gdb/i386-fbsd-nat.c

   1 /* Native-dependent code for FreeBSD/i386.
   2
   3    Copyright (C) 2001-2023 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 "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 "gdbsupport/x86-xstate.h"
  35 #include "x86-fbsd-nat.h"
  36
  37 class i386_fbsd_nat_target final : public x86_fbsd_nat_target
  38 {
  39 public:
  40   void fetch_registers (struct regcache *, int) override;
  41   void store_registers (struct regcache *, int) override;
  42
  43   const struct target_desc *read_description () override;
  44
  45   void resume (ptid_t, int, enum gdb_signal) override;
  46 };
  47
  48 static i386_fbsd_nat_target the_i386_fbsd_nat_target;
  49
  50 #ifdef PT_GETXSTATE_INFO
  51 static size_t xsave_len;
  52 #endif
  53
  54 static int have_ptrace_xmmregs;
  55
  56 /* Fetch register REGNUM from the inferior.  If REGNUM is -1, do this
  57    for all registers.  */
  58
  59 void
  60 i386_fbsd_nat_target::fetch_registers (struct regcache *regcache, int regnum)
  61 {
  62   struct gdbarch *gdbarch = regcache->arch ();
  63   pid_t pid = get_ptrace_pid (regcache->ptid ());
  64
  65   if (fetch_register_set<struct reg> (regcache, regnum, PT_GETREGS,
  66                                       &i386_fbsd_gregset))
  67     {
  68       if (regnum != -1)
  69         return;
  70     }
  71
  72 #ifdef PT_GETFSBASE
  73   if (regnum == -1 || regnum == I386_FSBASE_REGNUM)
  74     {
  75       register_t base;
  76
  77       if (ptrace (PT_GETFSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
  78         perror_with_name (_("Couldn't get segment register fs_base"));
  79
  80       regcache->raw_supply (I386_FSBASE_REGNUM, &base);
  81       if (regnum != -1)
  82         return;
  83     }
  84 #endif
  85 #ifdef PT_GETGSBASE
  86   if (regnum == -1 || regnum == I386_GSBASE_REGNUM)
  87     {
  88       register_t base;
  89
  90       if (ptrace (PT_GETGSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
  91         perror_with_name (_("Couldn't get segment register gs_base"));
  92
  93       regcache->raw_supply (I386_GSBASE_REGNUM, &base);
  94       if (regnum != -1)
  95         return;
  96     }
  97 #endif
  98
  99   /* There is no i386_fxsave_supplies or i386_xsave_supplies.
 100      Instead, the earlier register sets return early if the request
 101      was for a specific register that was already satisified to avoid
 102      fetching the FPU/XSAVE state unnecessarily.  */
 103
 104 #ifdef PT_GETXSTATE_INFO
 105   if (xsave_len != 0)
 106     {
 107       void *xstateregs = alloca (xsave_len);
 108
 109       if (ptrace (PT_GETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, 0) == -1)
 110         perror_with_name (_("Couldn't get extended state status"));
 111
 112       i387_supply_xsave (regcache, regnum, xstateregs);
 113       return;
 114     }
 115 #endif
 116   if (have_ptrace_xmmregs != 0)
 117     {
 118       char xmmregs[I387_SIZEOF_FXSAVE];
 119
 120       if (ptrace(PT_GETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
 121         perror_with_name (_("Couldn't get XMM registers"));
 122
 123       i387_supply_fxsave (regcache, regnum, xmmregs);
 124       return;
 125     }
 126
 127   struct fpreg fpregs;
 128
 129   if (ptrace (PT_GETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
 130     perror_with_name (_("Couldn't get floating point status"));
 131
 132   i387_supply_fsave (regcache, regnum, &fpregs);
 133 }
 134
 135 /* Store register REGNUM back into the inferior.  If REGNUM is -1, do
 136    this for all registers.  */
 137
 138 void
 139 i386_fbsd_nat_target::store_registers (struct regcache *regcache, int regnum)
 140 {
 141   struct gdbarch *gdbarch = regcache->arch ();
 142   pid_t pid = get_ptrace_pid (regcache->ptid ());
 143
 144   if (store_register_set<struct reg> (regcache, regnum, PT_GETREGS, PT_SETREGS,
 145                                       &i386_fbsd_gregset))
 146     {
 147       if (regnum != -1)
 148         return;
 149     }
 150
 151 #ifdef PT_SETFSBASE
 152   if (regnum == -1 || regnum == I386_FSBASE_REGNUM)
 153     {
 154       register_t base;
 155
 156       regcache->raw_collect (I386_FSBASE_REGNUM, &base);
 157
 158       if (ptrace (PT_SETFSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
 159         perror_with_name (_("Couldn't write segment register fs_base"));
 160       if (regnum != -1)
 161         return;
 162     }
 163 #endif
 164 #ifdef PT_SETGSBASE
 165   if (regnum == -1 || regnum == I386_GSBASE_REGNUM)
 166     {
 167       register_t base;
 168
 169       regcache->raw_collect (I386_GSBASE_REGNUM, &base);
 170
 171       if (ptrace (PT_SETGSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
 172         perror_with_name (_("Couldn't write segment register gs_base"));
 173       if (regnum != -1)
 174         return;
 175     }
 176 #endif
 177
 178   /* There is no i386_fxsave_supplies or i386_xsave_supplies.
