1 /* SPDX-License-Identifier: LGPL-2.1 OR MIT */
2 /*
3 * rseq.h
4 *
5 * (C) Copyright 2016-2018 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6 */
7
8 #ifndef RSEQ_H
9 #define RSEQ_H
10
11 #include <stdint.h>
12 #include <stdbool.h>
13 #include <pthread.h>
14 #include <signal.h>
15 #include <sched.h>
16 #include <errno.h>
17 #include <stdio.h>
18 #include <stdlib.h>
19 #include <stddef.h>
20 #include "rseq-abi.h"
21 #include "compiler.h"
22
23 #ifndef rseq_sizeof_field
24 #define rseq_sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
25 #endif
26
27 #ifndef rseq_offsetofend
28 #define rseq_offsetofend(TYPE, MEMBER) \
29 (offsetof(TYPE, MEMBER) + rseq_sizeof_field(TYPE, MEMBER))
30 #endif
31
32 /*
33 * Empty code injection macros, override when testing.
34 * It is important to consider that the ASM injection macros need to be
35 * fully reentrant (e.g. do not modify the stack).
36 */
37 #ifndef RSEQ_INJECT_ASM
38 #define RSEQ_INJECT_ASM(n)
39 #endif
40
41 #ifndef RSEQ_INJECT_C
42 #define RSEQ_INJECT_C(n)
43 #endif
44
45 #ifndef RSEQ_INJECT_INPUT
46 #define RSEQ_INJECT_INPUT
47 #endif
48
49 #ifndef RSEQ_INJECT_CLOBBER
50 #define RSEQ_INJECT_CLOBBER
51 #endif
52
53 #ifndef RSEQ_INJECT_FAILED
54 #define RSEQ_INJECT_FAILED
55 #endif
56
57 #include "rseq-thread-pointer.h"
58
59 /* Offset from the thread pointer to the rseq area. */
60 extern ptrdiff_t rseq_offset;
61
62 /*
63 * Size of the registered rseq area. 0 if the registration was
64 * unsuccessful.
65 */
66 extern unsigned int rseq_size;
67
68 /* Flags used during rseq registration. */
69 extern unsigned int rseq_flags;
70
71 enum rseq_mo {
72 RSEQ_MO_RELAXED = 0,
73 RSEQ_MO_CONSUME = 1, /* Unused */
74 RSEQ_MO_ACQUIRE = 2, /* Unused */
75 RSEQ_MO_RELEASE = 3,
76 RSEQ_MO_ACQ_REL = 4, /* Unused */
77 RSEQ_MO_SEQ_CST = 5, /* Unused */
78 };
79
80 enum rseq_percpu_mode {
81 RSEQ_PERCPU_CPU_ID = 0,
82 RSEQ_PERCPU_MM_CID = 1,
83 };
84
85 static inline struct rseq_abi *rseq_get_abi(void)
86 {
87 return (struct rseq_abi *) ((uintptr_t) rseq_thread_pointer() + rseq_offset);
88 }
89
90 #define rseq_likely(x) __builtin_expect(!!(x), 1)
91 #define rseq_unlikely(x) __builtin_expect(!!(x), 0)
92 #define rseq_barrier() __asm__ __volatile__("" : : : "memory")
93
94 #define RSEQ_ACCESS_ONCE(x) (*(__volatile__ __typeof__(x) *)&(x))
95 #define RSEQ_WRITE_ONCE(x, v) __extension__ ({ RSEQ_ACCESS_ONCE(x) = (v); })
96 #define RSEQ_READ_ONCE(x) RSEQ_ACCESS_ONCE(x)
97
98 #define __rseq_str_1(x) #x
99 #define __rseq_str(x) __rseq_str_1(x)
100
101 #define rseq_log(fmt, args...) \
102 fprintf(stderr, fmt "(in %s() at " __FILE__ ":" __rseq_str(__LINE__)"\n", \
103 ## args, __func__)
104
105 #define rseq_bug(fmt, args...) \
106 do { \
107 rseq_log(fmt, ##args); \
108 abort(); \
109 } while (0)
110
111 #if defined(__x86_64__) || defined(__i386__)
112 #include <rseq-x86.h>
113 #elif defined(__ARMEL__)
114 #include <rseq-arm.h>
115 #elif defined (__AARCH64EL__)
116 #include <rseq-arm64.h>
117 #elif defined(__PPC__)
118 #include <rseq-ppc.h>
119 #elif defined(__mips__)
120 #include <rseq-mips.h>
121 #elif defined(__s390__)
122 #include <rseq-s390.h>
123 #elif defined(__riscv)
124 #include <rseq-riscv.h>
125 #else
126 #error unsupported target
127 #endif
128
129 /*
130 * Register rseq for the current thread. This needs to be called once
131 * by any thread which uses restartable sequences, before they start
132 * using restartable sequences, to ensure restartable sequences
133 * succeed. A restartable sequence executed from a non-registered
134 * thread will always fail.
