1 /* Native-dependent code for OpenBSD/i386.
3 Copyright (C) 2002-2015 Free Software Foundation, Inc.
5 This file is part of GDB.
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 3 of the License, or
10 (at your option) any later version.
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.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
25 #include <sys/sysctl.h>
26 #include <machine/frame.h>
27 #include <machine/pcb.h>
29 #include "i386-tdep.h"
30 #include "i386bsd-nat.h"
35 i386obsd_supply_pcb (struct regcache
*regcache
, struct pcb
*pcb
)
37 struct gdbarch
*gdbarch
= get_regcache_arch (regcache
);
38 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
39 struct switchframe sf
;
41 /* The following is true for OpenBSD 3.6:
43 The pcb contains %esp and %ebp at the point of the context switch
44 in cpu_switch(). At that point we have a stack frame as
45 described by `struct switchframe', which for OpenBSD 3.6 has the
54 we reconstruct the register state as it would look when we just
55 returned from cpu_switch(). */
57 /* The stack pointer shouldn't be zero. */
58 if (pcb
->pcb_esp
== 0)
61 /* Read the stack frame, and check its validity. We do this by
62 checking if the saved interrupt priority level in the stack frame
65 if ((pcb
->pcb_flags
& PCB_SAVECTX
) == 0)
67 /* Yes, we have a frame that matches cpu_switch(). */
68 read_memory (pcb
->pcb_esp
, (gdb_byte
*) &sf
, sizeof sf
);
69 pcb
->pcb_esp
+= sizeof (struct switchframe
);
70 regcache_raw_supply (regcache
, I386_EDI_REGNUM
, &sf
.sf_edi
);
71 regcache_raw_supply (regcache
, I386_ESI_REGNUM
, &sf
.sf_esi
);
72 regcache_raw_supply (regcache
, I386_EBX_REGNUM
, &sf
.sf_ebx
);
73 regcache_raw_supply (regcache
, I386_EIP_REGNUM
, &sf
.sf_eip
);
78 /* No, the pcb must have been last updated by savectx(). */
79 pcb
->pcb_esp
= pcb
->pcb_ebp
;
80 pcb
->pcb_ebp
= read_memory_integer(pcb
->pcb_esp
, 4, byte_order
);
81 sf
.sf_eip
= read_memory_integer(pcb
->pcb_esp
+ 4, 4, byte_order
);
82 regcache_raw_supply (regcache
, I386_EIP_REGNUM
, &sf
.sf_eip
);
85 regcache_raw_supply (regcache
, I386_EBP_REGNUM
, &pcb
->pcb_ebp
);
86 regcache_raw_supply (regcache
, I386_ESP_REGNUM
, &pcb
->pcb_esp
);
92 /* Prevent warning from -Wmissing-prototypes. */
93 void _initialize_i386obsd_nat (void);
96 _initialize_i386obsd_nat (void)
98 /* Add some extra features to the common *BSD/i386 target. */
99 obsd_add_target (i386bsd_target ());
101 /* Support debugging kernel virtual memory images. */
102 bsd_kvm_add_target (i386obsd_supply_pcb
);
104 /* OpenBSD provides a vm.psstrings sysctl that we can use to locate
105 the sigtramp. That way we can still recognize a sigtramp if its
106 location is changed in a new kernel. This is especially
107 important for OpenBSD, since it uses a different memory layout
108 than NetBSD, yet we cannot distinguish between the two.
110 Of course this is still based on the assumption that the sigtramp
111 is placed directly under the location where the program arguments
112 and environment can be found. */
115 struct _ps_strings _ps
;
120 mib
[1] = VM_PSSTRINGS
;
122 if (sysctl (mib
, 2, &_ps
, &len
, NULL
, 0) == 0)
124 i386obsd_sigtramp_start_addr
= (u_long
) _ps
.val
- 128;
125 i386obsd_sigtramp_end_addr
= (u_long
) _ps
.val
;