gdb/riscv-linux-nat.c

   1 /* Native-dependent code for GNU/Linux RISC-V.
   2    Copyright (C) 2018-2022 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
  26 #include "elf/common.h"
  27
  28 #include "nat/riscv-linux-tdesc.h"
  29
  30 #include <sys/ptrace.h>
  31
  32 /* Work around glibc header breakage causing ELF_NFPREG not to be usable.  */
  33 #ifndef NFPREG
  34 # define NFPREG 33
  35 #endif
  36
  37 /* RISC-V Linux native additions to the default linux support.  */
  38
  39 class riscv_linux_nat_target final : public linux_nat_target
  40 {
  41 public:
  42   /* Add our register access methods.  */
  43   void fetch_registers (struct regcache *regcache, int regnum) override;
  44   void store_registers (struct regcache *regcache, int regnum) override;
  45
  46   /* Read suitable target description.  */
  47   const struct target_desc *read_description () override;
  48 };
  49
  50 static riscv_linux_nat_target the_riscv_linux_nat_target;
  51
  52 /* Copy general purpose register REGNUM (or all gp regs if REGNUM == -1)
  53    from regset GREGS into REGCACHE.  */
  54
  55 static void
  56 supply_gregset_regnum (struct regcache *regcache, const prgregset_t *gregs,
  57                        int regnum)
  58 {
  59   int i;
  60   const elf_greg_t *regp = *gregs;
  61
  62   if (regnum == -1)
  63     {
  64       /* We only support the integer registers and PC here.  */
  65       for (i = RISCV_ZERO_REGNUM + 1; i < RISCV_PC_REGNUM; i++)
  66         regcache->raw_supply (i, regp + i);
  67
  68       /* GDB stores PC in reg 32.  Linux kernel stores it in reg 0.  */
  69       regcache->raw_supply (32, regp + 0);
  70
  71       /* Fill the inaccessible zero register with zero.  */
  72       regcache->raw_supply_zeroed (0);
  73     }
  74   else if (regnum == RISCV_ZERO_REGNUM)
  75     regcache->raw_supply_zeroed (0);
  76   else if (regnum > RISCV_ZERO_REGNUM && regnum < RISCV_PC_REGNUM)
  77     regcache->raw_supply (regnum, regp + regnum);
  78   else if (regnum == RISCV_PC_REGNUM)
  79     regcache->raw_supply (32, regp + 0);
  80 }
  81
  82 /* Copy all general purpose registers from regset GREGS into REGCACHE.  */
  83
  84 void
  85 supply_gregset (struct regcache *regcache, const prgregset_t *gregs)
  86 {
  87   supply_gregset_regnum (regcache, gregs, -1);
  88 }
  89
  90 /* Copy floating point register REGNUM (or all fp regs if REGNUM == -1)
  91    from regset FPREGS into REGCACHE.  */
  92
  93 static void
  94 supply_fpregset_regnum (struct regcache *regcache, const prfpregset_t *fpregs,
  95                         int regnum)
  96 {
  97   int flen = register_size (regcache->arch (), RISCV_FIRST_FP_REGNUM);
  98   union
  99     {
 100       const prfpregset_t *fpregs;
 101       const gdb_byte *buf;
 102     }
 103   fpbuf = { .fpregs = fpregs };
 104   int i;
 105
 106   if (regnum == -1)
 107     {
 108       /* We only support the FP registers and FCSR here.  */
 109       for (i = RISCV_FIRST_FP_REGNUM;
 110            i <= RISCV_LAST_FP_REGNUM;
 111            i++, fpbuf.buf += flen)
 112         regcache->raw_supply (i, fpbuf.buf);
 113
 114       regcache->raw_supply (RISCV_CSR_FCSR_REGNUM, fpbuf.buf);
 115     }
 116   else if (regnum >= RISCV_FIRST_FP_REGNUM && regnum <= RISCV_LAST_FP_REGNUM)
 117     {
 118       fpbuf.buf += flen * (regnum - RISCV_FIRST_FP_REGNUM);
 119       regcache->raw_supply (regnum, fpbuf.buf);
 120     }
 121   else if (regnum == RISCV_CSR_FCSR_REGNUM)
 122     {
 123       fpbuf.buf += flen * (RISCV_LAST_FP_REGNUM - RISCV_FIRST_FP_REGNUM + 1);
