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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 | ||
883bbbff | 6 | #include <linux/cfi_types.h> |
e18eead3 | 7 | #include <linux/linkage.h> |
ee3e2469 | 8 | #include <asm/asm-offsets.h> |
e18eead3 SR |
9 | #include <asm/ptrace.h> |
10 | #include <asm/ftrace.h> | |
784d5699 | 11 | #include <asm/export.h> |
9351803b | 12 | #include <asm/nospec-branch.h> |
e2ac83d7 | 13 | #include <asm/unwind_hints.h> |
ea1ed38d | 14 | #include <asm/frame.h> |
e18eead3 SR |
15 | |
16 | .code64 | |
b9f6976b | 17 | .section .text, "ax" |
e18eead3 | 18 | |
0687c36e | 19 | #ifdef CONFIG_FRAME_POINTER |
0687c36e SRRH |
20 | /* Save parent and function stack frames (rip and rbp) */ |
21 | # define MCOUNT_FRAME_SIZE (8+16*2) | |
0687c36e SRRH |
22 | #else |
23 | /* No need to save a stack frame */ | |
e2ac83d7 | 24 | # define MCOUNT_FRAME_SIZE 0 |
0687c36e SRRH |
25 | #endif /* CONFIG_FRAME_POINTER */ |
26 | ||
85f6f029 | 27 | /* Size of stack used to save mcount regs in save_mcount_regs */ |
dc2745b6 | 28 | #define MCOUNT_REG_SIZE (FRAME_SIZE + MCOUNT_FRAME_SIZE) |
85f6f029 | 29 | |
05df710e SRRH |
30 | /* |
31 | * gcc -pg option adds a call to 'mcount' in most functions. | |
32 | * When -mfentry is used, the call is to 'fentry' and not 'mcount' | |
33 | * and is done before the function's stack frame is set up. | |
34 | * They both require a set of regs to be saved before calling | |
35 | * any C code and restored before returning back to the function. | |
36 | * | |
37 | * On boot up, all these calls are converted into nops. When tracing | |
38 | * is enabled, the call can jump to either ftrace_caller or | |
39 | * ftrace_regs_caller. Callbacks (tracing functions) that require | |
40 | * ftrace_regs_caller (like kprobes) need to have pt_regs passed to | |
41 | * it. For this reason, the size of the pt_regs structure will be | |
42 | * allocated on the stack and the required mcount registers will | |
43 | * be saved in the locations that pt_regs has them in. | |
44 | */ | |
45 | ||
f1ab00af SRRH |
46 | /* |
47 | * @added: the amount of stack added before calling this | |
48 | * | |
49 | * After this is called, the following registers contain: | |
50 | * | |
51 | * %rdi - holds the address that called the trampoline | |
52 | * %rsi - holds the parent function (traced function's return address) | |
53 | * %rdx - holds the original %rbp | |
54 | */ | |
527aa75b | 55 | .macro save_mcount_regs added=0 |
0687c36e | 56 | |
e2ac83d7 JP |
57 | #ifdef CONFIG_FRAME_POINTER |
58 | /* Save the original rbp */ | |
0687c36e SRRH |
59 | pushq %rbp |
60 | ||
0687c36e SRRH |
61 | /* |
62 | * Stack traces will stop at the ftrace trampoline if the frame pointer | |
63 | * is not set up properly. If fentry is used, we need to save a frame | |
64 | * pointer for the parent as well as the function traced, because the | |
