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/tmp/gdb-8.1/gdb/i386-obsd-nat.c
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1 /* Native-dependent code for OpenBSD/i386.
2
3 Copyright (C) 2002-2018 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 3 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, see <http://www.gnu.org/licenses/>. */
19
20 #include "defs.h"
21 #include "gdbcore.h"
22 #include "regcache.h"
23 #include "target.h"
24
25 #include <sys/sysctl.h>
26 #include <machine/frame.h>
27 #include <machine/pcb.h>
28
29 #include "i386-tdep.h"
30 #include "i386-bsd-nat.h"
31 #include "obsd-nat.h"
32 #include "bsd-kvm.h"
33
34 static int
35 i386obsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
36 {
37 struct gdbarch *gdbarch = regcache->arch ();
38 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
39 struct switchframe sf;
40
41 /* The following is true for OpenBSD 3.6:
42
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
46 following layout:
47
48 interrupt level
49 %edi
50 %esi
51 %ebx
52 %eip
53
54 we reconstruct the register state as it would look when we just
55 returned from cpu_switch(). */
56
57 /* The stack pointer shouldn't be zero. */
58 if (pcb->pcb_esp == 0)
59 return 0;
60
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
63 looks reasonable.. */
64 #ifdef PCB_SAVECTX
65 if ((pcb->pcb_flags & PCB_SAVECTX) == 0)
66 {
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);
74 }
75 else
76 #endif
77 {
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);
83 }
84
85 regcache_raw_supply (regcache, I386_EBP_REGNUM, &pcb->pcb_ebp);
86 regcache_raw_supply (regcache, I386_ESP_REGNUM, &pcb->pcb_esp);
87
88 return 1;
89 }
90
91 void
92 _initialize_i386obsd_nat (void)
93 {
94 /* Add some extra features to the common *BSD/i386 target. */
95 obsd_add_target (i386bsd_target ());
96
97 /* Support debugging kernel virtual memory images. */
98 bsd_kvm_add_target (i386obsd_supply_pcb);
99
100 /* OpenBSD provides a vm.psstrings sysctl that we can use to locate
101 the sigtramp. That way we can still recognize a sigtramp if its
102 location is changed in a new kernel. This is especially
103 important for OpenBSD, since it uses a different memory layout
104 than NetBSD, yet we cannot distinguish between the two.
105
106 Of course this is still based on the assumption that the sigtramp
107 is placed directly under the location where the program arguments
108 and environment can be found. */
109 #ifdef VM_PSSTRINGS
110 {
111 struct _ps_strings _ps;
112 int mib[2];
113 size_t len;
114
115 mib[0] = CTL_VM;
116 mib[1] = VM_PSSTRINGS;
117 len = sizeof (_ps);
118 if (sysctl (mib, 2, &_ps, &len, NULL, 0) == 0)
119 {
120 i386obsd_sigtramp_start_addr = (u_long) _ps.val - 128;
121 i386obsd_sigtramp_end_addr = (u_long) _ps.val;
122 }
123 }
124 #endif
125 }
gdbarch
Definition: gdbarch.c:127
obsd_add_target
void obsd_add_target(struct target_ops *t)
Definition: obsd-nat.c:181
obsd-nat.h
_initialize_i386obsd_nat
void _initialize_i386obsd_nat(void)
Definition: i386-obsd-nat.c:92
defs.h
I386_EBX_REGNUM
Definition: i386-tdep.h:274
i386obsd_supply_pcb
static int i386obsd_supply_pcb(struct regcache *regcache, struct pcb *pcb)
Definition: i386-obsd-nat.c:35
read_memory_integer
LONGEST read_memory_integer(CORE_ADDR memaddr, int len, enum bfd_endian byte_order)
Definition: corefile.c:316
I386_EIP_REGNUM
Definition: i386-tdep.h:279
u_long
unsigned long u_long
Definition: ser-go32.c:130
regcache.h
bsd-kvm.h
gdbarch_byte_order
enum bfd_endian gdbarch_byte_order(struct gdbarch *gdbarch)
Definition: gdbarch.c:1509
I386_ESP_REGNUM
Definition: i386-tdep.h:275
i386-bsd-nat.h
I386_ESI_REGNUM
Definition: i386-tdep.h:277
read_memory
void read_memory(CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
Definition: corefile.c:258
i386obsd_sigtramp_end_addr
CORE_ADDR i386obsd_sigtramp_end_addr
Definition: i386-obsd-tdep.c:141
gdb_byte
bfd_byte gdb_byte
Definition: common-types.h:38
gdbcore.h
i386obsd_sigtramp_start_addr
CORE_ADDR i386obsd_sigtramp_start_addr
Definition: i386-obsd-tdep.c:140
I386_EDI_REGNUM
Definition: i386-tdep.h:278
regcache::arch
gdbarch * arch() const
Definition: regcache.c:221
target.h
i386bsd_target
struct target_ops * i386bsd_target(void)
Definition: i386-bsd-nat.c:274
regcache_raw_supply
void regcache_raw_supply(struct regcache *regcache, int regnum, const void *buf)
Definition: regcache.c:1004
regcache
Definition: regcache.h:232
bsd_kvm_add_target
void bsd_kvm_add_target(int(*supply_pcb)(struct regcache *, struct pcb *))
Definition: bsd-kvm.c:354
i386-tdep.h
gdbarch::byte_order
enum bfd_endian byte_order
Definition: gdbarch.c:137
I386_EBP_REGNUM
Definition: i386-tdep.h:276