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 "inferior.h"
  21 #include "regcache.h"
  22 #include "target.h"
  23
  24 #include <sys/types.h>
  25 #include <sys/ptrace.h>
  26 #include <sys/sysctl.h>
  27 #include <sys/user.h>
  28
  29 #include "i386-tdep.h"
  30 #include "i386-fbsd-tdep.h"
  31 #include "i387-tdep.h"
  32 #include "x86-nat.h"
  33 #include "x86-fbsd-nat.h"
  34
  35 class i386_fbsd_nat_target final : public x86_fbsd_nat_target
  36 {
  37 public:
  38   void fetch_registers (struct regcache *, int) override;
  39   void store_registers (struct regcache *, int) override;
  40
  41   const struct target_desc *read_description () override;
  42
  43   void resume (ptid_t, int, enum gdb_signal) override;
  44 };
  45
  46 static i386_fbsd_nat_target the_i386_fbsd_nat_target;
  47
  48 static int have_ptrace_xmmregs;
  49
  50 /* Fetch register REGNUM from the inferior.  If REGNUM is -1, do this
  51    for all registers.  */
  52
  53 void
  54 i386_fbsd_nat_target::fetch_registers (struct regcache *regcache, int regnum)
  55 {
  56   struct gdbarch *gdbarch = regcache->arch ();
  57   pid_t pid = get_ptrace_pid (regcache->ptid ());
  58
  59   if (fetch_register_set<struct reg> (regcache, regnum, PT_GETREGS,
  60                                       &i386_fbsd_gregset))
  61     {
  62       if (regnum != -1)
  63         return;
  64     }
  65
  66 #ifdef PT_GETFSBASE
  67   if (regnum == -1 || regnum == I386_FSBASE_REGNUM)
  68     {
  69       register_t base;
  70
  71       if (ptrace (PT_GETFSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
  72         perror_with_name (_("Couldn't get segment register fs_base"));
  73
  74       regcache->raw_supply (I386_FSBASE_REGNUM, &base);
  75       if (regnum != -1)
  76         return;
  77     }
  78 #endif
  79 #ifdef PT_GETGSBASE
  80   if (regnum == -1 || regnum == I386_GSBASE_REGNUM)
  81     {
  82       register_t base;
  83
  84       if (ptrace (PT_GETGSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
  85         perror_with_name (_("Couldn't get segment register gs_base"));
  86
  87       regcache->raw_supply (I386_GSBASE_REGNUM, &base);
  88       if (regnum != -1)
  89         return;
  90     }
  91 #endif
  92
  93   /* There is no i386_fxsave_supplies or i386_xsave_supplies.
  94      Instead, the earlier register sets return early if the request
  95      was for a specific register that was already satisified to avoid
  96      fetching the FPU/XSAVE state unnecessarily.  */
  97
  98 #ifdef PT_GETXSTATE_INFO
  99   if (m_xsave_info.xsave_len != 0)
 100     {
 101       void *xstateregs = alloca (m_xsave_info.xsave_len);
 102
 103       if (ptrace (PT_GETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, 0) == -1)
 104         perror_with_name (_("Couldn't get extended state status"));
 105
 106       i387_supply_xsave (regcache, regnum, xstateregs);
 107       return;
 108     }
 109 #endif
 110   if (have_ptrace_xmmregs != 0)
 111     {
 112       char xmmregs[I387_SIZEOF_FXSAVE];
 113
 114       if (ptrace(PT_GETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
 115         perror_with_name (_("Couldn't get XMM registers"));
 116
 117       i387_supply_fxsave (regcache, regnum, xmmregs);
 118       return;
 119     }
 120
 121   struct fpreg fpregs;
 122
 123   if (ptrace (PT_GETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
 124     perror_with_name (_("Couldn't get floating point status"));
 125
 126   i387_supply_fsave (regcache, regnum, &fpregs);
 127 }
 128
 129 /* Store register REGNUM back into the inferior.  If REGNUM is -1, do
 130    this for all registers.  */
 131
 132 void
 133 i386_fbsd_nat_target::store_registers (struct regcache *regcache, int regnum)
 134 {
