1/* Native-dependent code for FreeBSD/i386.
2
3   Copyright 2001, 2002, 2003, 2004 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 2 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, write to the Free Software
19   Foundation, Inc., 59 Temple Place - Suite 330,
20   Boston, MA 02111-1307, USA.  */
21
22#include "defs.h"
23#include "inferior.h"
24#include "regcache.h"
25#include "target.h"
26
27#include <sys/types.h>
28#include <sys/ptrace.h>
29#include <sys/sysctl.h>
30
31#include "fbsd-nat.h"
32#include "i386-tdep.h"
33#include "i386bsd-nat.h"
34
35/* Resume execution of the inferior process.  If STEP is nonzero,
36   single-step it.  If SIGNAL is nonzero, give it that signal.  */
37
38static void
39i386fbsd_resume (ptid_t ptid, int step, enum target_signal signal)
40{
41  pid_t pid = ptid_get_pid (ptid);
42  int request = PT_STEP;
43
44  if (pid == -1)
45    /* Resume all threads.  This only gets used in the non-threaded
46       case, where "resume all threads" and "resume inferior_ptid" are
47       the same.  */
48    pid = ptid_get_pid (inferior_ptid);
49
50  if (!step)
51    {
52      ULONGEST eflags;
53
54      /* Workaround for a bug in FreeBSD.  Make sure that the trace
55 	 flag is off when doing a continue.  There is a code path
56 	 through the kernel which leaves the flag set when it should
57 	 have been cleared.  If a process has a signal pending (such
58 	 as SIGALRM) and we do a PT_STEP, the process never really has
59 	 a chance to run because the kernel needs to notify the
60 	 debugger that a signal is being sent.  Therefore, the process
61 	 never goes through the kernel's trap() function which would
62 	 normally clear it.  */
63
64      regcache_cooked_read_unsigned (current_regcache, I386_EFLAGS_REGNUM,
65				     &eflags);
66      if (eflags & 0x0100)
67	regcache_cooked_write_unsigned (current_regcache, I386_EFLAGS_REGNUM,
68					eflags & ~0x0100);
69
70      request = PT_CONTINUE;
71    }
72
73  /* An addres of (caddr_t) 1 tells ptrace to continue from where it
74     was.  (If GDB wanted it to start some other way, we have already
75     written a new PC value to the child.)  */
76  if (ptrace (request, pid, (caddr_t) 1,
77	      target_signal_to_host (signal)) == -1)
78    perror_with_name ("ptrace");
79}
80
81
82/* Support for debugging kernel virtual memory images.  */
83
84#include <sys/types.h>
85#include <machine/pcb.h>
86
87#include "bsd-kvm.h"
88
89static int
90i386fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
91{
92  /* The following is true for FreeBSD 4.7:
93
94     The pcb contains %eip, %ebx, %esp, %ebp, %esi, %edi and %gs.
95     This accounts for all callee-saved registers specified by the
96     psABI and then some.  Here %esp contains the stack pointer at the
97     point just after the call to cpu_switch().  From this information
98     we reconstruct the register state as it would look when we just
99     returned from cpu_switch().  */
100
101  /* The stack pointer shouldn't be zero.  */
102  if (pcb->pcb_esp == 0)
103    return 0;
104
105  pcb->pcb_esp += 4;
106  regcache_raw_supply (regcache, I386_EDI_REGNUM, &pcb->pcb_edi);
107  regcache_raw_supply (regcache, I386_ESI_REGNUM, &pcb->pcb_esi);
108  regcache_raw_supply (regcache, I386_EBP_REGNUM, &pcb->pcb_ebp);
109  regcache_raw_supply (regcache, I386_ESP_REGNUM, &pcb->pcb_esp);
110  regcache_raw_supply (regcache, I386_EBX_REGNUM, &pcb->pcb_ebx);
111  regcache_raw_supply (regcache, I386_EIP_REGNUM, &pcb->pcb_eip);
112  regcache_raw_supply (regcache, I386_GS_REGNUM, &pcb->pcb_gs);
113
114  return 1;
115}
116
117
118/* Prevent warning from -Wmissing-prototypes.  */
119void _initialize_i386fbsd_nat (void);
120
121void
122_initialize_i386fbsd_nat (void)
123{
124  struct target_ops *t;
125
126  /* Add some extra features to the common *BSD/i386 target.  */
127  t = i386bsd_target ();
128  t->to_resume = i386fbsd_resume;
129  t->to_pid_to_exec_file = fbsd_pid_to_exec_file;
130  t->to_find_memory_regions = fbsd_find_memory_regions;
131  t->to_make_corefile_notes = fbsd_make_corefile_notes;
132  add_target (t);
133
134  /* Support debugging kernel virtual memory images.  */
135  bsd_kvm_add_target (i386fbsd_supply_pcb);
136
137  /* FreeBSD provides a kern.ps_strings sysctl that we can use to
138     locate the sigtramp.  That way we can still recognize a sigtramp
139     if its location is changed in a new kernel.  Of course this is
140     still based on the assumption that the sigtramp is placed
141     directly under the location where the program arguments and
142     environment can be found.  */
143#ifdef KERN_PS_STRINGS
144  {
145    int mib[2];
146    int ps_strings;
147    size_t len;
148
149    mib[0] = CTL_KERN;
150    mib[1] = KERN_PS_STRINGS;
151    len = sizeof (ps_strings);
152    if (sysctl (mib, 2, &ps_strings, &len, NULL, 0) == 0)
153      {
154	i386fbsd_sigtramp_start_addr = ps_strings - 128;
155	i386fbsd_sigtramp_end_addr = ps_strings;
156      }
157  }
158#endif
159}
160