| 1 | /* Target-dependent code for OpenBSD/alpha. |
| 2 | |
| 3 | Copyright (C) 2006-2018 Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of GDB. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 19 | |
| 20 | #include "defs.h" |
| 21 | #include "frame.h" |
| 22 | #include "gdbcore.h" |
| 23 | #include "osabi.h" |
| 24 | |
| 25 | #include "obsd-tdep.h" |
| 26 | #include "alpha-tdep.h" |
| 27 | #include "alpha-bsd-tdep.h" |
| 28 | #include "solib-svr4.h" |
| 29 | |
| 30 | /* Signal trampolines. */ |
| 31 | |
| 32 | /* The OpenBSD kernel maps the signal trampoline at some random |
| 33 | location in user space, which means that the traditional BSD way of |
| 34 | detecting it won't work. |
| 35 | |
| 36 | The signal trampoline will be mapped at an address that is page |
| 37 | aligned. We recognize the signal trampoline by looking for the |
| 38 | sigreturn system call. */ |
| 39 | |
| 40 | static const int alphaobsd_page_size = 8192; |
| 41 | |
| 42 | static LONGEST |
| 43 | alphaobsd_sigtramp_offset (struct gdbarch *gdbarch, CORE_ADDR pc) |
| 44 | { |
| 45 | return (pc & (alphaobsd_page_size - 1)); |
| 46 | } |
| 47 | |
| 48 | static int |
| 49 | alphaobsd_pc_in_sigtramp (struct gdbarch *gdbarch, |
| 50 | CORE_ADDR pc, const char *name) |
| 51 | { |
| 52 | CORE_ADDR start_pc = (pc & ~(alphaobsd_page_size - 1)); |
| 53 | unsigned insn; |
| 54 | |
| 55 | if (name) |
| 56 | return 0; |
| 57 | |
| 58 | /* Check for "". */ |
| 59 | insn = alpha_read_insn (gdbarch, start_pc + 5 * ALPHA_INSN_SIZE); |
| 60 | if (insn != 0x201f0067) |
| 61 | return 0; |
| 62 | |
| 63 | /* Check for "". */ |
| 64 | insn = alpha_read_insn (gdbarch, start_pc + 6 * ALPHA_INSN_SIZE); |
| 65 | if (insn != 0x00000083) |
| 66 | return 0; |
| 67 | |
| 68 | return 1; |
| 69 | } |
| 70 | |
| 71 | static CORE_ADDR |
| 72 | alphaobsd_sigcontext_addr (struct frame_info *this_frame) |
| 73 | { |
| 74 | struct gdbarch *gdbarch = get_frame_arch (this_frame); |
| 75 | CORE_ADDR pc = get_frame_pc (this_frame); |
| 76 | |
| 77 | if (alphaobsd_sigtramp_offset (gdbarch, pc) < 3 * ALPHA_INSN_SIZE) |
| 78 | { |
| 79 | /* On entry, a pointer the `struct sigcontext' is passed in %a2. */ |
| 80 | return get_frame_register_unsigned (this_frame, ALPHA_A0_REGNUM + 2); |
| 81 | } |
| 82 | else if (alphaobsd_sigtramp_offset (gdbarch, pc) < 4 * ALPHA_INSN_SIZE) |
| 83 | { |
| 84 | /* It is stored on the stack Before calling the signal handler. */ |
| 85 | CORE_ADDR sp; |
| 86 | sp = get_frame_register_unsigned (this_frame, ALPHA_SP_REGNUM); |
| 87 | return get_frame_memory_unsigned (this_frame, sp, 8); |
| 88 | } |
| 89 | else |
| 90 | { |
| 91 | /* It is reloaded into %a0 for the sigreturn(2) call. */ |
| 92 | return get_frame_register_unsigned (this_frame, ALPHA_A0_REGNUM); |
| 93 | } |
| 94 | } |
| 95 | \f |
| 96 | |
| 97 | static void |
| 98 | alphaobsd_init_abi(struct gdbarch_info info, struct gdbarch *gdbarch) |
| 99 | { |
| 100 | struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| 101 | |
| 102 | /* Hook into the DWARF CFI frame unwinder. */ |
| 103 | alpha_dwarf2_init_abi (info, gdbarch); |
| 104 | |
| 105 | /* Hook into the MDEBUG frame unwinder. */ |
| 106 | alpha_mdebug_init_abi (info, gdbarch); |
| 107 | |
| 108 | /* OpenBSD/alpha 3.0 and earlier does not provide single step |
| 109 | support via ptrace(2); use software single-stepping for now. */ |
| 110 | set_gdbarch_software_single_step (gdbarch, alpha_software_single_step); |
| 111 | |
| 112 | /* OpenBSD/alpha has SVR4-style shared libraries. */ |
| 113 | set_solib_svr4_fetch_link_map_offsets |
| 114 | (gdbarch, svr4_lp64_fetch_link_map_offsets); |
| 115 | set_gdbarch_skip_solib_resolver (gdbarch, obsd_skip_solib_resolver); |
| 116 | |
| 117 | tdep->dynamic_sigtramp_offset = alphaobsd_sigtramp_offset; |
| 118 | tdep->pc_in_sigtramp = alphaobsd_pc_in_sigtramp; |
| 119 | tdep->sigcontext_addr = alphaobsd_sigcontext_addr; |
| 120 | |
| 121 | tdep->jb_pc = 2; |
| 122 | tdep->jb_elt_size = 8; |
| 123 | |
| 124 | set_gdbarch_iterate_over_regset_sections |
| 125 | (gdbarch, alphanbsd_iterate_over_regset_sections); |
| 126 | } |
| 127 | \f |
| 128 | |
| 129 | void |
| 130 | _initialize_alphaobsd_tdep (void) |
| 131 | { |
| 132 | gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_OPENBSD, |
| 133 | alphaobsd_init_abi); |
| 134 | } |