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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
e18eead3 | 2 | /* |
e18eead3 SR |
3 | * Copyright (C) 2014 Steven Rostedt, Red Hat Inc |
4 | */ | |
5 | ||
6 | #include <linux/linkage.h> | |
7 | #include <asm/ptrace.h> | |
8 | #include <asm/ftrace.h> | |
784d5699 | 9 | #include <asm/export.h> |
e18eead3 SR |
10 | |
11 | ||
12 | .code64 | |
13 | .section .entry.text, "ax" | |
14 | ||
e18eead3 SR |
15 | #ifdef CC_USING_FENTRY |
16 | # define function_hook __fentry__ | |
5de0a8c0 | 17 | EXPORT_SYMBOL(__fentry__) |
e18eead3 SR |
18 | #else |
19 | # define function_hook mcount | |
5de0a8c0 | 20 | EXPORT_SYMBOL(mcount) |
e18eead3 SR |
21 | #endif |
22 | ||
0687c36e SRRH |
23 | /* All cases save the original rbp (8 bytes) */ |
24 | #ifdef CONFIG_FRAME_POINTER | |
25 | # ifdef CC_USING_FENTRY | |
26 | /* Save parent and function stack frames (rip and rbp) */ | |
27 | # define MCOUNT_FRAME_SIZE (8+16*2) | |
28 | # else | |
29 | /* Save just function stack frame (rip and rbp) */ | |
30 | # define MCOUNT_FRAME_SIZE (8+16) | |
31 | # endif | |
32 | #else | |
33 | /* No need to save a stack frame */ | |
34 | # define MCOUNT_FRAME_SIZE 8 | |
35 | #endif /* CONFIG_FRAME_POINTER */ | |
36 | ||
85f6f029 | 37 | /* Size of stack used to save mcount regs in save_mcount_regs */ |
0687c36e | 38 | #define MCOUNT_REG_SIZE (SS+8 + MCOUNT_FRAME_SIZE) |
85f6f029 | 39 | |
05df710e SRRH |
40 | /* |
41 | * gcc -pg option adds a call to 'mcount' in most functions. | |
42 | * When -mfentry is used, the call is to 'fentry' and not 'mcount' | |
43 | * and is done before the function's stack frame is set up. | |
44 | * They both require a set of regs to be saved before calling | |
45 | * any C code and restored before returning back to the function. | |
46 | * | |
47 | * On boot up, all these calls are converted into nops. When tracing | |
48 | * is enabled, the call can jump to either ftrace_caller or | |
49 | * ftrace_regs_caller. Callbacks (tracing functions) that require | |
50 | * ftrace_regs_caller (like kprobes) need to have pt_regs passed to | |
51 | * it. For this reason, the size of the pt_regs structure will be | |
52 | * allocated on the stack and the required mcount registers will | |
53 | * be saved in the locations that pt_regs has them in. | |
54 | */ | |
55 | ||
f1ab00af SRRH |
56 | /* |
57 | * @added: the amount of stack added before calling this | |
58 | * | |
59 | * After this is called, the following registers contain: | |
60 | * | |
61 | * %rdi - holds the address that called the trampoline | |
62 | * %rsi - holds the parent function (traced function's return address) | |
63 | * %rdx - holds the original %rbp | |
64 | */ | |
527aa75b | 65 | .macro save_mcount_regs added=0 |
0687c36e SRRH |
66 | |
67 | /* Always save the original rbp */ | |
68 | pushq %rbp | |
69 | ||
70 | #ifdef CONFIG_FRAME_POINTER | |
71 | /* | |
72 | * Stack traces will stop at the ftrace trampoline if the frame pointer | |
