1/* Native-dependent code for FreeBSD/i386.
2
3   Copyright (C) 2001, 2002, 2003, 2004, 2007 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 "inferior.h"
22#include "regcache.h"
23#include "target.h"
24
25#include <sys/types.h>
26#include <sys/ptrace.h>
27#include <sys/sysctl.h>
28
29#include "fbsd-nat.h"
30#include "i386-tdep.h"
31#include "i386bsd-nat.h"
32
33/* Resume execution of the inferior process.  If STEP is nonzero,
34   single-step it.  If SIGNAL is nonzero, give it that signal.  */
35
36static void
37i386fbsd_resume (ptid_t ptid, int step, enum target_signal signal)
38{
39  pid_t pid = ptid_get_pid (ptid);
40  int request = PT_STEP;
41
42  if (pid == -1)
43    /* Resume all threads.  This only gets used in the non-threaded
44       case, where "resume all threads" and "resume inferior_ptid" are
45       the same.  */
46    pid = ptid_get_pid (inferior_ptid);
47
48  if (!step)
49    {
50      struct regcache *regcache = get_current_regcache ();
51      ULONGEST eflags;
52
53      /* Workaround for a bug in FreeBSD.  Make sure that the trace
54 	 flag is off when doing a continue.  There is a code path
55 	 through the kernel which leaves the flag set when it should
56 	 have been cleared.  If a process has a signal pending (such
57 	 as SIGALRM) and we do a PT_STEP, the process never really has
58 	 a chance to run because the kernel needs to notify the
59 	 debugger that a signal is being sent.  Therefore, the process
60 	 never goes through the kernel's trap() function which would
61 	 normally clear it.  */
62
63      regcache_cooked_read_unsigned (regcache, I386_EFLAGS_REGNUM,
64				     &eflags);
65      if (eflags & 0x0100)
66	regcache_cooked_write_unsigned (regcache, I386_EFLAGS_REGNUM,
67					eflags & ~0x0100);
68
69      request = PT_CONTINUE;
70    }
71
72  /* An addres of (caddr_t) 1 tells ptrace to continue from where it
73     was.  (If GDB wanted it to start some other way, we have already
74     written a new PC value to the child.)  */
75  if (ptrace (request, pid, (caddr_t) 1,
76	      target_signal_to_host (signal)) == -1)
77    perror_with_name (("ptrace"));
78}
79
80
81/* Support for debugging kernel virtual memory images.  */
82
83#include <sys/types.h>
84#include <machine/pcb.h>
85
86#include "bsd-kvm.h"
87
88static int
89i386fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
90{
91  /* The following is true for FreeBSD 4.7:
92
93     The pcb contains %eip, %ebx, %esp, %ebp, %esi, %edi and %gs.
94     This accounts for all callee-saved registers specified by the
95     psABI and then some.  Here %esp contains the stack pointer at the
96     point just after the call to cpu_switch().  From this information
97     we reconstruct the register state as it would look when we just
98     returned from cpu_switch().  */
99
100  /* The stack pointer shouldn't be zero.  */
101  if (pcb->pcb_esp == 0)
102    return 0;
103
104  pcb->pcb_esp += 4;
105  regcache_raw_supply (regcache, I386_EDI_REGNUM, &pcb->pcb_edi);
106  regcache_raw_supply (regcache, I386_ESI_REGNUM, &pcb->pcb_esi);
107  regcache_raw_supply (regcache, I386_EBP_REGNUM, &pcb->pcb_ebp);
108  regcache_raw_supply (regcache, I386_ESP_REGNUM, &pcb->pcb_esp);
109  regcache_raw_supply (regcache, I386_EBX_REGNUM, &pcb->pcb_ebx);
110  regcache_raw_supply (regcache, I386_EIP_REGNUM, &pcb->pcb_eip);
111  regcache_raw_supply (regcache, I386_GS_REGNUM, &pcb->pcb_gs);
112
113  return 1;
114}
115
116
117/* Prevent warning from -Wmissing-prototypes.  */
118void _initialize_i386fbsd_nat (void);
119
120void
121_initialize_i386fbsd_nat (void)
122{
123  struct target_ops *t;
124
125  /* Add some extra features to the common *BSD/i386 target.  */
126  t = i386bsd_target ();
127  t->to_resume = i386fbsd_resume;
128  t->to_pid_to_exec_file = fbsd_pid_to_exec_file;
129  t->to_find_memory_regions = fbsd_find_memory_regions;
130  t->to_make_corefile_notes = fbsd_make_corefile_notes;
131  add_target (t);
132
133  /* Support debugging kernel virtual memory images.  */
134  bsd_kvm_add_target (i386fbsd_supply_pcb);
135
136  /* FreeBSD provides a kern.ps_strings sysctl that we can use to
137     locate the sigtramp.  That way we can still recognize a sigtramp
138     if its location is changed in a new kernel.  Of course this is
139     still based on the assumption that the sigtramp is placed
140     directly under the location where the program arguments and
141     environment can be found.  */
142#ifdef KERN_PS_STRINGS
143  {
144    int mib[2];
145    u_long ps_strings;
146    size_t len;
147
148    mib[0] = CTL_KERN;
149    mib[1] = KERN_PS_STRINGS;
150    len = sizeof (ps_strings);
151    if (sysctl (mib, 2, &ps_strings, &len, NULL, 0) == 0)
152      {
153	i386fbsd_sigtramp_start_addr = ps_strings - 128;
154	i386fbsd_sigtramp_end_addr = ps_strings;
155      }
156  }
157#endif
158}
159