Commit | Line | Data |
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014c257c AS |
1 | /* |
2 | * Dynamic function tracing support. | |
3 | * | |
4 | * Copyright (C) 2008 Abhishek Sagar <sagar.abhishek@gmail.com> | |
3b6c223b | 5 | * Copyright (C) 2010 Rabin Vincent <rabin@rab.in> |
014c257c AS |
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 | |
3b6c223b RV |
11 | * mcount call-sites get patched with NOP till they are enabled. |
12 | * All code mutation routines here are called under stop_machine(). | |
014c257c AS |
13 | */ |
14 | ||
15 | #include <linux/ftrace.h> | |
6fa3eb70 | 16 | #include <linux/module.h> |
3b6c223b | 17 | #include <linux/uaccess.h> |
395a59d0 | 18 | |
014c257c | 19 | #include <asm/cacheflush.h> |
4394e282 | 20 | #include <asm/opcodes.h> |
395a59d0 | 21 | #include <asm/ftrace.h> |
014c257c | 22 | |
d82227cf RV |
23 | #include "insn.h" |
24 | ||
72dc43a9 | 25 | #ifdef CONFIG_THUMB2_KERNEL |
4394e282 | 26 | #define NOP 0xf85deb04 /* pop.w {lr} */ |
72dc43a9 | 27 | #else |
3b6c223b | 28 | #define NOP 0xe8bd4000 /* pop {lr} */ |
72dc43a9 | 29 | #endif |
014c257c | 30 | |
376cfa87 | 31 | #ifdef CONFIG_DYNAMIC_FTRACE |
3b6c223b RV |
32 | #ifdef CONFIG_OLD_MCOUNT |
33 | #define OLD_MCOUNT_ADDR ((unsigned long) mcount) | |
34 | #define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old) | |
014c257c | 35 | |
3b6c223b RV |
36 | #define OLD_NOP 0xe1a00000 /* mov r0, r0 */ |
37 | ||
38 | static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec) | |
39 | { | |
40 | return rec->arch.old_mcount ? OLD_NOP : NOP; | |
41 | } | |
42 | ||
43 | static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr) | |
44 | { | |
45 | if (!rec->arch.old_mcount) | |
46 | return addr; | |
47 | ||
48 | if (addr == MCOUNT_ADDR) | |
49 | addr = OLD_MCOUNT_ADDR; | |
50 | else if (addr == FTRACE_ADDR) | |
51 | addr = OLD_FTRACE_ADDR; | |
52 | ||
53 | return addr; | |
54 | } | |
55 | #else | |
56 | static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec) | |
57 | { | |
58 | return NOP; | |
59 | } | |
60 | ||
61 | static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr) | |
014c257c | 62 | { |
3b6c223b | 63 | return addr; |
014c257c | 64 | } |
3b6c223b | 65 | #endif |
014c257c | 66 | |
6fa3eb70 S |
67 | int ftrace_arch_code_modify_prepare(void) |
68 | { | |
69 | set_kernel_text_rw(); | |
70 | set_all_modules_text_rw(); | |
71 | return 0; | |
72 | } | |
73 | ||
74 | int ftrace_arch_code_modify_post_process(void) | |
75 | { | |
76 | set_all_modules_text_ro(); | |
77 | set_kernel_text_ro(); | |
78 | return 0; | |
79 | } | |
80 | ||
dd686eb1 RV |
81 | static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr) |
82 | { | |
d82227cf | 83 | return arm_gen_branch_link(pc, addr); |
dd686eb1 RV |
84 | } |
85 | ||
3b6c223b | 86 | static int ftrace_modify_code(unsigned long pc, unsigned long old, |
dc283d70 | 87 | unsigned long new, bool validate) |
3b6c223b RV |
88 | { |
89 | unsigned long replaced; | |
014c257c | 90 | |
4394e282 RV |
91 | if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) { |
92 | old = __opcode_to_mem_thumb32(old); | |
93 | new = __opcode_to_mem_thumb32(new); | |
94 | } else { | |
95 | old = __opcode_to_mem_arm(old); | |
96 | new = __opcode_to_mem_arm(new); | |
97 | } | |
98 | ||
dc283d70 RV |
99 | if (validate) { |
100 | if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE)) | |
101 | return -EFAULT; | |
014c257c | 102 | |
dc283d70 RV |
103 | if (replaced != old) |
104 | return -EINVAL; | |
105 | } | |
014c257c | 106 | |
3b6c223b RV |
107 | if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE)) |
108 | return -EPERM; | |
014c257c | 109 | |
3b6c223b | 110 | flush_icache_range(pc, pc + MCOUNT_INSN_SIZE); |
014c257c | 111 | |
3b6c223b | 112 | return 0; |
014c257c AS |
113 | } |
114 | ||
115 | int ftrace_update_ftrace_func(ftrace_func_t func) | |
116 | { | |
dc283d70 | 117 | unsigned long pc; |
3b6c223b RV |
118 | unsigned long new; |
119 | int ret; | |
014c257c AS |
120 | |
121 | pc = (unsigned long)&ftrace_call; | |
014c257c | 122 | new = ftrace_call_replace(pc, (unsigned long)func); |
3b6c223b | 123 | |
dc283d70 | 124 | ret = ftrace_modify_code(pc, 0, new, false); |
3b6c223b RV |
125 | |
126 | #ifdef CONFIG_OLD_MCOUNT | |
127 | if (!ret) { | |
128 | pc = (unsigned long)&ftrace_call_old; | |
3b6c223b RV |
