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1/*
2 * Dynamic function tracing support.
3 *
4 * Copyright (C) 2008 Abhishek Sagar <sagar.abhishek@gmail.com>
5 * Copyright (C) 2010 Rabin Vincent <rabin@rab.in>
6 *
7 * For licencing details, see COPYING.
8 *
9 * Defines low-level handling of mcount calls when the kernel
10 * is compiled with the -pg flag. When using dynamic ftrace, the
11 * mcount call-sites get patched with NOP till they are enabled.
12 * All code mutation routines here are called under stop_machine().
13 */
14
15#include <linux/ftrace.h>
16#include <linux/uaccess.h>
17#include <linux/module.h>
18#include <linux/stop_machine.h>
19
20#include <asm/cacheflush.h>
21#include <asm/opcodes.h>
22#include <asm/ftrace.h>
23#include <asm/insn.h>
24
25#ifdef CONFIG_THUMB2_KERNEL
26#define NOP 0xf85deb04 /* pop.w {lr} */
27#else
28#define NOP 0xe8bd4000 /* pop {lr} */
29#endif
30
31#ifdef CONFIG_DYNAMIC_FTRACE
32#ifdef CONFIG_OLD_MCOUNT
33#define OLD_MCOUNT_ADDR ((unsigned long) mcount)
34#define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old)
35
36#define OLD_NOP 0xe1a00000 /* mov r0, r0 */
37
38static int __ftrace_modify_code(void *data)
39{
40 int *command = data;
41
42 set_kernel_text_rw();
43 ftrace_modify_all_code(*command);
44 set_kernel_text_ro();
45
46 return 0;
47}
48
49void arch_ftrace_update_code(int command)
50{
51 stop_machine(__ftrace_modify_code, &command, NULL);
52}
53
54static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
55{
56 return rec->arch.old_mcount ? OLD_NOP : NOP;
57}
58
59static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
60{
61 if (!rec->arch.old_mcount)
62 return addr;
63
64 if (addr == MCOUNT_ADDR)
65 addr = OLD_MCOUNT_ADDR;
66 else if (addr == FTRACE_ADDR)
67 addr = OLD_FTRACE_ADDR;
68
69 return addr;
70}
71#else
72static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
73{
74 return NOP;
75}
76
77static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
78{
79 return addr;
80}
81#endif
82
83int ftrace_arch_code_modify_prepare(void)
84{
85 set_all_modules_text_rw();
86 return 0;
87}
88
89int ftrace_arch_code_modify_post_process(void)
90{
91 set_all_modules_text_ro();
92 /* Make sure any TLB misses during machine stop are cleared. */
93 flush_tlb_all();
94 return 0;
95}
96
97static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
98{
99 return arm_gen_branch_link(pc, addr);
100}
101
102static int ftrace_modify_code(unsigned long pc, unsigned long old,
103 unsigned long new, bool validate)
104{
105 unsigned long replaced;
106
107 if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
108 old = __opcode_to_mem_thumb32(old);
109 new = __opcode_to_mem_thumb32(new);
110 } else {
111 old = __opcode_to_mem_arm(old);
112 new = __opcode_to_mem_arm(new);
113 }
114
115 if (validate) {
116 if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
117 return -EFAULT;
118
119 if (replaced != old)
120 return -EINVAL;
121 }
122
123 if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE))
124 return -EPERM;
125
126 flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
127
128 return 0;
129}
130
131int ftrace_update_ftrace_func(ftrace_func_t func)
132{
133 unsigned long pc;
134 unsigned long new;
135 int ret;
136
137 pc = (unsigned long)&ftrace_call;
138 new = ftrace_call_replace(pc, (unsigned long)func);
139
140 ret = ftrace_modify_code(pc, 0, new, false);
141
142#ifdef CONFIG_OLD_MCOUNT
143 if (!ret) {
144 pc = (unsigned long)&ftrace_call_old;
145 new = ftrace_call_replace(pc, (unsigned long)func);
146
147 ret = ftrace_modify_code(pc, 0, new, false);
148 }
149#endif
150
151 return ret;
152}
