[net-next-2.6.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 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/cacheflush.h>
#include <asm/asm.h>
#include <asm/asm-offsets.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_insn_encode(op_code, addr) \
	((unsigned int)((op_code) | (((addr) >> 2) & ADDR_MASK)))

static unsigned int ftrace_nop = 0x00000000;

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;
}

static int lui_v1;
static int jal_mcount;

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

	/* We have compiled module with -mlong-calls, but compiled the kernel
	 * without it, we need to cope with them respectively. */
	if (ip & 0x40000000) {
		/* record it for ftrace_make_call */
		if (lui_v1 == 0) {
			/* lui_v1 = *(unsigned int *)ip; */
			safe_load_code(lui_v1, ip, faulted);

			if (unlikely(faulted))
				return -EFAULT;
		}

#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(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
		 */
		new = 0x10000005;
#else
		/* 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
		 */
		new = 0x10000004;
#endif
	} else {
		/* record/calculate it for ftrace_make_call */
		if (jal_mcount == 0) {
			/* We can record it directly like this:
			 *     jal_mcount = *(unsigned int *)ip;
			 * Herein, jump over the first two nop instructions */
			jal_mcount = jump_insn_encode(JAL, (MCOUNT_ADDR + 8));
		}

		/* move at, ra
		 * jalr v1		--> nop
		 */
		new = ftrace_nop;
	}
	return ftrace_modify_code(ip, new);
}

static int modified;	/* initialized as 0 by default */

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

	/* We just need to remove the "b ftrace_stub" at the fist time! */
	if (modified == 0) {
		modified = 1;
		ftrace_modify_code(addr, ftrace_nop);
	}
	/* ip, module: 0xc0000000, kernel: 0x80000000 */
	new = (ip & 0x40000000) ? lui_v1 : jal_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 = jump_insn_encode(JAL, (unsigned long)func);

	return ftrace_modify_code(FTRACE_CALL_IP, new);
}

int __init ftrace_dyn_arch_init(void *data)
{
	/* 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 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 */

#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_addr(unsigned long self_addr,
				     unsigned long parent,
				     unsigned long parent_addr,
				     unsigned long fp)
{
	unsigned long sp, ip, ra;
	unsigned int code;
	int faulted;

	/* in module or kernel? */
	if (self_addr & 0x40000000) {
		/* module: move to the instruction "lui v1, HI_16BIT_OF_MCOUNT" */
		ip = self_addr - 20;
	} else {
		/* kernel: move to the instruction "move ra, at" */
		ip = self_addr - 12;
	}

	/* search the text until finding the non-store instruction or "s{d,w}
	 * ra, offset(sp)" instruction */
	do {
		ip -= 4;

		/* 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_addr;

	} while (((code & S_RA_SP) != S_RA_SP));

	sp = fp + (code & OFFSET_MASK);

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

	if (ra == parent)
		return sp;
	return 0;
}

#endif

/*
 * Hook the return address and push it in the stack of return addrs
 * in current thread info.
 */
void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
			   unsigned long fp)
{
	unsigned long old;
	struct ftrace_graph_ent trace;
	unsigned long return_hooker = (unsigned long)
	    &return_to_handler;
	int faulted;

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

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

	if (ftrace_push_return_trace(old, self_addr, &trace.depth, fp) ==
	    -EBUSY) {
		*parent = old;
		return;
	}

	trace.func = self_addr;

