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1/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
2/*
3 * rseq.h
4 *
5 * (C) Copyright 2016-2018 - Mathieu Desnoyers <[email protected]>
6 */
7
8#ifndef RSEQ_H
9#define RSEQ_H
10
11#include <assert.h>
12#include <stdint.h>
13#include <stdbool.h>
14#include <pthread.h>
15#include <signal.h>
16#include <sched.h>
17#include <errno.h>
18#include <stdio.h>
19#include <stdlib.h>
20#include <stddef.h>
21#include "rseq-abi.h"
22#include "compiler.h"
23
24#ifndef rseq_sizeof_field
25#define rseq_sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
26#endif
27
28#ifndef rseq_offsetofend
29#define rseq_offsetofend(TYPE, MEMBER) \
30 (offsetof(TYPE, MEMBER) + rseq_sizeof_field(TYPE, MEMBER))
31#endif
32
33/*
34 * Empty code injection macros, override when testing.
35 * It is important to consider that the ASM injection macros need to be
36 * fully reentrant (e.g. do not modify the stack).
37 */
38#ifndef RSEQ_INJECT_ASM
39#define RSEQ_INJECT_ASM(n)
40#endif
41
42#ifndef RSEQ_INJECT_C
43#define RSEQ_INJECT_C(n)
44#endif
45
46#ifndef RSEQ_INJECT_INPUT
47#define RSEQ_INJECT_INPUT
48#endif
49
50#ifndef RSEQ_INJECT_CLOBBER
51#define RSEQ_INJECT_CLOBBER
52#endif
53
54#ifndef RSEQ_INJECT_FAILED
55#define RSEQ_INJECT_FAILED
56#endif
57
58#include "rseq-thread-pointer.h"
59
60/* Offset from the thread pointer to the rseq area. */
61extern ptrdiff_t rseq_offset;
62
63/*
64 * The rseq ABI is composed of extensible feature fields. The extensions
65 * are done by appending additional fields at the end of the structure.
66 * The rseq_size defines the size of the active feature set which can be
67 * used by the application for the current rseq registration. Features
68 * starting at offset >= rseq_size are inactive and should not be used.
69 *
70 * The rseq_size is the intersection between the available allocation
71 * size for the rseq area and the feature size supported by the kernel.
72 * unsuccessful.
73 */
74extern unsigned int rseq_size;
75
76/* Flags used during rseq registration. */
77extern unsigned int rseq_flags;
78
79enum rseq_mo {
80 RSEQ_MO_RELAXED = 0,
81 RSEQ_MO_CONSUME = 1, /* Unused */
82 RSEQ_MO_ACQUIRE = 2, /* Unused */
83 RSEQ_MO_RELEASE = 3,
84 RSEQ_MO_ACQ_REL = 4, /* Unused */
85 RSEQ_MO_SEQ_CST = 5, /* Unused */
86};
87
88enum rseq_percpu_mode {
89 RSEQ_PERCPU_CPU_ID = 0,
90 RSEQ_PERCPU_MM_CID = 1,
91};
92
93static inline struct rseq_abi *rseq_get_abi(void)
94{
95 return (struct rseq_abi *) ((uintptr_t) rseq_thread_pointer() + rseq_offset);
96}
97
98#define rseq_likely(x) __builtin_expect(!!(x), 1)
99#define rseq_unlikely(x) __builtin_expect(!!(x), 0)
100#define rseq_barrier() __asm__ __volatile__("" : : : "memory")
101
102#define RSEQ_ACCESS_ONCE(x) (*(__volatile__ __typeof__(x) *)&(x))
103#define RSEQ_WRITE_ONCE(x, v) __extension__ ({ RSEQ_ACCESS_ONCE(x) = (v); })
104#define RSEQ_READ_ONCE(x) RSEQ_ACCESS_ONCE(x)
105
106#define __rseq_str_1(x) #x
107#define __rseq_str(x) __rseq_str_1(x)
108
109#define rseq_log(fmt, args...) \
110 fprintf(stderr, fmt "(in %s() at " __FILE__ ":" __rseq_str(__LINE__)"\n", \
111 ## args, __func__)
112
113#define rseq_bug(fmt, args...) \
114 do { \
115 rseq_log(fmt, ##args); \
116 abort(); \
117 } while (0)
118
119#if defined(__x86_64__) || defined(__i386__)
120#include <rseq-x86.h>
121#elif defined(__ARMEL__)
122#include <rseq-arm.h>
123#elif defined (__AARCH64EL__)
124#include <rseq-arm64.h>
125#elif defined(__PPC__)
126#include <rseq-ppc.h>
127#elif defined(__mips__)
128#include <rseq-mips.h>
129#elif defined(__s390__)
130#include <rseq-s390.h>
131#elif defined(__riscv)
132#include <rseq-riscv.h>
133#elif defined(__or1k__)
134#include <rseq-or1k.h>
135#else
136#error unsupported target
137#endif
138
139/*
140 * Register rseq for the current thread. This needs to be called once
141 * by any thread which uses restartable sequences, before they start
142 * using restartable sequences, to ensure restartable sequences
143 * succeed. A restartable sequence executed from a non-registered
144 * thread will always fail.
