[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)
	);

	flush_dcache_range((u32)parent, (u32)parent + 4);
	flush_icache_range((u32)parent, (u32)parent + 4);

	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;

	flush_dcache_range(addr, addr + 4);
	flush_icache_range(addr, addr + 4);

	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)
{
	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);

	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);

	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);

	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	*/
6bd55f0b MS	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;" \
a0d3e665 MS	50	: "=&r" (old), "=r" (faulted)
	51	: "r" (parent), "r" (return_hooker)
	52	);
	53
9e1491de MS	54	flush_dcache_range((u32)parent, (u32)parent + 4);
	55	flush_icache_range((u32)parent, (u32)parent + 4);
	56
a0d3e665 MS	57	if (unlikely(faulted)) {
	58	ftrace_graph_stop();
	59	WARN_ON(1);
	60	return;
	61	}
	62
	63	err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0);
	64	if (err == -EBUSY) {
	65	*parent = old;
	66	return;
	67	}
	68
	69	trace.func = self_addr;
	70	/* Only trace if the calling function expects to */
	71	if (!ftrace_graph_entry(&trace)) {
	72	current->curr_ret_stack--;
	73	*parent = old;
	74	}
	75	}
	76	#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
	77
7d241ff0 MS	78	#ifdef CONFIG_DYNAMIC_FTRACE
	79	/* save value to addr - it is save to do it in asm */
	80	static int ftrace_modify_code(unsigned long addr, unsigned int value)
	81	{
	82	int faulted = 0;
	83
6bd55f0b MS	84	__asm__ __volatile__(" 1: swi %2, %1, 0;" \
	85	" addik %0, r0, 0;" \
	86	"2:" \
	87	" .section .fixup, \"ax\";" \
	88	"3: brid 2b;" \
	89	" addik %0, r0, 1;" \
	90	" .previous;" \
	91	" .section __ex_table,\"a\";" \
	92	" .word 1b,3b;" \
	93	" .previous;" \
7d241ff0 MS	94	: "=r" (faulted)
	95	: "r" (addr), "r" (value)
	96	);
	97
	98	if (unlikely(faulted))
	99	return -EFAULT;
	100
9e1491de MS	101	flush_dcache_range(addr, addr + 4);
	102	flush_icache_range(addr, addr + 4);
	103
7d241ff0 MS	104	return 0;
	105	}
	106
	107	#define MICROBLAZE_NOP 0x80000000
	108	#define MICROBLAZE_BRI 0xb800000C
	109
	110	static unsigned int recorded; /* if save was or not */
	111	static unsigned int imm; /* saving whole imm instruction */
	112
	113	/* There are two approaches howto solve ftrace_make nop function - look below */
	114	#undef USE_FTRACE_NOP
	115
	116	#ifdef USE_FTRACE_NOP
	117	static unsigned int bralid; /* saving whole bralid instruction */
	118	#endif
	119
	120	int ftrace_make_nop(struct module *mod,
	121	struct dyn_ftrace *rec, unsigned long addr)
	122	{
	123	/* we have this part of code which we are working with
	124	* b000c000 imm -16384
	125	* b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
	126	* 80000000 or r0, r0, r0
	127	*
	128	* The first solution (!USE_FTRACE_NOP-could be called branch solution)
	129	* b000c000 bri 12 (0xC - jump to any other instruction)
	130	* b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
	131	* 80000000 or r0, r0, r0
	132	* any other instruction
	133	*
	134	* The second solution (USE_FTRACE_NOP) - no jump just nops
	135	* 80000000 or r0, r0, r0
	136	* 80000000 or r0, r0, r0
	137	* 80000000 or r0, r0, r0
	138	*/
	139	int ret = 0;
	140
	141	if (recorded == 0) {
	142	recorded = 1;
	143	imm = (unsigned int )rec->ip;
	144	pr_debug("%s: imm:0x%x\n", __func__, imm);
	145	#ifdef USE_FTRACE_NOP
	146	bralid = (unsigned int )(rec->ip + 4);
	147	pr_debug("%s: bralid 0x%x\n", __func__, bralid);
	148	#endif /* USE_FTRACE_NOP */
	149	}
	150
	151	#ifdef USE_FTRACE_NOP
	152	ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP);
	153	ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP);
	154	#else /* USE_FTRACE_NOP */
	155	ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI);
	156	#endif /* USE_FTRACE_NOP */
	157	return ret;
	158	}
	159
7d241ff0 MS	160	/* I believe that first is called ftrace_make_nop before this function */
	161	int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
	162	{
	163	int ret;
7d241ff0 MS	164	pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n",
	165	__func__, (unsigned int)addr, (unsigned int)rec->ip, imm);
	166	ret = ftrace_modify_code(rec->ip, imm);
	167	#ifdef USE_FTRACE_NOP
	168	pr_debug("%s: bralid:0x%x\n", __func__, bralid);
	169	ret += ftrace_modify_code(rec->ip + 4, bralid);
	170	#endif /* USE_FTRACE_NOP */
	171	return ret;
	172	}
	173
	174	int __init ftrace_dyn_arch_init(void *data)
	175	{
7d241ff0 MS	176	return 0;
	177	}
	178
	179	int ftrace_update_ftrace_func(ftrace_func_t func)
	180	{
	181	unsigned long ip = (unsigned long)(&ftrace_call);
	182	unsigned int upper = (unsigned int)func;
	183	unsigned int lower = (unsigned int)func;
	184	int ret = 0;
	185
	186	/* create proper saving to ftrace_call poll */
	187	upper = 0xb0000000 + (upper >> 16); /* imm func_upper */
	188	lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */
	189
	190	pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n",
	191	__func__, (unsigned int)func, (unsigned int)ip, upper, lower);
	192
	193	/* save upper and lower code */
	194	ret = ftrace_modify_code(ip, upper);
	195	ret += ftrace_modify_code(ip + 4, lower);
	196
d2bf98e6 SM	197	/* We just need to replace the rtsd r15, 8 with NOP */
	198	ret += ftrace_modify_code((unsigned long)&ftrace_caller,
	199	MICROBLAZE_NOP);
7d241ff0	200
7d241ff0 MS	201	return ret;
	202	}
	203
4f911b0d MS	204	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	205	unsigned int old_jump; /* saving place for jump instruction */
	206
	207	int ftrace_enable_ftrace_graph_caller(void)
	208	{
	209	unsigned int ret;
	210	unsigned long ip = (unsigned long)(&ftrace_call_graph);
	211
	212	old_jump = (unsigned int )ip; /* save jump over instruction */
	213	ret = ftrace_modify_code(ip, MICROBLAZE_NOP);
4f911b0d MS	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);
4f911b0d MS	225
	226	pr_debug("%s\n", __func__);
	227	return ret;
	228	}
	229	#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
7d241ff0	230	#endif /* CONFIG_DYNAMIC_FTRACE */