| 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 2 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, write to the Free Software |
| 19 | Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| 20 | Boston, MA 02110-1301, USA. */ |
| 21 | |
| 22 | #include "defs.h" |
| 23 | #include "arch-utils.h" |
| 24 | #include "frame.h" |
| 25 | #include "frame-unwind.h" |
| 26 | #include "osabi.h" |
| 27 | #include "symtab.h" |
| 28 | #include "trad-frame.h" |
| 29 | |
| 30 | #include "vax-tdep.h" |
| 31 | |
| 32 | #include "gdb_string.h" |
| 33 | |
| 34 | /* Signal trampolines. */ |
| 35 | |
| 36 | /* Since OpenBSD 3.2, the sigtramp routine is mapped at a random page |
| 37 | in virtual memory. The randomness makes it somewhat tricky to |
| 38 | detect it, but fortunately we can rely on the fact that the start |
| 39 | of the sigtramp routine is page-aligned. We recognize the |
| 40 | trampoline by looking for the code that invokes the sigreturn |
| 41 | system call. The offset where we can find that code varies from |
| 42 | release to release. |
| 43 | |
| 44 | By the way, the mapping mentioned above is read-only, so you cannot |
| 45 | place a breakpoint in the signal trampoline. */ |
| 46 | |
| 47 | /* Default page size. */ |
| 48 | static const int vaxobsd_page_size = 4096; |
| 49 | |
| 50 | /* Offset for sigreturn(2). */ |
| 51 | static const int vaxobsd_sigreturn_offset = 0x11; |
| 52 | |
| 53 | /* Instruction sequence for sigreturn(2). VAX doesn't have |
| 54 | fixed-length instructions so we include the ensuing exit(2) to |
| 55 | reduce the chance of spurious matches. */ |
| 56 | static const gdb_byte vaxobsd_sigreturn[] = { |
| 57 | 0xbc, 0x8f, 0x67, 0x00, /* chmk $SYS_sigreturn */ |
| 58 | 0xbc, 0x01 /* chmk $SYS_exit */ |
| 59 | }; |
| 60 | |
| 61 | static int |
| 62 | vaxobsd_sigtramp_p (struct frame_info *next_frame) |
| 63 | { |
| 64 | CORE_ADDR pc = frame_pc_unwind (next_frame); |
| 65 | CORE_ADDR start_pc = (pc & ~(vaxobsd_page_size - 1)); |
| 66 | CORE_ADDR sigreturn_addr = start_pc + vaxobsd_sigreturn_offset; |
| 67 | gdb_byte *buf; |
| 68 | char *name; |
| 69 | |
| 70 | find_pc_partial_function (pc, &name, NULL, NULL); |
| 71 | if (name) |
| 72 | return 0; |
| 73 | |
| 74 | buf = alloca(sizeof vaxobsd_sigreturn); |
| 75 | if (!safe_frame_unwind_memory (next_frame, sigreturn_addr, |
| 76 | buf, sizeof vaxobsd_sigreturn)) |
| 77 | return 0; |
| 78 | |
| 79 | if (memcmp(buf, vaxobsd_sigreturn, sizeof vaxobsd_sigreturn) == 0) |
| 80 | return 1; |
| 81 | |
| 82 | return 0; |
| 83 | } |
| 84 | |
| 85 | static struct trad_frame_cache * |
| 86 | vaxobsd_sigtramp_frame_cache (struct frame_info *next_frame, void **this_cache) |
| 87 | { |
| 88 | struct trad_frame_cache *cache; |
| 89 | CORE_ADDR addr, base, func; |
| 90 | |
| 91 | if (*this_cache) |
| 92 | return *this_cache; |
| 93 | |
| 94 | cache = trad_frame_cache_zalloc (next_frame); |
| 95 | *this_cache = cache; |
| 96 | |
| 97 | func = frame_pc_unwind (next_frame); |
| 98 | func &= ~(vaxobsd_page_size - 1); |
| 99 | |
| 100 | base = frame_unwind_register_unsigned (next_frame, VAX_SP_REGNUM); |
| 101 | addr = get_frame_memory_unsigned (next_frame, base - 4, 4); |
| 102 | |
