gdb/riscv-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux on RISC-V processors.
   2    Copyright (C) 2018-2024 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 "riscv-tdep.h"
  20 #include "osabi.h"
  21 #include "glibc-tdep.h"
  22 #include "linux-tdep.h"
  23 #include "solib-svr4.h"
  24 #include "regset.h"
  25 #include "tramp-frame.h"
  26 #include "trad-frame.h"
  27 #include "gdbarch.h"
  28
  29 /* The following value is derived from __NR_rt_sigreturn in
  30    <include/uapi/asm-generic/unistd.h> from the Linux source tree.  */
  31
  32 #define RISCV_NR_rt_sigreturn 139
  33
  34 /* Define the general register mapping.  The kernel puts the PC at offset 0,
  35    gdb puts it at offset 32.  Register x0 is always 0 and can be ignored.
  36    Registers x1 to x31 are in the same place.  */
  37
  38 static const struct regcache_map_entry riscv_linux_gregmap[] =
  39 {
  40   { 1,  RISCV_PC_REGNUM, 0 },
  41   { 31, RISCV_RA_REGNUM, 0 }, /* x1 to x31 */
  42   { 0 }
  43 };
  44
  45 /* Define the FP register mapping.  The kernel puts the 32 FP regs first, and
  46    then FCSR.  */
  47
  48 static const struct regcache_map_entry riscv_linux_fregmap[] =
  49 {
  50   { 32, RISCV_FIRST_FP_REGNUM, 0 },
  51   { 1, RISCV_CSR_FCSR_REGNUM, 0 },
  52   { 0 }
  53 };
  54
  55 /* Define the general register regset.  */
  56
  57 static const struct regset riscv_linux_gregset =
  58 {
  59   riscv_linux_gregmap, riscv_supply_regset, regcache_collect_regset
  60 };
  61
  62 /* Define the FP register regset.  */
  63
  64 static const struct regset riscv_linux_fregset =
  65 {
  66   riscv_linux_fregmap, riscv_supply_regset, regcache_collect_regset
  67 };
  68
  69 /* Define hook for core file support.  */
  70
  71 static void
  72 riscv_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
  73                                           iterate_over_regset_sections_cb *cb,
  74                                           void *cb_data,
  75                                           const struct regcache *regcache)
  76 {
  77   cb (".reg", (32 * riscv_isa_xlen (gdbarch)), (32 * riscv_isa_xlen (gdbarch)),
  78       &riscv_linux_gregset, NULL, cb_data);
  79   /* The kernel is adding 8 bytes for FCSR.  */
  80   cb (".reg2", (32 * riscv_isa_flen (gdbarch)) + 8,
  81       (32 * riscv_isa_flen (gdbarch)) + 8,
  82       &riscv_linux_fregset, NULL, cb_data);
  83 }
  84
  85 /* Signal trampoline support.  */
  86
  87 static void riscv_linux_sigframe_init (const struct tramp_frame *self,
  88                                        const frame_info_ptr &this_frame,
  89                                        struct trad_frame_cache *this_cache,
  90                                        CORE_ADDR func);
  91
  92 #define RISCV_INST_LI_A7_SIGRETURN      0x08b00893
  93 #define RISCV_INST_ECALL                0x00000073
  94
  95 static const struct tramp_frame riscv_linux_sigframe = {
  96   SIGTRAMP_FRAME,
  97   4,
  98   {
  99     { RISCV_INST_LI_A7_SIGRETURN, ULONGEST_MAX },
 100     { RISCV_INST_ECALL, ULONGEST_MAX },
 101     { TRAMP_SENTINEL_INSN }
 102   },
 103   riscv_linux_sigframe_init,
 104   NULL
 105 };
 106
 107 /* Runtime signal frames look like this:
 108    struct rt_sigframe {
 109      struct siginfo info;
 110      struct ucontext uc;
 111    };
 112
 113    struct ucontext {
 114      unsigned long __uc_flags;
 115      struct ucontext *uclink;
 116      stack_t uc_stack;
 117      sigset_t uc_sigmask;
 118      char __glibc_reserved[1024 / 8 - sizeof (sigset_t)];
 119      mcontext_t uc_mcontext;
 120    }; */
 121
 122 #define SIGFRAME_SIGINFO_SIZE           128
 123 #define UCONTEXT_MCONTEXT_OFFSET        176
 124
 125 static void
