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

/*
 * Ftrace support for Microblaze.
 *
 * Copyright (C) 2009 Michal Simek <monstr@monstr.eu>
 * Copyright (C) 2009 PetaLogix
 *
 * Based on MIPS and PowerPC ftrace code
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License. See the file "COPYING" in the main directory of this archive
 * for more details.
 */

#include <asm/cacheflush.h>
#include <linux/ftrace.h>

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/*
 * 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 old;
	int faulted, err;
	struct ftrace_graph_ent trace;
	unsigned long return_hooker = (unsigned long)
				&return_to_handler;

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

	/*
	 * Protect against fault, even if it shouldn't
	 * happen. This tool is too much intrusive to
	 * ignore such a protection.
	 */
	asm volatile("	1:	lwi	%0, %2, 0;		\
			2:	swi	%3, %2, 0;		\
				addik	%1, r0, 0;		\
			3:					\
				.section .fixup, \"ax\";	\
			4:	brid	3b;			\
				addik	%1, r0, 1;		\
				.previous;			\
				.section __ex_table,\"a\";	\
				.word	1b,4b;			\
				.word	2b,4b;			\
				.previous;"			\
			: "=&r" (old), "=r" (faulted)
			: "r" (parent), "r" (return_hooker)
	);

	if (unlikely(faulted)) {
		ftrace_graph_stop();
		WARN_ON(1);
		return;
	}

	err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0);
	if (err == -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;
	}
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

#ifdef CONFIG_DYNAMIC_FTRACE
/* save value to addr - it is save to do it in asm */
static int ftrace_modify_code(unsigned long addr, unsigned int value)
{
	int faulted = 0;

	__asm__ __volatile__("	1:	swi	%2, %1, 0;		\
					addik	%0, r0, 0;		\
				2:					\
					.section .fixup, \"ax\";	\
				3:	brid	2b;			\
					addik	%0, r0, 1;		\
					.previous;			\
					.section __ex_table,\"a\";	\
					.word	1b,3b;			\
					.previous;"			\
				: "=r" (faulted)
				: "r" (addr), "r" (value)
	);

	if (unlikely(faulted))
		return -EFAULT;

	return 0;
}

#define MICROBLAZE_NOP 0x80000000
#define MICROBLAZE_BRI 0xb800000C

static unsigned int recorded; /* if save was or not */
static unsigned int imm; /* saving whole imm instruction */

/* There are two approaches howto solve ftrace_make nop function - look below */
#undef USE_FTRACE_NOP

#ifdef USE_FTRACE_NOP
static unsigned int bralid; /* saving whole bralid instruction */
#endif

int ftrace_make_nop(struct module *mod,
			struct dyn_ftrace *rec, unsigned long addr)
{
	/* we have this part of code which we are working with
	 * b000c000        imm     -16384
	 * b9fc8e30        bralid  r15, -29136     // c0008e30 <_mcount>
	 * 80000000        or      r0, r0, r0
	 *
	 * The first solution (!USE_FTRACE_NOP-could be called branch solution)
	 * b000c000        bri	12 (0xC - jump to any other instruction)
	 * b9fc8e30        bralid  r15, -29136     // c0008e30 <_mcount>
	 * 80000000        or      r0, r0, r0
	 * any other instruction
	 *
	 * The second solution (USE_FTRACE_NOP) - no jump just nops
	 * 80000000        or      r0, r0, r0
	 * 80000000        or      r0, r0, r0
	 * 80000000        or      r0, r0, r0
	 */
	int ret = 0;

	if (recorded == 0) {
		recorded = 1;
		imm = *(unsigned int *)rec->ip;
		pr_debug("%s: imm:0x%x\n", __func__, imm);
#ifdef USE_FTRACE_NOP
		bralid = *(unsigned int *)(rec->ip + 4);
		pr_debug("%s: bralid 0x%x\n", __func__, bralid);
#endif /* USE_FTRACE_NOP */
	}

#ifdef USE_FTRACE_NOP
	ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP);
	ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP);
#else /* USE_FTRACE_NOP */
	ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI);
#endif /* USE_FTRACE_NOP */
	return ret;
}

/* I believe that first is called ftrace_make_nop before this function */
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
	int ret;
	pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n",
		__func__, (unsigned int)addr, (unsigned int)rec->ip, imm);
	ret = ftrace_modify_code(rec->ip, imm);
#ifdef USE_FTRACE_NOP
	pr_debug("%s: bralid:0x%x\n", __func__, bralid);
	ret += ftrace_modify_code(rec->ip + 4, bralid);
#endif /* USE_FTRACE_NOP */
	return ret;
}

int __init ftrace_dyn_arch_init(void *data)
{
	/* The return code is retured via data */
	*(unsigned long *)data = 0;

	return 0;
}

int ftrace_update_ftrace_func(ftrace_func_t func)
{
	unsigned long ip = (unsigned long)(&ftrace_call);
	unsigned int upper = (unsigned int)func;
	unsigned int lower = (unsigned int)func;
	int ret = 0;

