gdb/riscv-linux-nat.c

   1 /* Native-dependent code for GNU/Linux RISC-V.
   2    Copyright (C) 2018-2019 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 "defs.h"
  20 #include "regcache.h"
  21 #include "gregset.h"
  22 #include "linux-nat.h"
  23 #include "riscv-tdep.h"
  24 #include "inferior.h"
  25 #include "target-descriptions.h"
  26
  27 #include "elf/common.h"
  28
  29 #include <sys/ptrace.h>
  30
  31 /* RISC-V Linux native additions to the default linux support.  */
  32
  33 class riscv_linux_nat_target final : public linux_nat_target
  34 {
  35 public:
  36   /* Add our register access methods.  */
  37   void fetch_registers (struct regcache *regcache, int regnum) override;
  38   void store_registers (struct regcache *regcache, int regnum) override;
  39
  40   /* Read suitable target description.  */
  41   const struct target_desc *read_description () override;
  42 };
  43
  44 static riscv_linux_nat_target the_riscv_linux_nat_target;
  45
  46 /* Copy general purpose register REGNUM (or all gp regs if REGNUM == -1)
  47    from regset GREGS into REGCACHE.  */
  48
  49 static void
  50 supply_gregset_regnum (struct regcache *regcache, const prgregset_t *gregs,
  51                        int regnum)
  52 {
  53   int i;
  54   const elf_greg_t *regp = *gregs;
  55
  56   if (regnum == -1)
  57     {
  58       /* We only support the integer registers and PC here.  */
  59       for (i = RISCV_ZERO_REGNUM + 1; i < RISCV_PC_REGNUM; i++)
  60         regcache->raw_supply (i, regp + i);
  61
  62       /* GDB stores PC in reg 32.  Linux kernel stores it in reg 0.  */
  63       regcache->raw_supply (32, regp + 0);
  64
  65       /* Fill the inaccessible zero register with zero.  */
  66       regcache->raw_supply_zeroed (0);
  67     }
  68   else if (regnum == RISCV_ZERO_REGNUM)
  69     regcache->raw_supply_zeroed (0);
  70   else if (regnum > RISCV_ZERO_REGNUM && regnum < RISCV_PC_REGNUM)
  71     regcache->raw_supply (regnum, regp + regnum);
  72   else if (regnum == RISCV_PC_REGNUM)
  73     regcache->raw_supply (32, regp + 0);
  74 }
  75
  76 /* Copy all general purpose registers from regset GREGS into REGCACHE.  */
  77
  78 void
  79 supply_gregset (struct regcache *regcache, const prgregset_t *gregs)
  80 {
  81   supply_gregset_regnum (regcache, gregs, -1);
  82 }
  83
  84 /* Copy floating point register REGNUM (or all fp regs if REGNUM == -1)
  85    from regset FPREGS into REGCACHE.  */
  86
  87 static void
  88 supply_fpregset_regnum (struct regcache *regcache, const prfpregset_t *fpregs,
  89                         int regnum)
  90 {
  91   int i;
  92
  93   if (regnum == -1)
  94     {
  95       /* We only support the FP registers and FCSR here.  */
  96       for (i = RISCV_FIRST_FP_REGNUM; i <= RISCV_LAST_FP_REGNUM; i++)
  97         regcache->raw_supply (i, &fpregs->__d.__f[i - RISCV_FIRST_FP_REGNUM]);
  98
  99       regcache->raw_supply (RISCV_CSR_FCSR_REGNUM, &fpregs->__d.__fcsr);
 100     }
 101   else if (regnum >= RISCV_FIRST_FP_REGNUM && regnum <= RISCV_LAST_FP_REGNUM)
 102     regcache->raw_supply (regnum,
 103                           &fpregs->__d.__f[regnum - RISCV_FIRST_FP_REGNUM]);
 104   else if (regnum == RISCV_CSR_FCSR_REGNUM)
 105     regcache->raw_supply (RISCV_CSR_FCSR_REGNUM, &fpregs->__d.__fcsr);
 106 }
 107
 108 /* Copy all floating point registers from regset FPREGS into REGCACHE.  */
 109
 110 void
 111 supply_fpregset (struct regcache *regcache, const prfpregset_t *fpregs)
