1 /* Target-dependent code for the GNU Hurd. 2 Copyright (C) 2002-2024 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 "extract-store-integer.h" 20 #include "gdbcore.h" 21 #include "osabi.h" 22 #include "solib-svr4.h" 23 24 #include "i386-tdep.h" 25 26 /* Recognizing signal handler frames. */ 27 28 /* When the GNU/Hurd libc calls a signal handler, the return address points 29 inside the trampoline assembly snippet. 30 31 If the trampoline function name can not be identified, we resort to reading 32 memory from the process in order to identify it. */ 33 34 static const gdb_byte gnu_sigtramp_code[] = 35 { 36 /* rpc_wait_trampoline: */ 37 0xb8, 0xe7, 0xff, 0xff, 0xff, /* mov $-25,%eax */ 38 0x9a, 0x00, 0x00, 0x00, 0x00, 0x07, 0x00, /* lcall $7,$0 */ 39 0x89, 0x01, /* movl %eax, (%ecx) */ 40 0x89, 0xdc, /* movl %ebx, %esp */ 41 42 /* trampoline: */ 43 0xff, 0xd2, /* call *%edx */ 44 /* RA HERE */ 45 0x83, 0xc4, 0x0c, /* addl $12, %esp */ 46 0xc3, /* ret */ 47 48 /* firewall: */ 49 0xf4, /* hlt */ 50 }; 51 52 #define GNU_SIGTRAMP_LEN (sizeof gnu_sigtramp_code) 53 #define GNU_SIGTRAMP_TAIL 5 /* length of tail after RA */ 54 55 /* If THIS_FRAME is a sigtramp routine, return the address of the 56 start of the routine. Otherwise, return 0. */ 57 58 static CORE_ADDR 59 i386_gnu_sigtramp_start (const frame_info_ptr &this_frame) 60 { 61 CORE_ADDR pc = get_frame_pc (this_frame); 62 gdb_byte buf[GNU_SIGTRAMP_LEN]; 63 64 if (!safe_frame_unwind_memory (this_frame, 65 pc + GNU_SIGTRAMP_TAIL - GNU_SIGTRAMP_LEN, 66 buf)) 67 return 0; 68 69 if (memcmp (buf, gnu_sigtramp_code, GNU_SIGTRAMP_LEN) != 0) 70 return 0; 71 72 return pc; 73 } 74 75 /* Return whether THIS_FRAME corresponds to a GNU/Linux sigtramp 76 routine. */ 77 78 static int 79 i386_gnu_sigtramp_p (const frame_info_ptr &this_frame) 80 { 81 CORE_ADDR pc = get_frame_pc (this_frame); 82 const char *name; 83 84 find_pc_partial_function (pc, &name, NULL, NULL); 85 86 /* If we have a NAME, we can check for the trampoline function */ 87 if (name != NULL && strcmp (name, "trampoline") == 0) 88 return 1; 89 90 return i386_gnu_sigtramp_start (this_frame) != 0; 91 } 92 93 /* Offset to sc_i386_thread_state in sigcontext, from <bits/sigcontext.h>. */ 94 #define I386_GNU_SIGCONTEXT_THREAD_STATE_OFFSET 20 95 96 /* Assuming THIS_FRAME is a GNU/Linux sigtramp routine, return the 97 address of the associated sigcontext structure. */ 98 99 static CORE_ADDR 100 i386_gnu_sigcontext_addr (const frame_info_ptr &this_frame) 101 { 102 struct gdbarch *gdbarch = get_frame_arch (this_frame); 103 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); 104 CORE_ADDR pc; 105 CORE_ADDR sp; 106 gdb_byte buf[4]; 107 108 get_frame_register (this_frame, I386_ESP_REGNUM, buf); 109 sp = extract_unsigned_integer (buf, 4, byte_order); 110 111 pc = i386_gnu_sigtramp_start (this_frame); 112 if (pc) 113 { 114 CORE_ADDR sigcontext_addr; 115 116 /* The sigcontext structure address is passed as the third argument to 117 the signal handler. */ 118 read_memory (sp + 8, buf, 4); 119 sigcontext_addr = extract_unsigned_integer (buf, 4, byte_order); 120 return sigcontext_addr + I386_GNU_SIGCONTEXT_THREAD_STATE_OFFSET; 121 } 122 123 error (_("Couldn't recognize signal trampoline.")); 124 return 0; 125 } 126 127 /* Mapping between the general-purpose registers in `struct 128 sigcontext' format (starting at sc_i386_thread_state) 129 and GDB's register cache layout. */ 130 131 /* From <bits/sigcontext.h>. */ 132 static int i386_gnu_sc_reg_offset[] = 133 { 134 11 * 4, /* %eax */ 135 10 * 4, /* %ecx */ 136 9 * 4, /* %edx */ 137 8 * 4, /* %ebx */ 138 7 * 4, /* %esp */ 139 6 * 4, /* %ebp */ 140 5 * 4, /* %esi */ 141 4 * 4, /* %edi */ 142 12 * 4, /* %eip */ 143 14 * 4, /* %eflags */ 144 13 * 4, /* %cs */ 145 16 * 4, /* %ss */ 146 3 * 4, /* %ds */ 147 2 * 4, /* %es */ 148 1 * 4, /* %fs */ 149 0 * 4 /* %gs */ 150 }; 151 152 /* From <sys/ucontext.h>. */ 153 static int i386gnu_gregset_reg_offset[] = 154 { 155 11 * 4, /* %eax */ 156 10 * 4, /* %ecx */ 157 9 * 4, /* %edx */ 158 8 * 4, /* %ebx */ 159 17 * 4, /* %uesp */ 160 6 * 4, /* %ebp */ 161 5 * 4, /* %esi */ 162 4 * 4, /* %edi */ 163 14 * 4, /* %eip */ 164 16 * 4, /* %efl */ 165 15 * 4, /* %cs */ 166 18 * 4, /* %ss */ 167 3 * 4, /* %ds */ 168 2 * 4, /* %es */ 169 1 * 4, /* %fs */ 170 0 * 4, /* %gs */ 171 }; 172 173 static void 174 i386gnu_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) 175 { 176 i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (gdbarch); 177 178 /* GNU uses ELF. */ 179 i386_elf_init_abi (info, gdbarch); 180 181 set_solib_svr4_fetch_link_map_offsets 182 (gdbarch, svr4_ilp32_fetch_link_map_offsets); 183 184 tdep->gregset_reg_offset = i386gnu_gregset_reg_offset; 185 tdep->gregset_num_regs = ARRAY_SIZE (i386gnu_gregset_reg_offset); 186 tdep->sizeof_gregset = 19 * 4; 187 188 tdep->jb_pc_offset = 20; /* From <bits/setjmp.h>. */ 189 190 tdep->sigtramp_p = i386_gnu_sigtramp_p; 191 tdep->sigcontext_addr = i386_gnu_sigcontext_addr; 192 tdep->sc_reg_offset = i386_gnu_sc_reg_offset; 193 tdep->sc_num_regs = ARRAY_SIZE (i386_gnu_sc_reg_offset); 194 } 195 196 void _initialize_i386gnu_tdep (); 197 void 198 _initialize_i386gnu_tdep () 199 { 200 gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_HURD, i386gnu_init_abi); 201 } 202
Indexes created Wed Mar 04 15:26:31 UTC 2026