gdb/i386-gnu-nat.c

/* Low level interface to i386 running the GNU Hurd.

   Copyright (C) 1992-2021 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/* Include this first, to pick up the <mach.h> 'thread_info' diversion.  */
#include "gnu-nat.h"

/* Mach/Hurd headers are not yet ready for C++ compilation.  */
extern "C"
{
#include <mach.h>
#include <mach_error.h>
#include <mach/message.h>
#include <mach/exception.h>
}

#include "defs.h"
#include "x86-nat.h"
#include "inferior.h"
#include "floatformat.h"
#include "regcache.h"

#include "i386-tdep.h"

#include "inf-child.h"
#include "i387-tdep.h"

/* Offset to the thread_state_t location where REG is stored.  */
#define REG_OFFSET(reg) offsetof (struct i386_thread_state, reg)

/* At REG_OFFSET[N] is the offset to the thread_state_t location where
   the GDB register N is stored.  */
static int reg_offset[] =
{
  REG_OFFSET (eax), REG_OFFSET (ecx), REG_OFFSET (edx), REG_OFFSET (ebx),
  REG_OFFSET (uesp), REG_OFFSET (ebp), REG_OFFSET (esi), REG_OFFSET (edi),
  REG_OFFSET (eip), REG_OFFSET (efl), REG_OFFSET (cs), REG_OFFSET (ss),
  REG_OFFSET (ds), REG_OFFSET (es), REG_OFFSET (fs), REG_OFFSET (gs)
};

#define REG_ADDR(state, regnum) ((char *)(state) + reg_offset[regnum])



/* The i386 GNU Hurd target.  */

#ifdef i386_DEBUG_STATE
using gnu_base_target = x86_nat_target<gnu_nat_target>;
#else
using gnu_base_target = gnu_nat_target;
#endif

struct i386_gnu_nat_target final : public gnu_base_target
{
  void fetch_registers (struct regcache *, int) override;
  void store_registers (struct regcache *, int) override;
};

static i386_gnu_nat_target the_i386_gnu_nat_target;

/* Get the whole floating-point state of THREAD and record the values
   of the corresponding (pseudo) registers.  */

static void
fetch_fpregs (struct regcache *regcache, struct proc *thread)
{
  mach_msg_type_number_t count = i386_FLOAT_STATE_COUNT;
  struct i386_float_state state;
  kern_return_t err;

  err = thread_get_state (thread->port, i386_FLOAT_STATE,
			  (thread_state_t) &state, &count);
  if (err)
    {
      warning (_("Couldn't fetch floating-point state from %s"),
	       proc_string (thread));
      return;
    }

  if (!state.initialized)
    {
      /* The floating-point state isn't initialized.  */
      i387_supply_fsave (regcache, -1, NULL);
    }
  else
    {
      /* Supply the floating-point registers.  */
      i387_supply_fsave (regcache, -1, state.hw_state);
    }
}

/* Fetch register REGNO, or all regs if REGNO is -1.  */
void
i386_gnu_nat_target::fetch_registers (struct regcache *regcache, int regno)
{
  struct proc *thread;
  ptid_t ptid = regcache->ptid ();

  /* Make sure we know about new threads.  */
  inf_update_procs (gnu_current_inf);

  thread = inf_tid_to_thread (gnu_current_inf, ptid.lwp ());
  if (!thread)
    error (_("Can't fetch registers from thread %s: No such thread"),
	   target_pid_to_str (ptid).c_str ());

  if (regno < I386_NUM_GREGS || regno == -1)
    {
      thread_state_t state;

      /* This does the dirty work for us.  */
      state = proc_get_state (thread, 0);
      if (!state)
	{
	  warning (_("Couldn't fetch registers from %s"),
		   proc_string (thread));
	  return;
	}

      if (regno == -1)
	{
	  int i;

	  proc_debug (thread, "fetching all register");

	  for (i = 0; i < I386_NUM_GREGS; i++)
	    regcache->raw_supply (i, REG_ADDR (state, i));
	  thread->fetched_regs = ~0;
	}
      else
	{
	  proc_debug (thread, "fetching register %s",
		      gdbarch_register_name (regcache->arch (),
					     regno));

	  regcache->raw_supply (regno, REG_ADDR (state, regno));
	  thread->fetched_regs |= (1 << regno);
	}
    }

  if (regno >= I386_NUM_GREGS || regno == -1)
    {
      proc_debug (thread, "fetching floating-point registers");

      fetch_fpregs (regcache, thread);
    }
}


/* Store the whole floating-point state into THREAD using information
   from the corresponding (pseudo) registers.  */
static void
store_fpregs (const struct regcache *regcache, struct proc *thread, int regno)
{
  mach_msg_type_number_t count = i386_FLOAT_STATE_COUNT;
  struct i386_float_state state;
  kern_return_t err;

  err = thread_get_state (thread->port, i386_FLOAT_STATE,
			  (thread_state_t) &state, &count);
  if (err)
    {
      warning (_("Couldn't fetch floating-point state from %s"),
	       proc_string (thread));
      return;
    }

