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

// SPDX-License-Identifier: GPL-2.0
/*
 * Code for replacing ftrace calls with jumps.
 *
 * Copyright (C) 2007-2008 Steven Rostedt <[email protected]>
 * Copyright (C) 2009, 2010 DSLab, Lanzhou University, China
 * Author: Wu Zhangjin <[email protected]>
 *
 * 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

#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_la_mcount[2] __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;

	/* la v1, _mcount */
	v1 = 3;
	buf = (u32 *)&insn_la_mcount[0];
	UASM_i_LA(&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;
	mm_segment_t old_fs;

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

	if (unlikely(faulted))
		return -EFAULT;

	old_fs = get_fs();
	set_fs(get_ds());
	flush_icache_range(ip, ip + 8);
	set_fs(old_fs);

	return 0;
}

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

	safe_store_code(new_code1, ip, faulted);
	if (unlikely(faulted))
		return -EFAULT;

	ip += 4;
	safe_store_code(new_code2, ip, faulted);
	if (unlikely(faulted))
		return -EFAULT;

	ip -= 4;
	old_fs = get_fs();
	set_fs(get_ds());
	flush_icache_range(ip, ip + 8);
	set_fs(old_fs);

	return 0;
}

static int ftrace_modify_code_2r(unsigned long ip, unsigned int new_code1,
				 unsigned int new_code2)
{
	int faulted;
	mm_segment_t old_fs;

	ip += 4;
	safe_store_code(new_code2, ip, faulted);
	if (unlikely(faulted))
		return -EFAULT;

	ip -= 4;
	safe_store_code(new_code1, ip, faulted);
	if (unlikely(faulted))
		return -EFAULT;

	old_fs = get_fs();
	set_fs(get_ds());
	flush_icache_range(ip, ip + 8);
	set_fs(old_fs);

	return 0;
}
#endif

/*
 * The details about the calling site of mcount on MIPS
 *
 * 1. For kernel:
 *
 * move at, ra
 * jal _mcount		--> nop
 *  sub sp, sp, 8	--> nop  (CONFIG_32BIT)
 *
 * 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 --> nop  (CONFIG_32BIT)
 * 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 --> nop  (CONFIG_32BIT)
 * 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 = core_kernel_text(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 = core_kernel_text(ip) ? insn_jal_ftrace_caller : insn_la_mcount[0];

#ifdef CONFIG_64BIT
	return ftrace_modify_code(ip, new);
#else
	return ftrace_modify_code_2r(ip, new, core_kernel_text(ip) ?
						INSN_NOP : insn_la_mcount[1]);
#endif
}

#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)
{
	/* 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);

	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 - (core_kernel_text(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;
	unsigned long return_hooker = (unsigned long)
	    &return_to_handler;
	int faulted, insns;

	if (unlikely(ftrace_graph_is_dead()))
		return;

	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 == NULL)
		goto out;
#endif
	/* *parent_ra_addr = return_hooker; */
	safe_store_stack(return_hooker, parent_ra_addr, faulted);
	if (unlikely(faulted))
		goto out;

	/*
	 * 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 = core_kernel_text(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1;
	self_ra -= (MCOUNT_INSN_SIZE * insns);

