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i386-obsd-nat.c
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1/* Native-dependent code for OpenBSD/i386.
2
3 Copyright (C) 2002-2023 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
34static int
35i386obsd_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 (I386_EDI_REGNUM, &sf.sf_edi);
71 regcache->raw_supply (I386_ESI_REGNUM, &sf.sf_esi);
72 regcache->raw_supply (I386_EBX_REGNUM, &sf.sf_ebx);
73 regcache->raw_supply (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 (I386_EIP_REGNUM, &sf.sf_eip);
83 }
84
85 regcache->raw_supply (I386_EBP_REGNUM, &pcb->pcb_ebp);
86 regcache->raw_supply (I386_ESP_REGNUM, &pcb->pcb_esp);
87
88 return 1;
89}
90
92
94void
96{
97 add_inf_child_target (&i386_obsd_nat_target);
98
99 /* Support debugging kernel virtual memory images. */
101
102 /* OpenBSD provides a vm.psstrings sysctl that we can use to locate
103 the sigtramp. That way we can still recognize a sigtramp if its
104 location is changed in a new kernel. This is especially
105 important for OpenBSD, since it uses a different memory layout
106 than NetBSD, yet we cannot distinguish between the two.
107
108 Of course this is still based on the assumption that the sigtramp
109 is placed directly under the location where the program arguments
110 and environment can be found. */
111#ifdef VM_PSSTRINGS
112 {
113 struct _ps_strings _ps;
114 int mib[2];
115 size_t len;
116
117 mib[0] = CTL_VM;
118 mib[1] = VM_PSSTRINGS;
119 len = sizeof (_ps);
120 if (sysctl (mib, 2, &_ps, &len, NULL, 0) == 0)
121 {
122 i386obsd_sigtramp_start_addr = (u_long) _ps.val - 128;
124 }
125 }
126#endif
127}
void bsd_kvm_add_target(int(*supply_pcb)(struct regcache *, struct pcb *))
Definition bsd-kvm.c:380
gdbarch * arch() const
Definition regcache.c:231
void raw_supply(int regnum, const void *buf) override
Definition regcache.c:1062
void read_memory(CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
Definition corefile.c:238
LONGEST read_memory_integer(CORE_ADDR memaddr, int len, enum bfd_endian byte_order)
Definition corefile.c:296
enum bfd_endian gdbarch_byte_order(struct gdbarch *gdbarch)
Definition gdbarch.c:1396
void _initialize_i386obsd_nat()
static int i386obsd_supply_pcb(struct regcache *regcache, struct pcb *pcb)
static i386_bsd_nat_target< obsd_nat_target > the_i386_obsd_nat_target
CORE_ADDR i386obsd_sigtramp_end_addr
CORE_ADDR i386obsd_sigtramp_start_addr
@ I386_ESI_REGNUM
Definition i386-tdep.h:287
@ I386_EIP_REGNUM
Definition i386-tdep.h:289
@ I386_EBP_REGNUM
Definition i386-tdep.h:286
@ I386_ESP_REGNUM
Definition i386-tdep.h:285
@ I386_EBX_REGNUM
Definition i386-tdep.h:284
@ I386_EDI_REGNUM
Definition i386-tdep.h:288
void add_inf_child_target(inf_child_target *target)
Definition inf-child.c:418
unsigned long u_long
Definition ser-go32.c:130