  /* FIXME: kettenis/2001-07-15: Is this right?  Should we somehow
     take into account DEPRECATED_REGISTER_VALID like the old code did?  */
  i387_collect_fsave (regcache, regno, state.hw_state);

  err = thread_set_state (thread->port, i386_FLOAT_STATE,
			  (thread_state_t) &state, i386_FLOAT_STATE_COUNT);
  if (err)
    {
      warning (_("Couldn't store floating-point state into %s"),
	       proc_string (thread));
      return;
    }
}

/* Store at least register REGNO, or all regs if REGNO == -1.  */
void
i386_gnu_nat_target::store_registers (struct regcache *regcache, int regno)
{
  struct proc *thread;
  struct gdbarch *gdbarch = regcache->arch ();
  ptid_t ptid = regcache->ptid ();

  /* Make sure we know about new threads.  */
  inf_update_procs (gnu_current_inf);

  thread = inf_tid_to_thread (gnu_current_inf, ptid.lwp ());
  if (!thread)
    error (_("Couldn't store registers into thread %s: No such thread"),
	   target_pid_to_str (ptid).c_str ());

  if (regno < I386_NUM_GREGS || regno == -1)
    {
      thread_state_t state;
      thread_state_data_t old_state;
      int was_aborted = thread->aborted;
      int was_valid = thread->state_valid;
      int trace;

      if (!was_aborted && was_valid)
	memcpy (&old_state, &thread->state, sizeof (old_state));

      state = proc_get_state (thread, 1);
      if (!state)
	{
	  warning (_("Couldn't store registers into %s"),
		   proc_string (thread));
	  return;
	}

      /* Save the T bit.  We might try to restore the %eflags register
	 below, but changing the T bit would seriously confuse GDB.  */
      trace = ((struct i386_thread_state *)state)->efl & 0x100;

      if (!was_aborted && was_valid)
	/* See which registers have changed after aborting the thread.  */
	{
	  int check_regno;

	  for (check_regno = 0; check_regno < I386_NUM_GREGS; check_regno++)
	    if ((thread->fetched_regs & (1 << check_regno))
		&& memcpy (REG_ADDR (&old_state, check_regno),
			   REG_ADDR (state, check_regno),
			   register_size (gdbarch, check_regno)))
	      /* Register CHECK_REGNO has changed!  Ack!  */
	      {
		warning (_("Register %s changed after the thread was aborted"),
			 gdbarch_register_name (gdbarch, check_regno));
		if (regno >= 0 && regno != check_regno)
		  /* Update GDB's copy of the register.  */
		  regcache->raw_supply (check_regno,
					REG_ADDR (state, check_regno));
		else
		  warning (_("... also writing this register!  "
			     "Suspicious..."));
	      }
	}

      if (regno == -1)
	{
	  int i;

	  proc_debug (thread, "storing all registers");

	  for (i = 0; i < I386_NUM_GREGS; i++)
	    if (REG_VALID == regcache->get_register_status (i))
	      regcache->raw_collect (i, REG_ADDR (state, i));
	}
      else
	{
	  proc_debug (thread, "storing register %s",
		      gdbarch_register_name (gdbarch, regno));

	  gdb_assert (REG_VALID == regcache->get_register_status (regno));
	  regcache->raw_collect (regno, REG_ADDR (state, regno));
	}

      /* Restore the T bit.  */
      ((struct i386_thread_state *)state)->efl &= ~0x100;
      ((struct i386_thread_state *)state)->efl |= trace;
    }

  if (regno >= I386_NUM_GREGS || regno == -1)
    {
      proc_debug (thread, "storing floating-point registers");

      store_fpregs (regcache, thread, regno);
    }
}


/* Support for debug registers.  */

#ifdef i386_DEBUG_STATE
/* Get debug registers for thread THREAD.  */

static void
i386_gnu_dr_get (struct i386_debug_state *regs, struct proc *thread)
{
  mach_msg_type_number_t count = i386_DEBUG_STATE_COUNT;
  kern_return_t err;

  err = thread_get_state (thread->port, i386_DEBUG_STATE,
			  (thread_state_t) regs, &count);
  if (err != 0 || count != i386_DEBUG_STATE_COUNT)
    warning (_("Couldn't fetch debug state from %s"),
	     proc_string (thread));
}

