aboutsummaryrefslogtreecommitdiffstats
path: root/arch/s390/kernel/ftrace.c
blob: 57bdcb1e3cdf0391928565dc26118e5272b3a21b (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
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
/*
 * Dynamic function tracer architecture backend.
 *
 * Copyright IBM Corp. 2009
 *
 *   Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
 *
 */

#include <linux/hardirq.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <trace/syscall.h>
#include <asm/lowcore.h>

#ifdef CONFIG_DYNAMIC_FTRACE

void ftrace_disable_code(void);
void ftrace_disable_return(void);
void ftrace_call_code(void);
void ftrace_nop_code(void);

#define FTRACE_INSN_SIZE 4

#ifdef CONFIG_64BIT

asm(
	"	.align	4\n"
	"ftrace_disable_code:\n"
	"	j	0f\n"
	"	.word	0x0024\n"
	"	lg	%r1,"__stringify(__LC_FTRACE_FUNC)"\n"
	"	basr	%r14,%r1\n"
	"ftrace_disable_return:\n"
	"	lg	%r14,8(15)\n"
	"	lgr	%r0,%r0\n"
	"0:\n");

asm(
	"	.align	4\n"
	"ftrace_nop_code:\n"
	"	j	.+"__stringify(MCOUNT_INSN_SIZE)"\n");

asm(
	"	.align	4\n"
	"ftrace_call_code:\n"
	"	stg	%r14,8(%r15)\n");

#else /* CONFIG_64BIT */

asm(
	"	.align	4\n"
	"ftrace_disable_code:\n"
	"	j	0f\n"
	"	l	%r1,"__stringify(__LC_FTRACE_FUNC)"\n"
	"	basr	%r14,%r1\n"
	"ftrace_disable_return:\n"
	"	l	%r14,4(%r15)\n"
	"	j	0f\n"
	"	bcr	0,%r7\n"
	"	bcr	0,%r7\n"
	"	bcr	0,%r7\n"
	"	bcr	0,%r7\n"
	"	bcr	0,%r7\n"
	"	bcr	0,%r7\n"
	"0:\n");

asm(
	"	.align	4\n"
	"ftrace_nop_code:\n"
	"	j	.+"__stringify(MCOUNT_INSN_SIZE)"\n");

asm(
	"	.align	4\n"
	"ftrace_call_code:\n"
	"	st	%r14,4(%r15)\n");

#endif /* CONFIG_64BIT */

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

	/*
	 * Note: Due to modules code can disappear and change.
	 *  We need to protect against faulting as well as code
	 *  changing. We do this by using the probe_kernel_*
	 *  functions.
	 *  This however is just a simple sanity check.
	 */
	if (probe_kernel_read(replaced, (void *)ip, old_size))
		return -EFAULT;
	if (memcmp(replaced, old_code, old_size) != 0)
		return -EINVAL;
	if (probe_kernel_write((void *)ip, new_code, new_size))
		return -EPERM;
	return 0;
}

static int ftrace_make_initial_nop(struct module *mod, struct dyn_ftrace *rec,
				   unsigned long addr)
{
	return ftrace_modify_code(rec->ip,
				  ftrace_call_code, FTRACE_INSN_SIZE,
				  ftrace_disable_code, MCOUNT_INSN_SIZE);
}

int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
		    unsigned long addr)
{
	if (addr == MCOUNT_ADDR)
		return ftrace_make_initial_nop(mod, rec, addr);
	return ftrace_modify_code(rec->ip,
				  ftrace_call_code, FTRACE_INSN_SIZE,
				  ftrace_nop_code, FTRACE_INSN_SIZE);
}

int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
	return ftrace_modify_code(rec->ip,
				  ftrace_nop_code, FTRACE_INSN_SIZE,
				  ftrace_call_code, FTRACE_INSN_SIZE);
}

int ftrace_update_ftrace_func(ftrace_func_t func)
{
	ftrace_dyn_func = (unsigned long)func;
	return 0;
}

int __init ftrace_dyn_arch_init(void *data)
{
	*(unsigned long *)data = 0;
	return 0;
}

