summaryrefslogtreecommitdiffstats
path: root/arch/ia64/kernel/ftrace.c
blob: cee411e647ca05fd27f6b1b0d025648ed619001c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
/*
 * Dynamic function tracing support.
 *
 * Copyright (C) 2008 Shaohua Li <shaohua.li@intel.com>
 *
 * For licencing details, see COPYING.
 *
 * Defines low-level handling of mcount calls when the kernel
 * is compiled with the -pg flag. When using dynamic ftrace, the
 * mcount call-sites get patched lazily with NOP till they are
 * enabled. All code mutation routines here take effect atomically.
 */

#include <linux/uaccess.h>
#include <linux/ftrace.h>

#include <asm/cacheflush.h>
#include <asm/patch.h>

/* In IA64, each function will be added below two bundles with -pg option */
static unsigned char __attribute__((aligned(8)))
ftrace_orig_code[MCOUNT_INSN_SIZE] = {
	0x02, 0x40, 0x31, 0x10, 0x80, 0x05, /* alloc r40=ar.pfs,12,8,0 */
	0xb0, 0x02, 0x00, 0x00, 0x42, 0x40, /* mov r43=r0;; */
	0x05, 0x00, 0xc4, 0x00,             /* mov r42=b0 */
	0x11, 0x48, 0x01, 0x02, 0x00, 0x21, /* mov r41=r1 */
	0x00, 0x00, 0x00, 0x02, 0x00, 0x00, /* nop.i 0x0 */
	0x08, 0x00, 0x00, 0x50              /* br.call.sptk.many b0 = _mcount;; */
};

struct ftrace_orig_insn {
	u64 dummy1, dummy2, dummy3;
	u64 dummy4:64-41+13;
	u64 imm20:20;
	u64 dummy5:3;
	u64 sign:1;
	u64 dummy6:4;
};

/* mcount stub will be converted below for nop */
static unsigned char ftrace_nop_code[MCOUNT_INSN_SIZE] = {
	0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */
	0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */
	0x00, 0x00, 0x04, 0x00,             /* nop.i 0x0 */
	0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* nop.x 0x0;; */
	0x00, 0x00, 0x04, 0x00
};

static unsigned char *ftrace_nop_replace(void)
{
	return ftrace_nop_code;
}

/*
 * mcount stub will be converted below for call
 * Note: Just the last instruction is changed against nop
 * */
static unsigned char __attribute__((aligned(8)))
ftrace_call_code[MCOUNT_INSN_SIZE] = {
	0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */
	0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */
	0x00, 0x00, 0x04, 0x00,             /* nop.i 0x0 */
	0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */
	0xff, 0xff, 0xff, 0xff, 0x7f, 0x00, /* brl.many .;;*/
	0xf8, 0xff, 0xff, 0xc8
};

struct ftrace_call_insn {
	u64 dummy1, dummy2;
	u64 dummy3:48;
	u64 imm39_l:16;
	u64 imm39_h:23;
	u64 dummy4:13;
	u64 imm20:20;
	u64 dummy5:3;
	u64 i:1;
	u64 dummy6:4;
};

static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
{
	struct ftrace_call_insn *code = (void *)ftrace_call_code;
	unsigned long offset = addr - (ip + 0x10);

	code->imm39_l = offset >> 24;
	code->imm39_h = offset >> 40;
	code->imm20 = offset >> 4;
	code->i = offset >> 63;
	return ftrace_call_code;
}

static int
ftrace_modify_code(unsigned long ip, unsigned char *old_code,
		   unsigned char *new_code, int do_check)
{
	unsigned char replaced[MCOUNT_INSN_SIZE];

	/*
	 * Note:
	 * We are paranoid about modifying text, as if a bug was to happen, it
	 * could cause us to read or write to someplace that could cause harm.
	 * Carefully read and modify the code with probe_kernel_*(), and make
	 * sure what we read is what we expected it to be before modifying it.
	 */

	if (!do_check)
		goto skip_check;

	/* read the text we want to modify */
	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
		return -EFAULT;

	/* Make sure it is what we expect it to be */
	if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
		return -EINVAL;

skip_check:
	/* replace the text with the new text */
	if (probe_kernel_write(((void *)ip), new_code, MCOUNT_INSN_SIZE))
		return -EPERM;
	flush_icache_range(ip, ip + MCOUNT_INSN_SIZE);

	return 0;
}

static int ftrace_make_nop_check(struct dyn_ftrace *rec, unsigned long addr)
{
	unsigned char __attribute__((aligned(8))) replaced[MCOUNT_INSN_SIZE];
	unsigned long ip = rec->ip;

	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
		return -EFAULT;
	if (rec->flags & FTRACE_FL_CONVERTED) {
		struct ftrace_call_insn *call_insn, *tmp_call;

		call_insn = (void *)ftrace_call_code;
		tmp_call = (void *)replaced;
		call_insn->imm39_l = tmp_call->imm39_l;
		call_insn->imm39_h = tmp_call->imm39_h;
		call_insn->imm20 = tmp_call->imm20;
		call_insn->i = tmp_call->i;
		if (memcmp(replaced, ftrace_call_code, MCOUNT_INSN_SIZE) != 0)
			return -EINVAL;
		return 0;
	} else {
		struct ftrace_orig_insn *call_insn, *tmp_call;

		call_insn = (void *)ftrace_orig_code;
		tmp_call = (void *)replaced;
		call_insn->sign = tmp_call->sign;
		call_insn->imm20 = tmp_call->imm20;
		if (memcmp(replaced, ftrace_orig_code, MCOUNT_INSN_SIZE) != 0)
			return -EINVAL;
		return 0;
	}
}

int ftrace_make_nop(struct module *mod,
		    struct dyn_ftrace *rec, unsigned long addr)
{
	int ret;
	char *new;

	ret = ftrace_make_nop_check(rec, addr);
	if (ret)
		return ret;
	new = ftrace_nop_replace();
	return ftrace_modify_code(rec->ip, NULL, new, 0);
}

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

	old=  ftrace_nop_replace();
	new = ftrace_call_replace(ip, addr);
	return ftrace_modify_code(ip, old, new, 1);
}

/* in IA64, _mcount can't directly call ftrace_stub. Only jump is ok */
int ftrace_update_ftrace_func(ftrace_func_t func)
{
	unsigned long ip;
	unsigned long addr = ((struct fnptr *)ftrace_call)->ip;

	if (func == ftrace_stub)
		return 0;
	ip = ((struct fnptr *)func)->ip;

	ia64_patch_imm64(addr + 2, ip);

	flush_icache_range(addr, addr + 16);
	return 0;
}

/* run from kstop_machine */
int __init ftrace_dyn_arch_init(void)
{
	return 0;
}
OpenPOWER on IntegriCloud