gdb/i386-fbsd-nat.c

   1 /* Native-dependent code for FreeBSD/i386.
   2
   3    Copyright (C) 2001-2024 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 "i386-tdep.h"
  31 #include "i386-fbsd-tdep.h"
  32 #include "i387-tdep.h"
  33 #include "x86-nat.h"
  34 #include "x86-fbsd-nat.h"
  35
  36 class i386_fbsd_nat_target final : public x86_fbsd_nat_target
  37 {
  38 public:
  39   void fetch_registers (struct regcache *, int) override;
  40   void store_registers (struct regcache *, int) override;
  41
  42   const struct target_desc *read_description () override;
  43
  44   void resume (ptid_t, int, enum gdb_signal) override;
  45 };
  46
  47 static i386_fbsd_nat_target the_i386_fbsd_nat_target;
  48
  49 static int have_ptrace_xmmregs;
  50
  51 /* Fetch register REGNUM from the inferior.  If REGNUM is -1, do this
  52    for all registers.  */
  53
  54 void
  55 i386_fbsd_nat_target::fetch_registers (struct regcache *regcache, int regnum)
  56 {
  57   struct gdbarch *gdbarch = regcache->arch ();
  58   pid_t pid = get_ptrace_pid (regcache->ptid ());
  59
  60   if (fetch_register_set<struct reg> (regcache, regnum, PT_GETREGS,
  61                                       &i386_fbsd_gregset))
  62     {
  63       if (regnum != -1)
  64         return;
  65     }
  66
  67 #ifdef PT_GETFSBASE
  68   if (regnum == -1 || regnum == I386_FSBASE_REGNUM)
  69     {
  70       register_t base;
  71
  72       if (ptrace (PT_GETFSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
  73         perror_with_name (_("Couldn't get segment register fs_base"));
  74
  75       regcache->raw_supply (I386_FSBASE_REGNUM, &base);
  76       if (regnum != -1)
  77         return;
  78     }
  79 #endif
  80 #ifdef PT_GETGSBASE
  81   if (regnum == -1 || regnum == I386_GSBASE_REGNUM)
  82     {
  83       register_t base;
  84
  85       if (ptrace (PT_GETGSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
  86         perror_with_name (_("Couldn't get segment register gs_base"));
  87
  88       regcache->raw_supply (I386_GSBASE_REGNUM, &base);
  89       if (regnum != -1)
  90         return;
  91     }
  92 #endif
  93
  94   /* There is no i386_fxsave_supplies or i386_xsave_supplies.
  95      Instead, the earlier register sets return early if the request
  96      was for a specific register that was already satisified to avoid
  97      fetching the FPU/XSAVE state unnecessarily.  */
  98
  99 #ifdef PT_GETXSTATE_INFO
 100   if (m_xsave_info.xsave_len != 0)
 101     {
 102       void *xstateregs = alloca (m_xsave_info.xsave_len);
 103
 104       if (ptrace (PT_GETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, 0) == -1)
 105         perror_with_name (_("Couldn't get extended state status"));
 106
 107       i387_supply_xsave (regcache, regnum, xstateregs);
 108       return;
 109     }
 110 #endif
 111   if (have_ptrace_xmmregs != 0)
 112     {
 113       char xmmregs[I387_SIZEOF_FXSAVE];
 114
 115       if (ptrace(PT_GETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
 116         perror_with_name (_("Couldn't get XMM registers"));
 117
 118       i387_supply_fxsave (regcache, regnum, xmmregs);
 119       return;
 120     }
 121
 122   struct fpreg fpregs;
 123
 124   if (ptrace (PT_GETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
 125     perror_with_name (_("Couldn't get floating point status"));
 126
 127   i387_supply_fsave (regcache, regnum, &fpregs);
 128 }
 129
 130 /* Store register REGNUM back into the inferior.  If REGNUM is -1, do
 131    this for all registers.  */
 132
 133 void
 134 i386_fbsd_nat_target::store_registers (struct regcache *regcache, int regnum)
 135 {
 136   struct gdbarch *gdbarch = regcache->arch ();
 137   pid_t pid = get_ptrace_pid (regcache->ptid ());