 124       regcache->raw_supply (RISCV_CSR_FCSR_REGNUM, fpbuf.buf);
 125     }
 126 }
 127
 128 /* Copy all floating point registers from regset FPREGS into REGCACHE.  */
 129
 130 void
 131 supply_fpregset (struct regcache *regcache, const prfpregset_t *fpregs)
 132 {
 133   supply_fpregset_regnum (regcache, fpregs, -1);
 134 }
 135
 136 /* Copy general purpose register REGNUM (or all gp regs if REGNUM == -1)
 137    from REGCACHE into regset GREGS.  */
 138
 139 void
 140 fill_gregset (const struct regcache *regcache, prgregset_t *gregs, int regnum)
 141 {
 142   elf_greg_t *regp = *gregs;
 143
 144   if (regnum == -1)
 145     {
 146       /* We only support the integer registers and PC here.  */
 147       for (int i = RISCV_ZERO_REGNUM + 1; i < RISCV_PC_REGNUM; i++)
 148         regcache->raw_collect (i, regp + i);
 149
 150       regcache->raw_collect (32, regp + 0);
 151     }
 152   else if (regnum == RISCV_ZERO_REGNUM)
 153     /* Nothing to do here.  */
 154     ;
 155   else if (regnum > RISCV_ZERO_REGNUM && regnum < RISCV_PC_REGNUM)
 156     regcache->raw_collect (regnum, regp + regnum);
 157   else if (regnum == RISCV_PC_REGNUM)
 158     regcache->raw_collect (32, regp + 0);
 159 }
 160
 161 /* Copy floating point register REGNUM (or all fp regs if REGNUM == -1)
 162    from REGCACHE into regset FPREGS.  */
 163
 164 void
 165 fill_fpregset (const struct regcache *regcache, prfpregset_t *fpregs,
 166                int regnum)
 167 {
 168   int flen = register_size (regcache->arch (), RISCV_FIRST_FP_REGNUM);
 169   union
 170     {
 171       prfpregset_t *fpregs;
 172       gdb_byte *buf;
 173     }
 174   fpbuf = { .fpregs = fpregs };
 175   int i;
 176
 177   if (regnum == -1)
 178     {
 179       /* We only support the FP registers and FCSR here.  */
 180       for (i = RISCV_FIRST_FP_REGNUM;
 181            i <= RISCV_LAST_FP_REGNUM;
 182            i++, fpbuf.buf += flen)
 183         regcache->raw_collect (i, fpbuf.buf);
 184
 185       regcache->raw_collect (RISCV_CSR_FCSR_REGNUM, fpbuf.buf);
 186     }
 187   else if (regnum >= RISCV_FIRST_FP_REGNUM && regnum <= RISCV_LAST_FP_REGNUM)
 188     {
 189       fpbuf.buf += flen * (regnum - RISCV_FIRST_FP_REGNUM);
 190       regcache->raw_collect (regnum, fpbuf.buf);
 191     }
 192   else if (regnum == RISCV_CSR_FCSR_REGNUM)
 193     {
 194       fpbuf.buf += flen * (RISCV_LAST_FP_REGNUM - RISCV_FIRST_FP_REGNUM + 1);
 195       regcache->raw_collect (RISCV_CSR_FCSR_REGNUM, fpbuf.buf);
 196     }
 197 }
 198
 199 /* Return a target description for the current target.  */
 200
 201 const struct target_desc *
 202 riscv_linux_nat_target::read_description ()
 203 {
 204   const struct riscv_gdbarch_features features
 205     = riscv_linux_read_features (inferior_ptid.pid ());
 206   return riscv_lookup_target_description (features);
 207 }
 208
 209 /* Fetch REGNUM (or all registers if REGNUM == -1) from the target
 210    into REGCACHE using PTRACE_GETREGSET.  */
 211
 212 void
 213 riscv_linux_nat_target::fetch_registers (struct regcache *regcache, int regnum)
 214 {
 215   int tid;
 216
 217   tid = get_ptrace_pid (regcache->ptid());
 218
 219   if ((regnum >= RISCV_ZERO_REGNUM && regnum <= RISCV_PC_REGNUM)
 220       || (regnum == -1))
 221     {
 222       struct iovec iov;
 223       elf_gregset_t regs;
 224
 225       iov.iov_base = &regs;
 226       iov.iov_len = sizeof (regs);
 227
 228       if (ptrace (PTRACE_GETREGSET, tid, NT_PRSTATUS,
 229                   (PTRACE_TYPE_ARG3) &iov) == -1)
 230         perror_with_name (_("Couldn't get registers"));
 231       else
