/* Which thread is running on an LWP?

   Copyright (C) 2003-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include "thread_dbP.h"

#include <stdlib.h>

#include <byteswap.h>

#include <sys/procfs.h>

td_err_e

__td_ta_lookup_th_unique (const td_thragent_t *ta_arg,

			  lwpid_t lwpid, td_thrhandle_t *th)

{

  td_thragent_t *const ta = (td_thragent_t *) ta_arg;

  ps_err_e err;

  td_err_e terr;

  prgregset_t regs;

  psaddr_t addr;

  if (ta->ta_howto == ta_howto_unknown)

    {

      /* We need to read in from the inferior the instructions what to do.  */

      psaddr_t howto;

      err = td_lookup (ta->ph, SYM_TH_UNIQUE_CONST_THREAD_AREA, &howto);

      if (err == PS_OK)

	{

	  err = ps_pdread (ta->ph, howto,

			   &ta->ta_howto_data.const_thread_area,

 			   sizeof ta->ta_howto_data.const_thread_area);

	  if (err != PS_OK)

	    return TD_ERR;

	  ta->ta_howto = ta_howto_const_thread_area;

	  if (ta->ta_howto_data.const_thread_area & 0xff000000U)

	    ta->ta_howto_data.const_thread_area

	      = bswap_32 (ta->ta_howto_data.const_thread_area);

	}

      else

	{

	  switch (sizeof (regs[0]))

	    {

	    case 8:

	      err = td_lookup (ta->ph, SYM_TH_UNIQUE_REGISTER64, &howto);

	      if (err == PS_OK)

		ta->ta_howto = ta_howto_reg;

	      else if (err == PS_NOSYM)

		{

		  err = td_lookup (ta->ph,

				   SYM_TH_UNIQUE_REGISTER64_THREAD_AREA,

				   &howto);

		  if (err == PS_OK)

		    ta->ta_howto = ta_howto_reg_thread_area;

		}

	      break;

	    case 4:

	      err = td_lookup (ta->ph, SYM_TH_UNIQUE_REGISTER32, &howto);

	      if (err == PS_OK)

		ta->ta_howto = ta_howto_reg;

	      else if (err == PS_NOSYM)

		{

		  err = td_lookup (ta->ph,

				   SYM_TH_UNIQUE_REGISTER32_THREAD_AREA,

				   &howto);

		  if (err == PS_OK)

		    ta->ta_howto = ta_howto_reg_thread_area;

		}

	      break;

	    default:

	      abort ();

	      return TD_DBERR;

	    }

	  if (err != PS_OK)

	    return TD_DBERR;

	  /* For either of these methods we read in the same descriptor.  */

	  err = ps_pdread (ta->ph, howto,

			   ta->ta_howto_data.reg, DB_SIZEOF_DESC);

	  if (err != PS_OK)

	    return TD_ERR;

	  if (DB_DESC_SIZE (ta->ta_howto_data.reg) == 0)

	    return TD_DBERR;

	  if (DB_DESC_SIZE (ta->ta_howto_data.reg) & 0xff000000U)

	    {

	      /* Byte-swap these words, though we leave the size word

		 in native order as the handy way to distinguish.  */

	      DB_DESC_OFFSET (ta->ta_howto_data.reg)

		= bswap_32 (DB_DESC_OFFSET (ta->ta_howto_data.reg));

	      DB_DESC_NELEM (ta->ta_howto_data.reg)

		= bswap_32 (DB_DESC_NELEM (ta->ta_howto_data.reg));

	    }

	}

    }

  switch (ta->ta_howto)

    {

    default:

      return TD_DBERR;

    case ta_howto_reg:

      /* On most machines, we are just looking at a register.  */

      if (ps_lgetregs (ta->ph, lwpid, regs) != PS_OK)

	return TD_ERR;

      terr = _td_fetch_value_local (ta, ta->ta_howto_data.reg, -1,

				    0, regs, &addr);

      if (terr != TD_OK)

	return terr;

      /* In this descriptor the nelem word is overloaded as the bias.  */

      addr += (int32_t) DB_DESC_NELEM (ta->ta_howto_data.reg);

      th->th_unique = addr;

      break;

    case ta_howto_const_thread_area:

      /* Some hosts don't have this call and this case won't be used.  */

# pragma weak ps_get_thread_area

      if (&ps_get_thread_area == NULL)

	return TD_NOCAPAB;

      /* A la x86-64, there is a magic index for get_thread_area.  */

      if (ps_get_thread_area (ta->ph, lwpid,

			      ta->ta_howto_data.const_thread_area,

			      &th->th_unique) != PS_OK)

	return TD_ERR;	/* XXX Other error value?  */

      break;

    case ta_howto_reg_thread_area:

      if (&ps_get_thread_area == NULL)

	return TD_NOCAPAB;

      /* A la i386, a register holds the index for get_thread_area.  */

      if (ps_lgetregs (ta->ph, lwpid, regs) != PS_OK)

	return TD_ERR;

      terr = _td_fetch_value_local (ta, ta->ta_howto_data.reg_thread_area,

				    -1, 0, regs, &addr);

      if (terr != TD_OK)

	return terr;

      /* In this descriptor the nelem word is overloaded as scale factor.  */

      if (ps_get_thread_area

	  (ta->ph, lwpid,

	   ((addr - (psaddr_t) 0)

	    >> DB_DESC_NELEM (ta->ta_howto_data.reg_thread_area)),

	   &th->th_unique) != PS_OK)

	return TD_ERR;	/* XXX Other error value?  */

      break;

    }

  /* Found it.  Now complete the `td_thrhandle_t' object.  */

  th->th_ta_p = ta;

  return TD_OK;

}

td_err_e

td_ta_map_lwp2thr (const td_thragent_t *ta_arg,

		   lwpid_t lwpid, td_thrhandle_t *th)

{

  td_thragent_t *const ta = (td_thragent_t *) ta_arg;

  LOG ("td_ta_map_lwp2thr");

  /* Test whether the TA parameter is ok.  */

  if (! ta_ok (ta))

    return TD_BADTA;

  /* We cannot rely on thread registers and such information at all

     before __pthread_initialize_minimal has gotten far enough.  They

     sometimes contain garbage that would confuse us, left by the kernel

     at exec.  So if it looks like initialization is incomplete, we only

     fake a special descriptor for the initial thread.  */

  psaddr_t list;

  td_err_e err = DB_GET_SYMBOL (list, ta, __stack_user);

  if (err != TD_OK)

    return err;

  err = DB_GET_FIELD (list, ta, list, list_t, next, 0);

  if (err != TD_OK)

    return err;

  if (list == 0)

    {

      if (ps_getpid (ta->ph) != lwpid)

	return TD_ERR;

      th->th_ta_p = ta;

      th->th_unique = 0;

      return TD_OK;

    }

  return __td_ta_lookup_th_unique (ta_arg, lwpid, th);

}