	/* Only trace if the calling function expects to */
	if (!ftrace_graph_entry(&trace)) {
		current->curr_ret_stack--;
		*parent = old;
	}
	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>
	5	* Copyright (C) 2009 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
	15	#include <asm/cacheflush.h>
29c5d346 WZ	16	#include <asm/asm.h>
29c5d346 WZ	17	#include <asm/asm-offsets.h>
538f1952 WZ	18
	19	#ifdef CONFIG_DYNAMIC_FTRACE
	20
	21	#define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */
	22	#define ADDR_MASK 0x03ffffff /* op_code\|addr : 31...26\|25 ....0 */
	23	#define jump_insn_encode(op_code, addr) \
	24	((unsigned int)((op_code) \| (((addr) >> 2) & ADDR_MASK)))
	25
	26	static unsigned int ftrace_nop = 0x00000000;
	27
	28	static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
	29	{
046199ca WZ	30	int faulted;
	31
	32	/* (unsigned int )ip = new_code; */
	33	safe_store_code(new_code, ip, faulted);
	34
	35	if (unlikely(faulted))
	36	return -EFAULT;
538f1952 WZ	37
	38	flush_icache_range(ip, ip + 8);
	39
	40	return 0;
	41	}
	42
	43	static int lui_v1;
	44	static int jal_mcount;
	45
	46	int ftrace_make_nop(struct module *mod,
	47	struct dyn_ftrace *rec, unsigned long addr)
	48	{
	49	unsigned int new;
046199ca	50	int faulted;
538f1952 WZ	51	unsigned long ip = rec->ip;
	52
	53	/* We have compiled module with -mlong-calls, but compiled the kernel
	54	* without it, we need to cope with them respectively. */
	55	if (ip & 0x40000000) {
	56	/* record it for ftrace_make_call */
046199ca WZ	57	if (lui_v1 == 0) {
	58	/* lui_v1 = (unsigned int )ip; */
	59	safe_load_code(lui_v1, ip, faulted);
	60
	61	if (unlikely(faulted))
	62	return -EFAULT;
	63	}
538f1952	64
3a2af2dc WZ	65	#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
	66	/* lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
	67	* addiu v1, v1, low_16bit_of_mcount
	68	* move at, ra
	69	* move $12, ra_address
	70	* jalr v1
	71	* sub sp, sp, 8
	72	* 1: offset = 5 instructions
	73	*/
	74	new = 0x10000005;
	75	#else
538f1952 WZ	76	/* lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
	77	* addiu v1, v1, low_16bit_of_mcount
	78	* move at, ra
	79	* jalr v1
3a2af2dc WZ	80	* nop \| move $12, ra_address \| sub sp, sp, 8
3a2af2dc WZ	81	* 1: offset = 4 instructions
538f1952 WZ	82	*/
538f1952 WZ	83	new = 0x10000004;
3a2af2dc	84	#endif
538f1952 WZ	85	} else {
	86	/* record/calculate it for ftrace_make_call */
	87	if (jal_mcount == 0) {
	88	/* We can record it directly like this:
	89	* jal_mcount = (unsigned int )ip;
	90	* Herein, jump over the first two nop instructions */
	91	jal_mcount = jump_insn_encode(JAL, (MCOUNT_ADDR + 8));
	92	}
	93
	94	/* move at, ra
	95	* jalr v1 --> nop
	96	*/
	97	new = ftrace_nop;
	98	}
	99	return ftrace_modify_code(ip, new);
	100	}
	101
	102	static int modified; /* initialized as 0 by default */
	103
	104	int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
	105	{
	106	unsigned int new;
	107	unsigned long ip = rec->ip;
	108
	109	/* We just need to remove the "b ftrace_stub" at the fist time! */
	110	if (modified == 0) {
	111	modified = 1;
	112	ftrace_modify_code(addr, ftrace_nop);
	113	}
	114	/* ip, module: 0xc0000000, kernel: 0x80000000 */
	115	new = (ip & 0x40000000) ? lui_v1 : jal_mcount;
	116
	117	return ftrace_modify_code(ip, new);
	118	}
	119
	120	#define FTRACE_CALL_IP ((unsigned long)(&ftrace_call))
	121
	122	int ftrace_update_ftrace_func(ftrace_func_t func)
	123	{
	124	unsigned int new;
	125
	126	new = jump_insn_encode(JAL, (unsigned long)func);
	127
	128	return ftrace_modify_code(FTRACE_CALL_IP, new);
	129	}
	130
	131	int __init ftrace_dyn_arch_init(void *data)
	132	{
	133	/* The return code is retured via data */
	134	(unsigned long )data = 0;
	135
	136	return 0;
	137	}
	138	#endif /* CONFIG_DYNAMIC_FTRACE */
29c5d346 WZ	139
	140	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	141
e17ff5fe WZ	142	#ifdef CONFIG_DYNAMIC_FTRACE
	143
	144	extern void ftrace_graph_call(void);
	145	#define JMP 0x08000000 /* jump to target directly */
	146	#define CALL_FTRACE_GRAPH_CALLER \
	147	jump_insn_encode(JMP, (unsigned long)(&ftrace_graph_caller))
	148	#define FTRACE_GRAPH_CALL_IP ((unsigned long)(&ftrace_graph_call))
	149
	150	int ftrace_enable_ftrace_graph_caller(void)
	151	{
	152	return ftrace_modify_code(FTRACE_GRAPH_CALL_IP,
	153	CALL_FTRACE_GRAPH_CALLER);
	154	}
	155
