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