145 */
146int __rseq_register_current_thread(bool nolibc, bool legacy);
147
148static inline int rseq_register_current_thread(void)
149{
150 return __rseq_register_current_thread(false, false);
151}
152
153/*
154 * Unregister rseq for current thread.
155 */
156int rseq_unregister_current_thread(void);
157
158/*
159 * Restartable sequence fallback for reading the current CPU number.
160 */
161int32_t rseq_fallback_current_cpu(void);
162
163/*
164 * Restartable sequence fallback for reading the current node number.
165 */
166int32_t rseq_fallback_current_node(void);
167
168/*
169 * Returns true if rseq is supported.
170 */
171bool rseq_available(void);
172
173/*
174 * Values returned can be either the current CPU number, -1 (rseq is
175 * uninitialized), or -2 (rseq initialization has failed).
176 */
177static inline int32_t rseq_current_cpu_raw(void)
178{
179 return RSEQ_ACCESS_ONCE(rseq_get_abi()->cpu_id);
180}
181
182/*
183 * Returns a possible CPU number, which is typically the current CPU.
184 * The returned CPU number can be used to prepare for an rseq critical
185 * section, which will confirm whether the cpu number is indeed the
186 * current one, and whether rseq is initialized.
187 *
188 * The CPU number returned by rseq_cpu_start should always be validated
189 * by passing it to a rseq asm sequence, or by comparing it to the
190 * return value of rseq_current_cpu_raw() if the rseq asm sequence
191 * does not need to be invoked.
192 */
193static inline uint32_t rseq_cpu_start(void)
194{
195 return RSEQ_ACCESS_ONCE(rseq_get_abi()->cpu_id_start);
196}
197
198static inline uint32_t rseq_current_cpu(void)
199{
200 int32_t cpu;
201
202 cpu = rseq_current_cpu_raw();
203 if (rseq_unlikely(cpu < 0))
204 cpu = rseq_fallback_current_cpu();
205 return cpu;
206}
207
208static inline bool rseq_node_id_available(void)
209{
210 return (int) rseq_size >= rseq_offsetofend(struct rseq_abi, node_id);
211}
212
213/*
214 * Current NUMA node number.
215 */
216static inline uint32_t rseq_current_node_id(void)
217{
218 assert(rseq_node_id_available());
219 return RSEQ_ACCESS_ONCE(rseq_get_abi()->node_id);
220}
221
222static inline bool rseq_mm_cid_available(void)
223{
224 return (int) rseq_size >= rseq_offsetofend(struct rseq_abi, mm_cid);
225}
226
227static inline uint32_t rseq_current_mm_cid(void)
228{
229 return RSEQ_ACCESS_ONCE(rseq_get_abi()->mm_cid);
230}
231
232static inline void rseq_clear_rseq_cs(void)
233{
234 RSEQ_WRITE_ONCE(rseq_get_abi()->rseq_cs.arch.ptr, 0);
235}
236
237/*
238 * rseq_prepare_unload() should be invoked by each thread executing a rseq
239 * critical section at least once between their last critical section and
240 * library unload of the library defining the rseq critical section (struct
241 * rseq_cs) or the code referred to by the struct rseq_cs start_ip and
242 * post_commit_offset fields. This also applies to use of rseq in code
243 * generated by JIT: rseq_prepare_unload() should be invoked at least once by
244 * each thread executing a rseq critical section before reclaim of the memory
245 * holding the struct rseq_cs or reclaim of the code pointed to by struct
246 * rseq_cs start_ip and post_commit_offset fields.
247 */
248static inline void rseq_prepare_unload(void)
249{
250 rseq_clear_rseq_cs();
251}
252
253static inline __attribute__((always_inline))
254int rseq_cmpeqv_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
255 intptr_t *v, intptr_t expect,
256 intptr_t newv, 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_cmpeqv_storev_relaxed_cpu_id(v, expect, newv, cpu);
263 case RSEQ_PERCPU_MM_CID:
264 return rseq_cmpeqv_storev_relaxed_mm_cid(v, expect, newv, cpu);
265 }
266 return -1;
267}
268
269/*
270 * Compare @v against @expectnot. When it does _not_ match, load @v
271 * into @load, and store the content of *@v + voffp into @v.