/* Set debug registers for thread THREAD.  */

static void
i386_gnu_dr_set (const struct i386_debug_state *regs, struct proc *thread)
{
  kern_return_t err;

  err = thread_set_state (thread->port, i386_DEBUG_STATE,
			  (thread_state_t) regs, i386_DEBUG_STATE_COUNT);
  if (err != 0)
    warning (_("Couldn't store debug state into %s"),
	     proc_string (thread));
}

/* Set DR_CONTROL in THREAD.  */

static void
i386_gnu_dr_set_control_one (struct proc *thread, void *arg)
{
  unsigned long *control = (unsigned long *) arg;
  struct i386_debug_state regs;

  i386_gnu_dr_get (&regs, thread);
  regs.dr[DR_CONTROL] = *control;
  i386_gnu_dr_set (&regs, thread);
}

/* Set DR_CONTROL to CONTROL in all threads.  */

static void
i386_gnu_dr_set_control (unsigned long control)
{
  inf_update_procs (gnu_current_inf);
  inf_threads (gnu_current_inf, i386_gnu_dr_set_control_one, &control);
}

/* Parameters to set a debugging address.  */

struct reg_addr
{
  int regnum;		/* Register number (zero based).  */
  CORE_ADDR addr;	/* Address.  */
};

/* Set address REGNUM (zero based) to ADDR in THREAD.  */

static void
i386_gnu_dr_set_addr_one (struct proc *thread, void *arg)
{
  struct reg_addr *reg_addr = (struct reg_addr *) arg;
  struct i386_debug_state regs;

  i386_gnu_dr_get (&regs, thread);
  regs.dr[reg_addr->regnum] = reg_addr->addr;
  i386_gnu_dr_set (&regs, thread);
}

/* Set address REGNUM (zero based) to ADDR in all threads.  */

static void
i386_gnu_dr_set_addr (int regnum, CORE_ADDR addr)
{
  struct reg_addr reg_addr;

  gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);

  reg_addr.regnum = regnum;
  reg_addr.addr = addr;

  inf_update_procs (gnu_current_inf);
  inf_threads (gnu_current_inf, i386_gnu_dr_set_addr_one, &reg_addr);
}

/* Get debug register REGNUM value from only the one LWP of PTID.  */

static unsigned long
i386_gnu_dr_get_reg (ptid_t ptid, int regnum)
{
  struct i386_debug_state regs;
  struct proc *thread;

  /* Make sure we know about new threads.  */
  inf_update_procs (gnu_current_inf);

  thread = inf_tid_to_thread (gnu_current_inf, ptid.lwp ());
  i386_gnu_dr_get (&regs, thread);

  return regs.dr[regnum];
}

/* Return the inferior's debug register REGNUM.  */

static CORE_ADDR
i386_gnu_dr_get_addr (int regnum)
{
  gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);

  return i386_gnu_dr_get_reg (inferior_ptid, regnum);
}

/* Get DR_STATUS from only the one thread of INFERIOR_PTID.  */

static unsigned long
i386_gnu_dr_get_status (void)
{
  return i386_gnu_dr_get_reg (inferior_ptid, DR_STATUS);
}

/* Return the inferior's DR7 debug control register.  */

static unsigned long
i386_gnu_dr_get_control (void)
{
  return i386_gnu_dr_get_reg (inferior_ptid, DR_CONTROL);
}
#endif /* i386_DEBUG_STATE */

void _initialize_i386gnu_nat ();
void
_initialize_i386gnu_nat ()
{
#ifdef i386_DEBUG_STATE
  x86_dr_low.set_control = i386_gnu_dr_set_control;
  gdb_assert (DR_FIRSTADDR == 0 && DR_LASTADDR < i386_DEBUG_STATE_COUNT);
  x86_dr_low.set_addr = i386_gnu_dr_set_addr;
  x86_dr_low.get_addr = i386_gnu_dr_get_addr;
  x86_dr_low.get_status = i386_gnu_dr_get_status;
  x86_dr_low.get_control = i386_gnu_dr_get_control;
  x86_set_debug_register_length (4);
#endif /* i386_DEBUG_STATE */

  gnu_target = &the_i386_gnu_nat_target;

  /* Register the target.  */
  add_inf_child_target (&the_i386_gnu_nat_target);
}