65 | * fentry is called before the stack frame is set up, where as mcount | |
66 | * is called afterward. | |
67 | */ | |
562e14f7 | 68 | |
0687c36e SRRH |
69 | /* Save the parent pointer (skip orig rbp and our return address) */ |
70 | pushq \added+8*2(%rsp) | |
71 | pushq %rbp | |
72 | movq %rsp, %rbp | |
73 | /* Save the return address (now skip orig rbp, rbp and parent) */ | |
74 | pushq \added+8*3(%rsp) | |
0687c36e SRRH |
75 | pushq %rbp |
76 | movq %rsp, %rbp | |
77 | #endif /* CONFIG_FRAME_POINTER */ | |
78 | ||
79 | /* | |
80 | * We add enough stack to save all regs. | |
81 | */ | |
dc2745b6 | 82 | subq $(FRAME_SIZE), %rsp |
4bcdf152 SRRH |
83 | movq %rax, RAX(%rsp) |
84 | movq %rcx, RCX(%rsp) | |
85 | movq %rdx, RDX(%rsp) | |
86 | movq %rsi, RSI(%rsp) | |
87 | movq %rdi, RDI(%rsp) | |
88 | movq %r8, R8(%rsp) | |
89 | movq %r9, R9(%rsp) | |
562955fe | 90 | movq $0, ORIG_RAX(%rsp) |
0687c36e SRRH |
91 | /* |
92 | * Save the original RBP. Even though the mcount ABI does not | |
93 | * require this, it helps out callers. | |
94 | */ | |
e2ac83d7 | 95 | #ifdef CONFIG_FRAME_POINTER |
0687c36e | 96 | movq MCOUNT_REG_SIZE-8(%rsp), %rdx |
e2ac83d7 JP |
97 | #else |
98 | movq %rbp, %rdx | |
99 | #endif | |
0687c36e SRRH |
100 | movq %rdx, RBP(%rsp) |
101 | ||
f1ab00af | 102 | /* Copy the parent address into %rsi (second parameter) */ |
f1ab00af | 103 | movq MCOUNT_REG_SIZE+8+\added(%rsp), %rsi |
f1ab00af | 104 | |
4bcdf152 | 105 | /* Move RIP to its proper location */ |
85f6f029 | 106 | movq MCOUNT_REG_SIZE+\added(%rsp), %rdi |
094dfc54 | 107 | movq %rdi, RIP(%rsp) |
f1ab00af SRRH |
108 | |
109 | /* | |
110 | * Now %rdi (the first parameter) has the return address of | |
111 | * where ftrace_call returns. But the callbacks expect the | |
6a06bdbf | 112 | * address of the call itself. |
f1ab00af SRRH |
113 | */ |
114 | subq $MCOUNT_INSN_SIZE, %rdi | |
4bcdf152 SRRH |
115 | .endm |
116 | ||
562955fe SRV |
117 | .macro restore_mcount_regs save=0 |
118 | ||
119 | /* ftrace_regs_caller or frame pointers require this */ | |
120 | movq RBP(%rsp), %rbp | |
121 | ||
4bcdf152 SRRH |
122 | movq R9(%rsp), %r9 |
123 | movq R8(%rsp), %r8 | |
124 | movq RDI(%rsp), %rdi | |
125 | movq RSI(%rsp), %rsi | |
126 | movq RDX(%rsp), %rdx | |
127 | movq RCX(%rsp), %rcx | |
128 | movq RAX(%rsp), %rax | |
0687c36e | 129 | |
562955fe | 130 | addq $MCOUNT_REG_SIZE-\save, %rsp |
0687c36e | 131 | |
4bcdf152 SRRH |
132 | .endm |
133 | ||
883bbbff | 134 | SYM_TYPED_FUNC_START(ftrace_stub) |
bd194611 | 135 | CALL_DEPTH_ACCOUNT |
883bbbff PZ |
136 | RET |
137 | SYM_FUNC_END(ftrace_stub) | |
138 | ||
aa69f814 | 139 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
883bbbff | 140 | SYM_TYPED_FUNC_START(ftrace_stub_graph) |
bd194611 | 141 | CALL_DEPTH_ACCOUNT |
883bbbff PZ |
142 | RET |
143 | SYM_FUNC_END(ftrace_stub_graph) | |
aa69f814 | 144 | #endif |
883bbbff | 145 | |
76c2f13c SRRH |
