gdb/i386-fbsd-nat.c

   1 /* Native-dependent code for FreeBSD/i386.
   2
   3    Copyright (C) 2001-2022 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 #if defined(PT_GETFSBASE) || defined(PT_GETGSBASE)
  64   const struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  65 #endif
  66   pid_t pid = get_ptrace_pid (regcache->ptid ());
  67
  68   if (fetch_register_set<struct reg> (regcache, regnum, PT_GETREGS,
  69                                       &i386_fbsd_gregset))
  70     {
  71       if (regnum != -1)
  72         return;
  73     }
  74
  75 #ifdef PT_GETFSBASE
  76   if (regnum == -1 || regnum == I386_FSBASE_REGNUM)
  77     {
  78       register_t base;
  79
  80       if (ptrace (PT_GETFSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
  81         perror_with_name (_("Couldn't get segment register fs_base"));
  82
  83       regcache->raw_supply (I386_FSBASE_REGNUM, &base);
  84       if (regnum != -1)
  85         return;
  86     }
  87 #endif
  88 #ifdef PT_GETGSBASE
  89   if (regnum == -1 || regnum == I386_GSBASE_REGNUM)
  90     {
  91       register_t base;
  92
  93       if (ptrace (PT_GETGSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
  94         perror_with_name (_("Couldn't get segment register gs_base"));
  95
  96       regcache->raw_supply (I386_GSBASE_REGNUM, &base);
  97       if (regnum != -1)
  98         return;
  99     }
 100 #endif
 101
 102   /* There is no i386_fxsave_supplies or i386_xsave_supplies.
 103      Instead, the earlier register sets return early if the request
 104      was for a specific register that was already satisified to avoid
 105      fetching the FPU/XSAVE state unnecessarily.  */
 106
 107 #ifdef PT_GETXSTATE_INFO
 108   if (xsave_len != 0)
 109     {
 110       void *xstateregs = alloca (xsave_len);
 111
 112       if (ptrace (PT_GETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, 0) == -1)
 113         perror_with_name (_("Couldn't get extended state status"));
 114
 115       i387_supply_xsave (regcache, regnum, xstateregs);
 116       return;
 117     }
 118 #endif
 119   if (have_ptrace_xmmregs != 0)
 120     {
 121       char xmmregs[I387_SIZEOF_FXSAVE];
 122
 123       if (ptrace(PT_GETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
 124         perror_with_name (_("Couldn't get XMM registers"));
 125
 126       i387_supply_fxsave (regcache, regnum, xmmregs);
 127       return;
 128     }
 129
 130   struct fpreg fpregs;
 131
 132   if (ptrace (PT_GETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
 133     perror_with_name (_("Couldn't get floating point status"));
 134
 135   i387_supply_fsave (regcache, regnum, &fpregs);
 136 }
 137
 138 /* Store register REGNUM back into the inferior.  If REGNUM is -1, do
 139    this for all registers.  */
 140
 141 void
 142 i386_fbsd_nat_target::store_registers (struct regcache *regcache, int regnum)
 143 {
 144   struct gdbarch *gdbarch = regcache->arch ();
 145 #if defined(PT_GETFSBASE) || defined(PT_GETGSBASE)
 146   const struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 147 #endif
 148   pid_t pid = get_ptrace_pid (regcache->ptid ());
 149
 150   if (store_register_set<struct reg> (regcache, regnum, PT_GETREGS, PT_SETREGS,
 151                                       &i386_fbsd_gregset))
 152     {
 153       if (regnum != -1)
 154         return;
 155     }
 156
 157 #ifdef PT_SETFSBASE
 158   if (regnum == -1 || regnum == I386_FSBASE_REGNUM)
 159     {
 160       register_t base;
 161
 162       regcache->raw_collect (I386_FSBASE_REGNUM, &base);
 163
 164       if (ptrace (PT_SETFSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
 165         perror_with_name (_("Couldn't write segment register fs_base"));
 166       if (regnum != -1)
 167         return;
 168     }
 169 #endif
 170 #ifdef PT_SETGSBASE
 171   if (regnum == -1 || regnum == I386_GSBASE_REGNUM)
 172     {
 173       register_t base;
 174
 175       regcache->raw_collect (I386_GSBASE_REGNUM, &base);
 176
 177       if (ptrace (PT_SETGSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
 178         perror_with_name (_("Couldn't write segment register gs_base"));
 179       if (regnum != -1)
 180         return;
 181     }
 182 #endif
 183
 184   /* There is no i386_fxsave_supplies or i386_xsave_supplies.