135 */
136 int rseq_register_current_thread(void);
137
138 /*
139 * Unregister rseq for current thread.
140 */
141 int rseq_unregister_current_thread(void);
142
143 /*
144 * Restartable sequence fallback for reading the current CPU number.
145 */
146 int32_t rseq_fallback_current_cpu(void);
147
148 /*
149 * Restartable sequence fallback for reading the current node number.
150 */
151 int32_t rseq_fallback_current_node(void);
152
153 /*
154 * Values returned can be either the current CPU number, -1 (rseq is
155 * uninitialized), or -2 (rseq initialization has failed).
156 */
157 static inline int32_t rseq_current_cpu_raw(void)
158 {
159 return RSEQ_ACCESS_ONCE(rseq_get_abi()->cpu_id);
160 }
161
162 /*
163 * Returns a possible CPU number, which is typically the current CPU.
164 * The returned CPU number can be used to prepare for an rseq critical
165 * section, which will confirm whether the cpu number is indeed the
166 * current one, and whether rseq is initialized.
167 *
168 * The CPU number returned by rseq_cpu_start should always be validated
169 * by passing it to a rseq asm sequence, or by comparing it to the
170 * return value of rseq_current_cpu_raw() if the rseq asm sequence
171 * does not need to be invoked.
172 */
173 static inline uint32_t rseq_cpu_start(void)
174 {
175 return RSEQ_ACCESS_ONCE(rseq_get_abi()->cpu_id_start);
176 }
177
178 static inline uint32_t rseq_current_cpu(void)
179 {
180 int32_t cpu;
181
182 cpu = rseq_current_cpu_raw();
183 if (rseq_unlikely(cpu < 0))
184 cpu = rseq_fallback_current_cpu();
185 return cpu;
186 }
187
188 static inline bool rseq_node_id_available(void)
189 {
190 return (int) rseq_size >= rseq_offsetofend(struct rseq_abi, node_id);
191 }
192
193 /*
194 * Current NUMA node number.
195 */
196 static inline uint32_t rseq_current_node_id(void)
197 {
198 assert(rseq_node_id_available());
199 return RSEQ_ACCESS_ONCE(rseq_get_abi()->node_id);
200 }
201
202 static inline bool rseq_mm_cid_available(void)
203 {
204 return (int) rseq_size >= rseq_offsetofend(struct rseq_abi, mm_cid);
205 }
206
207 static inline uint32_t rseq_current_mm_cid(void)
208 {
209 return RSEQ_ACCESS_ONCE(rseq_get_abi()->mm_cid);
210 }
211
212 static inline void rseq_clear_rseq_cs(void)
213 {
214 RSEQ_WRITE_ONCE(rseq_get_abi()->rseq_cs.arch.ptr, 0);
215 }
216
217 /*
218 * rseq_prepare_unload() should be invoked by each thread executing a rseq
219 * critical section at least once between their last critical section and
220 * library unload of the library defining the rseq critical section (struct
221 * rseq_cs) or the code referred to by the struct rseq_cs start_ip and
222 * post_commit_offset fields. This also applies to use of rseq in code
223 * generated by JIT: rseq_prepare_unload() should be invoked at least once by
224 * each thread executing a rseq critical section before reclaim of the memory
225 * holding the struct rseq_cs or reclaim of the code pointed to by struct
226 * rseq_cs start_ip and post_commit_offset fields.
227 */
228 static inline void rseq_prepare_unload(void)
229 {
230 rseq_clear_rseq_cs();
231 }
232
233 static inline __attribute__((always_inline))
234 int rseq_cmpeqv_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
235 intptr_t *v, intptr_t expect,
236 intptr_t newv, int cpu)
237 {
238 if (rseq_mo != RSEQ_MO_RELAXED)
239 return -1;
240 switch (percpu_mode) {
241 case RSEQ_PERCPU_CPU_ID:
242 return rseq_cmpeqv_storev_relaxed_cpu_id(v, expect, newv, cpu);
243 case RSEQ_PERCPU_MM_CID:
244 return rseq_cmpeqv_storev_relaxed_mm_cid(v, expect, newv, cpu);
245 }
246 return -1;
247 }
248
249 /*
250 * Compare @v against @expectnot. When it does _not_ match, load @v
251 * into @load, and store the content of *@v + voffp into @v.