	/* create proper saving to ftrace_call poll */
	upper = 0xb0000000 + (upper >> 16); /* imm func_upper */
	lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */

	pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n",
		__func__, (unsigned int)func, (unsigned int)ip, upper, lower);

	/* save upper and lower code */
	ret = ftrace_modify_code(ip, upper);
	ret += ftrace_modify_code(ip + 4, lower);

	/* We just need to replace the rtsd r15, 8 with NOP */
	ret += ftrace_modify_code((unsigned long)&ftrace_caller,
				  MICROBLAZE_NOP);

	/* All changes are done - lets do caches consistent */
	flush_icache();
	return ret;
}

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
unsigned int old_jump; /* saving place for jump instruction */

int ftrace_enable_ftrace_graph_caller(void)
{
	unsigned int ret;
	unsigned long ip = (unsigned long)(&ftrace_call_graph);

	old_jump = *(unsigned int *)ip; /* save jump over instruction */
	ret = ftrace_modify_code(ip, MICROBLAZE_NOP);
	flush_icache();

	pr_debug("%s: Replace instruction: 0x%x\n", __func__, old_jump);
	return ret;
}

int ftrace_disable_ftrace_graph_caller(void)
{
	unsigned int ret;
	unsigned long ip = (unsigned long)(&ftrace_call_graph);

	ret = ftrace_modify_code(ip, old_jump);
	flush_icache();