| 103 | trad_frame_set_reg_addr (cache, VAX_SP_REGNUM, addr + 8); |
| 104 | trad_frame_set_reg_addr (cache, VAX_FP_REGNUM, addr + 12); |
| 105 | trad_frame_set_reg_addr (cache, VAX_AP_REGNUM, addr + 16); |
| 106 | trad_frame_set_reg_addr (cache, VAX_PC_REGNUM, addr + 20); |
| 107 | trad_frame_set_reg_addr (cache, VAX_PS_REGNUM, addr + 24); |
| 108 | |
| 109 | /* Construct the frame ID using the function start. */ |
| 110 | trad_frame_set_id (cache, frame_id_build (base, func)); |
| 111 | |
| 112 | return cache; |
| 113 | } |
| 114 | |
| 115 | static void |
| 116 | vaxobsd_sigtramp_frame_this_id (struct frame_info *next_frame, |
| 117 | void **this_cache, struct frame_id *this_id) |
| 118 | { |
| 119 | struct trad_frame_cache *cache = |
| 120 | vaxobsd_sigtramp_frame_cache (next_frame, this_cache); |
| 121 | |
| 122 | trad_frame_get_id (cache, this_id); |
| 123 | } |
| 124 | |
| 125 | static void |
| 126 | vaxobsd_sigtramp_frame_prev_register (struct frame_info *next_frame, |
| 127 | void **this_cache, int regnum, |
| 128 | int *optimizedp, enum lval_type *lvalp, |
| 129 | CORE_ADDR *addrp, int *realnump, |
| 130 | gdb_byte *valuep) |
| 131 | { |
| 132 | struct trad_frame_cache *cache = |
| 133 | vaxobsd_sigtramp_frame_cache (next_frame, this_cache); |
| 134 | |
| 135 | trad_frame_get_register (cache, next_frame, regnum, |
| 136 | optimizedp, lvalp, addrp, realnump, valuep); |
| 137 | } |
| 138 | |
| 139 | static const struct frame_unwind vaxobsd_sigtramp_frame_unwind = { |
| 140 | SIGTRAMP_FRAME, |
| 141 | vaxobsd_sigtramp_frame_this_id, |
| 142 | vaxobsd_sigtramp_frame_prev_register |
| 143 | }; |
| 144 | |
| 145 | static const struct frame_unwind * |
| 146 | vaxobsd_sigtramp_frame_sniffer (struct frame_info *next_frame) |
| 147 | { |
| 148 | if (vaxobsd_sigtramp_p (next_frame)) |
| 149 | return &vaxobsd_sigtramp_frame_unwind; |
| 150 | |
| 151 | return NULL; |
| 152 | } |
| 153 | \f |
| 154 | |
| 155 | /* OpenBSD a.out. */ |
| 156 | |
| 157 | static void |
| 158 | vaxobsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| 159 | { |
| 160 | frame_unwind_append_sniffer (gdbarch, vaxobsd_sigtramp_frame_sniffer); |
| 161 | } |
| 162 | |
| 163 | /* FIXME: kettenis/20050821: Since OpenBSD/vax binaries are |
| 164 | indistingushable from NetBSD/vax a.out binaries, building a GDB |
| 165 | that should support both these targets will probably not work as |
| 166 | expected. */ |
| 167 | #define GDB_OSABI_OPENBSD_AOUT GDB_OSABI_NETBSD_AOUT |
| 168 | |
| 169 | static enum gdb_osabi |
| 170 | vaxobsd_aout_osabi_sniffer (bfd *abfd) |
| 171 | { |
| 172 | if (strcmp (bfd_get_target (abfd), "a.out-vax-netbsd") == 0) |
| 173 | return GDB_OSABI_OPENBSD_AOUT; |
| 174 | |
| 175 | return GDB_OSABI_UNKNOWN; |
| 176 | } |
| 177 | \f |
| 178 | |
| 179 | /* Provide a prototype to silence -Wmissing-prototypes. */ |
| 180 | void _initialize_vaxobsd_tdep (void); |
| 181 | |
| 182 | void |
| 183 | _initialize_vaxobsd_tdep (void) |
| 184 | { |
| 185 | gdbarch_register_osabi_sniffer (bfd_arch_vax, bfd_target_aout_flavour, |
| 186 | vaxobsd_aout_osabi_sniffer); |
| 187 | |
| 188 | gdbarch_register_osabi (bfd_arch_vax, 0, GDB_OSABI_OPENBSD_AOUT, |
| 189 | vaxobsd_init_abi); |
| 190 | } |