272 */
273static inline __attribute__((always_inline))
274int rseq_cmpnev_storeoffp_load(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
275 intptr_t *v, intptr_t expectnot, long voffp, intptr_t *load,
276 int cpu)
277{
278 if (rseq_mo != RSEQ_MO_RELAXED)
279 return -1;
280 switch (percpu_mode) {
281 case RSEQ_PERCPU_CPU_ID:
282 return rseq_cmpnev_storeoffp_load_relaxed_cpu_id(v, expectnot, voffp, load, cpu);
283 case RSEQ_PERCPU_MM_CID:
284 return rseq_cmpnev_storeoffp_load_relaxed_mm_cid(v, expectnot, voffp, load, cpu);
285 }
286 return -1;
287}
288
289static inline __attribute__((always_inline))
290int rseq_addv(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
291 intptr_t *v, intptr_t count, 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_addv_relaxed_cpu_id(v, count, cpu);
298 case RSEQ_PERCPU_MM_CID:
299 return rseq_addv_relaxed_mm_cid(v, count, cpu);
300 }
301 return -1;
302}
303
304#ifdef RSEQ_ARCH_HAS_OFFSET_DEREF_ADDV
305/*
306 * pval = *(ptr+off)
307 * *pval += inc;
308 */
309static inline __attribute__((always_inline))
310int rseq_offset_deref_addv(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
311 intptr_t *ptr, long off, intptr_t inc, int cpu)
312{
313 if (rseq_mo != RSEQ_MO_RELAXED)
314 return -1;
315 switch (percpu_mode) {
316 case RSEQ_PERCPU_CPU_ID:
317 return rseq_offset_deref_addv_relaxed_cpu_id(ptr, off, inc, cpu);
318 case RSEQ_PERCPU_MM_CID:
319 return rseq_offset_deref_addv_relaxed_mm_cid(ptr, off, inc, cpu);
320 }
321 return -1;
322}
323#endif
324
325static inline __attribute__((always_inline))
326int rseq_cmpeqv_trystorev_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
327 intptr_t *v, intptr_t expect,
328 intptr_t *v2, intptr_t newv2,
329 intptr_t newv, int cpu)
330{
331 switch (rseq_mo) {
332 case RSEQ_MO_RELAXED:
333 switch (percpu_mode) {
334 case RSEQ_PERCPU_CPU_ID:
335 return rseq_cmpeqv_trystorev_storev_relaxed_cpu_id(v, expect, v2, newv2, newv, cpu);
336 case RSEQ_PERCPU_MM_CID:
337 return rseq_cmpeqv_trystorev_storev_relaxed_mm_cid(v, expect, v2, newv2, newv, cpu);
338 }
339 return -1;
340 case RSEQ_MO_RELEASE:
341 switch (percpu_mode) {
342 case RSEQ_PERCPU_CPU_ID:
343 return rseq_cmpeqv_trystorev_storev_release_cpu_id(v, expect, v2, newv2, newv, cpu);
344 case RSEQ_PERCPU_MM_CID:
345 return rseq_cmpeqv_trystorev_storev_release_mm_cid(v, expect, v2, newv2, newv, cpu);
346 }
347 return -1;
348 default:
349 return -1;
350 }
351}
352
353static inline __attribute__((always_inline))
354int rseq_cmpeqv_cmpeqv_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
355 intptr_t *v, intptr_t expect,
356 intptr_t *v2, intptr_t expect2,
357 intptr_t newv, int cpu)
358{
359 if (rseq_mo != RSEQ_MO_RELAXED)
360 return -1;
361 switch (percpu_mode) {
362 case RSEQ_PERCPU_CPU_ID:
363 return rseq_cmpeqv_cmpeqv_storev_relaxed_cpu_id(v, expect, v2, expect2, newv, cpu);
364 case RSEQ_PERCPU_MM_CID:
365 return rseq_cmpeqv_cmpeqv_storev_relaxed_mm_cid(v, expect, v2, expect2, newv, cpu);
366 }
367 return -1;
368}
369
370static inline __attribute__((always_inline))
371int rseq_cmpeqv_trymemcpy_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
372 intptr_t *v, intptr_t expect,
373 void *dst, void *src, size_t len,
374 intptr_t newv, int cpu)
375{
376 switch (rseq_mo) {
377 case RSEQ_MO_RELAXED:
378 switch (percpu_mode) {
379 case RSEQ_PERCPU_CPU_ID:
380 return rseq_cmpeqv_trymemcpy_storev_relaxed_cpu_id(v, expect, dst, src, len, newv, cpu);
381 case RSEQ_PERCPU_MM_CID:
382 return rseq_cmpeqv_trymemcpy_storev_relaxed_mm_cid(v, expect, dst, src, len, newv, cpu);
383 }
384 return -1;
385 case RSEQ_MO_RELEASE:
386 switch (percpu_mode) {
387 case RSEQ_PERCPU_CPU_ID:
388 return rseq_cmpeqv_trymemcpy_storev_release_cpu_id(v, expect, dst, src, len, newv, cpu);
389 case RSEQ_PERCPU_MM_CID:
390 return rseq_cmpeqv_trymemcpy_storev_release_mm_cid(v, expect, dst, src, len, newv, cpu);
391 }
392 return -1;
393 default:
394 return -1;
395 }
396}
397
398#endif /* RSEQ_H_ */