1/* Target-dependent code for OpenBSD/vax. 2 3 Copyright (C) 2005, 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 "arch-utils.h" 22#include "frame.h" 23#include "frame-unwind.h" 24#include "osabi.h" 25#include "symtab.h" 26#include "trad-frame.h" 27 28#include "vax-tdep.h" 29 30#include "gdb_string.h" 31 32/* Signal trampolines. */ 33 34/* Since OpenBSD 3.2, the sigtramp routine is mapped at a random page 35 in virtual memory. The randomness makes it somewhat tricky to 36 detect it, but fortunately we can rely on the fact that the start 37 of the sigtramp routine is page-aligned. We recognize the 38 trampoline by looking for the code that invokes the sigreturn 39 system call. The offset where we can find that code varies from 40 release to release. 41 42 By the way, the mapping mentioned above is read-only, so you cannot 43 place a breakpoint in the signal trampoline. */ 44 45/* Default page size. */ 46static const int vaxobsd_page_size = 4096; 47 48/* Offset for sigreturn(2). */ 49static const int vaxobsd_sigreturn_offset = 0x11; 50 51/* Instruction sequence for sigreturn(2). VAX doesn't have 52 fixed-length instructions so we include the ensuing exit(2) to 53 reduce the chance of spurious matches. */ 54static const gdb_byte vaxobsd_sigreturn[] = { 55 0xbc, 0x8f, 0x67, 0x00, /* chmk $SYS_sigreturn */ 56 0xbc, 0x01 /* chmk $SYS_exit */ 57}; 58 59static int 60vaxobsd_sigtramp_p (struct frame_info *next_frame) 61{ 62 CORE_ADDR pc = frame_pc_unwind (next_frame); 63 CORE_ADDR start_pc = (pc & ~(vaxobsd_page_size - 1)); 64 CORE_ADDR sigreturn_addr = start_pc + vaxobsd_sigreturn_offset; 65 gdb_byte *buf; 66 char *name; 67 68 find_pc_partial_function (pc, &name, NULL, NULL); 69 if (name) 70 return 0; 71 72 buf = alloca(sizeof vaxobsd_sigreturn); 73 if (!safe_frame_unwind_memory (next_frame, sigreturn_addr, 74 buf, sizeof vaxobsd_sigreturn)) 75 return 0; 76 77 if (memcmp(buf, vaxobsd_sigreturn, sizeof vaxobsd_sigreturn) == 0) 78 return 1; 79 80 return 0; 81} 82 83static struct trad_frame_cache * 84vaxobsd_sigtramp_frame_cache (struct frame_info *next_frame, void **this_cache) 85{ 86 struct trad_frame_cache *cache; 87 CORE_ADDR addr, base, func; 88 89 if (*this_cache) 90 return *this_cache; 91 92 cache = trad_frame_cache_zalloc (next_frame); 93 *this_cache = cache; 94 95 func = frame_pc_unwind (next_frame); 96 func &= ~(vaxobsd_page_size - 1); 97 98 base = frame_unwind_register_unsigned (next_frame, VAX_SP_REGNUM); 99 addr = get_frame_memory_unsigned (next_frame, base - 4, 4); 100 101 trad_frame_set_reg_addr (cache, VAX_SP_REGNUM, addr + 8); 102 trad_frame_set_reg_addr (cache, VAX_FP_REGNUM, addr + 12); 103 trad_frame_set_reg_addr (cache, VAX_AP_REGNUM, addr + 16); 104 trad_frame_set_reg_addr (cache, VAX_PC_REGNUM, addr + 20); 105 trad_frame_set_reg_addr (cache, VAX_PS_REGNUM, addr + 24); 106 107 /* Construct the frame ID using the function start. */ 108 trad_frame_set_id (cache, frame_id_build (base, func)); 109 110 return cache; 111} 112 113static void 114vaxobsd_sigtramp_frame_this_id (struct frame_info *next_frame, 115 void **this_cache, struct frame_id *this_id) 116{ 117 struct trad_frame_cache *cache = 118 vaxobsd_sigtramp_frame_cache (next_frame, this_cache); 119 120 trad_frame_get_id (cache, this_id); 121} 122 123static void 124vaxobsd_sigtramp_frame_prev_register (struct frame_info *next_frame, 125 void **this_cache, int regnum, 126 int *optimizedp, enum lval_type *lvalp, 127 CORE_ADDR *addrp, int *realnump, 128 gdb_byte *valuep) 129{ 130 struct trad_frame_cache *cache = 131 vaxobsd_sigtramp_frame_cache (next_frame, this_cache); 132 133 trad_frame_get_register (cache, next_frame, regnum, 134 optimizedp, lvalp, addrp, realnump, valuep); 135} 136 137static const struct frame_unwind vaxobsd_sigtramp_frame_unwind = { 138 SIGTRAMP_FRAME, 139 vaxobsd_sigtramp_frame_this_id, 140 vaxobsd_sigtramp_frame_prev_register 141}; 142 143static const struct frame_unwind * 144vaxobsd_sigtramp_frame_sniffer (struct frame_info *next_frame) 145{ 146 if (vaxobsd_sigtramp_p (next_frame)) 147 return &vaxobsd_sigtramp_frame_unwind; 148 149 return NULL; 150} 151 152 153/* OpenBSD a.out. */ 154 155static void 156vaxobsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) 157{ 158 frame_unwind_append_sniffer (gdbarch, vaxobsd_sigtramp_frame_sniffer); 159} 160 161/* FIXME: kettenis/20050821: Since OpenBSD/vax binaries are 162 indistingushable from NetBSD/vax a.out binaries, building a GDB 163 that should support both these targets will probably not work as 164 expected. */ 165#define GDB_OSABI_OPENBSD_AOUT GDB_OSABI_NETBSD_AOUT 166 167static enum gdb_osabi 168vaxobsd_aout_osabi_sniffer (bfd *abfd) 169{ 170 if (strcmp (bfd_get_target (abfd), "a.out-vax-netbsd") == 0) 171 return GDB_OSABI_OPENBSD_AOUT; 172 173 return GDB_OSABI_UNKNOWN; 174} 175 176 177/* Provide a prototype to silence -Wmissing-prototypes. */ 178void _initialize_vaxobsd_tdep (void); 179 180void 181_initialize_vaxobsd_tdep (void) 182{ 183 gdbarch_register_osabi_sniffer (bfd_arch_vax, bfd_target_aout_flavour, 184 vaxobsd_aout_osabi_sniffer); 185 186 gdbarch_register_osabi (bfd_arch_vax, 0, GDB_OSABI_OPENBSD_AOUT, 187 vaxobsd_init_abi); 188} 189