	if (function_graph_enter(old_parent_ra, self_ra, fp, NULL))
		*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
b2441318	1	// SPDX-License-Identifier: GPL-2.0
538f1952 WZ	2	/*
	3	* Code for replacing ftrace calls with jumps.
	4	*
	5	* Copyright (C) 2007-2008 Steven Rostedt <[email protected]>
e4240540	6	* Copyright (C) 2009, 2010 DSLab, Lanzhou University, China
f7a904df	7	* Author: Wu Zhangjin <[email protected]>
538f1952 WZ	8	*
	9	* Thanks goes to Steven Rostedt for writing the original x86 version.
	10	*/
	11
	12	#include <linux/uaccess.h>
	13	#include <linux/init.h>
	14	#include <linux/ftrace.h>
19e2e172	15	#include <linux/syscalls.h>
538f1952	16
29c5d346 WZ	17	#include <asm/asm.h>
29c5d346 WZ	18	#include <asm/asm-offsets.h>
e4240540	19	#include <asm/cacheflush.h>
19e2e172	20	#include <asm/syscall.h>
e4240540	21	#include <asm/uasm.h>
19e2e172	22	#include <asm/unistd.h>
538f1952	23
d9cdb2f1	24	#include <asm-generic/sections.h>
c9f84873	25
49de830a TG	26	#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
	27	#define MCOUNT_OFFSET_INSNS 5
	28	#else
	29	#define MCOUNT_OFFSET_INSNS 4
	30	#endif
	31
cb2f9938 MC	32	#ifdef CONFIG_DYNAMIC_FTRACE
cb2f9938 MC	33
58b69401 AC	34	/* Arch override because MIPS doesn't need to run this from stop_machine() */
	35	void arch_ftrace_update_code(int command)
	36	{
	37	ftrace_modify_all_code(command);
	38	}
	39
cb2f9938 MC	40	#endif
cb2f9938 MC	41
538f1952 WZ	42	#ifdef CONFIG_DYNAMIC_FTRACE
	43
	44	#define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */
	45	#define ADDR_MASK 0x03ffffff /* op_code\|addr : 31...26\|25 ....0 */
c54794d1	46	#define JUMP_RANGE_MASK ((1UL << 28) - 1)
538f1952	47
4d6829f9	48	#define INSN_NOP 0x00000000 /* nop */
e4240540 WZ	49	#define INSN_JAL(addr) \
	50	((unsigned int)(JAL \| (((addr) >> 2) & ADDR_MASK)))
	51
	52	static unsigned int insn_jal_ftrace_caller __read_mostly;
dce0e7d5	53	static unsigned int insn_la_mcount[2] __read_mostly;
e4240540 WZ	54	static unsigned int insn_j_ftrace_graph_caller __maybe_unused __read_mostly;
	55
	56	static inline void ftrace_dyn_arch_init_insns(void)
	57	{
	58	u32 *buf;
	59	unsigned int v1;
	60
dce0e7d5	61	/* la v1, _mcount */
e4240540	62	v1 = 3;
dce0e7d5 PG	63	buf = (u32 *)&insn_la_mcount[0];
dce0e7d5 PG	64	UASM_i_LA(&buf, v1, MCOUNT_ADDR);
e4240540 WZ	65
	66	/* jal (ftrace_caller + 8), jump over the first two instruction */
	67	buf = (u32 *)&insn_jal_ftrace_caller;
c54794d1	68	uasm_i_jal(&buf, (FTRACE_ADDR + 8) & JUMP_RANGE_MASK);
e4240540 WZ	69
	70	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	71	/* j ftrace_graph_caller */
	72	buf = (u32 *)&insn_j_ftrace_graph_caller;
c54794d1	73	uasm_i_j(&buf, (unsigned long)ftrace_graph_caller & JUMP_RANGE_MASK);
e4240540 WZ	74	#endif
e4240540 WZ	75	}
538f1952 WZ	76
	77	static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
	78	{
046199ca	79	int faulted;
6ebda44f	80	mm_segment_t old_fs;
046199ca WZ	81
	82	/* (unsigned int )ip = new_code; */
	83	safe_store_code(new_code, ip, faulted);
	84
	85	if (unlikely(faulted))
	86	return -EFAULT;
538f1952	87
6ebda44f LY	88	old_fs = get_fs();
6ebda44f LY	89	set_fs(get_ds());
538f1952	90	flush_icache_range(ip, ip + 8);
6ebda44f	91	set_fs(old_fs);
538f1952 WZ	92
	93	return 0;
	94	}
	95
58b69401 AC	96	#ifndef CONFIG_64BIT
	97	static int ftrace_modify_code_2(unsigned long ip, unsigned int new_code1,
	98	unsigned int new_code2)
	99	{
	100	int faulted;
dce0e7d5	101	mm_segment_t old_fs;
58b69401 AC	102
	103	safe_store_code(new_code1, ip, faulted);
	104	if (unlikely(faulted))
	105	return -EFAULT;
dce0e7d5 PG	106
	107	ip += 4;
