gdb/i386-fbsd-nat.c

   1 /* Native-dependent code for FreeBSD/i386.
   2
   3    Copyright (C) 2001-2017 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 #include <sys/user.h>
  29
  30 #include "fbsd-nat.h"
  31 #include "i386-tdep.h"
  32 #include "x86-nat.h"
  33 #include "x86-bsd-nat.h"
  34 #include "i386-bsd-nat.h"
  35
  36 /* Resume execution of the inferior process.  If STEP is nonzero,
  37    single-step it.  If SIGNAL is nonzero, give it that signal.  */
  38
  39 static void
  40 i386fbsd_resume (struct target_ops *ops,
  41                  ptid_t ptid, int step, enum gdb_signal signal)
  42 {
  43   pid_t pid = ptid_get_pid (ptid);
  44   int request = PT_STEP;
  45
  46   if (pid == -1)
  47     /* Resume all threads.  This only gets used in the non-threaded
  48        case, where "resume all threads" and "resume inferior_ptid" are
  49        the same.  */
  50     pid = ptid_get_pid (inferior_ptid);
  51
  52   if (!step)
  53     {
  54       struct regcache *regcache = get_current_regcache ();
  55       ULONGEST eflags;
  56
  57       /* Workaround for a bug in FreeBSD.  Make sure that the trace
  58          flag is off when doing a continue.  There is a code path
  59          through the kernel which leaves the flag set when it should
  60          have been cleared.  If a process has a signal pending (such
  61          as SIGALRM) and we do a PT_STEP, the process never really has
  62          a chance to run because the kernel needs to notify the
  63          debugger that a signal is being sent.  Therefore, the process
  64          never goes through the kernel's trap() function which would
  65          normally clear it.  */
  66
  67       regcache_cooked_read_unsigned (regcache, I386_EFLAGS_REGNUM,
  68                                      &eflags);
  69       if (eflags & 0x0100)
  70         regcache_cooked_write_unsigned (regcache, I386_EFLAGS_REGNUM,
  71                                         eflags & ~0x0100);
  72
  73       request = PT_CONTINUE;
  74     }
  75
  76   /* An addres of (caddr_t) 1 tells ptrace to continue from where it
  77      was.  (If GDB wanted it to start some other way, we have already
  78      written a new PC value to the child.)  */
  79   if (ptrace (request, pid, (caddr_t) 1,
  80               gdb_signal_to_host (signal)) == -1)
  81     perror_with_name (("ptrace"));
  82 }
  83 \f
  84
  85 /* Support for debugging kernel virtual memory images.  */
  86
  87 #include <machine/pcb.h>
  88
  89 #include "bsd-kvm.h"
  90
  91 static int
  92 i386fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
  93 {
  94   /* The following is true for FreeBSD 4.7:
  95
  96      The pcb contains %eip, %ebx, %esp, %ebp, %esi, %edi and %gs.
  97      This accounts for all callee-saved registers specified by the
  98      psABI and then some.  Here %esp contains the stack pointer at the
  99      point just after the call to cpu_switch().  From this information
 100      we reconstruct the register state as it would look when we just
 101      returned from cpu_switch().  */
 102
 103   /* The stack pointer shouldn't be zero.  */
 104   if (pcb->pcb_esp == 0)
 105     return 0;
 106
 107   pcb->pcb_esp += 4;
 108   regcache_raw_supply (regcache, I386_EDI_REGNUM, &pcb->pcb_edi);
 109   regcache_raw_supply (regcache, I386_ESI_REGNUM, &pcb->pcb_esi);
 110   regcache_raw_supply (regcache, I386_EBP_REGNUM, &pcb->pcb_ebp);
 111   regcache_raw_supply (regcache, I386_ESP_REGNUM, &pcb->pcb_esp);
 112   regcache_raw_supply (regcache, I386_EBX_REGNUM, &pcb->pcb_ebx);
 113   regcache_raw_supply (regcache, I386_EIP_REGNUM, &pcb->pcb_eip);
 114   regcache_raw_supply (regcache, I386_GS_REGNUM, &pcb->pcb_gs);
 115
 116   return 1;
 117 }
 118 \f
 119
 120 #ifdef PT_GETXSTATE_INFO
 121 /* Implement the to_read_description method.  */
 122
 123 static const struct target_desc *
 124 i386fbsd_read_description (struct target_ops *ops)
 125 {
 126   static int xsave_probed;
 127   static uint64_t xcr0;
 128
 129   if (!xsave_probed)
 130     {
 131       struct ptrace_xstate_info info;
 132
 133       if (ptrace (PT_GETXSTATE_INFO, ptid_get_pid (inferior_ptid),
 134                   (PTRACE_TYPE_ARG3) &info, sizeof (info)) == 0)
 135         {
 136           x86bsd_xsave_len = info.xsave_len;
 137           xcr0 = info.xsave_mask;
 138         }
 139       xsave_probed = 1;
 140     }
 141
 142   if (x86bsd_xsave_len == 0)
 143     xcr0 = X86_XSTATE_SSE_MASK;
 144
 145   return i386_target_description (xcr0);
 146 }
 147 #endif
 148
 149 /* Prevent warning from -Wmissing-prototypes.  */
 150 void _initialize_i386fbsd_nat (void);
 151
 152 void
 153 _initialize_i386fbsd_nat (void)
 154 {
 155   struct target_ops *t;
 156
 157   /* Add some extra features to the common *BSD/i386 target.  */
 158   t = i386bsd_target ();
 159
 160 #ifdef PT_GETXSTATE_INFO
 161   t->to_read_description = i386fbsd_read_description;
 162 #endif
 163
 164   t->to_resume = i386fbsd_resume;
 165   fbsd_nat_add_target (t);
 166
 167   /* Support debugging kernel virtual memory images.  */
 168   bsd_kvm_add_target (i386fbsd_supply_pcb);
 169
 170 #ifdef KERN_PROC_SIGTRAMP
 171   /* Normally signal frames are detected via i386fbsd_sigtramp_p.
 172      However, FreeBSD 9.2 through 10.1 do not include the page holding
 173      the signal code in core dumps.  These releases do provide a
 174      kern.proc.sigtramp.<pid> sysctl that returns the location of the
 175      signal trampoline for a running process.  We fetch the location
 176      of the current (gdb) process and use this to identify signal
 177      frames in core dumps from these releases.  */
 178   {
 179     int mib[4];
 180     struct kinfo_sigtramp kst;
 181     size_t len;
 182
 183     mib[0] = CTL_KERN;
 184     mib[1] = KERN_PROC;
 185     mib[2] = KERN_PROC_SIGTRAMP;
 186     mib[3] = getpid ();
 187     len = sizeof (kst);
 188     if (sysctl (mib, 4, &kst, &len, NULL, 0) == 0)
 189       {
 190         i386fbsd_sigtramp_start_addr = (uintptr_t) kst.ksigtramp_start;
 191         i386fbsd_sigtramp_end_addr = (uintptr_t) kst.ksigtramp_end;
 192       }
 193   }
 194 #endif
 195 }