153
154int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
155{
156 unsigned long new, old;
157 unsigned long ip = rec->ip;
158
159 old = ftrace_nop_replace(rec);
160 new = ftrace_call_replace(ip, adjust_address(rec, addr));
161
162 return ftrace_modify_code(rec->ip, old, new, true);
163}
164
165int ftrace_make_nop(struct module *mod,
166 struct dyn_ftrace *rec, unsigned long addr)
167{
168 unsigned long ip = rec->ip;
169 unsigned long old;
170 unsigned long new;
171 int ret;
172
173 old = ftrace_call_replace(ip, adjust_address(rec, addr));
174 new = ftrace_nop_replace(rec);
175 ret = ftrace_modify_code(ip, old, new, true);
176
177#ifdef CONFIG_OLD_MCOUNT
178 if (ret == -EINVAL && addr == MCOUNT_ADDR) {
179 rec->arch.old_mcount = true;
180
181 old = ftrace_call_replace(ip, adjust_address(rec, addr));
182 new = ftrace_nop_replace(rec);
183 ret = ftrace_modify_code(ip, old, new, true);
184 }
185#endif
186
187 return ret;
188}
189
190int __init ftrace_dyn_arch_init(void)
191{
192 return 0;
193}
194#endif /* CONFIG_DYNAMIC_FTRACE */
195
196#ifdef CONFIG_FUNCTION_GRAPH_TRACER
197void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
198 unsigned long frame_pointer)
199{
200 unsigned long return_hooker = (unsigned long) &return_to_handler;
201 struct ftrace_graph_ent trace;
202 unsigned long old;
203 int err;
204
205 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
206 return;
207
208 old = *parent;
209 *parent = return_hooker;
210
211 trace.func = self_addr;
212 trace.depth = current->curr_ret_stack + 1;
213
214 /* Only trace if the calling function expects to */
215 if (!ftrace_graph_entry(&trace)) {
216 *parent = old;
217 return;
218 }
219
220 err = ftrace_push_return_trace(old, self_addr, &trace.depth,
221 frame_pointer);
222 if (err == -EBUSY) {
223 *parent = old;
224 return;
225 }
226}
227
228#ifdef CONFIG_DYNAMIC_FTRACE
229extern unsigned long ftrace_graph_call;
230extern unsigned long ftrace_graph_call_old;
231extern void ftrace_graph_caller_old(void);
232
233static int __ftrace_modify_caller(unsigned long *callsite,
234 void (*func) (void), bool enable)
235{
236 unsigned long caller_fn = (unsigned long) func;
237 unsigned long pc = (unsigned long) callsite;
238 unsigned long branch = arm_gen_branch(pc, caller_fn);
239 unsigned long nop = 0xe1a00000; /* mov r0, r0 */
240 unsigned long old = enable ? nop : branch;
241 unsigned long new = enable ? branch : nop;
242
243 return ftrace_modify_code(pc, old, new, true);
244}
245
246static int ftrace_modify_graph_caller(bool enable)
247{
248 int ret;
249
250 ret = __ftrace_modify_caller(&ftrace_graph_call,
251 ftrace_graph_caller,
252 enable);
253
254#ifdef CONFIG_OLD_MCOUNT
255 if (!ret)
256 ret = __ftrace_modify_caller(&ftrace_graph_call_old,
257 ftrace_graph_caller_old,
258 enable);
259#endif
260
261 return ret;
262}
263
264int ftrace_enable_ftrace_graph_caller(void)
265{
266 return ftrace_modify_graph_caller(true);
267}
268
269int ftrace_disable_ftrace_graph_caller(void)
270{
271 return ftrace_modify_graph_caller(false);
272}
273#endif /* CONFIG_DYNAMIC_FTRACE */
274#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
1/*
2 * Dynamic function tracing support.
3 *
4 * Copyright (C) 2008 Abhishek Sagar <sagar.abhishek@gmail.com>
5 * Copyright (C) 2010 Rabin Vincent <rabin@rab.in>
6 *
7 * For licencing details, see COPYING.
8 *
9 * Defines low-level handling of mcount calls when the kernel
10 * is compiled with the -pg flag. When using dynamic ftrace, the
11 * mcount call-sites get patched with NOP till they are enabled.
12 * All code mutation routines here are called under stop_machine().