 179      Instead, the earlier register sets return early if the request
 180      was for a specific register that was already satisified to avoid
 181      fetching the FPU/XSAVE state unnecessarily.  */
 182
 183 #ifdef PT_GETXSTATE_INFO
 184   if (xsave_len != 0)
 185     {
 186       void *xstateregs = alloca (xsave_len);
 187
 188       if (ptrace (PT_GETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, 0) == -1)
 189         perror_with_name (_("Couldn't get extended state status"));
 190
 191       i387_collect_xsave (regcache, regnum, xstateregs, 0);
 192
 193       if (ptrace (PT_SETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, xsave_len)
 194           == -1)
 195         perror_with_name (_("Couldn't write extended state status"));
 196       return;
 197     }
 198 #endif
 199   if (have_ptrace_xmmregs != 0)
 200     {
 201       char xmmregs[I387_SIZEOF_FXSAVE];
 202
 203       if (ptrace(PT_GETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
 204         perror_with_name (_("Couldn't get XMM registers"));
 205
 206       i387_collect_fxsave (regcache, regnum, xmmregs);
 207
 208       if (ptrace (PT_SETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
 209         perror_with_name (_("Couldn't write XMM registers"));
 210       return;
 211     }
 212
 213   struct fpreg fpregs;
 214
 215   if (ptrace (PT_GETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
 216     perror_with_name (_("Couldn't get floating point status"));
 217
 218   i387_collect_fsave (regcache, regnum, &fpregs);
 219
 220   if (ptrace (PT_SETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
 221     perror_with_name (_("Couldn't write floating point status"));
 222 }
 223
 224 /* Resume execution of the inferior process.  If STEP is nonzero,
 225    single-step it.  If SIGNAL is nonzero, give it that signal.  */
 226
 227 void
 228 i386_fbsd_nat_target::resume (ptid_t ptid, int step, enum gdb_signal signal)
 229 {
 230   pid_t pid = ptid.pid ();
 231   int request = PT_STEP;
 232
 233   if (pid == -1)
 234     /* Resume all threads.  This only gets used in the non-threaded
 235        case, where "resume all threads" and "resume inferior_ptid" are
 236        the same.  */
 237     pid = inferior_ptid.pid ();
 238
 239   if (!step)
 240     {
 241       struct regcache *regcache = get_current_regcache ();
 242       ULONGEST eflags;
 243
 244       /* Workaround for a bug in FreeBSD.  Make sure that the trace
 245          flag is off when doing a continue.  There is a code path
 246          through the kernel which leaves the flag set when it should
 247          have been cleared.  If a process has a signal pending (such
 248          as SIGALRM) and we do a PT_STEP, the process never really has
 249          a chance to run because the kernel needs to notify the
 250          debugger that a signal is being sent.  Therefore, the process
 251          never goes through the kernel's trap() function which would
 252          normally clear it.  */
 253
 254       regcache_cooked_read_unsigned (regcache, I386_EFLAGS_REGNUM,
 255                                      &eflags);
 256       if (eflags & 0x0100)
 257         regcache_cooked_write_unsigned (regcache, I386_EFLAGS_REGNUM,
 258                                         eflags & ~0x0100);
 259
 260       request = PT_CONTINUE;
 261     }
 262
 263   /* An addres of (caddr_t) 1 tells ptrace to continue from where it
 264      was.  (If GDB wanted it to start some other way, we have already
 265      written a new PC value to the child.)  */
 266   if (ptrace (request, pid, (caddr_t) 1,
 267               gdb_signal_to_host (signal)) == -1)
 268     perror_with_name (("ptrace"));
 269 }
 270 \f
 271
 272 /* Support for debugging kernel virtual memory images.  */
 273
 274 #include <machine/pcb.h>
 275
 276 #include "bsd-kvm.h"
 277
 278 static int
 279 i386fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
 280 {
 281   /* The following is true for FreeBSD 4.7:
 282
 283      The pcb contains %eip, %ebx, %esp, %ebp, %esi, %edi and %gs.
 284      This accounts for all callee-saved registers specified by the
 285      psABI and then some.  Here %esp contains the stack pointer at the
 286      point just after the call to cpu_switch().  From this information
 287      we reconstruct the register state as it would look when we just
 288      returned from cpu_switch().  */
 289
 290   /* The stack pointer shouldn't be zero.  */
 291   if (pcb->pcb_esp == 0)
 292     return 0;
 293
 294   pcb->pcb_esp += 4;
 295   regcache->raw_supply (I386_EDI_REGNUM, &pcb->pcb_edi);
 296   regcache->raw_supply (I386_ESI_REGNUM, &pcb->pcb_esi);
 297   regcache->raw_supply (I386_EBP_REGNUM, &pcb->pcb_ebp);
 298   regcache->raw_supply (I386_ESP_REGNUM, &pcb->pcb_esp);
 299   regcache->raw_supply (I386_EBX_REGNUM, &pcb->pcb_ebx);
 300   regcache->raw_supply (I386_EIP_REGNUM, &pcb->pcb_eip);
 301   regcache->raw_supply (I386_GS_REGNUM, &pcb->pcb_gs);
 302
 303   return 1;
 304 }
 305 \f
 306
 307 /* Implement the read_description method.  */
 308
 309 const struct target_desc *
 310 i386_fbsd_nat_target::read_description ()
 311 {
 312 #ifdef PT_GETXSTATE_INFO
 313   static int xsave_probed;
 314   static uint64_t xcr0;
 315 #endif
 316   static int xmm_probed;
 317
 318 #ifdef PT_GETXSTATE_INFO
 319   if (!xsave_probed)
 320     {
 321       struct ptrace_xstate_info info;
 322
 323       if (ptrace (PT_GETXSTATE_INFO, inferior_ptid.pid (),
 324                   (PTRACE_TYPE_ARG3) &info, sizeof (info)) == 0)
 325         {
 326           xsave_len = info.xsave_len;
 327           xcr0 = info.xsave_mask;
 328         }
 329       xsave_probed = 1;
 330     }
 331
 332   if (xsave_len != 0)
 333     return i386_target_description (xcr0, true);
 334 #endif
 335
 336   if (!xmm_probed)
 337     {
 338       char xmmregs[I387_SIZEOF_FXSAVE];
 339
 340       if (ptrace (PT_GETXMMREGS, inferior_ptid.pid (),
 341                   (PTRACE_TYPE_ARG3) xmmregs, 0) == 0)
 342         have_ptrace_xmmregs = 1;
 343       xmm_probed = 1;
 344     }
 345
 346   if (have_ptrace_xmmregs)
 347     return i386_target_description (X86_XSTATE_SSE_MASK, true);
 348
 349   return i386_target_description (X86_XSTATE_X87_MASK, true);
 350 }
 351
 352 void _initialize_i386fbsd_nat ();
 353 void
 354 _initialize_i386fbsd_nat ()
 355 {
 356   add_inf_child_target (&the_i386_fbsd_nat_target);
 357
 358   /* Support debugging kernel virtual memory images.  */
 359   bsd_kvm_add_target (i386fbsd_supply_pcb);
 360 }