	156	int ftrace_disable_ftrace_graph_caller(void)
	157	{
	158	return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, ftrace_nop);
	159	}
	160
	161	#endif /* !CONFIG_DYNAMIC_FTRACE */
	162
7326c4e5	163	#ifndef KBUILD_MCOUNT_RA_ADDRESS
29c5d346 WZ	164	#define S_RA_SP (0xafbf << 16) /* s{d,w} ra, offset(sp) */
	165	#define S_R_SP (0xafb0 << 16) /* s{d,w} R, offset(sp) */
	166	#define OFFSET_MASK 0xffff /* stack offset range: 0 ~ PT_SIZE */
	167
	168	unsigned long ftrace_get_parent_addr(unsigned long self_addr,
	169	unsigned long parent,
	170	unsigned long parent_addr,
	171	unsigned long fp)
	172	{
	173	unsigned long sp, ip, ra;
	174	unsigned int code;
046199ca	175	int faulted;
29c5d346 WZ	176
	177	/* in module or kernel? */
	178	if (self_addr & 0x40000000) {
	179	/* module: move to the instruction "lui v1, HI_16BIT_OF_MCOUNT" */
	180	ip = self_addr - 20;
	181	} else {
	182	/* kernel: move to the instruction "move ra, at" */
	183	ip = self_addr - 12;
	184	}
	185
	186	/* search the text until finding the non-store instruction or "s{d,w}
	187	* ra, offset(sp)" instruction */
	188	do {
	189	ip -= 4;
	190
046199ca WZ	191	/* get the code at "ip": code = (unsigned int )ip; */
	192	safe_load_code(code, ip, faulted);
	193
	194	if (unlikely(faulted))
	195	return 0;
29c5d346 WZ	196
	197	/* If we hit the non-store instruction before finding where the
	198	* ra is stored, then this is a leaf function and it does not
	199	* store the ra on the stack. */
	200	if ((code & S_R_SP) != S_R_SP)
	201	return parent_addr;
	202
	203	} while (((code & S_RA_SP) != S_RA_SP));
	204
	205	sp = fp + (code & OFFSET_MASK);
046199ca WZ	206
	207	/* ra = (unsigned long )sp; */
	208	safe_load_stack(ra, sp, faulted);
	209	if (unlikely(faulted))
	210	return 0;
29c5d346 WZ	211
	212	if (ra == parent)
	213	return sp;
29c5d346 WZ	214	return 0;
	215	}
	216
7326c4e5 WZ	217	#endif
7326c4e5 WZ	218
29c5d346 WZ	219	/*
	220	* Hook the return address and push it in the stack of return addrs
	221	* in current thread info.
	222	*/
	223	void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
	224	unsigned long fp)
	225	{
	226	unsigned long old;
	227	struct ftrace_graph_ent trace;
	228	unsigned long return_hooker = (unsigned long)
	229	&return_to_handler;
046199ca	230	int faulted;
29c5d346 WZ	231
	232	if (unlikely(atomic_read(&current->tracing_graph_pause)))
	233	return;
	234
	235	/* "parent" is the stack address saved the return address of the caller
7326c4e5 WZ	236	* of _mcount.
	237	*
	238	* if the gcc < 4.5, a leaf function does not save the return address
	239	* in the stack address, so, we "emulate" one in _mcount's stack space,
	240	* and hijack it directly, but for a non-leaf function, it save the
	241	* return address to the its own stack space, we can not hijack it
	242	* directly, but need to find the real stack address,
29c5d346	243	* ftrace_get_parent_addr() does it!
7326c4e5 WZ	244	*
	245	* if gcc>= 4.5, with the new -mmcount-ra-address option, for a
	246	* non-leaf function, the location of the return address will be saved
	247	* to $12 for us, and for a leaf function, only put a zero into $12. we
	248	* do it in ftrace_graph_caller of mcount.S.
29c5d346 WZ	249	*/
29c5d346 WZ	250
046199ca WZ	251	/* old = parent; /
	252	safe_load_stack(old, parent, faulted);
	253	if (unlikely(faulted))
	254	goto out;
7326c4e5	255	#ifndef KBUILD_MCOUNT_RA_ADDRESS
29c5d346 WZ	256	parent = (unsigned long *)ftrace_get_parent_addr(self_addr, old,
	257	(unsigned long)parent,
	258	fp);
29c5d346 WZ	259	/* If fails when getting the stack address of the non-leaf function's
29c5d346 WZ	260	* ra, stop function graph tracer and return */
046199ca WZ	261	if (parent == 0)
046199ca WZ	262	goto out;
7326c4e5	263	#endif
046199ca WZ	264	/* parent = return_hooker; /
	265	safe_store_stack(return_hooker, parent, faulted);
	266	if (unlikely(faulted))
	267	goto out;
29c5d346 WZ	268
	269	if (ftrace_push_return_trace(old, self_addr, &trace.depth, fp) ==
	270	-EBUSY) {
	271	*parent = old;
	272	return;
	273	}
	274
	275	trace.func = self_addr;
	276
	277	/* Only trace if the calling function expects to */
	278	if (!ftrace_graph_entry(&trace)) {
	279	current->curr_ret_stack--;
	280	*parent = old;
	281	}
046199ca WZ	282	return;
	283	out:
	284	ftrace_graph_stop();
	285	WARN_ON(1);
29c5d346 WZ	286	}
29c5d346 WZ	287	#endif /* CONFIG_FUNCTION_GRAPH_TRACER */