 126 riscv_linux_sigframe_init (const struct tramp_frame *self,
 127                            const frame_info_ptr &this_frame,
 128                            struct trad_frame_cache *this_cache,
 129                            CORE_ADDR func)
 130 {
 131   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 132   int xlen = riscv_isa_xlen (gdbarch);
 133   int flen = riscv_isa_flen (gdbarch);
 134   CORE_ADDR frame_sp = get_frame_sp (this_frame);
 135   CORE_ADDR mcontext_base;
 136   CORE_ADDR regs_base;
 137
 138   mcontext_base = frame_sp + SIGFRAME_SIGINFO_SIZE + UCONTEXT_MCONTEXT_OFFSET;
 139
 140   /* Handle the integer registers.  The first one is PC, followed by x1
 141      through x31.  */
 142   regs_base = mcontext_base;
 143   trad_frame_set_reg_addr (this_cache, RISCV_PC_REGNUM, regs_base);
 144   for (int i = 1; i < 32; i++)
 145     trad_frame_set_reg_addr (this_cache, RISCV_ZERO_REGNUM + i,
 146                              regs_base + (i * xlen));
 147
 148   /* Handle the FP registers.  First comes the 32 FP registers, followed by
 149      fcsr.  */
 150   regs_base += 32 * xlen;
 151   for (int i = 0; i < 32; i++)
 152     trad_frame_set_reg_addr (this_cache, RISCV_FIRST_FP_REGNUM + i,
 153                              regs_base + (i * flen));
 154   regs_base += 32 * flen;
 155   trad_frame_set_reg_addr (this_cache, RISCV_CSR_FCSR_REGNUM, regs_base);
 156
 157   /* Choice of the bottom of the sigframe is somewhat arbitrary.  */
 158   trad_frame_set_id (this_cache, frame_id_build (frame_sp, func));
 159 }
 160
 161 /* When FRAME is at a syscall instruction (ECALL), return the PC of the next
 162    instruction to be executed.  */
 163
 164 static CORE_ADDR
 165 riscv_linux_syscall_next_pc (const frame_info_ptr &frame)
 166 {
 167   const CORE_ADDR pc = get_frame_pc (frame);
 168   const ULONGEST a7 = get_frame_register_unsigned (frame, RISCV_A7_REGNUM);
 169
 170   if (a7 == RISCV_NR_rt_sigreturn)
 171     return frame_unwind_caller_pc (frame);
 172
 173   return pc + 4 /* Length of the ECALL insn.  */;
 174 }
 175
 176 /* Initialize RISC-V Linux ABI info.  */
 177
 178 static void
 179 riscv_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 180 {
 181   riscv_gdbarch_tdep *tdep = gdbarch_tdep<riscv_gdbarch_tdep> (gdbarch);
 182
 183   linux_init_abi (info, gdbarch, 0);
 184
 185   set_gdbarch_software_single_step (gdbarch, riscv_software_single_step);
 186
 187   set_solib_svr4_fetch_link_map_offsets (gdbarch,
 188                                          (riscv_isa_xlen (gdbarch) == 4
 189                                           ? linux_ilp32_fetch_link_map_offsets
 190                                           : linux_lp64_fetch_link_map_offsets));
 191
 192   /* GNU/Linux uses SVR4-style shared libraries.  */
 193   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 194
 195   /* GNU/Linux uses the dynamic linker included in the GNU C Library.  */
 196   set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
 197
 198   /* Enable TLS support.  */
 199   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 200                                              svr4_fetch_objfile_link_map);
 201
 202   set_gdbarch_iterate_over_regset_sections
 203     (gdbarch, riscv_linux_iterate_over_regset_sections);
 204
 205   tramp_frame_prepend_unwinder (gdbarch, &riscv_linux_sigframe);
 206
 207   tdep->syscall_next_pc = riscv_linux_syscall_next_pc;
 208 }
 209
 210 /* Initialize RISC-V Linux target support.  */
 211
 212 void _initialize_riscv_linux_tdep ();
 213 void
 214 _initialize_riscv_linux_tdep ()
 215 {
 216   gdbarch_register_osabi (bfd_arch_riscv, 0, GDB_OSABI_LINUX,
 217                           riscv_linux_init_abi);
 218 }