 138
 139   if (store_register_set<struct reg> (regcache, regnum, PT_GETREGS, PT_SETREGS,
 140                                       &i386_fbsd_gregset))
 141     {
 142       if (regnum != -1)
 143         return;
 144     }
 145
 146 #ifdef PT_SETFSBASE
 147   if (regnum == -1 || regnum == I386_FSBASE_REGNUM)
 148     {
 149       register_t base;
 150
 151       regcache->raw_collect (I386_FSBASE_REGNUM, &base);
 152
 153       if (ptrace (PT_SETFSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
 154         perror_with_name (_("Couldn't write segment register fs_base"));
 155       if (regnum != -1)
 156         return;
 157     }
 158 #endif
 159 #ifdef PT_SETGSBASE
 160   if (regnum == -1 || regnum == I386_GSBASE_REGNUM)
 161     {
 162       register_t base;
 163
 164       regcache->raw_collect (I386_GSBASE_REGNUM, &base);
 165
 166       if (ptrace (PT_SETGSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
 167         perror_with_name (_("Couldn't write segment register gs_base"));
 168       if (regnum != -1)
 169         return;
 170     }
 171 #endif
 172
 173   /* There is no i386_fxsave_supplies or i386_xsave_supplies.
 174      Instead, the earlier register sets return early if the request
 175      was for a specific register that was already satisified to avoid
 176      fetching the FPU/XSAVE state unnecessarily.  */
 177
 178 #ifdef PT_GETXSTATE_INFO
 179   if (m_xsave_info.xsave_len != 0)
 180     {
 181       void *xstateregs = alloca (m_xsave_info.xsave_len);
 182
 183       if (ptrace (PT_GETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, 0) == -1)
 184         perror_with_name (_("Couldn't get extended state status"));
 185
 186       i387_collect_xsave (regcache, regnum, xstateregs, 0);
 187
 188       if (ptrace (PT_SETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs,
 189                   m_xsave_info.xsave_len) == -1)
 190         perror_with_name (_("Couldn't write extended state status"));
 191       return;
 192     }
 193 #endif
 194   if (have_ptrace_xmmregs != 0)
 195     {
 196       char xmmregs[I387_SIZEOF_FXSAVE];
 197
 198       if (ptrace(PT_GETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
 199         perror_with_name (_("Couldn't get XMM registers"));
 200
 201       i387_collect_fxsave (regcache, regnum, xmmregs);
 202
 203       if (ptrace (PT_SETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
 204         perror_with_name (_("Couldn't write XMM registers"));
 205       return;
 206     }
 207
 208   struct fpreg fpregs;
 209
 210   if (ptrace (PT_GETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
 211     perror_with_name (_("Couldn't get floating point status"));
 212
 213   i387_collect_fsave (regcache, regnum, &fpregs);
 214
 215   if (ptrace (PT_SETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
 216     perror_with_name (_("Couldn't write floating point status"));
 217 }
 218
 219 /* Resume execution of the inferior process.  If STEP is nonzero,
 220    single-step it.  If SIGNAL is nonzero, give it that signal.  */
 221
 222 void
 223 i386_fbsd_nat_target::resume (ptid_t ptid, int step, enum gdb_signal signal)
 224 {
 225   pid_t pid = ptid.pid ();
 226   int request = PT_STEP;
 227
 228   if (pid == -1)
 229     /* Resume all threads.  This only gets used in the non-threaded
 230        case, where "resume all threads" and "resume inferior_ptid" are
 231        the same.  */
 232     pid = inferior_ptid.pid ();
 233
 234   if (!step)
 235     {
 236       regcache *regcache = get_thread_regcache (inferior_thread ());
 237       ULONGEST eflags;
 238
 239       /* Workaround for a bug in FreeBSD.  Make sure that the trace
 240          flag is off when doing a continue.  There is a code path