 232         supply_gregset_regnum (regcache, &regs, regnum);
 233     }
 234
 235   if ((regnum >= RISCV_FIRST_FP_REGNUM
 236        && regnum <= RISCV_LAST_FP_REGNUM)
 237       || (regnum == RISCV_CSR_FCSR_REGNUM)
 238       || (regnum == -1))
 239     {
 240       struct iovec iov;
 241       elf_fpregset_t regs;
 242
 243       iov.iov_base = &regs;
 244       iov.iov_len = ELF_NFPREG * register_size (regcache->arch (),
 245                                                 RISCV_FIRST_FP_REGNUM);
 246       gdb_assert (iov.iov_len <= sizeof (regs));
 247
 248       if (ptrace (PTRACE_GETREGSET, tid, NT_FPREGSET,
 249                   (PTRACE_TYPE_ARG3) &iov) == -1)
 250         perror_with_name (_("Couldn't get registers"));
 251       else
 252         supply_fpregset_regnum (regcache, &regs, regnum);
 253     }
 254
 255   if ((regnum == RISCV_CSR_MISA_REGNUM)
 256       || (regnum == -1))
 257     {
 258       /* TODO: Need to add a ptrace call for this.  */
 259       regcache->raw_supply_zeroed (RISCV_CSR_MISA_REGNUM);
 260     }
 261
 262   /* Access to other CSRs has potential security issues, don't support them for
 263      now.  */
 264 }
 265
 266 /* Store REGNUM (or all registers if REGNUM == -1) to the target
 267    from REGCACHE using PTRACE_SETREGSET.  */
 268
 269 void
 270 riscv_linux_nat_target::store_registers (struct regcache *regcache, int regnum)
 271 {
 272   int tid;
 273
 274   tid = get_ptrace_pid (regcache->ptid ());
 275
 276   if ((regnum >= RISCV_ZERO_REGNUM && regnum <= RISCV_PC_REGNUM)
 277       || (regnum == -1))
 278     {
 279       struct iovec iov;
 280       elf_gregset_t regs;
 281
 282       iov.iov_base = &regs;
 283       iov.iov_len = sizeof (regs);
 284
 285       if (ptrace (PTRACE_GETREGSET, tid, NT_PRSTATUS,
 286                   (PTRACE_TYPE_ARG3) &iov) == -1)
 287         perror_with_name (_("Couldn't get registers"));
 288       else
 289         {
 290           fill_gregset (regcache, &regs, regnum);
 291
 292           if (ptrace (PTRACE_SETREGSET, tid, NT_PRSTATUS,
 293                       (PTRACE_TYPE_ARG3) &iov) == -1)
 294             perror_with_name (_("Couldn't set registers"));
 295         }
 296     }
 297
 298   if ((regnum >= RISCV_FIRST_FP_REGNUM
 299        && regnum <= RISCV_LAST_FP_REGNUM)
 300       || (regnum == RISCV_CSR_FCSR_REGNUM)
 301       || (regnum == -1))
 302     {
 303       struct iovec iov;
 304       elf_fpregset_t regs;
 305
 306       iov.iov_base = &regs;
 307       iov.iov_len = ELF_NFPREG * register_size (regcache->arch (),
 308                                                 RISCV_FIRST_FP_REGNUM);
 309       gdb_assert (iov.iov_len <= sizeof (regs));
 310
 311       if (ptrace (PTRACE_GETREGSET, tid, NT_FPREGSET,
 312                   (PTRACE_TYPE_ARG3) &iov) == -1)
 313         perror_with_name (_("Couldn't get registers"));
 314       else
 315         {
 316           fill_fpregset (regcache, &regs, regnum);
 317
 318           if (ptrace (PTRACE_SETREGSET, tid, NT_FPREGSET,
 319                       (PTRACE_TYPE_ARG3) &iov) == -1)
 320             perror_with_name (_("Couldn't set registers"));
 321         }
 322     }
 323
 324   /* Access to CSRs has potential security issues, don't support them for
 325      now.  */
 326 }
 327
 328 /* Initialize RISC-V Linux native support.  */
 329
 330 void _initialize_riscv_linux_nat ();
 331 void
 332 _initialize_riscv_linux_nat ()
 333 {
 334   /* Register the target.  */
 335   linux_target = &the_riscv_linux_nat_target;
 336   add_inf_child_target (&the_riscv_linux_nat_target);
 337 }