146 | #ifdef CONFIG_DYNAMIC_FTRACE |
147 | ||
0f42c1ad | 148 | SYM_FUNC_START(__fentry__) |
ee3e2469 | 149 | CALL_DEPTH_ACCOUNT |
f94909ce | 150 | RET |
0f42c1ad BP |
151 | SYM_FUNC_END(__fentry__) |
152 | EXPORT_SYMBOL(__fentry__) | |
76c2f13c | 153 | |
6dcc5627 | 154 | SYM_FUNC_START(ftrace_caller) |
f1ab00af SRRH |
155 | /* save_mcount_regs fills in first two parameters */ |
156 | save_mcount_regs | |
157 | ||
ee3e2469 PZ |
158 | CALL_DEPTH_ACCOUNT |
159 | ||
02a474ca SRV |
160 | /* Stack - skipping return address of ftrace_caller */ |
161 | leaq MCOUNT_REG_SIZE+8(%rsp), %rcx | |
162 | movq %rcx, RSP(%rsp) | |
163 | ||
26ba4e57 | 164 | SYM_INNER_LABEL(ftrace_caller_op_ptr, SYM_L_GLOBAL) |
3215de84 | 165 | ANNOTATE_NOENDBR |
f1ab00af SRRH |
166 | /* Load the ftrace_ops into the 3rd parameter */ |
167 | movq function_trace_op(%rip), %rdx | |
168 | ||
02a474ca SRV |
169 | /* regs go into 4th parameter */ |
170 | leaq (%rsp), %rcx | |
171 | ||
172 | /* Only ops with REGS flag set should have CS register set */ | |
173 | movq $0, CS(%rsp) | |
e18eead3 | 174 | |
ee3e2469 PZ |
175 | /* Account for the function call below */ |
176 | CALL_DEPTH_ACCOUNT | |
177 | ||
26ba4e57 | 178 | SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL) |
3215de84 | 179 | ANNOTATE_NOENDBR |
e18eead3 SR |
180 | call ftrace_stub |
181 | ||
2860cd8a SRV |
182 | /* Handlers can change the RIP */ |
183 | movq RIP(%rsp), %rax | |
184 | movq %rax, MCOUNT_REG_SIZE(%rsp) | |
185 | ||
05df710e | 186 | restore_mcount_regs |
f3bea491 SRRH |
187 | |
188 | /* | |
f1b92bb6 BP |
189 | * The code up to this label is copied into trampolines so |
190 | * think twice before adding any new code or changing the | |
191 | * layout here. | |
f3bea491 | 192 | */ |
0298739b | 193 | SYM_INNER_LABEL(ftrace_caller_end, SYM_L_GLOBAL) |
3215de84 | 194 | ANNOTATE_NOENDBR |
eac828ea | 195 | RET |
0298739b | 196 | SYM_FUNC_END(ftrace_caller); |
7b6c7a87 | 197 | STACK_FRAME_NON_STANDARD_FP(ftrace_caller) |
0298739b | 198 | |
6dcc5627 | 199 | SYM_FUNC_START(ftrace_regs_caller) |
527aa75b | 200 | /* Save the current flags before any operations that can change them */ |
e18eead3 SR |
201 | pushfq |
202 | ||
527aa75b | 203 | /* added 8 bytes to save flags */ |
f1ab00af SRRH |
204 | save_mcount_regs 8 |
205 | /* save_mcount_regs fills in first two parameters */ | |
206 | ||
ee3e2469 PZ |
207 | CALL_DEPTH_ACCOUNT |
208 | ||
26ba4e57 | 209 | SYM_INNER_LABEL(ftrace_regs_caller_op_ptr, SYM_L_GLOBAL) |
3215de84 | 210 | ANNOTATE_NOENDBR |
f1ab00af SRRH |
211 | /* Load the ftrace_ops into the 3rd parameter */ |
212 | movq function_trace_op(%rip), %rdx | |
e18eead3 SR |
213 | |
214 | /* Save the rest of pt_regs */ | |
215 | movq %r15, R15(%rsp) | |
216 | movq %r14, R14(%rsp) | |
217 | movq %r13, R13(%rsp) | |
218 | movq %r12, R12(%rsp) | |
219 | movq %r11, R11(%rsp) | |
220 | movq %r10, R10(%rsp) | |
e18eead3 SR |
