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e18eead3 SR |
1 | /* |
2 | * linux/arch/x86_64/mcount_64.S | |
3 | * | |
4 | * Copyright (C) 2014 Steven Rostedt, Red Hat Inc | |
5 | */ | |
6 | ||
7 | #include <linux/linkage.h> | |
8 | #include <asm/ptrace.h> | |
9 | #include <asm/ftrace.h> | |
10 | ||
11 | ||
12 | .code64 | |
13 | .section .entry.text, "ax" | |
14 | ||
15 | ||
16 | #ifdef CONFIG_FUNCTION_TRACER | |
17 | ||
18 | #ifdef CC_USING_FENTRY | |
19 | # define function_hook __fentry__ | |
20 | #else | |
21 | # define function_hook mcount | |
22 | #endif | |
23 | ||
05df710e SRRH |
24 | /* |
25 | * gcc -pg option adds a call to 'mcount' in most functions. | |
26 | * When -mfentry is used, the call is to 'fentry' and not 'mcount' | |
27 | * and is done before the function's stack frame is set up. | |
28 | * They both require a set of regs to be saved before calling | |
29 | * any C code and restored before returning back to the function. | |
30 | * | |
31 | * On boot up, all these calls are converted into nops. When tracing | |
32 | * is enabled, the call can jump to either ftrace_caller or | |
33 | * ftrace_regs_caller. Callbacks (tracing functions) that require | |
34 | * ftrace_regs_caller (like kprobes) need to have pt_regs passed to | |
35 | * it. For this reason, the size of the pt_regs structure will be | |
36 | * allocated on the stack and the required mcount registers will | |
37 | * be saved in the locations that pt_regs has them in. | |
38 | */ | |
39 | ||
527aa75b SRRH |
40 | /* @added: the amount of stack added before calling this */ |
41 | .macro save_mcount_regs added=0 | |
4bcdf152 SRRH |
42 | /* |
43 | * We add enough stack to save all regs. | |
44 | */ | |
527aa75b | 45 | subq $(SS+8), %rsp |
4bcdf152 SRRH |
46 | movq %rax, RAX(%rsp) |
47 | movq %rcx, RCX(%rsp) | |
48 | movq %rdx, RDX(%rsp) | |
49 | movq %rsi, RSI(%rsp) | |
50 | movq %rdi, RDI(%rsp) | |
51 | movq %r8, R8(%rsp) | |
52 | movq %r9, R9(%rsp) | |
53 | /* Move RIP to its proper location */ | |
527aa75b | 54 | movq SS+8+\added(%rsp), %rdi |
094dfc54 | 55 | movq %rdi, RIP(%rsp) |
4bcdf152 SRRH |
56 | .endm |
57 | ||
527aa75b | 58 | .macro restore_mcount_regs |
4bcdf152 SRRH |
59 | movq R9(%rsp), %r9 |
60 | movq R8(%rsp), %r8 | |
61 | movq RDI(%rsp), %rdi | |
62 | movq RSI(%rsp), %rsi | |
63 | movq RDX(%rsp), %rdx | |
64 | movq RCX(%rsp), %rcx | |
65 | movq RAX(%rsp), %rax | |
527aa75b | 66 | addq $(SS+8), %rsp |
4bcdf152 SRRH |
67 | .endm |
68 | ||
e18eead3 | 69 | /* skip is set if stack has been adjusted */ |
527aa75b SRRH |
70 | .macro ftrace_caller_setup trace_label added=0 |
71 | save_mcount_regs \added | |
e18eead3 | 72 | |
f3bea491 SRRH |
73 | /* Save this location */ |
74 | GLOBAL(\trace_label) | |
e18eead3 SR |
75 | /* Load the ftrace_ops into the 3rd parameter */ |
76 | movq function_trace_op(%rip), %rdx | |
77 | ||
094dfc54 | 78 | /* %rdi already has %rip from the save_mcount_regs macro */ |
e18eead3 SR |
79 | subq $MCOUNT_INSN_SIZE, %rdi |
80 | /* Load the parent_ip into the second parameter */ | |
81 | #ifdef CC_USING_FENTRY | |
527aa75b | 82 | movq SS+16+\added(%rsp), %rsi |
e18eead3 | 83 | #else |
527aa75b | 84 | movq 8+\added(%rbp), %rsi |
e18eead3 SR |
85 | #endif |
86 | .endm | |