73 | * is not set up properly. If fentry is used, we need to save a frame | |
74 | * pointer for the parent as well as the function traced, because the | |
75 | * fentry is called before the stack frame is set up, where as mcount | |
76 | * is called afterward. | |
77 | */ | |
78 | #ifdef CC_USING_FENTRY | |
79 | /* Save the parent pointer (skip orig rbp and our return address) */ | |
80 | pushq \added+8*2(%rsp) | |
81 | pushq %rbp | |
82 | movq %rsp, %rbp | |
83 | /* Save the return address (now skip orig rbp, rbp and parent) */ | |
84 | pushq \added+8*3(%rsp) | |
85 | #else | |
86 | /* Can't assume that rip is before this (unless added was zero) */ | |
87 | pushq \added+8(%rsp) | |
88 | #endif | |
89 | pushq %rbp | |
90 | movq %rsp, %rbp | |
91 | #endif /* CONFIG_FRAME_POINTER */ | |
92 | ||
93 | /* | |
94 | * We add enough stack to save all regs. | |
95 | */ | |
96 | subq $(MCOUNT_REG_SIZE - MCOUNT_FRAME_SIZE), %rsp | |
4bcdf152 SRRH |
97 | movq %rax, RAX(%rsp) |
98 | movq %rcx, RCX(%rsp) | |
99 | movq %rdx, RDX(%rsp) | |
100 | movq %rsi, RSI(%rsp) | |
101 | movq %rdi, RDI(%rsp) | |
102 | movq %r8, R8(%rsp) | |
103 | movq %r9, R9(%rsp) | |
0687c36e SRRH |
104 | /* |
105 | * Save the original RBP. Even though the mcount ABI does not | |
106 | * require this, it helps out callers. | |
107 | */ | |
108 | movq MCOUNT_REG_SIZE-8(%rsp), %rdx | |
109 | movq %rdx, RBP(%rsp) | |
110 | ||
f1ab00af SRRH |
111 | /* Copy the parent address into %rsi (second parameter) */ |
112 | #ifdef CC_USING_FENTRY | |
113 | movq MCOUNT_REG_SIZE+8+\added(%rsp), %rsi | |
114 | #else | |
115 | /* %rdx contains original %rbp */ | |
116 | movq 8(%rdx), %rsi | |
117 | #endif | |
118 | ||
4bcdf152 | 119 | /* Move RIP to its proper location */ |
85f6f029 | 120 | movq MCOUNT_REG_SIZE+\added(%rsp), %rdi |
094dfc54 | 121 | movq %rdi, RIP(%rsp) |
f1ab00af SRRH |
122 | |
123 | /* | |
124 | * Now %rdi (the first parameter) has the return address of | |
125 | * where ftrace_call returns. But the callbacks expect the | |
6a06bdbf | 126 | * address of the call itself. |
f1ab00af SRRH |
127 | */ |
128 | subq $MCOUNT_INSN_SIZE, %rdi | |
4bcdf152 SRRH |
129 | .endm |
130 | ||
527aa75b | 131 | .macro restore_mcount_regs |
4bcdf152 SRRH |
132 | movq R9(%rsp), %r9 |
133 | movq R8(%rsp), %r8 | |
134 | movq RDI(%rsp), %rdi | |
135 | movq RSI(%rsp), %rsi | |
136 | movq RDX(%rsp), %rdx | |
137 | movq RCX(%rsp), %rcx | |
138 | movq RAX(%rsp), %rax | |
0687c36e SRRH |
139 | |
140 | /* ftrace_regs_caller can modify %rbp */ | |
141 | movq RBP(%rsp), %rbp | |
142 | ||
85f6f029 | 143 | addq $MCOUNT_REG_SIZE, %rsp |
0687c36e | 144 | |
4bcdf152 SRRH |
145 | .endm |
146 | ||
76c2f13c SRRH |
147 | #ifdef CONFIG_DYNAMIC_FTRACE |
148 | ||
149 | ENTRY(function_hook) | |
150 | retq | |
151 | END(function_hook) | |
152 | ||
e18eead3 | 153 | ENTRY(ftrace_caller) |
f1ab00af SRRH |
154 | /* save_mcount_regs fills in first two parameters */ |
155 | save_mcount_regs | |
156 | ||
157 | GLOBAL(ftrace_caller_op_ptr) | |
158 | /* Load the ftrace_ops into the 3rd parameter */ | |
