1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Copyright (C) 2014 Steven Rostedt, Red Ha
4 */
5
6 #include <linux/export.h>
7 #include <linux/cfi_types.h>
8 #include <linux/linkage.h>
9 #include <asm/asm-offsets.h>
10 #include <asm/ptrace.h>
11 #include <asm/ftrace.h>
12 #include <asm/nospec-branch.h>
13 #include <asm/unwind_hints.h>
14 #include <asm/frame.h>
15
16 .code64
17 .section .text, "ax"
18
19 #ifdef CONFIG_FRAME_POINTER
20 /* Save parent and function stack frames (rip
21 # define MCOUNT_FRAME_SIZE (8+16*2)
22 #else
23 /* No need to save a stack frame */
24 # define MCOUNT_FRAME_SIZE 0
25 #endif /* CONFIG_FRAME_POINTER */
26
27 /* Size of stack used to save mcount regs in s
28 #define MCOUNT_REG_SIZE (FRAME_SIZE +
29
30 /*
31 * gcc -pg option adds a call to 'mcount' in m
32 * When -mfentry is used, the call is to 'fent
33 * and is done before the function's stack fra
34 * They both require a set of regs to be saved
35 * any C code and restored before returning ba
36 *
37 * On boot up, all these calls are converted i
38 * is enabled, the call can jump to either ftr
39 * ftrace_regs_caller. Callbacks (tracing func
40 * ftrace_regs_caller (like kprobes) need to h
41 * it. For this reason, the size of the pt_reg
42 * allocated on the stack and the required mco
43 * be saved in the locations that pt_regs has
44 */
45
46 /*
47 * @added: the amount of stack added before ca
48 *
49 * After this is called, the following registe
50 *
51 * %rdi - holds the address that called the t
52 * %rsi - holds the parent function (traced f
53 * %rdx - holds the original %rbp
54 */
55 .macro save_mcount_regs added=0
56
57 #ifdef CONFIG_FRAME_POINTER
58 /* Save the original rbp */
59 pushq %rbp
60
61 /*
62 * Stack traces will stop at the ftrac
63 * is not set up properly. If fentry i
64 * pointer for the parent as well as t
65 * fentry is called before the stack f
66 * is called afterward.
67 */
68
69 /* Save the parent pointer (skip orig
70 pushq \added+8*2(%rsp)
71 pushq %rbp
72 movq %rsp, %rbp
73 /* Save the return address (now skip o
74 pushq \added+8*3(%rsp)
75 pushq %rbp
76 movq %rsp, %rbp
77 #endif /* CONFIG_FRAME_POINTER */
78
79 /*
80 * We add enough stack to save all reg
81 */
82 subq $(FRAME_SIZE), %rsp
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)
90 movq $0, ORIG_RAX(%rsp)
91 /*
92 * Save the original RBP. Even though
93 * require this, it helps out callers.
94 */
95 #ifdef CONFIG_FRAME_POINTER
96 movq MCOUNT_REG_SIZE-8(%rsp), %rdx
97 #else
98 movq %rbp, %rdx
99 #endif
100 movq %rdx, RBP(%rsp)
101
102 /* Copy the parent address into %rsi (
103 movq MCOUNT_REG_SIZE+8+\added(%rsp), %
104
105 /* Move RIP to its proper location */
106 movq MCOUNT_REG_SIZE+\added(%rsp), %rd
107 movq %rdi, RIP(%rsp)
108
109 /*
110 * Now %rdi (the first parameter) has
111 * where ftrace_call returns. But the
112 * address of the call itself.
113 */
114 subq $MCOUNT_INSN_SIZE, %rdi
115 .endm
116
117 .macro restore_mcount_regs save=0
118
119 /* ftrace_regs_caller or frame pointer
120 movq RBP(%rsp), %rbp
121
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
129
130 addq $MCOUNT_REG_SIZE-\save, %rsp
131
132 .endm
133
134 SYM_TYPED_FUNC_START(ftrace_stub)
135 CALL_DEPTH_ACCOUNT
136 RET
137 SYM_FUNC_END(ftrace_stub)
138
139 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
140 SYM_TYPED_FUNC_START(ftrace_stub_graph)
141 CALL_DEPTH_ACCOUNT
142 RET
143 SYM_FUNC_END(ftrace_stub_graph)
144 #endif
145
146 #ifdef CONFIG_DYNAMIC_FTRACE
147
148 SYM_FUNC_START(__fentry__)
149 CALL_DEPTH_ACCOUNT
150 RET
151 SYM_FUNC_END(__fentry__)
152 EXPORT_SYMBOL(__fentry__)
153
154 SYM_FUNC_START(ftrace_caller)
155 /* save_mcount_regs fills in first two
156 save_mcount_regs
157
158 CALL_DEPTH_ACCOUNT
159
160 /* Stack - skipping return address of
161 leaq MCOUNT_REG_SIZE+8(%rsp), %rcx
162 movq %rcx, RSP(%rsp)
163
164 SYM_INNER_LABEL(ftrace_caller_op_ptr, SYM_L_GL
165 ANNOTATE_NOENDBR
166 /* Load the ftrace_ops into the 3rd pa
167 movq function_trace_op(%rip), %rdx
168
169 /* regs go into 4th parameter */
170 leaq (%rsp), %rcx
171
172 /* Only ops with REGS flag set should
173 movq $0, CS(%rsp)
174
175 /* Account for the function call below
176 CALL_DEPTH_ACCOUNT
177
178 SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL)
179 ANNOTATE_NOENDBR
180 call ftrace_stub
181
182 /* Handlers can change the RIP */
183 movq RIP(%rsp), %rax
184 movq %rax, MCOUNT_REG_SIZE(%rsp)
185
186 restore_mcount_regs
187
188 /*
189 * The code up to this label is copied
190 * think twice before adding any new c
191 * layout here.
