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baadce09 | 1 | /* Native-dependent code for OpenBSD/i386. |
5d93ae8c | 2 | |
6aba47ca | 3 | Copyright (C) 2002, 2003, 2004, 2006, 2007 Free Software Foundation, Inc. |
baadce09 MK |
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 | |
a9762ec7 | 9 | the Free Software Foundation; either version 3 of the License, or |
baadce09 MK |
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 | |
a9762ec7 | 18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
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19 | |
20 | #include "defs.h" | |
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21 | #include "gdbcore.h" |
22 | #include "regcache.h" | |
23 | #include "target.h" | |
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24 | |
25 | #include <sys/param.h> | |
26 | #include <sys/sysctl.h> | |
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27 | #include <machine/frame.h> |
28 | #include <machine/pcb.h> | |
baadce09 | 29 | |
e2dbbd2d | 30 | #include "i386-tdep.h" |
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31 | #include "i386bsd-nat.h" |
32 | #include "bsd-kvm.h" | |
33 | ||
34 | static int | |
35 | i386obsd_supply_pcb (struct regcache *regcache, struct pcb *pcb) | |
36 | { | |
37 | struct switchframe sf; | |
38 | ||
39 | /* The following is true for OpenBSD 3.6: | |
40 | ||
41 | The pcb contains %esp and %ebp at the point of the context switch | |
42 | in cpu_switch(). At that point we have a stack frame as | |
43 | described by `struct switchframe', which for OpenBSD 3.6 has the | |
44 | following layout: | |
45 | ||
46 | interrupt level | |
47 | %edi | |
48 | %esi | |
49 | %ebx | |
50 | %eip | |
51 | ||
52 | we reconstruct the register state as it would look when we just | |
53 | returned from cpu_switch(). */ | |
54 | ||
55 | /* The stack pointer shouldn't be zero. */ | |
56 | if (pcb->pcb_esp == 0) | |
57 | return 0; | |
58 | ||
59 | /* Read the stack frame, and check its validity. We do this by | |
60 | checking if the saved interrupt priority level in the stack frame | |
61 | looks reasonable.. */ | |
62 | read_memory (pcb->pcb_esp, (char *) &sf, sizeof sf); | |
63 | if ((unsigned int) sf.sf_ppl < 0x100 && (sf.sf_ppl & 0xf) == 0) | |
64 | { | |
65 | /* Yes, we have a frame that matches cpu_switch(). */ | |
66 | pcb->pcb_esp += sizeof (struct switchframe); | |
67 | regcache_raw_supply (regcache, I386_EDI_REGNUM, &sf.sf_edi); | |
68 | regcache_raw_supply (regcache, I386_ESI_REGNUM, &sf.sf_esi); | |
69 | regcache_raw_supply (regcache, I386_EBX_REGNUM, &sf.sf_ebx); | |
70 | regcache_raw_supply (regcache, I386_EIP_REGNUM, &sf.sf_eip); | |
71 | } | |
72 | else | |
73 | { | |
74 | /* No, the pcb must have been last updated by savectx(). */ | |
75 | pcb->pcb_esp += 4; | |
76 | regcache_raw_supply (regcache, I386_EIP_REGNUM, &sf); | |
77 | } | |
78 | ||
79 | regcache_raw_supply (regcache, I386_EBP_REGNUM, &pcb->pcb_ebp); | |
80 | regcache_raw_supply (regcache, I386_ESP_REGNUM, &pcb->pcb_esp); | |
81 | ||
82 | return 1; | |
83 | } | |
84 | \f | |
e2dbbd2d | 85 | |
baadce09 | 86 | /* Prevent warning from -Wmissing-prototypes. */ |
e5e4acad | 87 | void _initialize_i386obsd_nat (void); |
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88 | |
89 | void | |
90 | _initialize_i386obsd_nat (void) | |
91 | { | |
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92 | /* We've got nothing to add to the common *BSD/i386 target. */ |
93 | add_target (i386bsd_target ()); | |
94 | ||
95 | /* Support debugging kernel virtual memory images. */ | |
96 | bsd_kvm_add_target (i386obsd_supply_pcb); | |
97 | ||
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98 | /* OpenBSD provides a vm.psstrings sysctl that we can use to locate |
99 | the sigtramp. That way we can still recognize a sigtramp if its | |
100 | location is changed in a new kernel. This is especially | |
101 | important for OpenBSD, since it uses a different memory layout | |
102 | than NetBSD, yet we cannot distinguish between the two. | |
103 | ||
104 | Of course this is still based on the assumption that the sigtramp | |
105 | is placed directly under the location where the program arguments | |
106 | and environment can be found. */ | |
107 | #ifdef VM_PSSTRINGS | |
108 | { | |
109 | struct _ps_strings _ps; | |
110 | int mib[2]; | |
111 | size_t len; | |
112 | ||
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113 | mib[0] = CTL_VM; |
114 | mib[1] = VM_PSSTRINGS; | |
115 | len = sizeof (_ps); | |
116 | if (sysctl (mib, 2, &_ps, &len, NULL, 0) == 0) | |
117 | { | |
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118 | i386obsd_sigtramp_start_addr = (u_long) _ps.val - 128; |
119 | i386obsd_sigtramp_end_addr = (u_long) _ps.val; | |
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120 | } |
121 | } | |
122 | #endif | |
123 | } |