1/* Target-dependent code for OpenBSD/alpha. 2 3 Copyright (C) 2006, 2007 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 "alphabsd-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 40static const int alphaobsd_page_size = 8192; 41 42static LONGEST 43alphaobsd_sigtramp_offset (CORE_ADDR pc) 44{ 45 return (pc & (alphaobsd_page_size - 1)); 46} 47 48static int 49alphaobsd_pc_in_sigtramp (CORE_ADDR pc, char *name) 50{ 51 CORE_ADDR start_pc = (pc & ~(alphaobsd_page_size - 1)); 52 unsigned insn; 53 54 if (name) 55 return 0; 56 57 /* Check for "". */ 58 insn = alpha_read_insn (start_pc + 5 * ALPHA_INSN_SIZE); 59 if (insn != 0x201f0067) 60 return 0; 61 62 /* Check for "". */ 63 insn = alpha_read_insn (start_pc + 6 * ALPHA_INSN_SIZE); 64 if (insn != 0x00000083) 65 return 0; 66 67 return 1; 68} 69 70static CORE_ADDR 71alphaobsd_sigcontext_addr (struct frame_info *next_frame) 72{ 73 CORE_ADDR pc = frame_pc_unwind (next_frame); 74 75 if (alphaobsd_sigtramp_offset (pc) < 3 * ALPHA_INSN_SIZE) 76 { 77 /* On entry, a pointer the `struct sigcontext' is passed in %a2. */ 78 return frame_unwind_register_unsigned (next_frame, ALPHA_A0_REGNUM + 2); 79 } 80 else if (alphaobsd_sigtramp_offset (pc) < 4 * ALPHA_INSN_SIZE) 81 { 82 /* It is stored on the stack Before calling the signal handler. */ 83 CORE_ADDR sp; 84 sp = frame_unwind_register_unsigned (next_frame, ALPHA_SP_REGNUM); 85 return get_frame_memory_unsigned (next_frame, sp, 8); 86 } 87 else 88 { 89 /* It is reloaded into %a0 for the sigreturn(2) call. */ 90 return frame_unwind_register_unsigned (next_frame, ALPHA_A0_REGNUM); 91 } 92} 93 94 95static void 96alphaobsd_init_abi(struct gdbarch_info info, struct gdbarch *gdbarch) 97{ 98 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); 99 100 /* Hook into the DWARF CFI frame unwinder. */ 101 alpha_dwarf2_init_abi (info, gdbarch); 102 103 /* Hook into the MDEBUG frame unwinder. */ 104 alpha_mdebug_init_abi (info, gdbarch); 105 106 /* OpenBSD/alpha 3.0 and earlier does not provide single step 107 support via ptrace(2); use software single-stepping for now. */ 108 set_gdbarch_software_single_step (gdbarch, alpha_software_single_step); 109 110 /* OpenBSD/alpha has SVR4-style shared libraries. */ 111 set_solib_svr4_fetch_link_map_offsets 112 (gdbarch, svr4_lp64_fetch_link_map_offsets); 113 set_gdbarch_skip_solib_resolver (gdbarch, obsd_skip_solib_resolver); 114 115 tdep->dynamic_sigtramp_offset = alphaobsd_sigtramp_offset; 116 tdep->pc_in_sigtramp = alphaobsd_pc_in_sigtramp; 117 tdep->sigcontext_addr = alphaobsd_sigcontext_addr; 118 119 tdep->jb_pc = 2; 120 tdep->jb_elt_size = 8; 121 122 set_gdbarch_regset_from_core_section 123 (gdbarch, alphanbsd_regset_from_core_section); 124} 125 126 127/* Provide a prototype to silence -Wmissing-prototypes. */ 128void _initialize_alphaobsd_tdep (void); 129 130void 131_initialize_alphaobsd_tdep (void) 132{ 133 gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_OPENBSD_ELF, 134 alphaobsd_init_abi); 135} 136