221 | movq %rbx, RBX(%rsp) |
222 | /* Copy saved flags */ | |
85f6f029 | 223 | movq MCOUNT_REG_SIZE(%rsp), %rcx |
e18eead3 SR |
224 | movq %rcx, EFLAGS(%rsp) |
225 | /* Kernel segments */ | |
226 | movq $__KERNEL_DS, %rcx | |
227 | movq %rcx, SS(%rsp) | |
228 | movq $__KERNEL_CS, %rcx | |
229 | movq %rcx, CS(%rsp) | |
527aa75b | 230 | /* Stack - skipping return address and flags */ |
85f6f029 | 231 | leaq MCOUNT_REG_SIZE+8*2(%rsp), %rcx |
e18eead3 SR |
232 | movq %rcx, RSP(%rsp) |
233 | ||
ea1ed38d PZ |
234 | ENCODE_FRAME_POINTER |
235 | ||
e18eead3 SR |
236 | /* regs go into 4th parameter */ |
237 | leaq (%rsp), %rcx | |
238 | ||
ee3e2469 PZ |
239 | /* Account for the function call below */ |
240 | CALL_DEPTH_ACCOUNT | |
241 | ||
26ba4e57 | 242 | SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL) |
3215de84 | 243 | ANNOTATE_NOENDBR |
e18eead3 SR |
244 | call ftrace_stub |
245 | ||
246 | /* Copy flags back to SS, to restore them */ | |
247 | movq EFLAGS(%rsp), %rax | |
85f6f029 | 248 | movq %rax, MCOUNT_REG_SIZE(%rsp) |
e18eead3 SR |
249 | |
250 | /* Handlers can change the RIP */ | |
251 | movq RIP(%rsp), %rax | |
85f6f029 | 252 | movq %rax, MCOUNT_REG_SIZE+8(%rsp) |
e18eead3 SR |
253 | |
254 | /* restore the rest of pt_regs */ | |
255 | movq R15(%rsp), %r15 | |
256 | movq R14(%rsp), %r14 | |
257 | movq R13(%rsp), %r13 | |
258 | movq R12(%rsp), %r12 | |
259 | movq R10(%rsp), %r10 | |
e18eead3 SR |
260 | movq RBX(%rsp), %rbx |
261 | ||
562955fe SRV |
262 | movq ORIG_RAX(%rsp), %rax |
263 | movq %rax, MCOUNT_REG_SIZE-8(%rsp) | |
264 | ||
0298739b PZ |
265 | /* |
266 | * If ORIG_RAX is anything but zero, make this a call to that. | |
267 | * See arch_ftrace_set_direct_caller(). | |
268 | */ | |
9f2dfd61 | 269 | testq %rax, %rax |
fe58acef | 270 | SYM_INNER_LABEL(ftrace_regs_caller_jmp, SYM_L_GLOBAL) |
3215de84 | 271 | ANNOTATE_NOENDBR |
0b4f8ddc | 272 | jnz 1f |
562955fe | 273 | |
0b4f8ddc | 274 | restore_mcount_regs |
e18eead3 SR |
275 | /* Restore flags */ |
276 | popfq | |
277 | ||
f3bea491 | 278 | /* |
eac828ea | 279 | * The trampoline will add the return. |
f3bea491 | 280 | */ |
5da7cd11 | 281 | SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL) |
3215de84 | 282 | ANNOTATE_NOENDBR |
eac828ea | 283 | RET |
fdc841b5 | 284 | |
0b4f8ddc SRV |
285 | /* Swap the flags with orig_rax */ |
286 | 1: movq MCOUNT_REG_SIZE(%rsp), %rdi | |
287 | movq %rdi, MCOUNT_REG_SIZE-8(%rsp) | |
288 | movq %rax, MCOUNT_REG_SIZE(%rsp) | |
289 | ||
290 | restore_mcount_regs 8 | |
291 | /* Restore flags */ | |
292 | popfq | |
b735bd3e | 293 | UNWIND_HINT_FUNC |
36b64f10 PZ |
294 | |
295 | /* | |
296 | * The above left an extra return value on the stack; effectively | |
297 | * doing a tail-call without using a register. This PUSH;RET | |
298 | * pattern unbalances the RSB, inject a pointless CALL to rebalance. | |
299 | */ | |
300 | ANNOTATE_INTRA_FUNCTION_CALL | |
