1 /* Target-dependent code for OpenBSD/alpha. 2 3 Copyright (C) 2006-2019 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 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 } 127 128 129 void 130 _initialize_alphaobsd_tdep (void) 131 { 132 gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_OPENBSD, 133 alphaobsd_init_abi); 134 } 135