gdb/nat/riscv-linux-tdesc.c

   1 /* GNU/Linux/RISC-V native target description support for GDB.
   2    Copyright (C) 2020-2024 Free Software Foundation, Inc.
   3
   4    This file is part of GDB.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19
  20 #include "gdb_proc_service.h"
  21 #include "arch/riscv.h"
  22 #include "elf/common.h"
  23 #include "nat/gdb_ptrace.h"
  24 #include "nat/riscv-linux-tdesc.h"
  25
  26 #include <sys/uio.h>
  27
  28 /* Work around glibc header breakage causing ELF_NFPREG not to be usable.  */
  29 #ifndef NFPREG
  30 # define NFPREG 33
  31 #endif
  32
  33 /* See nat/riscv-linux-tdesc.h.  */
  34
  35 struct riscv_gdbarch_features
  36 riscv_linux_read_features (int tid)
  37 {
  38   struct riscv_gdbarch_features features;
  39   elf_fpregset_t regs;
  40   int flen;
  41
  42   /* Figuring out xlen is easy.  */
  43   features.xlen = sizeof (elf_greg_t);
  44
  45   /* Start with no f-registers.  */
  46   features.flen = 0;
  47
  48   /* How much worth of f-registers can we fetch if any?  */
  49   for (flen = sizeof (regs.__f.__f[0]); ; flen *= 2)
  50     {
  51       size_t regset_size;
  52       struct iovec iov;
  53
  54       /* Regsets have a uniform slot size, so we count FSCR like
  55          an FP data register.  */
  56       regset_size = ELF_NFPREG * flen;
  57       if (regset_size > sizeof (regs))
  58         break;
  59
  60       iov.iov_base = &regs;
  61       iov.iov_len = regset_size;
  62       if (ptrace (PTRACE_GETREGSET, tid, NT_FPREGSET,
  63                   (PTRACE_TYPE_ARG3) &iov) == -1)
  64         {
  65           switch (errno)
  66             {
  67             case EINVAL:
  68               continue;
  69             case EIO:
  70               break;
  71             default:
  72               perror_with_name (_("Couldn't get registers"));
  73               break;
  74             }
  75         }
  76       else
  77         features.flen = flen;
  78       break;
  79     }
  80
  81   return features;
  82 }