1 /* Target-dependent code for GNU/Linux on Alpha.
2 Copyright 2002 Free Software Foundation, Inc.
4 This file is part of GDB.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
25 #include "alpha-tdep.h"
27 /* Under GNU/Linux, signal handler invocations can be identified by the
28 designated code sequence that is used to return from a signal
29 handler. In particular, the return address of a signal handler
30 points to the following sequence (the first instruction is quadword
37 Each instruction has a unique encoding, so we simply attempt to
38 match the instruction the pc is pointing to with any of the above
39 instructions. If there is a hit, we know the offset to the start
40 of the designated sequence and can then check whether we really are
41 executing in a designated sequence. If not, -1 is returned,
42 otherwise the offset from the start of the desingated sequence is
45 There is a slight chance of false hits: code could jump into the
46 middle of the designated sequence, in which case there is no
47 guarantee that we are in the middle of a sigreturn syscall. Don't
48 think this will be a problem in praxis, though. */
50 alpha_linux_sigtramp_offset (CORE_ADDR pc)
55 if (read_memory_nobpt (pc, (char *) &w, 4) != 0)
63 break; /* bis $30,$30,$16 */
66 break; /* addq $31,0x67,$0 */
69 break; /* call_pal callsys */
76 /* designated sequence is not quadword aligned */
79 if (read_memory_nobpt (pc, (char *) i, sizeof (i)) != 0)
82 if (i[0] == 0x47de0410 && i[1] == 0x43ecf400 && i[2] == 0x00000083)
89 alpha_linux_pc_in_sigtramp (CORE_ADDR pc, char *func_name)
91 return (alpha_linux_sigtramp_offset (pc) >= 0);
95 alpha_linux_init_abi (struct gdbarch_info info,
96 struct gdbarch *gdbarch)
98 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
100 set_gdbarch_pc_in_sigtramp (gdbarch, alpha_linux_pc_in_sigtramp);
102 tdep->dynamic_sigtramp_offset = alpha_linux_sigtramp_offset;
105 tdep->jb_elt_size = 8;
109 _initialize_alpha_linux_tdep (void)
111 alpha_gdbarch_register_os_abi (ALPHA_ABI_LINUX, alpha_linux_init_abi);