 112 {
 113   supply_fpregset_regnum (regcache, fpregs, -1);
 114 }
 115
 116 /* Copy general purpose register REGNUM (or all gp regs if REGNUM == -1)
 117    from REGCACHE into regset GREGS.  */
 118
 119 void
 120 fill_gregset (const struct regcache *regcache, prgregset_t *gregs, int regnum)
 121 {
 122   elf_greg_t *regp = *gregs;
 123
 124   if (regnum == -1)
 125     {
 126       /* We only support the integer registers and PC here.  */
 127       for (int i = RISCV_ZERO_REGNUM + 1; i < RISCV_PC_REGNUM; i++)
 128         regcache->raw_collect (i, regp + i);
 129
 130       regcache->raw_collect (32, regp + 0);
 131     }
 132   else if (regnum == RISCV_ZERO_REGNUM)
 133     /* Nothing to do here.  */
 134     ;
 135   else if (regnum > RISCV_ZERO_REGNUM && regnum < RISCV_PC_REGNUM)
 136     regcache->raw_collect (regnum, regp + regnum);
 137   else if (regnum == RISCV_PC_REGNUM)
 138     regcache->raw_collect (32, regp + 0);
 139 }
 140
 141 /* Copy floating point register REGNUM (or all fp regs if REGNUM == -1)
 142    from REGCACHE into regset FPREGS.  */
 143
 144 void
 145 fill_fpregset (const struct regcache *regcache, prfpregset_t *fpregs,
 146                int regnum)
 147 {
 148   if (regnum == -1)
 149     {
 150       /* We only support the FP registers and FCSR here.  */
 151       for (int i = RISCV_FIRST_FP_REGNUM; i <= RISCV_LAST_FP_REGNUM; i++)
 152         regcache->raw_collect (i, &fpregs->__d.__f[i - RISCV_FIRST_FP_REGNUM]);
 153
 154       regcache->raw_collect (RISCV_CSR_FCSR_REGNUM, &fpregs->__d.__fcsr);
 155     }
 156   else if (regnum >= RISCV_FIRST_FP_REGNUM && regnum <= RISCV_LAST_FP_REGNUM)
 157     regcache->raw_collect (regnum,
 158                            &fpregs->__d.__f[regnum - RISCV_FIRST_FP_REGNUM]);
 159   else if (regnum == RISCV_CSR_FCSR_REGNUM)
 160     regcache->raw_collect (RISCV_CSR_FCSR_REGNUM, &fpregs->__d.__fcsr);
 161 }
 162
 163 /* Return a target description for the current target.  */
 164
 165 const struct target_desc *
 166 riscv_linux_nat_target::read_description ()
 167 {
 168   struct riscv_gdbarch_features features;
 169   struct iovec iov;
 170   elf_fpregset_t regs;
 171   int tid;
 172
 173   /* Figuring out xlen is easy.  */
 174   features.xlen = sizeof (elf_greg_t);
 175
 176   tid = inferior_ptid.lwp ();
 177
 178   iov.iov_base = &regs;
 179   iov.iov_len = sizeof (regs);
 180
 181   /* Can we fetch the f-registers?  */
 182   if (ptrace (PTRACE_GETREGSET, tid, NT_FPREGSET,
 183               (PTRACE_TYPE_ARG3) &iov) == -1)
 184     features.flen = 0;          /* No f-registers.  */
 185   else
 186     {
 187       /* TODO: We need a way to figure out the actual length of the
 188          f-registers.  We could have 64-bit x-registers, with 32-bit
 189          f-registers.  For now, just assumed xlen and flen match.  */
 190       features.flen = features.xlen;
 191     }
 192
 193   return riscv_create_target_description (features);
 194 }
 195
 196 /* Fetch REGNUM (or all registers if REGNUM == -1) from the target
 197    into REGCACHE using PTRACE_GETREGSET.  */
 198
 199 void
 200 riscv_linux_nat_target::fetch_registers (struct regcache *regcache, int regnum)
 201 {
 202   int tid;
 203
 204   tid = get_ptrace_pid (regcache->ptid());
 205
 206   if ((regnum >= RISCV_ZERO_REGNUM && regnum <= RISCV_PC_REGNUM)
 207       || (regnum == -1))
 208     {
 209       struct iovec iov;
 210       elf_gregset_t regs;
 211
 212       iov.iov_base = &regs;