 185      Instead, the earlier register sets return early if the request
 186      was for a specific register that was already satisified to avoid
 187      fetching the FPU/XSAVE state unnecessarily.  */
 188
 189 #ifdef PT_GETXSTATE_INFO
 190   if (xsave_len != 0)
 191     {
 192       void *xstateregs = alloca (xsave_len);
 193
 194       if (ptrace (PT_GETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, 0) == -1)
 195         perror_with_name (_("Couldn't get extended state status"));
 196
 197       i387_collect_xsave (regcache, regnum, xstateregs, 0);
 198
 199       if (ptrace (PT_SETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, xsave_len)
 200           == -1)
 201         perror_with_name (_("Couldn't write extended state status"));
 202       return;
 203     }
 204 #endif
 205   if (have_ptrace_xmmregs != 0)
 206     {
 207       char xmmregs[I387_SIZEOF_FXSAVE];
 208
 209       if (ptrace(PT_GETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
 210         perror_with_name (_("Couldn't get XMM registers"));
 211
 212       i387_collect_fxsave (regcache, regnum, xmmregs);
 213
 214       if (ptrace (PT_SETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
 215         perror_with_name (_("Couldn't write XMM registers"));
 216       return;
 217     }
 218
 219   struct fpreg fpregs;
 220
 221   if (ptrace (PT_GETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
 222     perror_with_name (_("Couldn't get floating point status"));
 223
 224   i387_collect_fsave (regcache, regnum, &fpregs);
 225
 226   if (ptrace (PT_SETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
 227     perror_with_name (_("Couldn't write floating point status"));
 228 }
 229
 230 /* Resume execution of the inferior process.  If STEP is nonzero,
 231    single-step it.  If SIGNAL is nonzero, give it that signal.  */
 232
 233 void
 234 i386_fbsd_nat_target::resume (ptid_t ptid, int step, enum gdb_signal signal)
 235 {
 236   pid_t pid = ptid.pid ();
 237   int request = PT_STEP;
 238
 239   if (pid == -1)
 240     /* Resume all threads.  This only gets used in the non-threaded
 241        case, where "resume all threads" and "resume inferior_ptid" are
 242        the same.  */
 243     pid = inferior_ptid.pid ();
 244
 245   if (!step)
 246     {
 247       struct regcache *regcache = get_current_regcache ();
 248       ULONGEST eflags;
 249
 250       /* Workaround for a bug in FreeBSD.  Make sure that the trace
 251          flag is off when doing a continue.  There is a code path
 252          through the kernel which leaves the flag set when it should
 253          have been cleared.  If a process has a signal pending (such
 254          as SIGALRM) and we do a PT_STEP, the process never really has
 255          a chance to run because the kernel needs to notify the
 256          debugger that a signal is being sent.  Therefore, the process
 257          never goes through the kernel's trap() function which would
 258          normally clear it.  */
 259
 260       regcache_cooked_read_unsigned (regcache, I386_EFLAGS_REGNUM,
 261                                      &eflags);
 262       if (eflags & 0x0100)
 263         regcache_cooked_write_unsigned (regcache, I386_EFLAGS_REGNUM,
 264                                         eflags & ~0x0100);
 265
 266       request = PT_CONTINUE;
 267     }
 268
 269   /* An addres of (caddr_t) 1 tells ptrace to continue from where it
 270      was.  (If GDB wanted it to start some other way, we have already
 271      written a new PC value to the child.)  */
 272   if (ptrace (request, pid, (caddr_t) 1,
 273               gdb_signal_to_host (signal)) == -1)
 274     perror_with_name (("ptrace"));
 275 }
 276 \f
 277
 278 /* Support for debugging kernel virtual memory images.  */
 279
 280 #include <machine/pcb.h>
 281
 282 #include "bsd-kvm.h"
 283
 284 static int
 285 i386fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
 286 {
 287   /* The following is true for FreeBSD 4.7:
 288
 289      The pcb contains %eip, %ebx, %esp, %ebp, %esi, %edi and %gs.
 290      This accounts for all callee-saved registers specified by the
 291      psABI and then some.  Here %esp contains the stack pointer at the
 292      point just after the call to cpu_switch().  From this information
 293      we reconstruct the register state as it would look when we just
 294      returned from cpu_switch().  */
 295
 296   /* The stack pointer shouldn't be zero.  */
 297   if (pcb->pcb_esp == 0)
 298     return 0;
 299
 300   pcb->pcb_esp += 4;
 301   regcache->raw_supply (I386_EDI_REGNUM, &pcb->pcb_edi);
 302   regcache->raw_supply (I386_ESI_REGNUM, &pcb->pcb_esi);
 303   regcache->raw_supply (I386_EBP_REGNUM, &pcb->pcb_ebp);
 304   regcache->raw_supply (I386_ESP_REGNUM, &pcb->pcb_esp);
 305   regcache->raw_supply (I386_EBX_REGNUM, &pcb->pcb_ebx);
 306   regcache->raw_supply (I386_EIP_REGNUM, &pcb->pcb_eip);
 307   regcache->raw_supply (I386_GS_REGNUM, &pcb->pcb_gs);
 308
 309   return 1;
 310 }
 311 \f
 312
 313 /* Implement the read_description method.  */
 314
 315 const struct target_desc *
 316 i386_fbsd_nat_target::read_description ()
 317 {
 318 #ifdef PT_GETXSTATE_INFO
 319   static int xsave_probed;
 320   static uint64_t xcr0;
 321 #endif
 322   static int xmm_probed;
 323
 324 #ifdef PT_GETXSTATE_INFO
 325   if (!xsave_probed)
 326     {
 327       struct ptrace_xstate_info info;
 328
 329       if (ptrace (PT_GETXSTATE_INFO, inferior_ptid.pid (),
 330                   (PTRACE_TYPE_ARG3) &info, sizeof (info)) == 0)
 331         {
 332           xsave_len = info.xsave_len;
 333           xcr0 = info.xsave_mask;
 334         }
 335       xsave_probed = 1;
 336     }
 337
 338   if (xsave_len != 0)
 339     return i386_target_description (xcr0, true);
 340 #endif
 341
 342   if (!xmm_probed)
 343     {
 344       char xmmregs[I387_SIZEOF_FXSAVE];
 345
 346       if (ptrace (PT_GETXMMREGS, inferior_ptid.pid (),
 347                   (PTRACE_TYPE_ARG3) xmmregs, 0) == 0)
 348         have_ptrace_xmmregs = 1;
 349       xmm_probed = 1;
 350     }
 351
 352   if (have_ptrace_xmmregs)
 353     return i386_target_description (X86_XSTATE_SSE_MASK, true);
 354
 355   return i386_target_description (X86_XSTATE_X87_MASK, true);
 356 }
 357
 358 void _initialize_i386fbsd_nat ();
 359 void
 360 _initialize_i386fbsd_nat ()
 361 {
 362   add_inf_child_target (&the_i386_fbsd_nat_target);
 363
 364   /* Support debugging kernel virtual memory images.  */
 365   bsd_kvm_add_target (i386fbsd_supply_pcb);
 366 }