 135   struct gdbarch *gdbarch = regcache->arch ();
 136   pid_t pid = get_ptrace_pid (regcache->ptid ());
 137
 138   if (store_register_set<struct reg> (regcache, regnum, PT_GETREGS, PT_SETREGS,
 139                                       &i386_fbsd_gregset))
 140     {
 141       if (regnum != -1)
 142         return;
 143     }
 144
 145 #ifdef PT_SETFSBASE
 146   if (regnum == -1 || regnum == I386_FSBASE_REGNUM)
 147     {
 148       register_t base;
 149
 150       regcache->raw_collect (I386_FSBASE_REGNUM, &base);
 151
 152       if (ptrace (PT_SETFSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
 153         perror_with_name (_("Couldn't write segment register fs_base"));
 154       if (regnum != -1)
 155         return;
 156     }
 157 #endif
 158 #ifdef PT_SETGSBASE
 159   if (regnum == -1 || regnum == I386_GSBASE_REGNUM)
 160     {
 161       register_t base;
 162
 163       regcache->raw_collect (I386_GSBASE_REGNUM, &base);
 164
 165       if (ptrace (PT_SETGSBASE, pid, (PTRACE_TYPE_ARG3) &base, 0) == -1)
 166         perror_with_name (_("Couldn't write segment register gs_base"));
 167       if (regnum != -1)
 168         return;
 169     }
 170 #endif
 171
 172   /* There is no i386_fxsave_supplies or i386_xsave_supplies.
 173      Instead, the earlier register sets return early if the request
 174      was for a specific register that was already satisified to avoid
 175      fetching the FPU/XSAVE state unnecessarily.  */
 176
 177 #ifdef PT_GETXSTATE_INFO
 178   if (m_xsave_info.xsave_len != 0)
 179     {
 180       void *xstateregs = alloca (m_xsave_info.xsave_len);
 181
 182       if (ptrace (PT_GETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, 0) == -1)
 183         perror_with_name (_("Couldn't get extended state status"));
 184
 185       i387_collect_xsave (regcache, regnum, xstateregs, 0);
 186
 187       if (ptrace (PT_SETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs,
 188                   m_xsave_info.xsave_len) == -1)
 189         perror_with_name (_("Couldn't write extended state status"));
 190       return;
 191     }
 192 #endif
 193   if (have_ptrace_xmmregs != 0)
 194     {
 195       char xmmregs[I387_SIZEOF_FXSAVE];
 196
 197       if (ptrace(PT_GETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
 198         perror_with_name (_("Couldn't get XMM registers"));
 199
 200       i387_collect_fxsave (regcache, regnum, xmmregs);
 201
 202       if (ptrace (PT_SETXMMREGS, pid, (PTRACE_TYPE_ARG3) xmmregs, 0) == -1)
 203         perror_with_name (_("Couldn't write XMM registers"));
 204       return;
 205     }
 206
 207   struct fpreg fpregs;
 208
 209   if (ptrace (PT_GETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
 210     perror_with_name (_("Couldn't get floating point status"));
 211
 212   i387_collect_fsave (regcache, regnum, &fpregs);
 213
 214   if (ptrace (PT_SETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
 215     perror_with_name (_("Couldn't write floating point status"));
 216 }
 217
 218 /* Resume execution of the inferior process.  If STEP is nonzero,
 219    single-step it.  If SIGNAL is nonzero, give it that signal.  */
 220
 221 void
 222 i386_fbsd_nat_target::resume (ptid_t ptid, int step, enum gdb_signal signal)
 223 {
 224   pid_t pid = ptid.pid ();
 225   int request = PT_STEP;
 226
 227   if (pid == -1)
 228     /* Resume all threads.  This only gets used in the non-threaded
 229        case, where "resume all threads" and "resume inferior_ptid" are
 230        the same.  */
 231     pid = inferior_ptid.pid ();
 232
 233   if (!step)
 234     {
 235       regcache *regcache = get_thread_regcache (inferior_thread ());
 236       ULONGEST eflags;
 237
 238       /* Workaround for a bug in FreeBSD.  Make sure that the trace
