gdb/riscv-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux on RISC-V processors.
   2    Copyright (C) 2018 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 general register regset.  */
  41
  42 static const struct regset riscv_linux_gregset =
  43 {
  44   riscv_linux_gregmap, regcache_supply_regset, regcache_collect_regset
  45 };
  46
  47 /* Define hook for core file support.  */
  48
  49 static void
  50 riscv_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
  51                                           iterate_over_regset_sections_cb *cb,
  52                                           void *cb_data,
  53                                           const struct regcache *regcache)
  54 {
  55   cb (".reg", (32 * riscv_isa_xlen (gdbarch)), (32 * riscv_isa_xlen (gdbarch)),
  56       &riscv_linux_gregset, NULL, cb_data);
  57
  58   /* TODO: Add FP register support.  */
  59 }
  60
  61 /* Signal trampoline support.  */
  62
  63 static void riscv_linux_sigframe_init (const struct tramp_frame *self,
  64                                        struct frame_info *this_frame,
  65                                        struct trad_frame_cache *this_cache,
  66                                        CORE_ADDR func);
  67
  68 #define RISCV_INST_LI_A7_SIGRETURN      0x08b00893
  69 #define RISCV_INST_ECALL                0x00000073
  70
  71 static const struct tramp_frame riscv_linux_sigframe = {
  72   SIGTRAMP_FRAME,
  73   4,
  74   {
  75     { RISCV_INST_LI_A7_SIGRETURN, ULONGEST_MAX },
  76     { RISCV_INST_ECALL, ULONGEST_MAX },
  77     { TRAMP_SENTINEL_INSN }
  78   },
  79   riscv_linux_sigframe_init,
  80   NULL
  81 };
  82
  83 /* Runtime signal frames look like this:
  84    struct rt_sigframe {
  85      struct siginfo info;
  86      struct ucontext uc;
  87    };
  88
  89    struct ucontext {
  90      unsigned long __uc_flags;
  91      struct ucontext *uclink;
  92      stack_t uc_stack;
  93      sigset_t uc_sigmask;
  94      char __glibc_reserved[1024 / 8 - sizeof (sigset_t)];
  95      mcontext_t uc_mcontext;
  96    }; */
  97
  98 #define SIGFRAME_SIGINFO_SIZE           128
  99 #define UCONTEXT_MCONTEXT_OFFSET        176
 100
 101 static void
 102 riscv_linux_sigframe_init (const struct tramp_frame *self,
 103                            struct frame_info *this_frame,
 104                            struct trad_frame_cache *this_cache,
 105                            CORE_ADDR func)
 106 {
 107   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 108   int xlen = riscv_isa_xlen (gdbarch);
 109   int flen = riscv_isa_flen (gdbarch);
 110   CORE_ADDR frame_sp = get_frame_sp (this_frame);
 111   CORE_ADDR mcontext_base;
 112   CORE_ADDR regs_base;
 113
 114   mcontext_base = frame_sp + SIGFRAME_SIGINFO_SIZE + UCONTEXT_MCONTEXT_OFFSET;
 115
 116   /* Handle the integer registers.  The first one is PC, followed by x1
 117      through x31.  */
 118   regs_base = mcontext_base;
 119   trad_frame_set_reg_addr (this_cache, RISCV_PC_REGNUM, regs_base);
 120   for (int i = 1; i < 32; i++)
 121     trad_frame_set_reg_addr (this_cache, RISCV_ZERO_REGNUM + i,
 122                              regs_base + (i * xlen));
 123
 124   /* Handle the FP registers.  First comes the 32 FP registers, followed by
 125      fcsr.  */
 126   regs_base += 32 * xlen;
 127   for (int i = 0; i < 32; i++)
 128     trad_frame_set_reg_addr (this_cache, RISCV_FIRST_FP_REGNUM + i,
 129                              regs_base + (i * flen));
 130   regs_base += 32 * flen;
 131   trad_frame_set_reg_addr (this_cache, RISCV_CSR_FCSR_REGNUM, regs_base);
 132
 133   /* Choice of the bottom of the sigframe is somewhat arbitrary.  */
 134   trad_frame_set_id (this_cache, frame_id_build (frame_sp, func));
 135 }
 136
 137 /* Initialize RISC-V Linux ABI info.  */
 138
 139 static void
 140 riscv_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 141 {
 142   linux_init_abi (info, gdbarch);
 143
 144   set_gdbarch_software_single_step (gdbarch, riscv_software_single_step);
 145
 146   set_solib_svr4_fetch_link_map_offsets (gdbarch,
 147                                          (riscv_isa_xlen (gdbarch) == 4
 148                                           ? svr4_ilp32_fetch_link_map_offsets
 149                                           : svr4_lp64_fetch_link_map_offsets));
 150
 151   /* GNU/Linux uses SVR4-style shared libraries.  */
 152   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 153
 154   /* GNU/Linux uses the dynamic linker included in the GNU C Library.  */
 155   set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
 156
 157   /* Enable TLS support.  */
 158   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 159                                              svr4_fetch_objfile_link_map);
 160
 161   set_gdbarch_iterate_over_regset_sections
 162     (gdbarch, riscv_linux_iterate_over_regset_sections);
 163
 164   tramp_frame_prepend_unwinder (gdbarch, &riscv_linux_sigframe);
 165 }
 166
 167 /* Initialize RISC-V Linux target support.  */
 168
 169 void
 170 _initialize_riscv_linux_tdep (void)
 171 {
 172   gdbarch_register_osabi (bfd_arch_riscv, 0, GDB_OSABI_LINUX,
 173                           riscv_linux_init_abi);
 174 }