159 | movq function_trace_op(%rip), %rdx | |
160 | ||
e18eead3 SR |
161 | /* regs go into 4th parameter (but make it NULL) */ |
162 | movq $0, %rcx | |
163 | ||
164 | GLOBAL(ftrace_call) | |
165 | call ftrace_stub | |
166 | ||
05df710e | 167 | restore_mcount_regs |
f3bea491 SRRH |
168 | |
169 | /* | |
f1b92bb6 | 170 | * The copied trampoline must call ftrace_epilogue as it |
f3bea491 | 171 | * still may need to call the function graph tracer. |
f1b92bb6 BP |
172 | * |
173 | * The code up to this label is copied into trampolines so | |
174 | * think twice before adding any new code or changing the | |
175 | * layout here. | |
f3bea491 | 176 | */ |
f1b92bb6 | 177 | GLOBAL(ftrace_epilogue) |
e18eead3 SR |
178 | |
179 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
180 | GLOBAL(ftrace_graph_call) | |
181 | jmp ftrace_stub | |
182 | #endif | |
183 | ||
8329e818 SR |
184 | /* This is weak to keep gas from relaxing the jumps */ |
185 | WEAK(ftrace_stub) | |
e18eead3 SR |
186 | retq |
187 | END(ftrace_caller) | |
188 | ||
189 | ENTRY(ftrace_regs_caller) | |
527aa75b | 190 | /* Save the current flags before any operations that can change them */ |
e18eead3 SR |
191 | pushfq |
192 | ||
527aa75b | 193 | /* added 8 bytes to save flags */ |
f1ab00af SRRH |
194 | save_mcount_regs 8 |
195 | /* save_mcount_regs fills in first two parameters */ | |
196 | ||
197 | GLOBAL(ftrace_regs_caller_op_ptr) | |
198 | /* Load the ftrace_ops into the 3rd parameter */ | |
199 | movq function_trace_op(%rip), %rdx | |
e18eead3 SR |
200 | |
201 | /* Save the rest of pt_regs */ | |
202 | movq %r15, R15(%rsp) | |
203 | movq %r14, R14(%rsp) | |
204 | movq %r13, R13(%rsp) | |
205 | movq %r12, R12(%rsp) | |
206 | movq %r11, R11(%rsp) | |
207 | movq %r10, R10(%rsp) | |
e18eead3 SR |
208 | movq %rbx, RBX(%rsp) |
209 | /* Copy saved flags */ | |
85f6f029 | 210 | movq MCOUNT_REG_SIZE(%rsp), %rcx |
e18eead3 SR |
211 | movq %rcx, EFLAGS(%rsp) |
212 | /* Kernel segments */ | |
213 | movq $__KERNEL_DS, %rcx | |
214 | movq %rcx, SS(%rsp) | |
215 | movq $__KERNEL_CS, %rcx | |
216 | movq %rcx, CS(%rsp) | |
527aa75b | 217 | /* Stack - skipping return address and flags */ |
85f6f029 | 218 | leaq MCOUNT_REG_SIZE+8*2(%rsp), %rcx |
e18eead3 SR |
219 | movq %rcx, RSP(%rsp) |
220 | ||
221 | /* regs go into 4th parameter */ | |
222 | leaq (%rsp), %rcx | |
223 | ||
224 | GLOBAL(ftrace_regs_call) | |
225 | call ftrace_stub | |
226 | ||
227 | /* Copy flags back to SS, to restore them */ | |
228 | movq EFLAGS(%rsp), %rax | |
85f6f029 | 229 | movq %rax, MCOUNT_REG_SIZE(%rsp) |
e18eead3 SR |
230 | |
231 | /* Handlers can change the RIP */ | |
232 | movq RIP(%rsp), %rax | |
85f6f029 | 233 | movq %rax, MCOUNT_REG_SIZE+8(%rsp) |
e18eead3 SR |
234 | |
235 | /* restore the rest of pt_regs */ | |
236 | movq R15(%rsp), %r15 | |
237 | movq R14(%rsp), %r14 | |
238 | movq R13(%rsp), %r13 | |
239 | movq R12(%rsp), %r12 | |
240 | movq R10(%rsp), %r10 | |
e18eead3 SR |
241 | movq RBX(%rsp), %rbx |
242 | ||
