libringbuffer/rseq.c

   1 /*
   2  * rseq.c
   3  *
   4  * Copyright (C) 2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; only
   9  * version 2.1 of the License.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14  * Lesser General Public License for more details.
  15  */
  16
  17 #define _GNU_SOURCE
  18 #include <errno.h>
  19 #include <sched.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24 #include <syscall.h>
  25 #include <assert.h>
  26 #include <signal.h>
  27
  28 #include <rseq.h>
  29
  30 __attribute__((weak)) __thread volatile struct rseq __rseq_abi = {
  31         .u.e.cpu_id = -1,
  32 };
  33
  34 static int sys_rseq(volatile struct rseq *rseq_abi, int flags)
  35 {
  36         return syscall(__NR_rseq, rseq_abi, flags);
  37 }
  38
  39 static void signal_off_save(sigset_t *oldset)
  40 {
  41         sigset_t set;
  42         int ret;
  43
  44         sigfillset(&set);
  45         ret = pthread_sigmask(SIG_BLOCK, &set, oldset);
  46         if (ret)
  47                 abort();
  48 }
  49
  50 static void signal_restore(sigset_t oldset)
  51 {
  52         int ret;
  53
  54         ret = pthread_sigmask(SIG_SETMASK, &oldset, NULL);
  55         if (ret)
  56                 abort();
  57 }
  58
  59 int rseq_register_current_thread(void)
  60 {
  61         int rc;
  62
  63         rc = sys_rseq(&__rseq_abi, 0);
  64         if (rc) {
  65                 fprintf(stderr, "Error: sys_rseq(...) failed(%d): %s\n",
  66                         errno, strerror(errno));
  67                 return -1;
  68         }
  69         assert(rseq_current_cpu() >= 0);
  70         return 0;
  71 }
  72
  73 int rseq_unregister_current_thread(void)
  74 {
  75         int rc;
  76
  77         rc = sys_rseq(NULL, 0);
  78         if (rc) {
  79                 fprintf(stderr, "Error: sys_rseq(...) failed(%d): %s\n",
  80                         errno, strerror(errno));
  81                 return -1;
  82         }
  83         return 0;
  84 }