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/* BSD user-level threads support.

   Copyright (C) 2005, 2007, 2008 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 "defs.h"

#include "gdbcore.h"

#include "gdbthread.h"

#include "inferior.h"

#include "objfiles.h"

#include "observer.h"

#include "regcache.h"

#include "solib.h"

#include "solist.h"

#include "symfile.h"

#include "target.h"

#include "gdb_assert.h"

#include "gdb_obstack.h"

#include "bsd-uthread.h"

/* HACK: Save the bsd_uthreads ops returned by bsd_uthread_target.  */

static struct target_ops *bsd_uthread_ops_hack;

/* Architecture-specific operations.  */

/* Per-architecture data key.  */

static struct gdbarch_data *bsd_uthread_data;

struct bsd_uthread_ops

{

  /* Supply registers for an inactive thread to a register cache.  */

  void (*supply_uthread)(struct regcache *, int, CORE_ADDR);

  /* Collect registers for an inactive thread from a register cache.  */

  void (*collect_uthread)(const struct regcache *, int, CORE_ADDR);

};

static void *

bsd_uthread_init (struct obstack *obstack)

{

  struct bsd_uthread_ops *ops;

  ops = OBSTACK_ZALLOC (obstack, struct bsd_uthread_ops);

  return ops;

}

/* Set the function that supplies registers from an inactive thread

   for architecture GDBARCH to SUPPLY_UTHREAD.  */

void

bsd_uthread_set_supply_uthread (struct gdbarch *gdbarch,

                                void (*supply_uthread) (struct regcache *,

                                                        int, CORE_ADDR))

{

  struct bsd_uthread_ops *ops = gdbarch_data (gdbarch, bsd_uthread_data);

  ops->supply_uthread = supply_uthread;

}

/* Set the function that collects registers for an inactive thread for

   architecture GDBARCH to SUPPLY_UTHREAD.  */

void

bsd_uthread_set_collect_uthread (struct gdbarch *gdbarch,

                         void (*collect_uthread) (const struct regcache *,

                                                  int, CORE_ADDR))

{

  struct bsd_uthread_ops *ops = gdbarch_data (gdbarch, bsd_uthread_data);

  ops->collect_uthread = collect_uthread;

}

/* Magic number to help recognize a valid thread structure.  */

#define BSD_UTHREAD_PTHREAD_MAGIC       0xd09ba115

/* Check whether the thread structure at ADDR is valid.  */

static void

bsd_uthread_check_magic (CORE_ADDR addr)

{

  ULONGEST magic = read_memory_unsigned_integer (addr, 4);

  if (magic != BSD_UTHREAD_PTHREAD_MAGIC)

    error (_("Bad magic"));

}

/* Thread states.  */

#define BSD_UTHREAD_PS_RUNNING  0

#define BSD_UTHREAD_PS_DEAD     18

/* Address of the pointer to the the thread structure for the running

   thread.  */

static CORE_ADDR bsd_uthread_thread_run_addr;

/* Address of the list of all threads.  */

static CORE_ADDR bsd_uthread_thread_list_addr;

/* Offsets of various "interesting" bits in the thread structure.  */

static int bsd_uthread_thread_state_offset = -1;

static int bsd_uthread_thread_next_offset = -1;

static int bsd_uthread_thread_ctx_offset;

/* Name of shared threads library.  */

static const char *bsd_uthread_solib_name;

/* Non-zero if the thread startum implemented by this module is active.  */

static int bsd_uthread_active;

static CORE_ADDR

bsd_uthread_lookup_address (const char *name, struct objfile *objfile)

{

  struct minimal_symbol *sym;

  sym = lookup_minimal_symbol (name, NULL, objfile);

  if (sym)

    return SYMBOL_VALUE_ADDRESS (sym);

  return 0;

}

static int

bsd_uthread_lookup_offset (const char *name, struct objfile *objfile)

{

  CORE_ADDR addr;

  addr = bsd_uthread_lookup_address (name, objfile);

  if (addr == 0)

    return 0;

  return read_memory_unsigned_integer (addr, 4);

