1  /* Copyright (C) 2007-2023 Free Software Foundation, Inc.
       2     This file is part of the GNU C Library.
       3  
       4     The GNU C Library is free software; you can redistribute it and/or
       5     modify it under the terms of the GNU Lesser General Public
       6     License as published by the Free Software Foundation; either
       7     version 2.1 of the License, or (at your option) any later version.
       8  
       9     The GNU C Library is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12     Lesser General Public License for more details.
      13  
      14     You should have received a copy of the GNU Lesser General Public
      15     License along with the GNU C Library; if not, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <errno.h>
      19  #include <sched.h>
      20  #include <sysdep.h>
      21  #include <sysdep-vdso.h>
      22  
      23  static int
      24  vsyscall_sched_getcpu (void)
      25  {
      26    unsigned int cpu;
      27    int r = -1;
      28  #ifdef HAVE_GETCPU_VSYSCALL
      29    r = INLINE_VSYSCALL (getcpu, 3, &cpu, NULL, NULL);
      30  #else
      31    r = INLINE_SYSCALL_CALL (getcpu, &cpu, NULL, NULL);
      32  #endif
      33    return r == -1 ? r : cpu;
      34  }
      35  
      36  #ifdef RSEQ_SIG
      37  int
      38  sched_getcpu (void)
      39  {
      40    int cpu_id = THREAD_GETMEM_VOLATILE (THREAD_SELF, rseq_area.cpu_id);
      41    return __glibc_likely (cpu_id >= 0) ? cpu_id : vsyscall_sched_getcpu ();
      42  }
      43  #else /* RSEQ_SIG */
      44  int
      45  sched_getcpu (void)
      46  {
      47    return vsyscall_sched_getcpu ();
      48  }
      49  #endif /* RSEQ_SIG */