[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_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;
}

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

/* 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;
	ret_addr = addr; /* saving where the barrier jump is */
	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 remove the rtsd r15, 8 by NOP */
	BUG_ON(!ret_addr);
	if (ret_addr)
		ret += ftrace_modify_code(ret_addr, MICROBLAZE_NOP);
	else
		ret = 1; /* fault */

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

#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
	17	#ifdef CONFIG_DYNAMIC_FTRACE
	18	/* save value to addr - it is save to do it in asm */
	19	static int ftrace_modify_code(unsigned long addr, unsigned int value)
	20	{
	21	int faulted = 0;
	22
	23	__asm__ __volatile__(" 1: swi %2, %1, 0; \
	24	addik %0, r0, 0; \
	25	2: \
	26	.section .fixup, \"ax\"; \
	27	3: brid 2b; \
	28	addik %0, r0, 1; \
	29	.previous; \
	30	.section __ex_table,\"a\"; \
	31	.word 1b,3b; \
	32	.previous;" \
	33	: "=r" (faulted)
	34	: "r" (addr), "r" (value)
	35	);
	36
	37	if (unlikely(faulted))
	38	return -EFAULT;
	39
	40	return 0;
	41	}
	42
	43	#define MICROBLAZE_NOP 0x80000000
	44	#define MICROBLAZE_BRI 0xb800000C
	45
	46	static unsigned int recorded; /* if save was or not */
	47	static unsigned int imm; /* saving whole imm instruction */
	48
	49	/* There are two approaches howto solve ftrace_make nop function - look below */
	50	#undef USE_FTRACE_NOP
	51
	52	#ifdef USE_FTRACE_NOP
	53	static unsigned int bralid; /* saving whole bralid instruction */
	54	#endif
	55
	56	int ftrace_make_nop(struct module *mod,
	57	struct dyn_ftrace *rec, unsigned long addr)
	58	{
	59	/* we have this part of code which we are working with
	60	* b000c000 imm -16384
	61	* b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
	62	* 80000000 or r0, r0, r0
	63	*
	64	* The first solution (!USE_FTRACE_NOP-could be called branch solution)
65	* b000c000 bri 12 (0xC - jump to any other instruction)
66	* b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
67	* 80000000 or r0, r0, r0
68	* any other instruction
69	*
70	* The second solution (USE_FTRACE_NOP) - no jump just nops
71	* 80000000 or r0, r0, r0
72	* 80000000 or r0, r0, r0
73	* 80000000 or r0, r0, r0
74	*/
75	int ret = 0;
76
77	if (recorded == 0) {
78	recorded = 1;
79	imm = (unsigned int )rec->ip;
80	pr_debug("%s: imm:0x%x\n", __func__, imm);
81	#ifdef USE_FTRACE_NOP
82	bralid = (unsigned int )(rec->ip + 4);
83	pr_debug("%s: bralid 0x%x\n", __func__, bralid);
84	#endif /* USE_FTRACE_NOP */
85	}
86
87	#ifdef USE_FTRACE_NOP
88	ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP);
89	ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP);
90	#else /* USE_FTRACE_NOP */
91	ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI);
92	#endif /* USE_FTRACE_NOP */
93	return ret;
94	}
95
96	static int ret_addr; /* initialized as 0 by default */
97
98	/* I believe that first is called ftrace_make_nop before this function */
99	int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
100	{
101	int ret;
102	ret_addr = addr; /* saving where the barrier jump is */
103	pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n",
104	__func__, (unsigned int)addr, (unsigned int)rec->ip, imm);
105	ret = ftrace_modify_code(rec->ip, imm);
106	#ifdef USE_FTRACE_NOP
107	pr_debug("%s: bralid:0x%x\n", __func__, bralid);
108	ret += ftrace_modify_code(rec->ip + 4, bralid);
109	#endif /* USE_FTRACE_NOP */
110	return ret;
111	}
112
113	int __init ftrace_dyn_arch_init(void *data)
114	{
115	/* The return code is retured via data */
116	(unsigned long )data = 0;
117
118	return 0;
119	}
120
121	int ftrace_update_ftrace_func(ftrace_func_t func)
122	{
123	unsigned long ip = (unsigned long)(&ftrace_call);
124	unsigned int upper = (unsigned int)func;
125	unsigned int lower = (unsigned int)func;
126	int ret = 0;
127
128	/* create proper saving to ftrace_call poll */
129	upper = 0xb0000000 + (upper >> 16); /* imm func_upper */
130	lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */
131
132	pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n",
133	__func__, (unsigned int)func, (unsigned int)ip, upper, lower);
134
135	/* save upper and lower code */
136	ret = ftrace_modify_code(ip, upper);
137	ret += ftrace_modify_code(ip + 4, lower);
138
139	/* We just need to remove the rtsd r15, 8 by NOP */
140	BUG_ON(!ret_addr);
141	if (ret_addr)
142	ret += ftrace_modify_code(ret_addr, MICROBLAZE_NOP);
143	else
144	ret = 1; /* fault */
145
146	/* All changes are done - lets do caches consistent */
147	flush_icache();
148	return ret;
149	}
150
151	#endif /* CONFIG_DYNAMIC_FTRACE */