301 | CALL .Ldo_rebalance | |
302 | int3 | |
303 | .Ldo_rebalance: | |
304 | add $8, %rsp | |
ee3e2469 PZ |
305 | ALTERNATIVE __stringify(RET), \ |
306 | __stringify(ANNOTATE_UNRET_SAFE; ret; int3), \ | |
307 | X86_FEATURE_CALL_DEPTH | |
0b4f8ddc | 308 | |
6dcc5627 | 309 | SYM_FUNC_END(ftrace_regs_caller) |
7b6c7a87 | 310 | STACK_FRAME_NON_STANDARD_FP(ftrace_regs_caller) |
e18eead3 | 311 | |
fee86a4e MR |
312 | SYM_FUNC_START(ftrace_stub_direct_tramp) |
313 | CALL_DEPTH_ACCOUNT | |
314 | RET | |
315 | SYM_FUNC_END(ftrace_stub_direct_tramp) | |
e18eead3 SR |
316 | |
317 | #else /* ! CONFIG_DYNAMIC_FTRACE */ | |
318 | ||
0f42c1ad | 319 | SYM_FUNC_START(__fentry__) |
ee3e2469 PZ |
320 | CALL_DEPTH_ACCOUNT |
321 | ||
e18eead3 SR |
322 | cmpq $ftrace_stub, ftrace_trace_function |
323 | jnz trace | |
f94909ce | 324 | RET |
e18eead3 SR |
325 | |
326 | trace: | |
f1ab00af SRRH |
327 | /* save_mcount_regs fills in first two parameters */ |
328 | save_mcount_regs | |
e18eead3 | 329 | |
112677d6 NK |
330 | /* |
331 | * When DYNAMIC_FTRACE is not defined, ARCH_SUPPORTS_FTRACE_OPS is not | |
332 | * set (see include/asm/ftrace.h and include/linux/ftrace.h). Only the | |
333 | * ip and parent ip are used and the list function is called when | |
334 | * function tracing is enabled. | |
335 | */ | |
9351803b | 336 | movq ftrace_trace_function, %r8 |
34fdce69 | 337 | CALL_NOSPEC r8 |
05df710e | 338 | restore_mcount_regs |
e18eead3 | 339 | |
0c0593b4 | 340 | jmp ftrace_stub |
0f42c1ad BP |
341 | SYM_FUNC_END(__fentry__) |
342 | EXPORT_SYMBOL(__fentry__) | |
7b6c7a87 JP |
343 | STACK_FRAME_NON_STANDARD_FP(__fentry__) |
344 | ||
e18eead3 | 345 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
e18eead3 SR |
346 | |
347 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
7b6c7a87 | 348 | SYM_CODE_START(return_to_handler) |
fb799447 | 349 | UNWIND_HINT_UNDEFINED |
7b6c7a87 | 350 | ANNOTATE_NOENDBR |
e52fc2cf | 351 | subq $16, %rsp |
e18eead3 SR |
352 | |
353 | /* Save the return values */ | |
354 | movq %rax, (%rsp) | |
355 | movq %rdx, 8(%rsp) | |
356 | movq %rbp, %rdi | |
357 | ||
358 | call ftrace_return_to_handler | |
359 | ||
360 | movq %rax, %rdi | |
361 | movq 8(%rsp), %rdx | |
362 | movq (%rsp), %rax | |
e52fc2cf PZ |
363 | |
364 | addq $16, %rsp | |
365 | /* | |
366 | * Jump back to the old return address. This cannot be JMP_NOSPEC rdi | |
367 | * since IBT would demand that contain ENDBR, which simply isn't so for | |
368 | * return addresses. Use a retpoline here to keep the RSB balanced. | |
369 | */ | |
370 | ANNOTATE_INTRA_FUNCTION_CALL | |
371 | call .Ldo_rop | |
372 | int3 | |
373 | .Ldo_rop: | |
374 | mov %rdi, (%rsp) | |
ee3e2469 PZ |
375 | ALTERNATIVE __stringify(RET), \ |
376 | __stringify(ANNOTATE_UNRET_SAFE; ret; int3), \ | |
377 | X86_FEATURE_CALL_DEPTH | |
7b6c7a87 | 378 | SYM_CODE_END(return_to_handler) |
e18eead3 | 379 | #endif |