129 | new = ftrace_call_replace(pc, (unsigned long)func); |
130 | ||
dc283d70 | 131 | ret = ftrace_modify_code(pc, 0, new, false); |
3b6c223b RV |
132 | } |
133 | #endif | |
134 | ||
135 | return ret; | |
136 | } | |
137 | ||
138 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
139 | { | |
140 | unsigned long new, old; | |
141 | unsigned long ip = rec->ip; | |
142 | ||
143 | old = ftrace_nop_replace(rec); | |
144 | new = ftrace_call_replace(ip, adjust_address(rec, addr)); | |
145 | ||
dc283d70 | 146 | return ftrace_modify_code(rec->ip, old, new, true); |
3b6c223b RV |
147 | } |
148 | ||
149 | int ftrace_make_nop(struct module *mod, | |
150 | struct dyn_ftrace *rec, unsigned long addr) | |
151 | { | |
152 | unsigned long ip = rec->ip; | |
153 | unsigned long old; | |
154 | unsigned long new; | |
155 | int ret; | |
156 | ||
157 | old = ftrace_call_replace(ip, adjust_address(rec, addr)); | |
158 | new = ftrace_nop_replace(rec); | |
dc283d70 | 159 | ret = ftrace_modify_code(ip, old, new, true); |
3b6c223b RV |
160 | |
161 | #ifdef CONFIG_OLD_MCOUNT | |
162 | if (ret == -EINVAL && addr == MCOUNT_ADDR) { | |
163 | rec->arch.old_mcount = true; | |
164 | ||
165 | old = ftrace_call_replace(ip, adjust_address(rec, addr)); | |
166 | new = ftrace_nop_replace(rec); | |
dc283d70 | 167 | ret = ftrace_modify_code(ip, old, new, true); |
3b6c223b RV |
168 | } |
169 | #endif | |
170 | ||
014c257c AS |
171 | return ret; |
172 | } | |
173 | ||
6fa3eb70 | 174 | int __init ftrace_dyn_arch_init(void) |
014c257c | 175 | { |
014c257c AS |
176 | return 0; |
177 | } | |
376cfa87 TB |
178 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
179 | ||
180 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
181 | void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, | |
182 | unsigned long frame_pointer) | |
183 | { | |
184 | unsigned long return_hooker = (unsigned long) &return_to_handler; | |
185 | struct ftrace_graph_ent trace; | |
186 | unsigned long old; | |
187 | int err; | |
188 | ||
189 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) | |
190 | return; | |
191 | ||
192 | old = *parent; | |
193 | *parent = return_hooker; | |
194 | ||
376cfa87 | 195 | trace.func = self_addr; |
4c36595e | 196 | trace.depth = current->curr_ret_stack + 1; |
376cfa87 TB |
197 | |
198 | /* Only trace if the calling function expects to */ | |
199 | if (!ftrace_graph_entry(&trace)) { | |
376cfa87 | 200 | *parent = old; |
4c36595e CC |
201 | return; |
202 | } | |
203 | ||
204 | err = ftrace_push_return_trace(old, self_addr, &trace.depth, | |
205 | frame_pointer); | |
206 | if (err == -EBUSY) { | |
207 | *parent = old; | |
208 | return; | |
376cfa87 TB |
209 | } |
210 | } | |
dd686eb1 RV |
211 | |
212 | #ifdef CONFIG_DYNAMIC_FTRACE | |
213 | extern unsigned long ftrace_graph_call; | |
214 | extern unsigned long ftrace_graph_call_old; | |
215 | extern void ftrace_graph_caller_old(void); | |
216 | ||
217 | static int __ftrace_modify_caller(unsigned long *callsite, | |
218 | void (*func) (void), bool enable) | |
219 | { | |
220 | unsigned long caller_fn = (unsigned long) func; | |
221 | unsigned long pc = (unsigned long) callsite; | |
d82227cf | 222 | unsigned long branch = arm_gen_branch(pc, caller_fn); |
dd686eb1 RV |
223 | unsigned long nop = 0xe1a00000; /* mov r0, r0 */ |
224 | unsigned long old = enable ? nop : branch; | |
225 | unsigned long new = enable ? branch : nop; | |
226 | ||
dc283d70 | 227 | return ftrace_modify_code(pc, old, new, true); |
dd686eb1 RV |
228 | } |
229 | ||
230 | static int ftrace_modify_graph_caller(bool enable) | |
231 | { | |
232 | int ret; | |
233 | ||
234 | ret = __ftrace_modify_caller(&ftrace_graph_call, | |
235 | ftrace_graph_caller, | |
236 | enable); | |
237 | ||
238 | #ifdef CONFIG_OLD_MCOUNT | |
239 | if (!ret) | |
240 | ret = __ftrace_modify_caller(&ftrace_graph_call_old, | |
241 | ftrace_graph_caller_old, | |
242 | enable); | |
243 | #endif | |
244 | ||
245 | return ret; | |
246 | } | |
247 | ||
248 | int ftrace_enable_ftrace_graph_caller(void) | |
249 | { | |
250 | return ftrace_modify_graph_caller(true); | |
251 | } | |
252 | ||
253 | int ftrace_disable_ftrace_graph_caller(void) | |
254 | { | |
255 | return ftrace_modify_graph_caller(false); | |
256 | } | |
257 | #endif /* CONFIG_DYNAMIC_FTRACE */ | |
376cfa87 | 258 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |