int new;
	157	unsigned long ip = rec->ip;
	158
e4240540	159	/*
d9cdb2f1 WZ	160	* If ip is in kernel space, no long call, otherwise, long call is
d9cdb2f1 WZ	161	* needed.
e4240540	162	*/
7f21a609	163	new = in_kernel_space(ip) ? INSN_NOP : INSN_B_1F;
58b69401	164	#ifdef CONFIG_64BIT
538f1952	165	return ftrace_modify_code(ip, new);
58b69401 AC	166	#else
	167	/*
	168	* On 32 bit MIPS platforms, gcc adds a stack adjust
	169	* instruction in the delay slot after the branch to
	170	* mcount and expects mcount to restore the sp on return.
	171	* This is based on a legacy API and does nothing but
	172	* waste instructions so it's being removed at runtime.
	173	*/
	174	return ftrace_modify_code_2(ip, new, INSN_NOP);
	175	#endif
538f1952 WZ	176	}
538f1952 WZ	177
538f1952 WZ	178	int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
	179	{
	180	unsigned int new;
	181	unsigned long ip = rec->ip;
	182
d9cdb2f1 WZ	183	new = in_kernel_space(ip) ? insn_jal_ftrace_caller :
d9cdb2f1 WZ	184	insn_lui_v1_hi16_mcount;
538f1952 WZ	185
	186	return ftrace_modify_code(ip, new);
	187	}
	188
	189	#define FTRACE_CALL_IP ((unsigned long)(&ftrace_call))
	190
	191	int ftrace_update_ftrace_func(ftrace_func_t func)
	192	{
	193	unsigned int new;
	194
4d6829f9	195	new = INSN_JAL((unsigned long)func);
538f1952 WZ	196
	197	return ftrace_modify_code(FTRACE_CALL_IP, new);
	198	}
	199
	200	int __init ftrace_dyn_arch_init(void *data)
	201	{
e4240540 WZ	202	/* Encode the instructions when booting */
	203	ftrace_dyn_arch_init_insns();
	204
	205	/* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */
	206	ftrace_modify_code(MCOUNT_ADDR, INSN_NOP);
	207
538f1952 WZ	208	/* The return code is retured via data */
	209	(unsigned long )data = 0;
	210
	211	return 0;
	212	}
68ccf752	213	#endif /* CONFIG_DYNAMIC_FTRACE */
29c5d346 WZ	214
	215	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	216
e17ff5fe WZ	217	#ifdef CONFIG_DYNAMIC_FTRACE
	218
	219	extern void ftrace_graph_call(void);
e17ff5fe WZ	220	#define FTRACE_GRAPH_CALL_IP ((unsigned long)(&ftrace_graph_call))
	221
	222	int ftrace_enable_ftrace_graph_caller(void)
	223	{
	224	return ftrace_modify_code(FTRACE_GRAPH_CALL_IP,
e4240540	225	insn_j_ftrace_graph_caller);
e17ff5fe WZ	226	}
	227
	228	int ftrace_disable_ftrace_graph_caller(void)
	229	{
4d6829f9	230	return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, INSN_NOP);
e17ff5fe WZ	231	}
e17ff5fe WZ	232
68ccf752	233	#endif /* CONFIG_DYNAMIC_FTRACE */
e17ff5fe	234
7326c4e5	235	#ifndef KBUILD_MCOUNT_RA_ADDRESS
68ccf752	236
70342287 RB	237	#define S_RA_SP (0xafbf << 16) /* s{d,w} ra, offset(sp) */
70342287 RB	238	#define S_R_SP (0xafb0 << 16) /* s{d,w} R, offset(sp) */
29c5d346 WZ	239	#define OFFSET_MASK 0xffff /* stack offset range: 0 ~ PT_SIZE */
29c5d346 WZ	240
2816e325 WZ	241	unsigned long ftrace_get_parent_ra_addr(unsigned long self_ra, unsigned long
2816e325 WZ	242	old_parent_ra, unsigned long parent_ra_addr, unsigned long fp)
29c5d346	243	{
2816e325	244	unsigned long sp, ip, tmp;
29c5d346	245	unsigned int code;
046199ca	246	int faulted;
29c5d346	247
68ccf752	248	/*
2816e325	249	* For module, move the ip from the return address after the
9a620a55 WZ	250	* instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for
9a620a55 WZ	251	* kernel, move after the instruction "move ra, at"(offset is 16)
68ccf752	252	*/
2816e325	253	ip = self_ra - (in_kernel_space(self_ra) ? 16 : 24);
29c5d346	254
68ccf752 WZ	255	/*
	256	* search the text until finding the non-store instruction or "s{d,w}
	257	* ra, offset(sp)" instruction
	258	*/
29c5d346	259	do {
046199ca WZ	260	/* get the code at "ip": code = (unsigned int )ip; */
	261	safe_load_code(code, ip, faulted);
	262
	263	if (unlikely(faulted))
	264	return 0;
68ccf752 WZ	265	/*
68ccf752 WZ	266	* If we hit the non-store instruction before finding where the
29c5d346	267	* ra is stored, then this is a leaf function and it does not
68ccf752 WZ	268	* store the ra on the stack
68ccf752 WZ	269	*/
29c5d346	270	if ((code & S_R_SP) != S_R_SP)
2816e325	271	return parent_ra_addr;
29c5d346	272
9a620a55 WZ	273	/* Move to the next instruction */
	274	ip -= 4;
	275	} while ((code & S_RA_SP) != S_RA_SP);
29c5d346 WZ	276
29c5d346 WZ	277	sp = fp + (code & OFFSET_MASK);
046199ca	278
2816e325 WZ	279	/* tmp = (unsigned long )sp; */
2816e325 WZ	280	safe_load_stack(tmp, sp, faulted);
046199ca WZ	281	if (unlikely(faulted))
046199ca WZ	282	return 0;
29c5d346	283
2816e325	284	if (tmp == old_parent_ra)
29c5d346	285	return sp;
29c5d346 WZ	286	return 0;
	287	}
	288
68ccf752	289	#endif /* !KBUILD_MCOUNT_RA_ADDRESS */
7326c4e5	290
29c5d346 WZ	291	/*
	292	* Hook the return address and push it in the stack of return addrs
	293	* in current thread info.
