libatomic/config/linux/aarch64/host-config.h

   1 /* Copyright (C) 2017-2023 Free Software Foundation, Inc.
   2
   3    This file is part of the GNU Atomic Library (libatomic).
   4
   5    Libatomic is free software; you can redistribute it and/or modify it
   6    under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    Libatomic is distributed in the hope that it will be useful, but WITHOUT ANY
  11    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  12    FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13    more details.
  14
  15    Under Section 7 of GPL version 3, you are granted additional
  16    permissions described in the GCC Runtime Library Exception, version
  17    3.1, as published by the Free Software Foundation.
  18
  19    You should have received a copy of the GNU General Public License and
  20    a copy of the GCC Runtime Library Exception along with this program;
  21    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  22    <http://www.gnu.org/licenses/>.  */
  23
  24 #if HAVE_IFUNC
  25 #include <sys/auxv.h>
  26
  27 #ifdef HWCAP_USCAT
  28 # if N == 16
  29 #  define IFUNC_COND_1  ifunc1 (hwcap)
  30 # else
  31 #  define IFUNC_COND_1  (hwcap & HWCAP_ATOMICS)
  32 # endif
  33 #else
  34 #  define IFUNC_COND_1  (false)
  35 #endif
  36 #define IFUNC_NCOND(N)  (1)
  37
  38 #endif /* HAVE_IFUNC */
  39
  40 /* All 128-bit atomic functions are defined in aarch64/atomic_16.S.  */
  41 #if N == 16
  42 # define DONE 1
  43 #endif
  44
  45 #ifdef HWCAP_USCAT
  46
  47 #define MIDR_IMPLEMENTOR(midr)  (((midr) >> 24) & 255)
  48 #define MIDR_PARTNUM(midr)      (((midr) >> 4) & 0xfff)
  49
  50 static inline bool
  51 ifunc1 (unsigned long hwcap)
  52 {
  53   if (hwcap & HWCAP_USCAT)
  54     return true;
  55   if (!(hwcap & HWCAP_CPUID))
  56     return false;
  57
  58   unsigned long midr;
  59   asm volatile ("mrs %0, midr_el1" : "=r" (midr));
  60
  61   /* Neoverse N1 supports atomic 128-bit load/store.  */
  62   if (MIDR_IMPLEMENTOR (midr) == 'A' && MIDR_PARTNUM (midr) == 0xd0c)
  63     return true;
  64
  65   return false;
  66 }
  67 #endif
  68
  69 #include_next <host-config.h>