 241          through the kernel which leaves the flag set when it should
 242          have been cleared.  If a process has a signal pending (such
 243          as SIGALRM) and we do a PT_STEP, the process never really has
 244          a chance to run because the kernel needs to notify the
 245          debugger that a signal is being sent.  Therefore, the process
 246          never goes through the kernel's trap() function which would
 247          normally clear it.  */
 248
 249       regcache_cooked_read_unsigned (regcache, I386_EFLAGS_REGNUM,
 250                                      &eflags);
 251       if (eflags & 0x0100)
 252         regcache_cooked_write_unsigned (regcache, I386_EFLAGS_REGNUM,
 253                                         eflags & ~0x0100);
 254
 255       request = PT_CONTINUE;
 256     }
 257
 258   /* An addres of (caddr_t) 1 tells ptrace to continue from where it
 259      was.  (If GDB wanted it to start some other way, we have already
 260      written a new PC value to the child.)  */
 261   if (ptrace (request, pid, (caddr_t) 1,
 262               gdb_signal_to_host (signal)) == -1)
 263     perror_with_name (("ptrace"));
 264 }
 265 \f
 266
 267 /* Support for debugging kernel virtual memory images.  */
 268
 269 #include <machine/pcb.h>
 270
 271 #include "bsd-kvm.h"
 272
 273 static int
 274 i386fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
 275 {
 276   /* The following is true for FreeBSD 4.7:
 277
 278      The pcb contains %eip, %ebx, %esp, %ebp, %esi, %edi and %gs.
 279      This accounts for all callee-saved registers specified by the
 280      psABI and then some.  Here %esp contains the stack pointer at the
 281      point just after the call to cpu_switch().  From this information
 282      we reconstruct the register state as it would look when we just
 283      returned from cpu_switch().  */
 284
 285   /* The stack pointer shouldn't be zero.  */
 286   if (pcb->pcb_esp == 0)
 287     return 0;
 288
 289   pcb->pcb_esp += 4;
 290   regcache->raw_supply (I386_EDI_REGNUM, &pcb->pcb_edi);
 291   regcache->raw_supply (I386_ESI_REGNUM, &pcb->pcb_esi);
 292   regcache->raw_supply (I386_EBP_REGNUM, &pcb->pcb_ebp);
 293   regcache->raw_supply (I386_ESP_REGNUM, &pcb->pcb_esp);
 294   regcache->raw_supply (I386_EBX_REGNUM, &pcb->pcb_ebx);
 295   regcache->raw_supply (I386_EIP_REGNUM, &pcb->pcb_eip);
 296   regcache->raw_supply (I386_GS_REGNUM, &pcb->pcb_gs);
 297
 298   return 1;
 299 }
 300 \f
 301
 302 /* Implement the read_description method.  */
 303
 304 const struct target_desc *
 305 i386_fbsd_nat_target::read_description ()
 306 {
 307   static int xmm_probed;
 308
 309   if (inferior_ptid == null_ptid)
 310     return this->beneath ()->read_description ();
 311
 312 #ifdef PT_GETXSTATE_INFO
 313   probe_xsave_layout (inferior_ptid.pid ());
 314   if (m_xsave_info.xsave_len != 0)
 315     return i386_target_description (m_xsave_info.xsave_mask, true);
 316 #endif
 317
 318   if (!xmm_probed)
 319     {
 320       char xmmregs[I387_SIZEOF_FXSAVE];
 321
 322       if (ptrace (PT_GETXMMREGS, inferior_ptid.pid (),
 323                   (PTRACE_TYPE_ARG3) xmmregs, 0) == 0)
 324         have_ptrace_xmmregs = 1;
 325       xmm_probed = 1;
 326     }
 327
 328   if (have_ptrace_xmmregs)
 329     return i386_target_description (X86_XSTATE_SSE_MASK, true);
 330
 331   return i386_target_description (X86_XSTATE_X87_MASK, true);
 332 }
 333
 334 void _initialize_i386fbsd_nat ();
 335 void
 336 _initialize_i386fbsd_nat ()
 337 {
 338   add_inf_child_target (&the_i386_fbsd_nat_target);
 339
 340   /* Support debugging kernel virtual memory images.  */
 341   bsd_kvm_add_target (i386fbsd_supply_pcb);
 342 }