| /* Target-dependent code for the GNU Hurd. |
| Copyright (C) 2002-2021 Free Software Foundation, Inc. |
| |
| This file is part of GDB. |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| |
| #include "defs.h" |
| #include "gdbcore.h" |
| #include "osabi.h" |
| #include "solib-svr4.h" |
| |
| #include "i386-tdep.h" |
| |
| /* Recognizing signal handler frames. */ |
| |
| /* When the GNU/Hurd libc calls a signal handler, the return address points |
| inside the trampoline assembly snippet. |
| |
| If the trampoline function name can not be identified, we resort to reading |
| memory from the process in order to identify it. */ |
| |
| static const gdb_byte gnu_sigtramp_code[] = |
| { |
| /* rpc_wait_trampoline: */ |
| 0xb8, 0xe7, 0xff, 0xff, 0xff, /* mov $-25,%eax */ |
| 0x9a, 0x00, 0x00, 0x00, 0x00, 0x07, 0x00, /* lcall $7,$0 */ |
| 0x89, 0x01, /* movl %eax, (%ecx) */ |
| 0x89, 0xdc, /* movl %ebx, %esp */ |
| |
| /* trampoline: */ |
| 0xff, 0xd2, /* call *%edx */ |
| /* RA HERE */ |
| 0x83, 0xc4, 0x0c, /* addl $12, %esp */ |
| 0xc3, /* ret */ |
| |
| /* firewall: */ |
| 0xf4, /* hlt */ |
| }; |
| |
| #define GNU_SIGTRAMP_LEN (sizeof gnu_sigtramp_code) |
| #define GNU_SIGTRAMP_TAIL 5 /* length of tail after RA */ |
| |
| /* If THIS_FRAME is a sigtramp routine, return the address of the |
| start of the routine. Otherwise, return 0. */ |
| |
| static CORE_ADDR |
| i386_gnu_sigtramp_start (struct frame_info *this_frame) |
| { |
| CORE_ADDR pc = get_frame_pc (this_frame); |
| gdb_byte buf[GNU_SIGTRAMP_LEN]; |
| |
| if (!safe_frame_unwind_memory (this_frame, |
| pc + GNU_SIGTRAMP_TAIL - GNU_SIGTRAMP_LEN, |
| buf)) |
| return 0; |
| |
| if (memcmp (buf, gnu_sigtramp_code, GNU_SIGTRAMP_LEN) != 0) |
| return 0; |
| |
| return pc; |
| } |
| |
| /* Return whether THIS_FRAME corresponds to a GNU/Linux sigtramp |
| routine. */ |
| |
| static int |
| i386_gnu_sigtramp_p (struct frame_info *this_frame) |
| { |
| CORE_ADDR pc = get_frame_pc (this_frame); |
| const char *name; |
| |
| find_pc_partial_function (pc, &name, NULL, NULL); |
| |
| /* If we have a NAME, we can check for the trampoline function */ |
| if (name != NULL && strcmp (name, "trampoline") == 0) |
| return 1; |
| |
| return i386_gnu_sigtramp_start (this_frame) != 0; |
| } |
| |
| /* Offset to sc_i386_thread_state in sigcontext, from <bits/sigcontext.h>. */ |
| #define I386_GNU_SIGCONTEXT_THREAD_STATE_OFFSET 20 |
| |
| /* Assuming THIS_FRAME is a GNU/Linux sigtramp routine, return the |
| address of the associated sigcontext structure. */ |
| |
| static CORE_ADDR |
| i386_gnu_sigcontext_addr (struct frame_info *this_frame) |
| { |
| struct gdbarch *gdbarch = get_frame_arch (this_frame); |
| enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| CORE_ADDR pc; |
| CORE_ADDR sp; |
| gdb_byte buf[4]; |
| |
| get_frame_register (this_frame, I386_ESP_REGNUM, buf); |
| sp = extract_unsigned_integer (buf, 4, byte_order); |
| |
| pc = i386_gnu_sigtramp_start (this_frame); |
| if (pc) |
| { |
| CORE_ADDR sigcontext_addr; |
| |
| /* The sigcontext structure address is passed as the third argument to |
| the signal handler. */ |
| read_memory (sp + 8, buf, 4); |
| sigcontext_addr = extract_unsigned_integer (buf, 4, byte_order); |
| return sigcontext_addr + I386_GNU_SIGCONTEXT_THREAD_STATE_OFFSET; |
| } |
| |
| error (_("Couldn't recognize signal trampoline.")); |
| return 0; |
| } |
| |
| /* Mapping between the general-purpose registers in `struct |
| sigcontext' format (starting at sc_i386_thread_state) |
| and GDB's register cache layout. */ |
| |
| /* From <bits/sigcontext.h>. */ |
| static int i386_gnu_sc_reg_offset[] = |
| { |
| 11 * 4, /* %eax */ |
| 10 * 4, /* %ecx */ |
| 9 * 4, /* %edx */ |
| 8 * 4, /* %ebx */ |
| 7 * 4, /* %esp */ |
| 6 * 4, /* %ebp */ |
| 5 * 4, /* %esi */ |
| 4 * 4, /* %edi */ |
| 12 * 4, /* %eip */ |
| 14 * 4, /* %eflags */ |
| 13 * 4, /* %cs */ |
| 16 * 4, /* %ss */ |
| 3 * 4, /* %ds */ |
| 2 * 4, /* %es */ |
| 1 * 4, /* %fs */ |
| 0 * 4 /* %gs */ |
| }; |
| |
| /* From <sys/ucontext.h>. */ |
| static int i386gnu_gregset_reg_offset[] = |
| { |
| 11 * 4, /* %eax */ |
| 10 * 4, /* %ecx */ |
| 9 * 4, /* %edx */ |
| 8 * 4, /* %ebx */ |
| 17 * 4, /* %uesp */ |
| 6 * 4, /* %ebp */ |
| 5 * 4, /* %esi */ |
| 4 * 4, /* %edi */ |
| 14 * 4, /* %eip */ |
| 16 * 4, /* %efl */ |
| 15 * 4, /* %cs */ |
| 18 * 4, /* %ss */ |
| 3 * 4, /* %ds */ |
| 2 * 4, /* %es */ |
| 1 * 4, /* %fs */ |
| 0 * 4, /* %gs */ |
| }; |
| |
| static void |
| i386gnu_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| { |
| struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| |
| /* GNU uses ELF. */ |
| i386_elf_init_abi (info, gdbarch); |
| |
| set_solib_svr4_fetch_link_map_offsets |
| (gdbarch, svr4_ilp32_fetch_link_map_offsets); |
| |
| tdep->gregset_reg_offset = i386gnu_gregset_reg_offset; |
| tdep->gregset_num_regs = ARRAY_SIZE (i386gnu_gregset_reg_offset); |
| tdep->sizeof_gregset = 19 * 4; |
| |
| tdep->jb_pc_offset = 20; /* From <bits/setjmp.h>. */ |
| |
| tdep->sigtramp_p = i386_gnu_sigtramp_p; |
| tdep->sigcontext_addr = i386_gnu_sigcontext_addr; |
| tdep->sc_reg_offset = i386_gnu_sc_reg_offset; |
| tdep->sc_num_regs = ARRAY_SIZE (i386_gnu_sc_reg_offset); |
| } |
| |
| void _initialize_i386gnu_tdep (); |
| void |
| _initialize_i386gnu_tdep () |
| { |
| gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_HURD, i386gnu_init_abi); |
| } |