#endif /* CONFIG_DYNAMIC_FTRACE */

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
#ifdef CONFIG_DYNAMIC_FTRACE
/*
 * Patch the kernel code at ftrace_graph_caller location:
 * The instruction there is branch relative on condition. The condition mask
 * is either all ones (always branch aka disable ftrace_graph_caller) or all
 * zeroes (nop aka enable ftrace_graph_caller).
 * Instruction format for brc is a7m4xxxx where m is the condition mask.
 */
int ftrace_enable_ftrace_graph_caller(void)
{
	unsigned short opcode = 0xa704;

	return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode));
}

int ftrace_disable_ftrace_graph_caller(void)
{
	unsigned short opcode = 0xa7f4;

	return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode));
}

static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr)
{
	return addr - (ftrace_disable_return - ftrace_disable_code);
}

#else /* CONFIG_DYNAMIC_FTRACE */

static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr)
{
	return addr - MCOUNT_OFFSET_RET;
}

#endif /* CONFIG_DYNAMIC_FTRACE */

/*
 * Hook the return address and push it in the stack of return addresses
 * in current thread info.
 */
unsigned long prepare_ftrace_return(unsigned long ip, unsigned long parent)
{
	struct ftrace_graph_ent trace;

	/* Nmi's are currently unsupported. */
	if (unlikely(in_nmi()))
		goto out;
	if (unlikely(atomic_read(&current->tracing_graph_pause)))
		goto out;
	if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY)
		goto out;
	trace.func = ftrace_mcount_call_adjust(ip) & PSW_ADDR_INSN;
	/* Only trace if the calling function expects to. */
	if (!ftrace_graph_entry(&trace)) {
		current->curr_ret_stack--;
		goto out;
	}
	parent = (unsigned long)return_to_handler;
out:
	return parent;
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

#ifdef CONFIG_FTRACE_SYSCALLS

extern unsigned long __start_syscalls_metadata[];
extern unsigned long __stop_syscalls_metadata[];
extern unsigned int sys_call_table[];

static struct syscall_metadata **syscalls_metadata;

struct syscall_metadata *syscall_nr_to_meta(int nr)
{
	if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
		return NULL;

	return syscalls_metadata[nr];
}

int syscall_name_to_nr(char *name)
{
	int i;

	if (!syscalls_metadata)
		return -1;
	for (i = 0; i < NR_syscalls; i++)
		if (syscalls_metadata[i])
			if (!strcmp(syscalls_metadata[i]->name, name))
				return i;
	return -1;
}

void set_syscall_enter_id(int num, int id)
{
	syscalls_metadata[num]->enter_id = id;
}

void set_syscall_exit_id(int num, int id)
{
	syscalls_metadata[num]->exit_id = id;
}

static struct syscall_metadata *find_syscall_meta(unsigned long syscall)
{
	struct syscall_metadata *start;
	struct syscall_metadata *stop;
	char str[KSYM_SYMBOL_LEN];

	start = (struct syscall_metadata *)__start_syscalls_metadata;
	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
	kallsyms_lookup(syscall, NULL, NULL, NULL, str);

	for ( ; start < stop; start++) {
		if (start->name && !strcmp(start->name + 3, str + 3))
			return start;
	}
	return NULL;
}

static int __init arch_init_ftrace_syscalls(void)
{
	struct syscall_metadata *meta;
	int i;
	syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) * NR_syscalls,
				    GFP_KERNEL);
	if (!syscalls_metadata)
		return -ENOMEM;
	for (i = 0; i < NR_syscalls; i++) {
		meta = find_syscall_meta((unsigned long)sys_call_table[i]);
		syscalls_metadata[i] = meta;
	}
	return 0;
}
arch_initcall(arch_init_ftrace_syscalls);
#endif