87 | ||
76c2f13c SRRH |
88 | #ifdef CONFIG_DYNAMIC_FTRACE |
89 | ||
90 | ENTRY(function_hook) | |
91 | retq | |
92 | END(function_hook) | |
93 | ||
9960efeb SRRH |
94 | #ifdef CONFIG_FRAME_POINTER |
95 | /* | |
96 | * Stack traces will stop at the ftrace trampoline if the frame pointer | |
97 | * is not set up properly. If fentry is used, we need to save a frame | |
98 | * pointer for the parent as well as the function traced, because the | |
99 | * fentry is called before the stack frame is set up, where as mcount | |
100 | * is called afterward. | |
101 | */ | |
102 | .macro create_frame parent rip | |
103 | #ifdef CC_USING_FENTRY | |
104 | pushq \parent | |
105 | pushq %rbp | |
106 | movq %rsp, %rbp | |
107 | #endif | |
108 | pushq \rip | |
109 | pushq %rbp | |
110 | movq %rsp, %rbp | |
111 | .endm | |
112 | ||
113 | .macro restore_frame | |
114 | #ifdef CC_USING_FENTRY | |
115 | addq $16, %rsp | |
116 | #endif | |
117 | popq %rbp | |
118 | addq $8, %rsp | |
119 | .endm | |
120 | #else | |
121 | .macro create_frame parent rip | |
122 | .endm | |
123 | .macro restore_frame | |
124 | .endm | |
125 | #endif /* CONFIG_FRAME_POINTER */ | |
126 | ||
e18eead3 | 127 | ENTRY(ftrace_caller) |
f3bea491 | 128 | ftrace_caller_setup ftrace_caller_op_ptr |
e18eead3 SR |
129 | /* regs go into 4th parameter (but make it NULL) */ |
130 | movq $0, %rcx | |
131 | ||
9960efeb SRRH |
132 | create_frame %rsi, %rdi |
133 | ||
e18eead3 SR |
134 | GLOBAL(ftrace_call) |
135 | call ftrace_stub | |
136 | ||
9960efeb SRRH |
137 | restore_frame |
138 | ||
05df710e | 139 | restore_mcount_regs |
f3bea491 SRRH |
140 | |
141 | /* | |
142 | * The copied trampoline must call ftrace_return as it | |
143 | * still may need to call the function graph tracer. | |
144 | */ | |
145 | GLOBAL(ftrace_caller_end) | |
146 | ||
147 | GLOBAL(ftrace_return) | |
e18eead3 SR |
148 | |
149 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
150 | GLOBAL(ftrace_graph_call) | |
151 | jmp ftrace_stub | |
152 | #endif | |
153 | ||
154 | GLOBAL(ftrace_stub) | |
155 | retq | |
156 | END(ftrace_caller) | |
157 | ||
158 | ENTRY(ftrace_regs_caller) | |
527aa75b | 159 | /* Save the current flags before any operations that can change them */ |
e18eead3 SR |
160 | pushfq |
161 | ||
527aa75b | 162 | /* added 8 bytes to save flags */ |
f3bea491 | 163 | ftrace_caller_setup ftrace_regs_caller_op_ptr 8 |
e18eead3 SR |
164 | |
165 | /* Save the rest of pt_regs */ | |
166 | movq %r15, R15(%rsp) | |
167 | movq %r14, R14(%rsp) | |
168 | movq %r13, R13(%rsp) | |
169 | movq %r12, R12(%rsp) | |
170 | movq %r11, R11(%rsp) | |
171 | movq %r10, R10(%rsp) | |
172 | movq %rbp, RBP(%rsp) | |
173 | movq %rbx, RBX(%rsp) | |
174 | /* Copy saved flags */ | |
527aa75b | 175 | movq SS+8(%rsp), %rcx |
e18eead3 SR |
176 | movq %rcx, EFLAGS(%rsp) |
177 | /* Kernel segments */ | |
178 | movq $__KERNEL_DS, %rcx | |
179 | movq %rcx, SS(%rsp) | |
180 | movq $__KERNEL_CS, %rcx | |
181 | movq %rcx, CS(%rsp) | |
527aa75b SRRH |
182 | /* Stack - skipping return address and flags */ |
183 | leaq SS+8*3(%rsp), %rcx | |
e18eead3 SR |
184 | movq %rcx, RSP(%rsp) |
185 | ||
186 | /* regs go into 4th parameter */ | |
187 | leaq (%rsp), %rcx | |
188 | ||
9960efeb SRRH |
