1 /* Native-dependent code for OpenBSD/i386.
2
3 Copyright 2002, 2003, 2004 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., 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
21
22 #include "defs.h"
23 #include "gdbcore.h"
24 #include "regcache.h"
25 #include "target.h"
26
27 #include "i386-tdep.h"
28 #include "obsd-nat.h"
29 #include "i386bsd-nat.h"
30
31 #include <sys/param.h>
32 #include <sys/sysctl.h>
33
34 /* Support for debugging kernel virtual memory images. */
35
36 #include <machine/frame.h>
37 #include <machine/pcb.h>
38
39 #include "bsd-kvm.h"
40
41 static int
i386obsd_supply_pcb(struct regcache * regcache,struct pcb * pcb)42 i386obsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
43 {
44 struct switchframe sf;
45
46 /* The following is true for OpenBSD 4.3:
47
48 The pcb contains %esp and %ebp at the point of the context switch
49 in cpu_switchto(). At that point we have a stack frame as
50 described by `struct switchframe', which for OpenBSD 4.3 has the
51 following layout:
52
53 %edi
54 %esi
55 %ebx
56 %eip
57
58 we reconstruct the register state as it would look when we just
59 returned from cpu_switchto().
60
61 For crash dumps, the state is saved by savectx(). In that case
62 we just reconstruct the register state as if we just returned
63 from dumsys(). */
64
65 /* The stack pointer shouldn't be zero. */
66 if (pcb->pcb_esp == 0)
67 return 0;
68
69 if ((pcb->pcb_flags & PCB_SAVECTX) == 0)
70 {
71 /* Yes, we have a frame that matches cpu_switchto(). */
72 read_memory (pcb->pcb_esp, (char *) &sf, sizeof sf);
73 pcb->pcb_esp += sizeof (struct switchframe);
74 regcache_raw_supply (regcache, I386_EDI_REGNUM, &sf.sf_edi);
75 regcache_raw_supply (regcache, I386_ESI_REGNUM, &sf.sf_esi);
76 regcache_raw_supply (regcache, I386_EBX_REGNUM, &sf.sf_ebx);
77 regcache_raw_supply (regcache, I386_EIP_REGNUM, &sf.sf_eip);
78 }
79 else
80 {
81 /* No, the pcb must have been last updated by savectx(). */
82 pcb->pcb_esp = pcb->pcb_ebp;
83 pcb->pcb_ebp = read_memory_integer(pcb->pcb_esp, 4);
84 sf.sf_eip = read_memory_integer(pcb->pcb_esp + 4, 4);
85 regcache_raw_supply (regcache, I386_EIP_REGNUM, &sf.sf_eip);
86 }
87
88 regcache_raw_supply (regcache, I386_EBP_REGNUM, &pcb->pcb_ebp);
89 regcache_raw_supply (regcache, I386_ESP_REGNUM, &pcb->pcb_esp);
90
91 return 1;
92 }
93
94
95 /* Prevent warning from -Wmissing-prototypes. */
96 void _initialize_i386obsd_nat (void);
97
98 void
_initialize_i386obsd_nat(void)99 _initialize_i386obsd_nat (void)
100 {
101 struct target_ops *t;
102
103 /* OpenBSD provides a vm.psstrings sysctl that we can use to locate
104 the sigtramp. That way we can still recognize a sigtramp if its
105 location is changed in a new kernel. This is especially
106 important for OpenBSD, since it uses a different memory layout
107 than NetBSD, yet we cannot distinguish between the two.
108
109 Of course this is still based on the assumption that the sigtramp
110 is placed directly under the location where the program arguments
111 and environment can be found. */
112 #ifdef VM_PSSTRINGS
113 {
114 struct _ps_strings _ps;
115 int mib[2];
116 size_t len;
117
118 mib[0] = CTL_VM;
119 mib[1] = VM_PSSTRINGS;
120 len = sizeof (_ps);
121 if (sysctl (mib, 2, &_ps, &len, NULL, 0) == 0)
122 {
123 i386obsd_sigtramp_start_addr = (CORE_ADDR)_ps.val - 128;
124 i386obsd_sigtramp_end_addr = (CORE_ADDR)_ps.val;
125 }
126 }
127 #endif
128
129 /* Add some extra features to the common *BSD/i386 target. */
130 t = i386bsd_target ();
131 t->to_pid_to_str = obsd_pid_to_str;
132 t->to_find_new_threads = obsd_find_new_threads;
133 t->to_wait = obsd_wait;
134 add_target (t);
135
136 /* Support debugging kernel virtual memory images. */
137 bsd_kvm_add_target (i386obsd_supply_pcb);
138 }
139