sysdeps/powerpc/hwcapinfo.c

   1 /* powerpc HWCAP/HWCAP2 and AT_PLATFORM data pre-processing.
   2    Copyright (C) 2015-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <unistd.h>
  20 #include <shlib-compat.h>
  21 #include <dl-procinfo.h>
  22
  23 tcbhead_t __tcb __attribute__ ((visibility ("hidden")));
  24
  25 /* This function parses the HWCAP/HWCAP2 fields, adding the previous supported
  26    ISA bits, as well as converting the AT_PLATFORM string to a number.  This
  27    data is stored in two global variables that can be used later by the
  28    powerpc-specific code to store it into the TCB.  */
  29 void
  30 __tcb_parse_hwcap_and_convert_at_platform (void)
  31 {
  32
  33   uint64_t h1, h2;
  34
  35   /* Read AT_PLATFORM string from auxv and convert it to a number.  */
  36   __tcb.at_platform = _dl_string_platform (GLRO (dl_platform));
  37
  38   /* Read HWCAP and HWCAP2 from auxv.  */
  39   h1 = GLRO (dl_hwcap);
  40   h2 = GLRO (dl_hwcap2);
  41
  42   /* hwcap contains only the latest supported ISA, the code checks which is
  43      and fills the previous supported ones.  */
  44
  45   if (h2 & PPC_FEATURE2_ARCH_2_07)
  46     h1 |= PPC_FEATURE_ARCH_2_06
  47        | PPC_FEATURE_ARCH_2_05
  48        | PPC_FEATURE_POWER5_PLUS
  49        | PPC_FEATURE_POWER5
  50        | PPC_FEATURE_POWER4;
  51   else if (h1 & PPC_FEATURE_ARCH_2_06)
  52     h1 |= PPC_FEATURE_ARCH_2_05
  53        | PPC_FEATURE_POWER5_PLUS
  54        | PPC_FEATURE_POWER5
  55        | PPC_FEATURE_POWER4;
  56   else if (h1 & PPC_FEATURE_ARCH_2_05)
  57     h1 |= PPC_FEATURE_POWER5_PLUS
  58        | PPC_FEATURE_POWER5
  59        | PPC_FEATURE_POWER4;
  60   else if (h1 & PPC_FEATURE_POWER5_PLUS)
  61     h1 |= PPC_FEATURE_POWER5
  62        | PPC_FEATURE_POWER4;
  63   else if (h1 & PPC_FEATURE_POWER5)
  64     h1 |= PPC_FEATURE_POWER4;
  65
  66   /* Consolidate both HWCAP and HWCAP2 into a single doubleword so that
  67      we can read both in a single load later.  */
  68   __tcb.hwcap = (h1 << 32) | (h2 & 0xffffffff);
  69
  70 }
  71 #if IS_IN (rtld)
  72 versioned_symbol (ld, __tcb_parse_hwcap_and_convert_at_platform, \
  73                   __parse_hwcap_and_convert_at_platform, GLIBC_2_23);
  74 #endif
  75
  76 /* Export __parse_hwcap_and_convert_at_platform in libc.a.  This is used by
  77    GCC to make sure that the HWCAP/Platform bits are stored in the TCB when
  78    using __builtin_cpu_is()/__builtin_cpu_supports() in the static case.  */
  79 #ifndef SHARED
  80 weak_alias (__tcb_parse_hwcap_and_convert_at_platform, \
  81             __parse_hwcap_and_convert_at_platform);
  82 #endif