	108	safe_store_code(new_code2, ip, faulted);
58b69401 AC	109	if (unlikely(faulted))
58b69401 AC	110	return -EFAULT;
dce0e7d5 PG	111
	112	ip -= 4;
	113	old_fs = get_fs();
	114	set_fs(get_ds());
a4671094	115	flush_icache_range(ip, ip + 8);
dce0e7d5 PG	116	set_fs(old_fs);
	117
	118	return 0;
	119	}
	120
	121	static int ftrace_modify_code_2r(unsigned long ip, unsigned int new_code1,
	122	unsigned int new_code2)
	123	{
	124	int faulted;
	125	mm_segment_t old_fs;
	126
	127	ip += 4;
	128	safe_store_code(new_code2, ip, faulted);
	129	if (unlikely(faulted))
	130	return -EFAULT;
	131
	132	ip -= 4;
	133	safe_store_code(new_code1, ip, faulted);
	134	if (unlikely(faulted))
	135	return -EFAULT;
	136
	137	old_fs = get_fs();
	138	set_fs(get_ds());
	139	flush_icache_range(ip, ip + 8);
	140	set_fs(old_fs);
	141
58b69401 AC	142	return 0;
	143	}
	144	#endif
	145
7f21a609 WZ	146	/*
	147	* The details about the calling site of mcount on MIPS
	148	*
	149	* 1. For kernel:
	150	*
	151	* move at, ra
	152	* jal _mcount --> nop
dce0e7d5	153	* sub sp, sp, 8 --> nop (CONFIG_32BIT)
7f21a609 WZ	154	*
	155	* 2. For modules:
	156	*
	157	* 2.1 For KBUILD_MCOUNT_RA_ADDRESS and CONFIG_32BIT
	158	*
70342287	159	* lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
dce0e7d5	160	* addiu v1, v1, low_16bit_of_mcount --> nop (CONFIG_32BIT)
7f21a609 WZ	161	* move at, ra
	162	* move $12, ra_address
	163	* jalr v1
	164	* sub sp, sp, 8
70342287	165	* 1: offset = 5 instructions
7f21a609 WZ	166	* 2.2 For the Other situations
7f21a609 WZ	167	*
70342287	168	* lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
dce0e7d5	169	* addiu v1, v1, low_16bit_of_mcount --> nop (CONFIG_32BIT)
7f21a609 WZ	170	* move at, ra
	171	* jalr v1
	172	* nop \| move $12, ra_address \| sub sp, sp, 8
70342287	173	* 1: offset = 4 instructions
7f21a609 WZ	174	*/
7f21a609 WZ	175
7f21a609 WZ	176	#define INSN_B_1F (0x10000000 \| MCOUNT_OFFSET_INSNS)
7f21a609 WZ	177
538f1952 WZ	178	int ftrace_make_nop(struct module *mod,
	179	struct dyn_ftrace *rec, unsigned long addr)
	180	{
	181	unsigned int new;
	182	unsigned long ip = rec->ip;
	183
e4240540	184	/*
d9cdb2f1 WZ	185	* If ip is in kernel space, no long call, otherwise, long call is
d9cdb2f1 WZ	186	* needed.
e4240540	187	*/
87051ec1	188	new = core_kernel_text(ip) ? INSN_NOP : INSN_B_1F;
58b69401	189	#ifdef CONFIG_64BIT
538f1952	190	return ftrace_modify_code(ip, new);
58b69401 AC	191	#else
	192	/*
	193	* On 32 bit MIPS platforms, gcc adds a stack adjust
	194	* instruction in the delay slot after the branch to
	195	* mcount and expects mcount to restore the sp on return.
	196	* This is based on a legacy API and does nothing but
	197	* waste instructions so it's being removed at runtime.
	198	*/
	199	return ftrace_modify_code_2(ip, new, INSN_NOP);
	200	#endif
538f1952 WZ	201	}
538f1952 WZ	202
538f1952 WZ	203	int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
	204	{
	205	unsigned int new;
	206	unsigned long ip = rec->ip;
	207
87051ec1	208	new = core_kernel_text(ip) ? insn_jal_ftrace_caller : insn_la_mcount[0];
538f1952	209
dce0e7d5	210	#ifdef CONFIG_64BIT
538f1952	211	return ftrace_modify_code(ip, new);
dce0e7d5	212	#else
87051ec1	213	return ftrace_modify_code_2r(ip, new, core_kernel_text(ip) ?
dce0e7d5 PG	214	INSN_NOP : insn_la_mcount[1]);
dce0e7d5 PG	215	#endif
538f1952 WZ	216	}
	217
	218	#define FTRACE_CALL_IP ((unsigned long)(&ftrace_call))
	219
	220	int ftrace_update_ftrace_func(ftrace_func_t func)
	221	{
	222	unsigned int new;
	223
4d6829f9	224	new = INSN_JAL((unsigned long)func);
538f1952 WZ	225
	226	return ftrace_modify_code(FTRACE_CALL_IP, new);
