gdb/nat/riscv-linux-tdesc.c

   1 /* GNU/Linux/RISC-V native target description support for GDB.
   2    Copyright (C) 2020-2021 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 #include "gdbsupport/common-defs.h"
  20
  21 #include "gdb_proc_service.h"
  22 #include "arch/riscv.h"
  23 #include "elf/common.h"
  24 #include "nat/gdb_ptrace.h"
  25 #include "nat/riscv-linux-tdesc.h"
  26
  27 #include <sys/uio.h>
  28
  29 /* Work around glibc header breakage causing ELF_NFPREG not to be usable.  */
  30 #ifndef NFPREG
  31 # define NFPREG 33
  32 #endif
  33
  34 /* See nat/riscv-linux-tdesc.h.  */
  35
  36 struct riscv_gdbarch_features
  37 riscv_linux_read_features (int tid)
  38 {
  39   struct riscv_gdbarch_features features;
  40   elf_fpregset_t regs;
  41   int flen;
  42
  43   /* Figuring out xlen is easy.  */
  44   features.xlen = sizeof (elf_greg_t);
  45
  46   /* Start with no f-registers.  */
  47   features.flen = 0;
  48
  49   /* How much worth of f-registers can we fetch if any?  */
  50   for (flen = sizeof (regs.__f.__f[0]); ; flen *= 2)
  51     {
  52       size_t regset_size;
  53       struct iovec iov;
  54
  55       /* Regsets have a uniform slot size, so we count FSCR like
  56          an FP data register.  */
  57       regset_size = ELF_NFPREG * flen;
  58       if (regset_size > sizeof (regs))
  59         break;
  60
  61       iov.iov_base = &regs;
  62       iov.iov_len = regset_size;
  63       if (ptrace (PTRACE_GETREGSET, tid, NT_FPREGSET,
  64                   (PTRACE_TYPE_ARG3) &iov) == -1)
  65         {
  66           switch (errno)
  67             {
  68             case EINVAL:
  69               continue;
  70             case EIO:
  71               break;
  72             default:
  73               perror_with_name (_("Couldn't get registers"));
  74               break;
  75             }
  76         }
  77       else
  78         features.flen = flen;
  79       break;
  80     }
  81
  82   return features;
  83 }