}

/* If OBJFILE contains the symbols corresponding to one of the

   supported user-level threads libraries, activate the thread stratum

   implemented by this module.  */

static int

bsd_uthread_activate (struct objfile *objfile)

{

  struct gdbarch *gdbarch = current_gdbarch;

  struct bsd_uthread_ops *ops = gdbarch_data (gdbarch, bsd_uthread_data);

  /* Skip if the thread stratum has already been activated.  */

  if (bsd_uthread_active)

    return 0;

  /* There's no point in enabling this module if no

     architecture-specific operations are provided.  */

  if (!ops->supply_uthread)

    return 0;

  bsd_uthread_thread_run_addr =

    bsd_uthread_lookup_address ("_thread_run", objfile);

  if (bsd_uthread_thread_run_addr == 0)

    return 0;

  bsd_uthread_thread_list_addr =

    bsd_uthread_lookup_address ("_thread_list", objfile);

  if (bsd_uthread_thread_list_addr == 0)

    return 0;

  bsd_uthread_thread_state_offset =

    bsd_uthread_lookup_offset ("_thread_state_offset", objfile);

  if (bsd_uthread_thread_state_offset == 0)

    return 0;

  bsd_uthread_thread_next_offset =

    bsd_uthread_lookup_offset ("_thread_next_offset", objfile);

  if (bsd_uthread_thread_next_offset == 0)

    return 0;

  bsd_uthread_thread_ctx_offset =

    bsd_uthread_lookup_offset ("_thread_ctx_offset", objfile);

  push_target (bsd_uthread_ops_hack);

  bsd_uthread_active = 1;

  return 1;

}

/* Deactivate the thread stratum implemented by this module.  */

static void

bsd_uthread_deactivate (void)

{

  /* Skip if the thread stratum has already been deactivated.  */

  if (!bsd_uthread_active)

    return;

  bsd_uthread_active = 0;

  unpush_target (bsd_uthread_ops_hack);

  bsd_uthread_thread_run_addr = 0;

  bsd_uthread_thread_list_addr = 0;

  bsd_uthread_thread_state_offset = 0;

  bsd_uthread_thread_next_offset = 0;

  bsd_uthread_thread_ctx_offset = 0;

  bsd_uthread_solib_name = NULL;

}

void

bsd_uthread_inferior_created (struct target_ops *ops, int from_tty)

{

  bsd_uthread_activate (NULL);

}

/* Likely candidates for the threads library.  */

static const char *bsd_uthread_solib_names[] =

{

  "/usr/lib/libc_r.so",         /* FreeBSD */

  "/usr/lib/libpthread.so",     /* OpenBSD */

  NULL

};

void

bsd_uthread_solib_loaded (struct so_list *so)

{

  const char **names = bsd_uthread_solib_names;

  for (names = bsd_uthread_solib_names; *names; names++)

    {

      if (strncmp (so->so_original_name, *names, strlen (*names)) == 0)

        {

          solib_read_symbols (so, so->from_tty);

          if (bsd_uthread_activate (so->objfile))

            {

              bsd_uthread_solib_name == so->so_original_name;

              return;

            }

        }

    }

}

void

bsd_uthread_solib_unloaded (struct so_list *so)

{

  if (!bsd_uthread_solib_name)

    return;

  if (strcmp (so->so_original_name, bsd_uthread_solib_name) == 0)

    bsd_uthread_deactivate ();

}

static void

bsd_uthread_mourn_inferior (void)

{

  find_target_beneath (bsd_uthread_ops_hack)->to_mourn_inferior ();

  bsd_uthread_deactivate ();

}

static void

bsd_uthread_fetch_registers (struct regcache *regcache, int regnum)

{

  struct gdbarch *gdbarch = get_regcache_arch (regcache);

  struct bsd_uthread_ops *ops = gdbarch_data (gdbarch, bsd_uthread_data);

  CORE_ADDR addr = ptid_get_tid (inferior_ptid);

  CORE_ADDR active_addr;

  /* Always fetch the appropriate registers from the layer beneath.  */

  find_target_beneath (bsd_uthread_ops_hack)->to_fetch_registers (regcache, regnum);

