gdb/riscv-fbsd-tdep.c

   1 /* Target-dependent code for FreeBSD on RISC-V processors.
   2    Copyright (C) 2018-2020 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 "fbsd-tdep.h"
  21 #include "osabi.h"
  22 #include "riscv-tdep.h"
  23 #include "riscv-fbsd-tdep.h"
  24 #include "solib-svr4.h"
  25 #include "target.h"
  26 #include "trad-frame.h"
  27 #include "tramp-frame.h"
  28 #include "gdbarch.h"
  29
  30 /* Register maps.  */
  31
  32 static const struct regcache_map_entry riscv_fbsd_gregmap[] =
  33   {
  34     { 1, RISCV_RA_REGNUM, 0 },
  35     { 1, RISCV_SP_REGNUM, 0 },
  36     { 1, RISCV_GP_REGNUM, 0 },
  37     { 1, RISCV_TP_REGNUM, 0 },
  38     { 3, 5, 0 },                /* t0 - t2 */
  39     { 4, 28, 0 },               /* t3 - t6 */
  40     { 2, RISCV_FP_REGNUM, 0 },  /* s0 - s1 */
  41     { 10, 18, 0 },              /* s2 - s11 */
  42     { 8, RISCV_A0_REGNUM, 0 },  /* a0 - a7 */
  43     { 1, RISCV_PC_REGNUM, 0 },
  44     { 1, RISCV_CSR_SSTATUS_REGNUM, 0 },
  45     { 0 }
  46   };
  47
  48 static const struct regcache_map_entry riscv_fbsd_fpregmap[] =
  49   {
  50     { 32, RISCV_FIRST_FP_REGNUM, 16 },
  51     { 1, RISCV_CSR_FCSR_REGNUM, 8 },
  52     { 0 }
  53   };
  54
  55 /* Supply the general-purpose registers stored in GREGS to REGCACHE.
  56    This function only exists to supply the always-zero x0 in addition
  57    to the registers in GREGS.  */
  58
  59 static void
  60 riscv_fbsd_supply_gregset (const struct regset *regset,
  61                            struct regcache *regcache, int regnum,
  62                            const void *gregs, size_t len)
  63 {
  64   regcache->supply_regset (&riscv_fbsd_gregset, regnum, gregs, len);
  65   if (regnum == -1 || regnum == RISCV_ZERO_REGNUM)
  66     regcache->raw_supply_zeroed (RISCV_ZERO_REGNUM);
  67 }
  68
  69 /* Register set definitions.  */
  70
  71 const struct regset riscv_fbsd_gregset =
  72   {
  73     riscv_fbsd_gregmap,
  74     riscv_fbsd_supply_gregset, regcache_collect_regset
  75   };
  76
  77 const struct regset riscv_fbsd_fpregset =
  78   {
  79     riscv_fbsd_fpregmap,
  80     regcache_supply_regset, regcache_collect_regset
  81   };
  82
  83 /* Implement the "regset_from_core_section" gdbarch method.  */
  84
  85 static void
  86 riscv_fbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
  87                                          iterate_over_regset_sections_cb *cb,
  88                                          void *cb_data,
  89                                          const struct regcache *regcache)
  90 {
  91   cb (".reg", RISCV_FBSD_NUM_GREGS * riscv_isa_xlen (gdbarch),
  92       RISCV_FBSD_NUM_GREGS * riscv_isa_xlen (gdbarch),
  93       &riscv_fbsd_gregset, NULL, cb_data);
  94   cb (".reg2", RISCV_FBSD_SIZEOF_FPREGSET, RISCV_FBSD_SIZEOF_FPREGSET,
  95       &riscv_fbsd_fpregset, NULL, cb_data);
  96 }
  97
  98 /* In a signal frame, sp points to a 'struct sigframe' which is
  99    defined as:
 100
 101    struct sigframe {
 102            siginfo_t    sf_si;
 103            ucontext_t   sf_uc;
 104    };
 105
 106    ucontext_t is defined as:
 107
 108    struct __ucontext {
 109            sigset_t     uc_sigmask;
 110            mcontext_t   uc_mcontext;
 111            ...