 213       iov.iov_len = sizeof (regs);
 214
 215       if (ptrace (PTRACE_GETREGSET, tid, NT_PRSTATUS,
 216                   (PTRACE_TYPE_ARG3) &iov) == -1)
 217         perror_with_name (_("Couldn't get registers"));
 218       else
 219         supply_gregset_regnum (regcache, &regs, regnum);
 220     }
 221
 222   if ((regnum >= RISCV_FIRST_FP_REGNUM
 223        && regnum <= RISCV_LAST_FP_REGNUM)
 224       || (regnum == RISCV_CSR_FCSR_REGNUM)
 225       || (regnum == -1))
 226     {
 227       struct iovec iov;
 228       elf_fpregset_t regs;
 229
 230       iov.iov_base = &regs;
 231       iov.iov_len = sizeof (regs);
 232
 233       if (ptrace (PTRACE_GETREGSET, tid, NT_FPREGSET,
 234                   (PTRACE_TYPE_ARG3) &iov) == -1)
 235         perror_with_name (_("Couldn't get registers"));
 236       else
 237         supply_fpregset_regnum (regcache, &regs, regnum);
 238     }
 239
 240   if ((regnum == RISCV_CSR_MISA_REGNUM)
 241       || (regnum == -1))
 242     {
 243       /* TODO: Need to add a ptrace call for this.  */
 244       regcache->raw_supply_zeroed (RISCV_CSR_MISA_REGNUM);
 245     }
 246
 247   /* Access to other CSRs has potential security issues, don't support them for
 248      now.  */
 249 }
 250
 251 /* Store REGNUM (or all registers if REGNUM == -1) to the target
 252    from REGCACHE using PTRACE_SETREGSET.  */
 253
 254 void
 255 riscv_linux_nat_target::store_registers (struct regcache *regcache, int regnum)
 256 {
 257   int tid;
 258
 259   tid = get_ptrace_pid (regcache->ptid ());
 260
 261   if ((regnum >= RISCV_ZERO_REGNUM && regnum <= RISCV_PC_REGNUM)
 262       || (regnum == -1))
 263     {
 264       struct iovec iov;
 265       elf_gregset_t regs;
 266
 267       iov.iov_base = &regs;
 268       iov.iov_len = sizeof (regs);
 269
 270       if (ptrace (PTRACE_GETREGSET, tid, NT_PRSTATUS,
 271                   (PTRACE_TYPE_ARG3) &iov) == -1)
 272         perror_with_name (_("Couldn't get registers"));
 273       else
 274         {
 275           fill_gregset (regcache, &regs, regnum);
 276
 277           if (ptrace (PTRACE_SETREGSET, tid, NT_PRSTATUS,
 278                       (PTRACE_TYPE_ARG3) &iov) == -1)
 279             perror_with_name (_("Couldn't set registers"));
 280         }
 281     }
 282
 283   if ((regnum >= RISCV_FIRST_FP_REGNUM
 284        && regnum <= RISCV_LAST_FP_REGNUM)
 285       || (regnum == RISCV_CSR_FCSR_REGNUM)
 286       || (regnum == -1))
 287     {
 288       struct iovec iov;
 289       elf_fpregset_t regs;
 290
 291       iov.iov_base = &regs;
 292       iov.iov_len = sizeof (regs);
 293
 294       if (ptrace (PTRACE_GETREGSET, tid, NT_FPREGSET,
 295                   (PTRACE_TYPE_ARG3) &iov) == -1)
 296         perror_with_name (_("Couldn't get registers"));
 297       else
 298         {
 299           fill_fpregset (regcache, &regs, regnum);
 300
 301           if (ptrace (PTRACE_SETREGSET, tid, NT_FPREGSET,
 302                       (PTRACE_TYPE_ARG3) &iov) == -1)
 303             perror_with_name (_("Couldn't set registers"));
 304         }
 305     }
 306
 307   /* Access to CSRs has potential security issues, don't support them for
 308      now.  */
 309 }
 310
 311 /* Initialize RISC-V Linux native support.  */
 312
 313 void
 314 _initialize_riscv_linux_nat (void)
 315 {
 316   /* Register the target.  */
 317   linux_target = &the_riscv_linux_nat_target;
 318   add_inf_child_target (&the_riscv_linux_nat_target);
 319 }