	294	*/
2816e325	295	void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra,
29c5d346 WZ	296	unsigned long fp)
29c5d346 WZ	297	{
2816e325	298	unsigned long old_parent_ra;
29c5d346 WZ	299	struct ftrace_graph_ent trace;
	300	unsigned long return_hooker = (unsigned long)
	301	&return_to_handler;
b9f07eb2	302	int faulted, insns;
29c5d346 WZ	303
	304	if (unlikely(atomic_read(&current->tracing_graph_pause)))
	305	return;
	306
68ccf752	307	/*
2816e325 WZ	308	* "parent_ra_addr" is the stack address saved the return address of
2816e325 WZ	309	* the caller of _mcount.
7326c4e5 WZ	310	*
	311	* if the gcc < 4.5, a leaf function does not save the return address
	312	* in the stack address, so, we "emulate" one in _mcount's stack space,
	313	* and hijack it directly, but for a non-leaf function, it save the
	314	* return address to the its own stack space, we can not hijack it
	315	* directly, but need to find the real stack address,
29c5d346	316	* ftrace_get_parent_addr() does it!
7326c4e5 WZ	317	*
	318	* if gcc>= 4.5, with the new -mmcount-ra-address option, for a
	319	* non-leaf function, the location of the return address will be saved
	320	* to $12 for us, and for a leaf function, only put a zero into $12. we
	321	* do it in ftrace_graph_caller of mcount.S.
29c5d346 WZ	322	*/
29c5d346 WZ	323
2816e325 WZ	324	/* old_parent_ra = parent_ra_addr; /
2816e325 WZ	325	safe_load_stack(old_parent_ra, parent_ra_addr, faulted);
046199ca WZ	326	if (unlikely(faulted))
046199ca WZ	327	goto out;
7326c4e5	328	#ifndef KBUILD_MCOUNT_RA_ADDRESS
2816e325 WZ	329	parent_ra_addr = (unsigned long *)ftrace_get_parent_ra_addr(self_ra,
2816e325 WZ	330	old_parent_ra, (unsigned long)parent_ra_addr, fp);
68ccf752 WZ	331	/*
	332	* If fails when getting the stack address of the non-leaf function's
	333	* ra, stop function graph tracer and return
	334	*/
2816e325	335	if (parent_ra_addr == 0)
046199ca	336	goto out;
7326c4e5	337	#endif
2816e325 WZ	338	/* parent_ra_addr = return_hooker; /
2816e325 WZ	339	safe_store_stack(return_hooker, parent_ra_addr, faulted);
046199ca WZ	340	if (unlikely(faulted))
046199ca WZ	341	goto out;
29c5d346	342
2816e325 WZ	343	if (ftrace_push_return_trace(old_parent_ra, self_ra, &trace.depth, fp)
	344	== -EBUSY) {
	345	*parent_ra_addr = old_parent_ra;
29c5d346 WZ	346	return;
	347	}
	348
b9f07eb2 WZ	349	/*
	350	* Get the recorded ip of the current mcount calling site in the
	351	* __mcount_loc section, which will be used to filter the function
	352	* entries configured through the tracing/set_graph_function interface.
	353	*/
	354
	355	insns = in_kernel_space(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1;
	356	trace.func = self_ra - (MCOUNT_INSN_SIZE * insns);
29c5d346 WZ	357
	358	/* Only trace if the calling function expects to */
	359	if (!ftrace_graph_entry(&trace)) {
	360	current->curr_ret_stack--;
2816e325	361	*parent_ra_addr = old_parent_ra;
29c5d346	362	}
046199ca WZ	363	return;
	364	out:
	365	ftrace_graph_stop();
	366	WARN_ON(1);
29c5d346	367	}
68ccf752	368	#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
19e2e172 RB	369
	370	#ifdef CONFIG_FTRACE_SYSCALLS
	371
	372	#ifdef CONFIG_32BIT
	373	unsigned long __init arch_syscall_addr(int nr)
	374	{
	375	return (unsigned long)sys_call_table[nr - __NR_O32_Linux];
	376	}
	377	#endif
	378
	379	#ifdef CONFIG_64BIT
	380
	381	unsigned long __init arch_syscall_addr(int nr)
	382	{
	383	#ifdef CONFIG_MIPS32_N32
	384	if (nr >= __NR_N32_Linux && nr <= __NR_N32_Linux + __NR_N32_Linux_syscalls)
46e12c07	385	return (unsigned long)sysn32_call_table[nr - __NR_N32_Linux];
19e2e172 RB	386	#endif
	387	if (nr >= __NR_64_Linux && nr <= __NR_64_Linux + __NR_64_Linux_syscalls)
	388	return (unsigned long)sys_call_table[nr - __NR_64_Linux];
	389	#ifdef CONFIG_MIPS32_O32
	390	if (nr >= __NR_O32_Linux && nr <= __NR_O32_Linux + __NR_O32_Linux_syscalls)
	391	return (unsigned long)sys32_call_table[nr - __NR_O32_Linux];
	392	#endif
	393
	394	return (unsigned long) &sys_ni_syscall;
	395	}
	396	#endif
	397
	398	#endif /* CONFIG_FTRACE_SYSCALLS */