  /* FIXME: That might have gotten us more than we asked for.  Make

     sure we overwrite all relevant registers with values from the

     thread structure.  This can go once we fix the underlying target.  */

  regnum = -1;

  active_addr = read_memory_typed_address (bsd_uthread_thread_run_addr,

                                           builtin_type_void_data_ptr);

  if (addr != 0 && addr != active_addr)

    {

      bsd_uthread_check_magic (addr);

      ops->supply_uthread (regcache, regnum,

                           addr + bsd_uthread_thread_ctx_offset);

    }

}

static void

bsd_uthread_store_registers (struct regcache *regcache, int regnum)

{

  struct gdbarch *gdbarch = get_regcache_arch (regcache);

  struct bsd_uthread_ops *ops = gdbarch_data (gdbarch, bsd_uthread_data);

  CORE_ADDR addr = ptid_get_tid (inferior_ptid);

  CORE_ADDR active_addr;

  active_addr = read_memory_typed_address (bsd_uthread_thread_run_addr,

                                           builtin_type_void_data_ptr);

  if (addr != 0 && addr != active_addr)

    {

      bsd_uthread_check_magic (addr);

      ops->collect_uthread (regcache, regnum,

                            addr + bsd_uthread_thread_ctx_offset);

    }

  else

    {

      /* Updating the thread that is currently running; pass the

         request to the layer beneath.  */

      find_target_beneath (bsd_uthread_ops_hack)->to_store_registers (regcache, regnum);

    }

}

/* FIXME: This function is only there because otherwise GDB tries to

   invoke deprecate_xfer_memory.  */

static LONGEST

bsd_uthread_xfer_partial (struct target_ops *ops, enum target_object object,

                          const char *annex, gdb_byte *readbuf,

                          const gdb_byte *writebuf,

                          ULONGEST offset, LONGEST len)

{

  gdb_assert (ops->beneath->to_xfer_partial);

  return ops->beneath->to_xfer_partial (ops->beneath, object, annex, readbuf,

                                        writebuf, offset, len);

}

static ptid_t

bsd_uthread_wait (ptid_t ptid, struct target_waitstatus *status)

{

  CORE_ADDR addr;

  /* Pass the request to the layer beneath.  */

  ptid = find_target_beneath (bsd_uthread_ops_hack)->to_wait (ptid, status);

  /* If the process is no longer alive, there's no point in figuring

     out the thread ID.  It will fail anyway.  */

  if (status->kind == TARGET_WAITKIND_SIGNALLED

      || status->kind == TARGET_WAITKIND_EXITED)

    return ptid;

  /* Fetch the corresponding thread ID, and augment the returned

     process ID with it.  */

  addr = read_memory_typed_address (bsd_uthread_thread_run_addr,

                                    builtin_type_void_data_ptr);

  if (addr != 0)

    {

      gdb_byte buf[4];

      /* FIXME: For executables linked statically with the threads

         library, we end up here before the program has actually been

         executed.  In that case ADDR will be garbage since it has

         been read from the wrong virtual memory image.  */

      if (target_read_memory (addr, buf, 4) == 0)

        {

          ULONGEST magic = extract_unsigned_integer (buf, 4);

          if (magic == BSD_UTHREAD_PTHREAD_MAGIC)

            ptid = ptid_build (ptid_get_pid (ptid), 0, addr);

        }

    }

  /* HACK: Twiddle INFERIOR_PTID such that the initial thread of a

     process isn't recognized as a new thread.  */

  if (ptid_get_tid (ptid) != 0 && !in_thread_list (ptid)

      && ptid_get_tid (inferior_ptid) == 0)

    {

      add_thread_silent (ptid);

      inferior_ptid = ptid;

    }

  return ptid;

}

static void

bsd_uthread_resume (ptid_t ptid, int step, enum target_signal sig)

{

  /* Pass the request to the layer beneath.  */

  find_target_beneath (bsd_uthread_ops_hack)->to_resume (ptid, step, sig);

}

static int

bsd_uthread_thread_alive (ptid_t ptid)

{

  CORE_ADDR addr = ptid_get_tid (inferior_ptid);

  if (addr != 0)