527aa75b | 243 | restore_mcount_regs |
e18eead3 SR |
244 | |
245 | /* Restore flags */ | |
246 | popfq | |
247 | ||
f3bea491 | 248 | /* |
f1b92bb6 | 249 | * As this jmp to ftrace_epilogue can be a short jump |
f3bea491 SRRH |
250 | * it must not be copied into the trampoline. |
251 | * The trampoline will add the code to jump | |
252 | * to the return. | |
253 | */ | |
254 | GLOBAL(ftrace_regs_caller_end) | |
255 | ||
f1b92bb6 | 256 | jmp ftrace_epilogue |
fdc841b5 | 257 | |
e18eead3 SR |
258 | END(ftrace_regs_caller) |
259 | ||
260 | ||
261 | #else /* ! CONFIG_DYNAMIC_FTRACE */ | |
262 | ||
263 | ENTRY(function_hook) | |
e18eead3 SR |
264 | cmpq $ftrace_stub, ftrace_trace_function |
265 | jnz trace | |
266 | ||
62a207d7 | 267 | fgraph_trace: |
e18eead3 SR |
268 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
269 | cmpq $ftrace_stub, ftrace_graph_return | |
270 | jnz ftrace_graph_caller | |
271 | ||
272 | cmpq $ftrace_graph_entry_stub, ftrace_graph_entry | |
273 | jnz ftrace_graph_caller | |
274 | #endif | |
275 | ||
276 | GLOBAL(ftrace_stub) | |
277 | retq | |
278 | ||
279 | trace: | |
f1ab00af SRRH |
280 | /* save_mcount_regs fills in first two parameters */ |
281 | save_mcount_regs | |
e18eead3 | 282 | |
112677d6 NK |
283 | /* |
284 | * When DYNAMIC_FTRACE is not defined, ARCH_SUPPORTS_FTRACE_OPS is not | |
285 | * set (see include/asm/ftrace.h and include/linux/ftrace.h). Only the | |
286 | * ip and parent ip are used and the list function is called when | |
287 | * function tracing is enabled. | |
288 | */ | |
e18eead3 SR |
289 | call *ftrace_trace_function |
290 | ||
05df710e | 291 | restore_mcount_regs |
e18eead3 | 292 | |
62a207d7 | 293 | jmp fgraph_trace |
e18eead3 SR |
294 | END(function_hook) |
295 | #endif /* CONFIG_DYNAMIC_FTRACE */ | |
e18eead3 SR |
296 | |
297 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
298 | ENTRY(ftrace_graph_caller) | |
6a06bdbf | 299 | /* Saves rbp into %rdx and fills first parameter */ |
05df710e | 300 | save_mcount_regs |
e18eead3 SR |
301 | |
302 | #ifdef CC_USING_FENTRY | |
6a06bdbf | 303 | leaq MCOUNT_REG_SIZE+8(%rsp), %rsi |
e18eead3 SR |
304 | movq $0, %rdx /* No framepointers needed */ |
305 | #else | |
f1ab00af | 306 | /* Save address of the return address of traced function */ |
6a06bdbf | 307 | leaq 8(%rdx), %rsi |
f1ab00af | 308 | /* ftrace does sanity checks against frame pointers */ |
0687c36e | 309 | movq (%rdx), %rdx |
e18eead3 | 310 | #endif |
e18eead3 SR |
311 | call prepare_ftrace_return |
312 | ||
05df710e | 313 | restore_mcount_regs |
e18eead3 SR |
314 | |
315 | retq | |
316 | END(ftrace_graph_caller) | |
317 | ||
318 | GLOBAL(return_to_handler) | |
319 | subq $24, %rsp | |
320 | ||
321 | /* Save the return values */ | |
322 | movq %rax, (%rsp) | |
323 | movq %rdx, 8(%rsp) | |
324 | movq %rbp, %rdi | |
325 | ||
326 | call ftrace_return_to_handler | |
327 | ||
328 | movq %rax, %rdi | |
329 | movq 8(%rsp), %rdx | |
330 | movq (%rsp), %rax | |
331 | addq $24, %rsp | |
332 | jmp *%rdi | |
333 | #endif |