13 */
14
15#include <linux/ftrace.h>
16#include <linux/uaccess.h>
17#include <linux/module.h>
18#include <linux/stop_machine.h>
19
20#include <asm/cacheflush.h>
21#include <asm/opcodes.h>
22#include <asm/ftrace.h>
23#include <asm/insn.h>
24#include <asm/set_memory.h>
25
26#ifdef CONFIG_THUMB2_KERNEL
27#define NOP 0xf85deb04 /* pop.w {lr} */
28#else
29#define NOP 0xe8bd4000 /* pop {lr} */
30#endif
31
32#ifdef CONFIG_DYNAMIC_FTRACE
33
34static int __ftrace_modify_code(void *data)
35{
36 int *command = data;
37
38 set_kernel_text_rw();
39 ftrace_modify_all_code(*command);
40 set_kernel_text_ro();
41
42 return 0;
43}
44
45void arch_ftrace_update_code(int command)
46{
47 stop_machine(__ftrace_modify_code, &command, NULL);
48}
49
50static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
51{
52 return NOP;
53}
54
55static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
56{
57 return addr;
58}
59
60int ftrace_arch_code_modify_prepare(void)
61{
62 set_all_modules_text_rw();
63 return 0;
64}
65
66int ftrace_arch_code_modify_post_process(void)
67{
68 set_all_modules_text_ro();
69 /* Make sure any TLB misses during machine stop are cleared. */
70 flush_tlb_all();
71 return 0;
72}
73
74static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
75{
76 return arm_gen_branch_link(pc, addr);
77}
78
79static int ftrace_modify_code(unsigned long pc, unsigned long old,
80 unsigned long new, bool validate)
81{
82 unsigned long replaced;
83
84 if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
85 old = __opcode_to_mem_thumb32(old);
86 new = __opcode_to_mem_thumb32(new);
87 } else {
88 old = __opcode_to_mem_arm(old);
89 new = __opcode_to_mem_arm(new);
90 }
91
92 if (validate) {
93 if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
94 return -EFAULT;
95
96 if (replaced != old)
97 return -EINVAL;
98 }
99
100 if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE))
101 return -EPERM;
102
103 flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
104
105 return 0;
106}
107
108int ftrace_update_ftrace_func(ftrace_func_t func)
109{
110 unsigned long pc;
111 unsigned long new;
112 int ret;
113
114 pc = (unsigned long)&ftrace_call;
115 new = ftrace_call_replace(pc, (unsigned long)func);
116
117 ret = ftrace_modify_code(pc, 0, new, false);
118
119#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
120 if (!ret) {
121 pc = (unsigned long)&ftrace_regs_call;
122 new = ftrace_call_replace(pc, (unsigned long)func);
123
124 ret = ftrace_modify_code(pc, 0, new, false);
125 }
126#endif
127
128 return ret;
129}
130
131int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
132{
133 unsigned long new, old;
134 unsigned long ip = rec->ip;
135
136 old = ftrace_nop_replace(rec);
137
138 new = ftrace_call_replace(ip, adjust_address(rec, addr));
139
140 return ftrace_modify_code(rec->ip, old, new, true);
141}
142
143#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
144
145int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
146 unsigned long addr)
147{
148 unsigned long new, old;
149 unsigned long ip = rec->ip;
150
151 old = ftrace_call_replace(ip, adjust_address(rec, old_addr));
152
153 new = ftrace_call_replace(ip, adjust_address(rec, addr));
154
155 return ftrace_modify_code(rec->ip, old, new, true);
156}
157
158#endif
159
160int ftrace_make_nop(struct module *mod,
161 struct dyn_ftrace *rec, unsigned long addr)
162{
163 unsigned long ip = rec->ip;
164 unsigned long old;
165 unsigned long new;
166 int ret;
167
168 old = ftrace_call_replace(ip, adjust_address(rec, addr));
169 new = ftrace_nop_replace(rec);
170 ret = ftrace_modify_code(ip, old, new, true);
171
172 return ret;
173}
174
175int __init ftrace_dyn_arch_init(void)
176{
177 return 0;
178}
179#endif /* CONFIG_DYNAMIC_FTRACE */
180
181#ifdef CONFIG_FUNCTION_GRAPH_TRACER
182void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
183 unsigned long frame_pointer)
184{
185 unsigned long return_hooker = (unsigned long) &return_to_handler;
186 unsigned long old;
187
188 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
189 return;
190
191 old = *parent;
192 *parent = return_hooker;
193
194 if (function_graph_enter(old, self_addr, frame_pointer, NULL))
195 *parent = old;
196}
197
198#ifdef CONFIG_DYNAMIC_FTRACE
199extern unsigned long ftrace_graph_call;
200extern unsigned long ftrace_graph_call_old;
201extern void ftrace_graph_caller_old(void);
202extern unsigned long ftrace_graph_regs_call;
203extern void ftrace_graph_regs_caller(void);
204
205static int __ftrace_modify_caller(unsigned long *callsite,
206 void (*func) (void), bool enable)
207{
208 unsigned long caller_fn = (unsigned long) func;
209 unsigned long pc = (unsigned long) callsite;
210 unsigned long branch = arm_gen_branch(pc, caller_fn);
211 unsigned long nop = 0xe1a00000; /* mov r0, r0 */
212 unsigned long old = enable ? nop : branch;
213 unsigned long new = enable ? branch : nop;
214
215 return ftrace_modify_code(pc, old, new, true);
216}
217
218static int ftrace_modify_graph_caller(bool enable)
219{
220 int ret;
221
222 ret = __ftrace_modify_caller(&ftrace_graph_call,
223 ftrace_graph_caller,
224 enable);
225
226#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
227 if (!ret)
228 ret = __ftrace_modify_caller(&ftrace_graph_regs_call,
229 ftrace_graph_regs_caller,
230 enable);
231#endif
232
233
234 return ret;
235}
236
237int ftrace_enable_ftrace_graph_caller(void)
238{
239 return ftrace_modify_graph_caller(true);
240}
241
242int ftrace_disable_ftrace_graph_caller(void)
243{
244 return ftrace_modify_graph_caller(false);
245}
246#endif /* CONFIG_DYNAMIC_FTRACE */
247#endif /* CONFIG_FUNCTION_GRAPH_TRACER */