1 /* Target-dependent code for GNU/Linux on RISC-V processors. 2 Copyright (C) 2018-2023 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 #include "gdbarch.h" 29 30 /* The following value is derived from __NR_rt_sigreturn in 31 <include/uapi/asm-generic/unistd.h> from the Linux source tree. */ 32 33 #define RISCV_NR_rt_sigreturn 139 34 35 /* Define the general register mapping. The kernel puts the PC at offset 0, 36 gdb puts it at offset 32. Register x0 is always 0 and can be ignored. 37 Registers x1 to x31 are in the same place. */ 38 39 static const struct regcache_map_entry riscv_linux_gregmap[] = 40 { 41 { 1, RISCV_PC_REGNUM, 0 }, 42 { 31, RISCV_RA_REGNUM, 0 }, /* x1 to x31 */ 43 { 0 } 44 }; 45 46 /* Define the FP register mapping. The kernel puts the 32 FP regs first, and 47 then FCSR. */ 48 49 static const struct regcache_map_entry riscv_linux_fregmap[] = 50 { 51 { 32, RISCV_FIRST_FP_REGNUM, 0 }, 52 { 1, RISCV_CSR_FCSR_REGNUM, 0 }, 53 { 0 } 54 }; 55 56 /* Define the general register regset. */ 57 58 static const struct regset riscv_linux_gregset = 59 { 60 riscv_linux_gregmap, riscv_supply_regset, regcache_collect_regset 61 }; 62 63 /* Define the FP register regset. */ 64 65 static const struct regset riscv_linux_fregset = 66 { 67 riscv_linux_fregmap, riscv_supply_regset, regcache_collect_regset 68 }; 69 70 /* Define hook for core file support. */ 71 72 static void 73 riscv_linux_iterate_over_regset_sections (struct gdbarch *gdbarch, 74 iterate_over_regset_sections_cb *cb, 75 void *cb_data, 76 const struct regcache *regcache) 77 { 78 cb (".reg", (32 * riscv_isa_xlen (gdbarch)), (32 * riscv_isa_xlen (gdbarch)), 79 &riscv_linux_gregset, NULL, cb_data); 80 /* The kernel is adding 8 bytes for FCSR. */ 81 cb (".reg2", (32 * riscv_isa_flen (gdbarch)) + 8, 82 (32 * riscv_isa_flen (gdbarch)) + 8, 83 &riscv_linux_fregset, NULL, cb_data); 84 } 85 86 /* Signal trampoline support. */ 87 88 static void riscv_linux_sigframe_init (const struct tramp_frame *self, 89 frame_info_ptr this_frame, 90 struct trad_frame_cache *this_cache, 91 CORE_ADDR func); 92 93 #define RISCV_INST_LI_A7_SIGRETURN 0x08b00893 94 #define RISCV_INST_ECALL 0x00000073 95 96 static const struct tramp_frame riscv_linux_sigframe = { 97 SIGTRAMP_FRAME, 98 4, 99 { 100 { RISCV_INST_LI_A7_SIGRETURN, ULONGEST_MAX }, 101 { RISCV_INST_ECALL, ULONGEST_MAX }, 102 { TRAMP_SENTINEL_INSN } 103 }, 104 riscv_linux_sigframe_init, 105 NULL 106 }; 107 108 /* Runtime signal frames look like this: 109 struct rt_sigframe { 110 struct siginfo info; 111 struct ucontext uc; 112 }; 113 114 struct ucontext { 115 unsigned long __uc_flags; 116 struct ucontext *uclink; 117 stack_t uc_stack; 118 sigset_t uc_sigmask; 119 char __glibc_reserved[1024 / 8 - sizeof (sigset_t)]; 120 mcontext_t uc_mcontext; 121 }; */ 122 123 #define SIGFRAME_SIGINFO_SIZE 128 124 #define UCONTEXT_MCONTEXT_OFFSET 176 125 126 static void 127 riscv_linux_sigframe_init (const struct tramp_frame *self, 128 frame_info_ptr this_frame, 129 struct trad_frame_cache *this_cache, 130 CORE_ADDR