 112    };
 113
 114    The mcontext_t contains the general purpose register set followed
 115    by the floating point register set.  The floating point register
 116    set is only valid if the _MC_FP_VALID flag is set in mc_flags.  */
 117
 118 #define RISCV_SIGFRAME_UCONTEXT_OFFSET          80
 119 #define RISCV_UCONTEXT_MCONTEXT_OFFSET          16
 120 #define RISCV_MCONTEXT_FLAG_FP_VALID            0x1
 121
 122 /* Implement the "init" method of struct tramp_frame.  */
 123
 124 static void
 125 riscv_fbsd_sigframe_init (const struct tramp_frame *self,
 126                           struct frame_info *this_frame,
 127                           struct trad_frame_cache *this_cache,
 128                           CORE_ADDR func)
 129 {
 130   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 131   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 132   CORE_ADDR sp = get_frame_register_unsigned (this_frame, RISCV_SP_REGNUM);
 133   CORE_ADDR mcontext_addr
 134     = (sp
 135        + RISCV_SIGFRAME_UCONTEXT_OFFSET
 136        + RISCV_UCONTEXT_MCONTEXT_OFFSET);
 137   gdb_byte buf[4];
 138
 139   trad_frame_set_reg_regmap (this_cache, riscv_fbsd_gregmap, mcontext_addr,
 140                              RISCV_FBSD_NUM_GREGS * riscv_isa_xlen (gdbarch));
 141
 142   CORE_ADDR fpregs_addr
 143     = mcontext_addr + RISCV_FBSD_NUM_GREGS * riscv_isa_xlen (gdbarch);
 144   CORE_ADDR fp_flags_addr
 145     = fpregs_addr + RISCV_FBSD_SIZEOF_FPREGSET;
 146   if (target_read_memory (fp_flags_addr, buf, 4) == 0
 147       && (extract_unsigned_integer (buf, 4, byte_order)
 148           & RISCV_MCONTEXT_FLAG_FP_VALID))
 149     trad_frame_set_reg_regmap (this_cache, riscv_fbsd_fpregmap, fpregs_addr,
 150                                RISCV_FBSD_SIZEOF_FPREGSET);
 151
 152   trad_frame_set_id (this_cache, frame_id_build (sp, func));
 153 }
 154
 155 /* RISC-V supports 16-bit instructions ("C") as well as 32-bit
 156    instructions.  The signal trampoline on FreeBSD uses a mix of
 157    these, but tramp_frame assumes a fixed instruction size.  To cope,
 158    claim that all instructions are 16 bits and use two "slots" for
 159    32-bit instructions.  */
 160
 161 static const struct tramp_frame riscv_fbsd_sigframe =
 162 {
 163   SIGTRAMP_FRAME,
 164   2,
 165   {
 166     {0x850a, ULONGEST_MAX},             /* mov  a0, sp  */
 167     {0x0513, ULONGEST_MAX},             /* addi a0, a0, #SF_UC  */
 168     {0x0505, ULONGEST_MAX},
 169     {0x0293, ULONGEST_MAX},             /* li   t0, #SYS_sigreturn  */
 170     {0x1a10, ULONGEST_MAX},
 171     {0x0073, ULONGEST_MAX},             /* ecall  */
 172     {0x0000, ULONGEST_MAX},
 173     {TRAMP_SENTINEL_INSN, ULONGEST_MAX}
 174   },
 175   riscv_fbsd_sigframe_init
 176 };
 177
 178 /* Implement the "get_thread_local_address" gdbarch method.  */
 179
 180 static CORE_ADDR
 181 riscv_fbsd_get_thread_local_address (struct gdbarch *gdbarch, ptid_t ptid,
 182                                      CORE_ADDR lm_addr, CORE_ADDR offset)
 183 {
 184   struct regcache *regcache;
 185
 186   regcache = get_thread_arch_regcache (ptid, gdbarch);
 187
 188   target_fetch_registers (regcache, RISCV_TP_REGNUM);
 189
 190   ULONGEST tp;
 191   if (regcache->cooked_read (RISCV_TP_REGNUM, &tp) != REG_VALID)
 192     error (_("Unable to fetch %%tp"));
 193
 194   /* %tp points to the end of the TCB which contains two pointers.
 195       The first pointer in the TCB points to the DTV array.  */
 196   CORE_ADDR dtv_addr = tp - (gdbarch_ptr_bit (gdbarch) / 8) * 2;
 197   return fbsd_get_thread_local_address (gdbarch, dtv_addr, lm_addr, offset);
 198 }
 199
 200 /* Implement the 'init_osabi' method of struct gdb_osabi_handler.  */
 201
 202 static void
 203 riscv_fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 204 {
 205   /* Generic FreeBSD support.  */
 206   fbsd_init_abi (info, gdbarch);
 207
 208   set_gdbarch_software_single_step (gdbarch, riscv_software_single_step);
 209
 210   set_solib_svr4_fetch_link_map_offsets (gdbarch,
 211                                          (riscv_isa_xlen (gdbarch) == 4
 212                                           ? svr4_ilp32_fetch_link_map_offsets
 213                                           : svr4_lp64_fetch_link_map_offsets));
 214
 215   tramp_frame_prepend_unwinder (gdbarch, &riscv_fbsd_sigframe);
 216
 217   set_gdbarch_iterate_over_regset_sections
 218     (gdbarch, riscv_fbsd_iterate_over_regset_sections);
 219
 220   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 221                                              svr4_fetch_objfile_link_map);
 222   set_gdbarch_get_thread_local_address (gdbarch,
 223                                         riscv_fbsd_get_thread_local_address);
 224 }
 225
 226 void
 227 _initialize_riscv_fbsd_tdep (void)
 228 {
 229   gdbarch_register_osabi (bfd_arch_riscv, 0, GDB_OSABI_FREEBSD,
 230                           riscv_fbsd_init_abi);
 231 }