	227	}
	228
3a36cb11	229	int __init ftrace_dyn_arch_init(void)
538f1952	230	{
e4240540 WZ	231	/* Encode the instructions when booting */
	232	ftrace_dyn_arch_init_insns();
	233
	234	/* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */
	235	ftrace_modify_code(MCOUNT_ADDR, INSN_NOP);
	236
538f1952 WZ	237	return 0;
538f1952 WZ	238	}
68ccf752	239	#endif /* CONFIG_DYNAMIC_FTRACE */
29c5d346 WZ	240
	241	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	242
e17ff5fe WZ	243	#ifdef CONFIG_DYNAMIC_FTRACE
	244
	245	extern void ftrace_graph_call(void);
e17ff5fe WZ	246	#define FTRACE_GRAPH_CALL_IP ((unsigned long)(&ftrace_graph_call))
	247
	248	int ftrace_enable_ftrace_graph_caller(void)
	249	{
	250	return ftrace_modify_code(FTRACE_GRAPH_CALL_IP,
e4240540	251	insn_j_ftrace_graph_caller);
e17ff5fe WZ	252	}
	253
	254	int ftrace_disable_ftrace_graph_caller(void)
	255	{
4d6829f9	256	return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, INSN_NOP);
e17ff5fe WZ	257	}
e17ff5fe WZ	258
68ccf752	259	#endif /* CONFIG_DYNAMIC_FTRACE */
e17ff5fe	260
7326c4e5	261	#ifndef KBUILD_MCOUNT_RA_ADDRESS
68ccf752	262
70342287 RB	263	#define S_RA_SP (0xafbf << 16) /* s{d,w} ra, offset(sp) */
70342287 RB	264	#define S_R_SP (0xafb0 << 16) /* s{d,w} R, offset(sp) */
29c5d346 WZ	265	#define OFFSET_MASK 0xffff /* stack offset range: 0 ~ PT_SIZE */
29c5d346 WZ	266
2816e325 WZ	267	unsigned long ftrace_get_parent_ra_addr(unsigned long self_ra, unsigned long
2816e325 WZ	268	old_parent_ra, unsigned long parent_ra_addr, unsigned long fp)
29c5d346	269	{
2816e325	270	unsigned long sp, ip, tmp;
29c5d346	271	unsigned int code;
046199ca	272	int faulted;
29c5d346	273
68ccf752	274	/*
2816e325	275	* For module, move the ip from the return address after the
9a620a55 WZ	276	* instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for
9a620a55 WZ	277	* kernel, move after the instruction "move ra, at"(offset is 16)
68ccf752	278	*/
87051ec1	279	ip = self_ra - (core_kernel_text(self_ra) ? 16 : 24);
29c5d346	280
68ccf752 WZ	281	/*
	282	* search the text until finding the non-store instruction or "s{d,w}
	283	* ra, offset(sp)" instruction
	284	*/
29c5d346	285	do {
046199ca WZ	286	/* get the code at "ip": code = (unsigned int )ip; */
	287	safe_load_code(code, ip, faulted);
	288
	289	if (unlikely(faulted))
	290	return 0;
68ccf752 WZ	291	/*
68ccf752 WZ	292	* If we hit the non-store instruction before finding where the
29c5d346	293	* ra is stored, then this is a leaf function and it does not
68ccf752 WZ	294	* store the ra on the stack
68ccf752 WZ	295	*/
29c5d346	296	if ((code & S_R_SP) != S_R_SP)
2816e325	297	return parent_ra_addr;
29c5d346	298
9a620a55 WZ	299	/* Move to the next instruction */
	300	ip -= 4;
	301	} while ((code & S_RA_SP) != S_RA_SP);
29c5d346 WZ	302
29c5d346 WZ	303	sp = fp + (code & OFFSET_MASK);
046199ca	304
2816e325 WZ	305	/* tmp = (unsigned long )sp; */
2816e325 WZ	306	safe_load_stack(tmp, sp, faulted);
046199ca WZ	307	if (unlikely(faulted))
046199ca WZ	308	return 0;
29c5d346	309
2816e325	310	if (tmp == old_parent_ra)
29c5d346	311	return sp;
29c5d346 WZ	312	return 0;
	313	}
	314
68ccf752	315	#endif /* !KBUILD_MCOUNT_RA_ADDRESS */
7326c4e5	316
29c5d346 WZ	317	/*
	318	* Hook the return address and push it in the stack of return addrs
	319	* in current thread info.
	320	*/
2816e325	321	void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra,
29c5d346 WZ	322	unsigned long fp)
29c5d346 WZ	323	{
2816e325	324	unsigned long old_parent_ra;
29c5d346 WZ	325	unsigned long return_hooker = (unsigned long)
29c5d346 WZ	326	&return_to_handler;