    {

      int offset = bsd_uthread_thread_state_offset;

      ULONGEST state;

      bsd_uthread_check_magic (addr);

      state = read_memory_unsigned_integer (addr + offset, 4);

      if (state == BSD_UTHREAD_PS_DEAD)

        return 0;

    }

  return find_target_beneath (bsd_uthread_ops_hack)->to_thread_alive (ptid);

}

static void

bsd_uthread_find_new_threads (void)

{

  pid_t pid = ptid_get_pid (inferior_ptid);

  int offset = bsd_uthread_thread_next_offset;

  CORE_ADDR addr;

  addr = read_memory_typed_address (bsd_uthread_thread_list_addr,

                                    builtin_type_void_data_ptr);

  while (addr != 0)

    {

      ptid_t ptid = ptid_build (pid, 0, addr);

      if (!in_thread_list (ptid))

        add_thread (ptid);

      addr = read_memory_typed_address (addr + offset,

                                        builtin_type_void_data_ptr);

    }

}

/* Possible states a thread can be in.  */

static char *bsd_uthread_state[] =

{

  "RUNNING",

  "SIGTHREAD",

  "MUTEX_WAIT",

  "COND_WAIT",

  "FDLR_WAIT",

  "FDLW_WAIT",

  "FDR_WAIT",

  "FDW_WAIT",

  "FILE_WAIT",

  "POLL_WAIT",

  "SELECT_WAIT",

  "SLEEP_WAIT",

  "WAIT_WAIT",

  "SIGSUSPEND",

  "SIGWAIT",

  "SPINBLOCK",

  "JOIN",

  "SUSPENDED",

  "DEAD",

  "DEADLOCK"

};

/* Return a string describing th state of the thread specified by

   INFO.  */

static char *

bsd_uthread_extra_thread_info (struct thread_info *info)

{

  CORE_ADDR addr = ptid_get_tid (info->ptid);

  if (addr != 0)

    {

      int offset = bsd_uthread_thread_state_offset;

      ULONGEST state;

      state = read_memory_unsigned_integer (addr + offset, 4);

      if (state < ARRAY_SIZE (bsd_uthread_state))

        return bsd_uthread_state[state];

    }

  return NULL;

}

static char *

bsd_uthread_pid_to_str (ptid_t ptid)

{

  if (ptid_get_tid (ptid) != 0)

    {

      static char buf[64];

      xsnprintf (buf, sizeof buf, "process %d, thread 0x%lx",

                 ptid_get_pid (ptid), ptid_get_tid (ptid));

      return buf;

    }

  return normal_pid_to_str (ptid);

}

struct target_ops *

bsd_uthread_target (void)

{

  struct target_ops *t = XZALLOC (struct target_ops);

  t->to_shortname = "bsd-uthreads";

  t->to_longname = "BSD user-level threads";

  t->to_doc = "BSD user-level threads";

  t->to_mourn_inferior = bsd_uthread_mourn_inferior;

  t->to_fetch_registers = bsd_uthread_fetch_registers;

  t->to_store_registers = bsd_uthread_store_registers;

  t->to_xfer_partial = bsd_uthread_xfer_partial;

  t->to_wait = bsd_uthread_wait;

  t->to_resume = bsd_uthread_resume;

  t->to_thread_alive = bsd_uthread_thread_alive;

  t->to_find_new_threads = bsd_uthread_find_new_threads;

  t->to_extra_thread_info = bsd_uthread_extra_thread_info;

  t->to_pid_to_str = bsd_uthread_pid_to_str;

  t->to_stratum = thread_stratum;

  t->to_magic = OPS_MAGIC;

  bsd_uthread_ops_hack = t;

  return t;

}

void

_initialize_bsd_uthread (void)

{

  add_target (bsd_uthread_target ());

  bsd_uthread_data = gdbarch_data_register_pre_init (bsd_uthread_init);

  observer_attach_inferior_created (bsd_uthread_inferior_created);

  observer_attach_solib_loaded (bsd_uthread_solib_loaded);

  observer_attach_solib_unloaded (bsd_uthread_solib_unloaded);

}