tools/testing/selftests/rseq/rseq.h

   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 <linux/rseq.h>
  20
  21 /*
  22  * Empty code injection macros, override when testing.
  23  * It is important to consider that the ASM injection macros need to be
  24  * fully reentrant (e.g. do not modify the stack).
  25  */
  26 #ifndef RSEQ_INJECT_ASM
  27 #define RSEQ_INJECT_ASM(n)
  28 #endif
  29
  30 #ifndef RSEQ_INJECT_C
  31 #define RSEQ_INJECT_C(n)
  32 #endif
  33
  34 #ifndef RSEQ_INJECT_INPUT
  35 #define RSEQ_INJECT_INPUT
  36 #endif
  37
  38 #ifndef RSEQ_INJECT_CLOBBER
  39 #define RSEQ_INJECT_CLOBBER
  40 #endif
  41
  42 #ifndef RSEQ_INJECT_FAILED
  43 #define RSEQ_INJECT_FAILED
  44 #endif
  45
  46 extern __thread volatile struct rseq __rseq_abi;
  47
  48 #define rseq_likely(x)          __builtin_expect(!!(x), 1)
  49 #define rseq_unlikely(x)        __builtin_expect(!!(x), 0)
  50 #define rseq_barrier()          __asm__ __volatile__("" : : : "memory")
  51
  52 #define RSEQ_ACCESS_ONCE(x)     (*(__volatile__  __typeof__(x) *)&(x))
  53 #define RSEQ_WRITE_ONCE(x, v)   __extension__ ({ RSEQ_ACCESS_ONCE(x) = (v); })
  54 #define RSEQ_READ_ONCE(x)       RSEQ_ACCESS_ONCE(x)
  55
  56 #define __rseq_str_1(x) #x
  57 #define __rseq_str(x)           __rseq_str_1(x)
  58
  59 #define rseq_log(fmt, args...)                                                 \
  60         fprintf(stderr, fmt "(in %s() at " __FILE__ ":" __rseq_str(__LINE__)"\n", \
  61                 ## args, __func__)
  62
  63 #define rseq_bug(fmt, args...)          \
  64         do {                            \
  65                 rseq_log(fmt, ##args);  \
  66                 abort();                \
  67         } while (0)
  68
  69 #if defined(__x86_64__) || defined(__i386__)
  70 #include <rseq-x86.h>
  71 #elif defined(__ARMEL__)
  72 #include <rseq-arm.h>
  73 #elif defined (__AARCH64EL__)
  74 #include <rseq-arm64.h>
  75 #elif defined(__PPC__)
  76 #include <rseq-ppc.h>
  77 #elif defined(__mips__)
  78 #include <rseq-mips.h>
  79 #elif defined(__s390__)
  80 #include <rseq-s390.h>
  81 #else
  82 #error unsupported target
  83 #endif
  84
  85 /*
  86  * Register rseq for the current thread. This needs to be called once
  87  * by any thread which uses restartable sequences, before they start
  88  * using restartable sequences, to ensure restartable sequences
  89  * succeed. A restartable sequence executed from a non-registered
  90  * thread will always fail.
  91  */
  92 int rseq_register_current_thread(void);
  93
  94 /*
  95  * Unregister rseq for current thread.
  96  */
  97 int rseq_unregister_current_thread(void);
  98
  99 /*
 100  * Restartable sequence fallback for reading the current CPU number.
 101  */
 102 int32_t rseq_fallback_current_cpu(void);
 103
 104 /*
 105  * Values returned can be either the current CPU number, -1 (rseq is
 106  * uninitialized), or -2 (rseq initialization has failed).
 107  */
 108 static inline int32_t rseq_current_cpu_raw(void)
 109 {
 110         return RSEQ_ACCESS_ONCE(__rseq_abi.cpu_id);
 111 }
 112
 113 /*
 114  * Returns a possible CPU number, which is typically the current CPU.
 115  * The returned CPU number can be used to prepare for an rseq critical
 116  * section, which will confirm whether the cpu number is indeed the
 117  * current one, and whether rseq is initialized.
 118  *
 119  * The CPU number returned by rseq_cpu_start should always be validated
 120  * by passing it to a rseq asm sequence, or by comparing it to the
 121  * return value of rseq_current_cpu_raw() if the rseq asm sequence
 122  * does not need to be invoked.
 123  */
 124 static inline uint32_t rseq_cpu_start(void)
 125 {
 126         return RSEQ_ACCESS_ONCE(__rseq_abi.cpu_id_start);
 127 }
 128
 129 static inline uint32_t rseq_current_cpu(void)
 130 {
 131         int32_t cpu;
 132
 133         cpu = rseq_current_cpu_raw();
 134         if (rseq_unlikely(cpu < 0))
 135                 cpu = rseq_fallback_current_cpu();
 136         return cpu;
 137 }
 138
 139 static inline void rseq_clear_rseq_cs(void)
 140 {
 141 #ifdef __LP64__
 142         __rseq_abi.rseq_cs.ptr = 0;
 143 #else
 144         __rseq_abi.rseq_cs.ptr.ptr32 = 0;
 145 #endif
 146 }
 147
 148 /*
 149  * rseq_prepare_unload() should be invoked by each thread executing a rseq
 150  * critical section at least once between their last critical section and
 151  * library unload of the library defining the rseq critical section
 152  * (struct rseq_cs). This also applies to use of rseq in code generated by
 153  * JIT: rseq_prepare_unload() should be invoked at least once by each
 154  * thread executing a rseq critical section before reclaim of the memory
 155  * holding the struct rseq_cs.
 156  */
 157 static inline void rseq_prepare_unload(void)
 158 {
 159         rseq_clear_rseq_cs();
 160 }
 161
 162 #endif  /* RSEQ_H_ */