b9f07eb2	327	int faulted, insns;
29c5d346	328
6a8a5051 SRRH	329	if (unlikely(ftrace_graph_is_dead()))
	330	return;
	331
29c5d346 WZ	332	if (unlikely(atomic_read(&current->tracing_graph_pause)))
	333	return;
	334
68ccf752	335	/*
2816e325 WZ	336	* "parent_ra_addr" is the stack address saved the return address of
2816e325 WZ	337	* the caller of _mcount.
7326c4e5 WZ	338	*
	339	* if the gcc < 4.5, a leaf function does not save the return address
	340	* in the stack address, so, we "emulate" one in _mcount's stack space,
	341	* and hijack it directly, but for a non-leaf function, it save the
	342	* return address to the its own stack space, we can not hijack it
	343	* directly, but need to find the real stack address,
29c5d346	344	* ftrace_get_parent_addr() does it!
7326c4e5 WZ	345	*
	346	* if gcc>= 4.5, with the new -mmcount-ra-address option, for a
	347	* non-leaf function, the location of the return address will be saved
	348	* to $12 for us, and for a leaf function, only put a zero into $12. we
	349	* do it in ftrace_graph_caller of mcount.S.
29c5d346 WZ	350	*/
29c5d346 WZ	351
2816e325 WZ	352	/* old_parent_ra = parent_ra_addr; /
2816e325 WZ	353	safe_load_stack(old_parent_ra, parent_ra_addr, faulted);
046199ca WZ	354	if (unlikely(faulted))
046199ca WZ	355	goto out;
7326c4e5	356	#ifndef KBUILD_MCOUNT_RA_ADDRESS
2816e325 WZ	357	parent_ra_addr = (unsigned long *)ftrace_get_parent_ra_addr(self_ra,
2816e325 WZ	358	old_parent_ra, (unsigned long)parent_ra_addr, fp);
68ccf752 WZ	359	/*
	360	* If fails when getting the stack address of the non-leaf function's
	361	* ra, stop function graph tracer and return
	362	*/
83aa53eb	363	if (parent_ra_addr == NULL)
046199ca	364	goto out;
7326c4e5	365	#endif
2816e325 WZ	366	/* parent_ra_addr = return_hooker; /
2816e325 WZ	367	safe_store_stack(return_hooker, parent_ra_addr, faulted);
046199ca WZ	368	if (unlikely(faulted))
046199ca WZ	369	goto out;
29c5d346	370
b9f07eb2 WZ	371	/*
	372	* Get the recorded ip of the current mcount calling site in the
	373	* __mcount_loc section, which will be used to filter the function
	374	* entries configured through the tracing/set_graph_function interface.
	375	*/
	376
87051ec1	377	insns = core_kernel_text(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1;
8712b27c	378	self_ra -= (MCOUNT_INSN_SIZE * insns);
29c5d346	379
8712b27c	380	if (function_graph_enter(old_parent_ra, self_ra, fp, NULL))
2816e325	381	*parent_ra_addr = old_parent_ra;
046199ca WZ	382	return;
	383	out:
	384	ftrace_graph_stop();
	385	WARN_ON(1);
29c5d346	386	}
68ccf752	387	#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
19e2e172 RB	388
	389	#ifdef CONFIG_FTRACE_SYSCALLS
	390
	391	#ifdef CONFIG_32BIT
	392	unsigned long __init arch_syscall_addr(int nr)
	393	{
	394	return (unsigned long)sys_call_table[nr - __NR_O32_Linux];
	395	}
	396	#endif
	397
	398	#ifdef CONFIG_64BIT
	399
	400	unsigned long __init arch_syscall_addr(int nr)
	401	{
	402	#ifdef CONFIG_MIPS32_N32
	403	if (nr >= __NR_N32_Linux && nr <= __NR_N32_Linux + __NR_N32_Linux_syscalls)
46e12c07	404	return (unsigned long)sysn32_call_table[nr - __NR_N32_Linux];
19e2e172 RB	405	#endif
	406	if (nr >= __NR_64_Linux && nr <= __NR_64_Linux + __NR_64_Linux_syscalls)
	407	return (unsigned long)sys_call_table[nr - __NR_64_Linux];
	408	#ifdef CONFIG_MIPS32_O32
	409	if (nr >= __NR_O32_Linux && nr <= __NR_O32_Linux + __NR_O32_Linux_syscalls)
	410	return (unsigned long)sys32_call_table[nr - __NR_O32_Linux];
	411	#endif
	412
	413	return (unsigned long) &sys_ni_syscall;
	414	}
	415	#endif
	416
	417	#endif /* CONFIG_FTRACE_SYSCALLS */