 239          flag is off when doing a continue.  There is a code path
 240          through the kernel which leaves the flag set when it should
 241          have been cleared.  If a process has a signal pending (such
 242          as SIGALRM) and we do a PT_STEP, the process never really has
 243          a chance to run because the kernel needs to notify the
 244          debugger that a signal is being sent.  Therefore, the process
 245          never goes through the kernel's trap() function which would
 246          normally clear it.  */
 247
 248       regcache_cooked_read_unsigned (regcache, I386_EFLAGS_REGNUM,
 249                                      &eflags);
 250       if (eflags & 0x0100)
 251         regcache_cooked_write_unsigned (regcache, I386_EFLAGS_REGNUM,
 252                                         eflags & ~0x0100);
 253
 254       request = PT_CONTINUE;
 255     }
 256
 257   /* An addres of (caddr_t) 1 tells ptrace to continue from where it
 258      was.  (If GDB wanted it to start some other way, we have already
 259      written a new PC value to the child.)  */
 260   if (ptrace (request, pid, (caddr_t) 1,
 261               gdb_signal_to_host (signal)) == -1)
 262     perror_with_name (("ptrace"));
 263 }
 264 \f
 265
 266 /* Support for debugging kernel virtual memory images.  */
 267
 268 #include <machine/pcb.h>
 269
 270 #include "bsd-kvm.h"
 271
 272 static int
 273 i386fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
 274 {
 275   /* The following is true for FreeBSD 4.7:
 276
 277      The pcb contains %eip, %ebx, %esp, %ebp, %esi, %edi and %gs.
 278      This accounts for all callee-saved registers specified by the
 279      psABI and then some.  Here %esp contains the stack pointer at the
 280      point just after the call to cpu_switch().  From this information
 281      we reconstruct the register state as it would look when we just
 282      returned from cpu_switch().  */
 283
 284   /* The stack pointer shouldn't be zero.  */
 285   if (pcb->pcb_esp == 0)
 286     return 0;
 287
 288   pcb->pcb_esp += 4;
 289   regcache->raw_supply (I386_EDI_REGNUM, &pcb->pcb_edi);
 290   regcache->raw_supply (I386_ESI_REGNUM, &pcb->pcb_esi);
 291   regcache->raw_supply (I386_EBP_REGNUM, &pcb->pcb_ebp);
 292   regcache->raw_supply (I386_ESP_REGNUM, &pcb->pcb_esp);
 293   regcache->raw_supply (I386_EBX_REGNUM, &pcb->pcb_ebx);
 294   regcache->raw_supply (I386_EIP_REGNUM, &pcb->pcb_eip);
 295   regcache->raw_supply (I386_GS_REGNUM, &pcb->pcb_gs);
 296
 297   return 1;
 298 }
 299 \f
 300
 301 /* Implement the read_description method.  */
 302
 303 const struct target_desc *
 304 i386_fbsd_nat_target::read_description ()
 305 {
 306   static int xmm_probed;
 307
 308   if (inferior_ptid == null_ptid)
 309     return this->beneath ()->read_description ();
 310
 311 #ifdef PT_GETXSTATE_INFO
 312   probe_xsave_layout (inferior_ptid.pid ());
 313   if (m_xsave_info.xsave_len != 0)
 314     return i386_target_description (m_xsave_info.xsave_mask, true);
 315 #endif
 316
 317   if (!xmm_probed)
 318     {
 319       char xmmregs[I387_SIZEOF_FXSAVE];
 320
 321       if (ptrace (PT_GETXMMREGS, inferior_ptid.pid (),
 322                   (PTRACE_TYPE_ARG3) xmmregs, 0) == 0)
 323         have_ptrace_xmmregs = 1;
 324       xmm_probed = 1;
 325     }
 326
 327   if (have_ptrace_xmmregs)
 328     return i386_target_description (X86_XSTATE_SSE_MASK, true);
 329
 330   return i386_target_description (X86_XSTATE_X87_MASK, true);
 331 }
 332
 333 void _initialize_i386fbsd_nat ();
 334 void
 335 _initialize_i386fbsd_nat ()
 336 {
 337   add_inf_child_target (&the_i386_fbsd_nat_target);
 338
 339   /* Support debugging kernel virtual memory images.  */
 340   bsd_kvm_add_target (i386fbsd_supply_pcb);
 341 }