189 | create_frame %rsi, %rdi |
190 | ||
e18eead3 SR |
191 | GLOBAL(ftrace_regs_call) |
192 | call ftrace_stub | |
193 | ||
9960efeb SRRH |
194 | restore_frame |
195 | ||
e18eead3 SR |
196 | /* Copy flags back to SS, to restore them */ |
197 | movq EFLAGS(%rsp), %rax | |
527aa75b | 198 | movq %rax, SS+8(%rsp) |
e18eead3 SR |
199 | |
200 | /* Handlers can change the RIP */ | |
201 | movq RIP(%rsp), %rax | |
527aa75b | 202 | movq %rax, SS+8*2(%rsp) |
e18eead3 SR |
203 | |
204 | /* restore the rest of pt_regs */ | |
205 | movq R15(%rsp), %r15 | |
206 | movq R14(%rsp), %r14 | |
207 | movq R13(%rsp), %r13 | |
208 | movq R12(%rsp), %r12 | |
209 | movq R10(%rsp), %r10 | |
210 | movq RBP(%rsp), %rbp | |
211 | movq RBX(%rsp), %rbx | |
212 | ||
527aa75b | 213 | restore_mcount_regs |
e18eead3 SR |
214 | |
215 | /* Restore flags */ | |
216 | popfq | |
217 | ||
f3bea491 SRRH |
218 | /* |
219 | * As this jmp to ftrace_return can be a short jump | |
220 | * it must not be copied into the trampoline. | |
221 | * The trampoline will add the code to jump | |
222 | * to the return. | |
223 | */ | |
224 | GLOBAL(ftrace_regs_caller_end) | |
225 | ||
e18eead3 | 226 | jmp ftrace_return |
fdc841b5 | 227 | |
e18eead3 SR |
228 | popfq |
229 | jmp ftrace_stub | |
230 | ||
231 | END(ftrace_regs_caller) | |
232 | ||
233 | ||
234 | #else /* ! CONFIG_DYNAMIC_FTRACE */ | |
235 | ||
236 | ENTRY(function_hook) | |
e18eead3 SR |
237 | cmpq $ftrace_stub, ftrace_trace_function |
238 | jnz trace | |
239 | ||
62a207d7 | 240 | fgraph_trace: |
e18eead3 SR |
241 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
242 | cmpq $ftrace_stub, ftrace_graph_return | |
243 | jnz ftrace_graph_caller | |
244 | ||
245 | cmpq $ftrace_graph_entry_stub, ftrace_graph_entry | |
246 | jnz ftrace_graph_caller | |
247 | #endif | |
248 | ||
249 | GLOBAL(ftrace_stub) | |
250 | retq | |
251 | ||
252 | trace: | |
76c2f13c | 253 | ftrace_caller_setup ftrace_caller_op_ptr |
e18eead3 SR |
254 | |
255 | call *ftrace_trace_function | |
256 | ||
05df710e | 257 | restore_mcount_regs |
e18eead3 | 258 | |
62a207d7 | 259 | jmp fgraph_trace |
e18eead3 SR |
260 | END(function_hook) |
261 | #endif /* CONFIG_DYNAMIC_FTRACE */ | |
262 | #endif /* CONFIG_FUNCTION_TRACER */ | |
263 | ||
264 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
265 | ENTRY(ftrace_graph_caller) | |
05df710e | 266 | save_mcount_regs |
e18eead3 SR |
267 | |
268 | #ifdef CC_USING_FENTRY | |
269 | leaq SS+16(%rsp), %rdi | |
270 | movq $0, %rdx /* No framepointers needed */ | |
271 | #else | |
272 | leaq 8(%rbp), %rdi | |
273 | movq (%rbp), %rdx | |
274 | #endif | |
275 | movq RIP(%rsp), %rsi | |
276 | subq $MCOUNT_INSN_SIZE, %rsi | |
277 | ||
278 | call prepare_ftrace_return | |
279 | ||
05df710e | 280 | restore_mcount_regs |
e18eead3 SR |
281 | |
282 | retq | |
283 | END(ftrace_graph_caller) | |
284 | ||
285 | GLOBAL(return_to_handler) | |
286 | subq $24, %rsp | |
287 | ||
288 | /* Save the return values */ | |
289 | movq %rax, (%rsp) | |
290 | movq %rdx, 8(%rsp) | |
291 | movq %rbp, %rdi | |
292 | ||
293 | call ftrace_return_to_handler | |
294 | ||
295 | movq %rax, %rdi | |
296 | movq 8(%rsp), %rdx | |
297 | movq (%rsp), %rax | |
298 | addq $24, %rsp | |
299 | jmp *%rdi | |
300 | #endif |