func) 131 { 132 struct gdbarch *gdbarch = get_frame_arch (this_frame); 133 int xlen = riscv_isa_xlen (gdbarch); 134 int flen = riscv_isa_flen (gdbarch); 135 CORE_ADDR frame_sp = get_frame_sp (this_frame); 136 CORE_ADDR mcontext_base; 137 CORE_ADDR regs_base; 138 139 mcontext_base = frame_sp + SIGFRAME_SIGINFO_SIZE + UCONTEXT_MCONTEXT_OFFSET; 140 141 /* Handle the integer registers. The first one is PC, followed by x1 142 through x31. */ 143 regs_base = mcontext_base; 144 trad_frame_set_reg_addr (this_cache, RISCV_PC_REGNUM, regs_base); 145 for (int i = 1; i < 32; i++) 146 trad_frame_set_reg_addr (this_cache, RISCV_ZERO_REGNUM + i, 147 regs_base + (i * xlen)); 148 149 /* Handle the FP registers. First comes the 32 FP registers, followed by 150 fcsr. */ 151 regs_base += 32 * xlen; 152 for (int i = 0; i < 32; i++) 153 trad_frame_set_reg_addr (this_cache, RISCV_FIRST_FP_REGNUM + i, 154 regs_base + (i * flen)); 155 regs_base += 32 * flen; 156 trad_frame_set_reg_addr (this_cache, RISCV_CSR_FCSR_REGNUM, regs_base); 157 158 /* Choice of the bottom of the sigframe is somewhat arbitrary. */ 159 trad_frame_set_id (this_cache, frame_id_build (frame_sp, func)); 160 } 161 162 /* When FRAME is at a syscall instruction (ECALL), return the PC of the next 163 instruction to be executed. */ 164 165 static CORE_ADDR 166 riscv_linux_syscall_next_pc (frame_info_ptr frame) 167 { 168 const CORE_ADDR pc = get_frame_pc (frame); 169 const ULONGEST a7 = get_frame_register_unsigned (frame, RISCV_A7_REGNUM); 170 171 if (a7 == RISCV_NR_rt_sigreturn) 172 return frame_unwind_caller_pc (frame); 173 174 return pc + 4 /* Length of the ECALL insn. */; 175 } 176 177 /* Initialize RISC-V Linux ABI info. */ 178 179 static void 180 riscv_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) 181 { 182 riscv_gdbarch_tdep *tdep = gdbarch_tdep<riscv_gdbarch_tdep> (gdbarch); 183 184 linux_init_abi (info, gdbarch, 0); 185 186 set_gdbarch_software_single_step (gdbarch, riscv_software_single_step); 187 188 set_solib_svr4_fetch_link_map_offsets (gdbarch, 189 (riscv_isa_xlen (gdbarch) == 4 190 ? linux_ilp32_fetch_link_map_offsets 191 : linux_lp64_fetch_link_map_offsets)); 192 193 /* GNU/Linux uses SVR4-style shared libraries. */ 194 set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target); 195 196 /* GNU/Linux uses the dynamic linker included in the GNU C Library. */ 197 set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver); 198 199 /* Enable TLS support. */ 200 set_gdbarch_fetch_tls_load_module_address (gdbarch, 201 svr4_fetch_objfile_link_map); 202 203 set_gdbarch_iterate_over_regset_sections 204 (gdbarch, riscv_linux_iterate_over_regset_sections); 205 206 tramp_frame_prepend_unwinder (gdbarch, &riscv_linux_sigframe); 207 208 tdep->syscall_next_pc = riscv_linux_syscall_next_pc; 209 } 210 211 /* Initialize RISC-V Linux target support. */ 212 213 void _initialize_riscv_linux_tdep (); 214 void 215 _initialize_riscv_linux_tdep () 216 { 217 gdbarch_register_osabi (bfd_arch_riscv, 0, GDB_OSABI_LINUX, 218 riscv_linux_init_abi); 219 } 220