	pr_debug("%s\n", __func__);
	return ret;
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
#endif /* CONFIG_DYNAMIC_FTRACE */
Commit	Line	Data
7d241ff0 MS	1	/*
	2	* Ftrace support for Microblaze.
	3	*
	4	* Copyright (C) 2009 Michal Simek <monstr@monstr.eu>
	5	* Copyright (C) 2009 PetaLogix
	6	*
	7	* Based on MIPS and PowerPC ftrace code
	8	*
	9	* This file is subject to the terms and conditions of the GNU General Public
	10	* License. See the file "COPYING" in the main directory of this archive
	11	* for more details.
	12	*/
	13
	14	#include <asm/cacheflush.h>
	15	#include <linux/ftrace.h>
	16
a0d3e665 MS	17	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	18	/*
	19	* Hook the return address and push it in the stack of return addrs
	20	* in current thread info.
	21	*/
	22	void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
	23	{
	24	unsigned long old;
	25	int faulted, err;
	26	struct ftrace_graph_ent trace;
	27	unsigned long return_hooker = (unsigned long)
	28	&return_to_handler;
	29
	30	if (unlikely(atomic_read(&current->tracing_graph_pause)))
	31	return;
	32
	33	/*
	34	* Protect against fault, even if it shouldn't
	35	* happen. This tool is too much intrusive to
	36	* ignore such a protection.
	37	*/
	38	asm volatile(" 1: lwi %0, %2, 0; \
	39	2: swi %3, %2, 0; \
	40	addik %1, r0, 0; \
	41	3: \
	42	.section .fixup, \"ax\"; \
	43	4: brid 3b; \
	44	addik %1, r0, 1; \
	45	.previous; \
	46	.section __ex_table,\"a\"; \
	47	.word 1b,4b; \
	48	.word 2b,4b; \
	49	.previous;" \
	50	: "=&r" (old), "=r" (faulted)
	51	: "r" (parent), "r" (return_hooker)
	52	);
	53
	54	if (unlikely(faulted)) {
	55	ftrace_graph_stop();
	56	WARN_ON(1);
	57	return;
	58	}
	59
	60	err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0);
	61	if (err == -EBUSY) {
	62	*parent = old;
	63	return;
	64	}
	65
	66	trace.func = self_addr;
	67	/* Only trace if the calling function expects to */
	68	if (!ftrace_graph_entry(&trace)) {
	69	current->curr_ret_stack--;
	70	*parent = old;
	71	}
	72	}
	73	#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
	74
7d241ff0 MS	75	#ifdef CONFIG_DYNAMIC_FTRACE
	76	/* save value to addr - it is save to do it in asm */
	77	static int ftrace_modify_code(unsigned long addr, unsigned int value)
	78	{
	79	int faulted = 0;
	80
	81	__asm__ __volatile__(" 1: swi %2, %1, 0; \
	82	addik %0, r0, 0; \
	83	2: \
	84	.section .fixup, \"ax\"; \
	85	3: brid 2b; \
	86	addik %0, r0, 1; \
	87	.previous; \
	88	.section __ex_table,\"a\"; \
	89	.word 1b,3b; \
	90	.previous;" \
	91	: "=r" (faulted)
	92	: "r" (addr), "r" (value)
	93	);
	94
	95	if (unlikely(faulted))
	96	return -EFAULT;
	97
	98	return 0;
	99	}
	100
	101	#define MICROBLAZE_NOP 0x80000000
	102	#define MICROBLAZE_BRI 0xb800000C
	103
	104	static unsigned int recorded; /* if save was or not */
	105	static unsigned int imm; /* saving whole imm instruction */
	106
	107	/* There are two approaches howto solve ftrace_make nop function - look below */
	108	#undef USE_FTRACE_NOP
	109
	110	#ifdef USE_FTRACE_NOP
	111	static unsigned int bralid; /* saving whole bralid instruction */
	112	#endif
	113
	114	int ftrace_make_nop(struct module *mod,
	115	struct dyn_ftrace *rec, unsigned long addr)
	116	{
	117	/* we have this part of code which we are working with
	118	* b000c000 imm -16384
	119	* b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
	120	* 80000000 or r0, r0, r0
	121	*
	122	* The first solution (!USE_FTRACE_NOP-could be called branch solution)
	123	* b000c000 bri 12 (0xC - jump to any other instruction)
	124	* b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
	125	* 80000000 or r0, r0, r0
	126	* any other instruction
	127	*
	128	* The second solution (USE_FTRACE_NOP) - no jump just nops
	129	* 80000000 or r0, r0, r0
	130	* 80000000 or r0, r0, r0
	131	* 80000000 or r0, r0, r0
	132	*/
	133	int ret = 0;
	134
	135	if (recorded == 0) {
	136	recorded = 1;
	137	imm = (unsigned int )rec->ip;
	138	pr_debug("%s: imm:0x%x\n", __func__, imm);
139	#ifdef USE_FTRACE_NOP
140	bralid = (unsigned int )(rec->ip + 4);
141	pr_debug("%s: bralid 0x%x\n", __func__, bralid);
142	#endif /* USE_FTRACE_NOP */
143	}
144
145	#ifdef USE_FTRACE_NOP
146	ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP);
147	ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP);
148	#else /* USE_FTRACE_NOP */
149	ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI);
150	#endif /* USE_FTRACE_NOP */
151	return ret;
152	}
153
7d241ff0 MS	154	/* I believe that first is called ftrace_make_nop before this function */
	155	int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
	156	{
	157	int ret;
7d241ff0 MS	158	pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n",
	159	__func__, (unsigned int)addr, (unsigned int)rec->ip, imm);
	160	ret = ftrace_modify_code(rec->ip, imm);
	161	#ifdef USE_FTRACE_NOP
	162	pr_debug("%s: bralid:0x%x\n", __func__, bralid);
	163	ret += ftrace_modify_code(rec->ip + 4, bralid);
	164	#endif /* USE_FTRACE_NOP */
	165	return ret;
	166	}
	167
	168	int __init ftrace_dyn_arch_init(void *data)
	169	{
	170	/* The return code is retured via data */
	171	(unsigned long )data = 0;
	172
	173	return 0;
	174	}
	175
	176	int ftrace_update_ftrace_func(ftrace_func_t func)
	177	{
	178	unsigned long ip = (unsigned long)(&ftrace_call);
	179	unsigned int upper = (unsigned int)func;
	180	unsigned int lower = (unsigned int)func;
	181	int ret = 0;
	182
	183	/* create proper saving to ftrace_call poll */
	184	upper = 0xb0000000 + (upper >> 16); /* imm func_upper */
	185	lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */
	186
	187	pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n",
	188	__func__, (unsigned int)func, (unsigned int)ip, upper, lower);
	189
	190	/* save upper and lower code */
	191	ret = ftrace_modify_code(ip, upper);
	192	ret += ftrace_modify_code(ip + 4, lower);
	193
d2bf98e6 SM	194	/* We just need to replace the rtsd r15, 8 with NOP */
	195	ret += ftrace_modify_code((unsigned long)&ftrace_caller,
	196	MICROBLAZE_NOP);
7d241ff0 MS	197
	198	/* All changes are done - lets do caches consistent */
	199	flush_icache();
	200	return ret;
	201	}
	202
4f911b0d MS	203	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	204	unsigned int old_jump; /* saving place for jump instruction */
	205
	206	int ftrace_enable_ftrace_graph_caller(void)
	207	{
	208	unsigned int ret;
	209	unsigned long ip = (unsigned long)(&ftrace_call_graph);
	210
	211	old_jump = (unsigned int )ip; /* save jump over instruction */
	212	ret = ftrace_modify_code(ip, MICROBLAZE_NOP);
	213	flush_icache();
	214
	215	pr_debug("%s: Replace instruction: 0x%x\n", __func__, old_jump);
	216	return ret;
	217	}
	218
	219	int ftrace_disable_ftrace_graph_caller(void)
	220	{
	221	unsigned int ret;
	222	unsigned long ip = (unsigned long)(&ftrace_call_graph);
	223
	224	ret = ftrace_modify_code(ip, old_jump);
	225	flush_icache();
	226
	227	pr_debug("%s\n", __func__);
	228	return ret;
	229	}
	230	#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
7d241ff0	231	#endif /* CONFIG_DYNAMIC_FTRACE */