gdb/riscv-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux on RISC-V processors.
   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 "riscv-tdep.h"
  21 #include "osabi.h"
  22 #include "glibc-tdep.h"
  23 #include "linux-tdep.h"
  24 #include "solib-svr4.h"
  25 #include "regset.h"
  26 #include "tramp-frame.h"
  27 #include "trad-frame.h"
  28
  29 /* Define the general register mapping.  The kernel puts the PC at offset 0,
  30    gdb puts it at offset 32.  Register x0 is always 0 and can be ignored.
  31    Registers x1 to x31 are in the same place.  */
  32
  33 static const struct regcache_map_entry riscv_linux_gregmap[] =
  34 {
  35   { 1,  RISCV_PC_REGNUM, 0 },
  36   { 31, RISCV_RA_REGNUM, 0 }, /* x1 to x31 */
  37   { 0 }
  38 };
  39
  40 /* Define the FP register mapping.  The kernel puts the 32 FP regs first, and
  41    then FCSR.  */
  42
  43 static const struct regcache_map_entry riscv_linux_fregmap[] =
  44 {
  45   { 32, RISCV_FIRST_FP_REGNUM, 0 },
  46   { 1, RISCV_CSR_FCSR_REGNUM, 0 },
  47   { 0 }
  48 };
  49
  50 /* Define the general register regset.  */
  51
  52 static const struct regset riscv_linux_gregset =
  53 {
  54   riscv_linux_gregmap, regcache_supply_regset, regcache_collect_regset
  55 };
  56
  57 /* Define the FP register regset.  */
  58
  59 static const struct regset riscv_linux_fregset =
  60 {
  61   riscv_linux_fregmap, regcache_supply_regset, regcache_collect_regset
  62 };
  63
  64 /* Define hook for core file support.  */
  65
  66 static void
  67 riscv_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
  68                                           iterate_over_regset_sections_cb *cb,
  69                                           void *cb_data,
  70                                           const struct regcache *regcache)
  71 {
  72   cb (".reg", (32 * riscv_isa_xlen (gdbarch)), (32 * riscv_isa_xlen (gdbarch)),
  73       &riscv_linux_gregset, NULL, cb_data);
  74   /* The kernel is adding 8 bytes for FCSR.  */
  75   cb (".reg2", (32 * riscv_isa_flen (gdbarch)) + 8,
  76       (32 * riscv_isa_flen (gdbarch)) + 8,
  77       &riscv_linux_fregset, NULL, cb_data);
  78 }
  79
  80 /* Signal trampoline support.  */
  81
  82 static void riscv_linux_sigframe_init (const struct tramp_frame *self,
  83                                        struct frame_info *this_frame,
  84                                        struct trad_frame_cache *this_cache,
  85                                        CORE_ADDR func);
  86
  87 #define RISCV_INST_LI_A7_SIGRETURN      0x08b00893
  88 #define RISCV_INST_ECALL                0x00000073
  89
  90 static const struct tramp_frame riscv_linux_sigframe = {
  91   SIGTRAMP_FRAME,
  92   4,
  93   {
  94     { RISCV_INST_LI_A7_SIGRETURN, ULONGEST_MAX },
  95     { RISCV_INST_ECALL, ULONGEST_MAX },
  96     { TRAMP_SENTINEL_INSN }
  97   },
  98   riscv_linux_sigframe_init,
  99   NULL
 100 };
 101
 102 /* Runtime signal frames look like this:
 103    struct rt_sigframe {
 104      struct siginfo info;
 105      struct ucontext uc;
 106    };
 107
 108    struct ucontext {
 109      unsigned long __uc_flags;
 110      struct ucontext *uclink;
 111      stack_t uc_stack;
 112      sigset_t uc_sigmask;
 113      char __glibc_reserved[1024 / 8 - sizeof (sigset_t)];
 114      mcontext_t uc_mcontext;
 115    }; */
 116
 117 #define SIGFRAME_SIGINFO_SIZE           128
 118 #define UCONTEXT_MCONTEXT_OFFSET        176
 119
 120 static void
 121 riscv_linux_sigframe_init (const struct tramp_frame *self,
 122                            struct frame_info *this_frame,
 123                            struct trad_frame_cache *this_cache,
 124                            CORE_ADDR func)
 125 {
 126   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 127   int xlen = riscv_isa_xlen (gdbarch);
 128   int flen = riscv_isa_flen (gdbarch);
 129   CORE_ADDR frame_sp = get_frame_sp (this_frame);
 130   CORE_ADDR mcontext_base;
 131   CORE_ADDR regs_base;
 132
 133   mcontext_base = frame_sp + SIGFRAME_SIGINFO_SIZE + UCONTEXT_MCONTEXT_OFFSET;
 134
 135   /* Handle the integer registers.  The first one is PC, followed by x1
 136      through x31.  */
 137   regs_base = mcontext_base;
 138   trad_frame_set_reg_addr (this_cache, RISCV_PC_REGNUM, regs_base);
 139   for (int i = 1; i < 32; i++)
 140     trad_frame_set_reg_addr (this_cache, RISCV_ZERO_REGNUM + i,
 141                              regs_base + (i * xlen));
 142
 143   /* Handle the FP registers.  First comes the 32 FP registers, followed by
 144      fcsr.  */
 145   regs_base += 32 * xlen;
 146   for (int i = 0; i < 32; i++)
 147     trad_frame_set_reg_addr (this_cache, RISCV_FIRST_FP_REGNUM + i,
 148                              regs_base + (i * flen));
 149   regs_base += 32 * flen;
 150   trad_frame_set_reg_addr (this_cache, RISCV_CSR_FCSR_REGNUM, regs_base);
 151
 152   /* Choice of the bottom of the sigframe is somewhat arbitrary.  */
 153   trad_frame_set_id (this_cache, frame_id_build (frame_sp, func));
 154 }
 155
 156 /* Initialize RISC-V Linux ABI info.  */
 157
 158 static void
 159 riscv_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 160 {
 161   linux_init_abi (info, gdbarch);
 162
 163   set_gdbarch_software_single_step (gdbarch, riscv_software_single_step);
 164
 165   set_solib_svr4_fetch_link_map_offsets (gdbarch,
 166                                          (riscv_isa_xlen (gdbarch) == 4
 167                                           ? svr4_ilp32_fetch_link_map_offsets
 168                                           : svr4_lp64_fetch_link_map_offsets));
 169
 170   /* GNU/Linux uses SVR4-style shared libraries.  */
 171   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 172
 173   /* GNU/Linux uses the dynamic linker included in the GNU C Library.  */
 174   set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
 175
 176   /* Enable TLS support.  */
 177   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 178                                              svr4_fetch_objfile_link_map);
 179
 180   set_gdbarch_iterate_over_regset_sections
 181     (gdbarch, riscv_linux_iterate_over_regset_sections);
 182
 183   tramp_frame_prepend_unwinder (gdbarch, &riscv_linux_sigframe);
 184 }
 185
 186 /* Initialize RISC-V Linux target support.  */
 187
 188 void
 189 _initialize_riscv_linux_tdep (void)
 190 {
 191   gdbarch_register_osabi (bfd_arch_riscv, 0, GDB_OSABI_LINUX,
 192                           riscv_linux_init_abi);
 193 }