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