gdb/nat/ppc-linux.c

   1 /*Copyright (C) 2015-2024 Free Software Foundation, Inc.
   2
   3    This file is part of GDB.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it 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    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #include "ppc-linux.h"
  19 #include "nat/gdb_ptrace.h"
  20 #include <elf.h>
  21
  22 #ifdef HAVE_GETAUXVAL
  23 #include <sys/auxv.h>
  24 #endif
  25
  26 #ifdef __powerpc64__
  27
  28 /* Get the HWCAP from the process of GDB or GDBserver.  If success,
  29    save it in *VALP.   */
  30
  31 static void
  32 ppc64_host_hwcap (unsigned long *valp)
  33 {
  34 #ifdef HAVE_GETAUXVAL
  35   *valp = getauxval (AT_HWCAP);
  36 #else
  37   unsigned long data[2];
  38   FILE *f = fopen ("/proc/self/auxv", "r");
  39
  40   if (f == NULL)
  41     return;
  42
  43   while (fread (data, sizeof (data), 1, f) > 0)
  44     {
  45       if (data[0] == AT_HWCAP)
  46         {
  47           *valp = data[1];
  48           break;
  49         }
  50     }
  51
  52   fclose (f);
  53 #endif /* HAVE_GETAUXVAL */
  54 }
  55
  56 static inline int
  57 ppc64_64bit_inferior_p (long msr)
  58 {
  59   unsigned long ppc_host_hwcap = 0;
  60
  61   /* Get host's HWCAP to check whether the machine is Book E.  */
  62   ppc64_host_hwcap (&ppc_host_hwcap);
  63
  64   /* We actually have a 64-bit inferior only if the certain bit of the
  65      MSR is set.  The PowerISA Book III-S MSR is different from the
  66      PowerISA Book III-E MSR.  The Book III-S MSR is 64 bits wide, and
  67      its MSR[SF] is the bit 0 of a 64-bit value.  Book III-E MSR is 32
  68      bits wide, and its MSR[CM] is the bit 0 of a 32-bit value.   */
  69   if (ppc_host_hwcap & PPC_FEATURE_BOOKE)
  70     return msr & 0x80000000;
  71   else
  72     return msr < 0;
  73 }
  74
  75 #endif
  76
  77 int
  78 ppc_linux_target_wordsize (int tid)
  79 {
  80   gdb_assert (tid != 0);
  81
  82   int wordsize = 4;
  83
  84   /* Check for 64-bit inferior process.  This is the case when the host is
  85      64-bit, and in addition the top bit of the MSR register is set.  */
  86 #ifdef __powerpc64__
  87   long msr;
  88
  89   errno = 0;
  90   msr = (long) ptrace (PTRACE_PEEKUSER, tid, PT_MSR * 8, 0);
  91   if (errno == 0 && ppc64_64bit_inferior_p (msr))
  92     wordsize = 8;
  93 #endif
  94
  95   return wordsize;
  96 }