192 */
193 SYM_INNER_LABEL(ftrace_caller_end, SYM_L_GLOBA
194 ANNOTATE_NOENDBR
195 RET
196 SYM_FUNC_END(ftrace_caller);
197 STACK_FRAME_NON_STANDARD_FP(ftrace_caller)
198
199 SYM_FUNC_START(ftrace_regs_caller)
200 /* Save the current flags before any o
201 pushfq
202
203 /* added 8 bytes to save flags */
204 save_mcount_regs 8
205 /* save_mcount_regs fills in first two
206
207 CALL_DEPTH_ACCOUNT
208
209 SYM_INNER_LABEL(ftrace_regs_caller_op_ptr, SYM
210 ANNOTATE_NOENDBR
211 /* Load the ftrace_ops into the 3rd pa
212 movq function_trace_op(%rip), %rdx
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)
221 movq %rbx, RBX(%rsp)
222 /* Copy saved flags */
223 movq MCOUNT_REG_SIZE(%rsp), %rcx
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)
230 /* Stack - skipping return address and
231 leaq MCOUNT_REG_SIZE+8*2(%rsp), %rcx
232 movq %rcx, RSP(%rsp)
233
234 ENCODE_FRAME_POINTER
235
236 /* regs go into 4th parameter */
237 leaq (%rsp), %rcx
238
239 /* Account for the function call below
240 CALL_DEPTH_ACCOUNT
241
242 SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL
243 ANNOTATE_NOENDBR
244 call ftrace_stub
245
246 /* Copy flags back to SS, to restore t
247 movq EFLAGS(%rsp), %rax
248 movq %rax, MCOUNT_REG_SIZE(%rsp)
249
250 /* Handlers can change the RIP */
251 movq RIP(%rsp), %rax
252 movq %rax, MCOUNT_REG_SIZE+8(%rsp)
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
260 movq RBX(%rsp), %rbx
261
262 movq ORIG_RAX(%rsp), %rax
263 movq %rax, MCOUNT_REG_SIZE-8(%rsp)
264
265 /*
266 * If ORIG_RAX is anything but zero, m
267 * See arch_ftrace_set_direct_caller()
268 */
269 testq %rax, %rax
270 SYM_INNER_LABEL(ftrace_regs_caller_jmp, SYM_L_
271 ANNOTATE_NOENDBR
272 jnz 1f
273
274 restore_mcount_regs
275 /* Restore flags */
276 popfq
277
278 /*
279 * The trampoline will add the return.
280 */
281 SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_
282 ANNOTATE_NOENDBR
283 RET
284
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
293 UNWIND_HINT_FUNC
294
295 /*
296 * The above left an extra return valu
297 * doing a tail-call without using a r
298 * pattern unbalances the RSB, inject
299 */
300 ANNOTATE_INTRA_FUNCTION_CALL
301 CALL .Ldo_rebalance
302 int3
303 .Ldo_rebalance:
304 add $8, %rsp
305 ALTERNATIVE __stringify(RET), \
306 __stringify(ANNOTATE_UNRET
307 X86_FEATURE_CALL_DEPTH
308
309 SYM_FUNC_END(ftrace_regs_caller)
310 STACK_FRAME_NON_STANDARD_FP(ftrace_regs_caller
311
312 SYM_FUNC_START(ftrace_stub_direct_tramp)
313 CALL_DEPTH_ACCOUNT
314 RET
315 SYM_FUNC_END(ftrace_stub_direct_tramp)
316
317 #else /* ! CONFIG_DYNAMIC_FTRACE */
318
319 SYM_FUNC_START(__fentry__)
320 CALL_DEPTH_ACCOUNT
321
322 cmpq $ftrace_stub, ftrace_trace_functi
323 jnz trace
324 RET
325
326 trace:
327 /* save_mcount_regs fills in first two
328 save_mcount_regs
329
330 /*
331 * When DYNAMIC_FTRACE is not defined,
332 * set (see include/asm/ftrace.h and i
333 * ip and parent ip are used and the l
334 * function tracing is enabled.
335 */
336 movq ftrace_trace_function, %r8
337 CALL_NOSPEC r8
338 restore_mcount_regs
339
340 jmp ftrace_stub
341 SYM_FUNC_END(__fentry__)
342 EXPORT_SYMBOL(__fentry__)
343 STACK_FRAME_NON_STANDARD_FP(__fentry__)
344
345 #endif /* CONFIG_DYNAMIC_FTRACE */
346
347 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
348 SYM_CODE_START(return_to_handler)
349 UNWIND_HINT_UNDEFINED
350 ANNOTATE_NOENDBR
351 subq $24, %rsp
352
353 /* Save the return values */
354 movq %rax, (%rsp)
355 movq %rdx, 8(%rsp)
356 movq %rbp, 16(%rsp)
357 movq %rsp, %rdi
358
359 call ftrace_return_to_handler
360
361 movq %rax, %rdi
362 movq 8(%rsp), %rdx
363 movq (%rsp), %rax
364
365 addq $24, %rsp
366 /*
367 * Jump back to the old return address
368 * since IBT would demand that contain
369 * return addresses. Use a retpoline h
370 */
371 ANNOTATE_INTRA_FUNCTION_CALL
372 call .Ldo_rop
373 int3
374 .Ldo_rop:
375 mov %rdi, (%rsp)
376 ALTERNATIVE __stringify(RET), \
377 __stringify(ANNOTATE_UNRET
378 X86_FEATURE_CALL_DEPTH
379 SYM_CODE_END(return_to_handler)
380 #endif
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