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1/* Target-dependent code for OpenBSD/alpha.
2
6aba47ca 3 Copyright (C) 2006, 2007 Free Software Foundation, Inc.
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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 "frame.h"
24#include "gdbcore.h"
25#include "osabi.h"
26
6ea0ec3f 27#include "obsd-tdep.h"
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28#include "alpha-tdep.h"
29#include "alphabsd-tdep.h"
30#include "solib-svr4.h"
31
32/* Signal trampolines. */
33
34/* The OpenBSD kernel maps the signal trampoline at some random
35 location in user space, which means that the traditional BSD way of
36 detecting it won't work.
37
38 The signal trampoline will be mapped at an address that is page
39 aligned. We recognize the signal trampoline by looking for the
40 sigreturn system call. */
41
42static const int alphaobsd_page_size = 8192;
43
44static LONGEST
45alphaobsd_sigtramp_offset (CORE_ADDR pc)
46{
47 return (pc & (alphaobsd_page_size - 1));
48}
49
50static int
51alphaobsd_pc_in_sigtramp (CORE_ADDR pc, char *name)
52{
53 CORE_ADDR start_pc = (pc & ~(alphaobsd_page_size - 1));
54 unsigned insn;
55
56 if (name)
57 return 0;
58
59 /* Check for "". */
60 insn = alpha_read_insn (start_pc + 5 * ALPHA_INSN_SIZE);
61 if (insn != 0x201f0067)
62 return 0;
63
64 /* Check for "". */
65 insn = alpha_read_insn (start_pc + 6 * ALPHA_INSN_SIZE);
66 if (insn != 0x00000083)
67 return 0;
68
69 return 1;
70}
71
72static CORE_ADDR
73alphaobsd_sigcontext_addr (struct frame_info *next_frame)
74{
75 CORE_ADDR pc = frame_pc_unwind (next_frame);
76
77 if (alphaobsd_sigtramp_offset (pc) < 3 * ALPHA_INSN_SIZE)
78 {
79 /* On entry, a pointer the `struct sigcontext' is passed in %a2. */
80 return frame_unwind_register_unsigned (next_frame, ALPHA_A0_REGNUM + 2);
81 }
82 else if (alphaobsd_sigtramp_offset (pc) < 4 * ALPHA_INSN_SIZE)
83 {
84 /* It is stored on the stack Before calling the signal handler. */
85 CORE_ADDR sp;
86 sp = frame_unwind_register_unsigned (next_frame, ALPHA_SP_REGNUM);
87 return get_frame_memory_unsigned (next_frame, sp, 8);
88 }
89 else
90 {
91 /* It is reloaded into %a0 for the sigreturn(2) call. */
92 return frame_unwind_register_unsigned (next_frame, ALPHA_A0_REGNUM);
93 }
94}
95\f
96
97static void
98alphaobsd_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);
6ea0ec3f 115 set_gdbarch_skip_solib_resolver (gdbarch, obsd_skip_solib_resolver);
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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_regset_from_core_section
125 (gdbarch, alphanbsd_regset_from_core_section);
126}
127\f
128
129/* Provide a prototype to silence -Wmissing-prototypes. */
130void _initialize_alphaobsd_tdep (void);
131
132void
133_initialize_alphaobsd_tdep (void)
134{
135 gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_OPENBSD_ELF,
136 alphaobsd_init_abi);
137}