252 */
253 static inline __attribute__((always_inline))
254 int rseq_cmpnev_storeoffp_load(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
255 intptr_t *v, intptr_t expectnot, long voffp, intptr_t *load,
256 int cpu)
257 {
258 if (rseq_mo != RSEQ_MO_RELAXED)
259 return -1;
260 switch (percpu_mode) {
261 case RSEQ_PERCPU_CPU_ID:
262 return rseq_cmpnev_storeoffp_load_relaxed_cpu_id(v, expectnot, voffp, load, cpu);
263 case RSEQ_PERCPU_MM_CID:
264 return rseq_cmpnev_storeoffp_load_relaxed_mm_cid(v, expectnot, voffp, load, cpu);
265 }
266 return -1;
267 }
268
269 static inline __attribute__((always_inline))
270 int rseq_addv(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
271 intptr_t *v, intptr_t count, int cpu)
272 {
273 if (rseq_mo != RSEQ_MO_RELAXED)
274 return -1;
275 switch (percpu_mode) {
276 case RSEQ_PERCPU_CPU_ID:
277 return rseq_addv_relaxed_cpu_id(v, count, cpu);
278 case RSEQ_PERCPU_MM_CID:
279 return rseq_addv_relaxed_mm_cid(v, count, cpu);
280 }
281 return -1;
282 }
283
284 #ifdef RSEQ_ARCH_HAS_OFFSET_DEREF_ADDV
285 /*
286 * pval = *(ptr+off)
287 * *pval += inc;
288 */
289 static inline __attribute__((always_inline))
290 int rseq_offset_deref_addv(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
291 intptr_t *ptr, long off, intptr_t inc, int cpu)
292 {
293 if (rseq_mo != RSEQ_MO_RELAXED)
294 return -1;
295 switch (percpu_mode) {
296 case RSEQ_PERCPU_CPU_ID:
297 return rseq_offset_deref_addv_relaxed_cpu_id(ptr, off, inc, cpu);
298 case RSEQ_PERCPU_MM_CID:
299 return rseq_offset_deref_addv_relaxed_mm_cid(ptr, off, inc, cpu);
300 }
301 return -1;
302 }
303 #endif
304
305 static inline __attribute__((always_inline))
306 int rseq_cmpeqv_trystorev_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
307 intptr_t *v, intptr_t expect,
308 intptr_t *v2, intptr_t newv2,
309 intptr_t newv, int cpu)
310 {
311 switch (rseq_mo) {
312 case RSEQ_MO_RELAXED:
313 switch (percpu_mode) {
314 case RSEQ_PERCPU_CPU_ID:
315 return rseq_cmpeqv_trystorev_storev_relaxed_cpu_id(v, expect, v2, newv2, newv, cpu);
316 case RSEQ_PERCPU_MM_CID:
317 return rseq_cmpeqv_trystorev_storev_relaxed_mm_cid(v, expect, v2, newv2, newv, cpu);
318 }
319 return -1;
320 case RSEQ_MO_RELEASE:
321 switch (percpu_mode) {
322 case RSEQ_PERCPU_CPU_ID:
323 return rseq_cmpeqv_trystorev_storev_release_cpu_id(v, expect, v2, newv2, newv, cpu);
324 case RSEQ_PERCPU_MM_CID:
325 return rseq_cmpeqv_trystorev_storev_release_mm_cid(v, expect, v2, newv2, newv, cpu);
326 }
327 return -1;
328 default:
329 return -1;
330 }
331 }
332
333 static inline __attribute__((always_inline))
334 int rseq_cmpeqv_cmpeqv_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
335 intptr_t *v, intptr_t expect,
336 intptr_t *v2, intptr_t expect2,
337 intptr_t newv, int cpu)
338 {
339 if (rseq_mo != RSEQ_MO_RELAXED)
340 return -1;
341 switch (percpu_mode) {
342 case RSEQ_PERCPU_CPU_ID:
343 return rseq_cmpeqv_cmpeqv_storev_relaxed_cpu_id(v, expect, v2, expect2, newv, cpu);
344 case RSEQ_PERCPU_MM_CID:
345 return rseq_cmpeqv_cmpeqv_storev_relaxed_mm_cid(v, expect, v2, expect2, newv, cpu);
346 }
347 return -1;
348 }
349
350 static inline __attribute__((always_inline))
351 int rseq_cmpeqv_trymemcpy_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
352 intptr_t *v, intptr_t expect,
353 void *dst, void *src, size_t len,
354 intptr_t newv, int cpu)
355 {
356 switch (rseq_mo) {
357 case RSEQ_MO_RELAXED:
358 switch (percpu_mode) {
359 case RSEQ_PERCPU_CPU_ID:
360 return rseq_cmpeqv_trymemcpy_storev_relaxed_cpu_id(v, expect, dst, src, len, newv, cpu);
361 case RSEQ_PERCPU_MM_CID:
362 return rseq_cmpeqv_trymemcpy_storev_relaxed_mm_cid(v, expect, dst, src, len, newv, cpu);
363 }
364 return -1;
365 case RSEQ_MO_RELEASE:
366 switch (percpu_mode) {
367 case RSEQ_PERCPU_CPU_ID:
368 return rseq_cmpeqv_trymemcpy_storev_release_cpu_id(v, expect, dst, src, len, newv, cpu);
369 case RSEQ_PERCPU_MM_CID:
370 return rseq_cmpeqv_trymemcpy_storev_release_mm_cid(v, expect, dst, src, len, newv, cpu);
371 }
372 return -1;
373 default:
374 return -1;
375 }
376 }
377
378 #endif /* RSEQ_H_ */
379
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