nptl_db/td_ta_map_lwp2thr.c

   1 /* Which thread is running on an LWP?
   2    Copyright (C) 2003-2018 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include "thread_dbP.h"
  20 #include <stdlib.h>
  21 #include <byteswap.h>
  22 #include <sys/procfs.h>
  23
  24
  25 td_err_e
  26 __td_ta_lookup_th_unique (const td_thragent_t *ta_arg,
  27                           lwpid_t lwpid, td_thrhandle_t *th)
  28 {
  29   td_thragent_t *const ta = (td_thragent_t *) ta_arg;
  30   ps_err_e err;
  31   td_err_e terr;
  32   prgregset_t regs;
  33   psaddr_t addr;
  34
  35   if (ta->ta_howto == ta_howto_unknown)
  36     {
  37       /* We need to read in from the inferior the instructions what to do.  */
  38       psaddr_t howto;
  39
  40       err = td_lookup (ta->ph, SYM_TH_UNIQUE_CONST_THREAD_AREA, &howto);
  41       if (err == PS_OK)
  42         {
  43           err = ps_pdread (ta->ph, howto,
  44                            &ta->ta_howto_data.const_thread_area,
  45                            sizeof ta->ta_howto_data.const_thread_area);
  46           if (err != PS_OK)
  47             return TD_ERR;
  48           ta->ta_howto = ta_howto_const_thread_area;
  49           if (ta->ta_howto_data.const_thread_area & 0xff000000U)
  50             ta->ta_howto_data.const_thread_area
  51               = bswap_32 (ta->ta_howto_data.const_thread_area);
  52         }
  53       else
  54         {
  55           switch (sizeof (regs[0]))
  56             {
  57             case 8:
  58               err = td_lookup (ta->ph, SYM_TH_UNIQUE_REGISTER64, &howto);
  59               if (err == PS_OK)
  60                 ta->ta_howto = ta_howto_reg;
  61               else if (err == PS_NOSYM)
  62                 {
  63                   err = td_lookup (ta->ph,
  64                                    SYM_TH_UNIQUE_REGISTER64_THREAD_AREA,
  65                                    &howto);
  66                   if (err == PS_OK)
  67                     ta->ta_howto = ta_howto_reg_thread_area;
  68                 }
  69               break;
  70
  71             case 4:
  72               err = td_lookup (ta->ph, SYM_TH_UNIQUE_REGISTER32, &howto);
  73               if (err == PS_OK)
  74                 ta->ta_howto = ta_howto_reg;
  75               else if (err == PS_NOSYM)
  76                 {
  77                   err = td_lookup (ta->ph,
  78                                    SYM_TH_UNIQUE_REGISTER32_THREAD_AREA,
  79                                    &howto);
  80                   if (err == PS_OK)
  81                     ta->ta_howto = ta_howto_reg_thread_area;
  82                 }
  83               break;
  84
  85             default:
  86               abort ();
  87               return TD_DBERR;
  88             }
  89
  90           if (err != PS_OK)
  91             return TD_DBERR;
  92
  93           /* For either of these methods we read in the same descriptor.  */
  94           err = ps_pdread (ta->ph, howto,
  95                            ta->ta_howto_data.reg, DB_SIZEOF_DESC);
  96           if (err != PS_OK)
  97             return TD_ERR;
  98           if (DB_DESC_SIZE (ta->ta_howto_data.reg) == 0)
  99             return TD_DBERR;
 100           if (DB_DESC_SIZE (ta->ta_howto_data.reg) & 0xff000000U)
 101             {
 102               /* Byte-swap these words, though we leave the size word
 103                  in native order as the handy way to distinguish.  */
 104               DB_DESC_OFFSET (ta->ta_howto_data.reg)
 105                 = bswap_32 (DB_DESC_OFFSET (ta->ta_howto_data.reg));
 106               DB_DESC_NELEM (ta->ta_howto_data.reg)
 107                 = bswap_32 (DB_DESC_NELEM (ta->ta_howto_data.reg));
 108             }
 109         }
 110     }
 111
 112   switch (ta->ta_howto)
 113     {
 114     default:
 115       return TD_DBERR;
 116
 117     case ta_howto_reg:
 118       /* On most machines, we are just looking at a register.  */
 119       if (ps_lgetregs (ta->ph, lwpid, regs) != PS_OK)
 120         return TD_ERR;
 121       terr = _td_fetch_value_local (ta, ta->ta_howto_data.reg, -1,
 122                                     0, regs, &addr);
 123       if (terr != TD_OK)
 124         return terr;
 125
 126       /* In this descriptor the nelem word is overloaded as the bias.  */
 127       addr += (int32_t) DB_DESC_NELEM (ta->ta_howto_data.reg);
 128       th->th_unique = addr;
 129       break;
 130
 131     case ta_howto_const_thread_area:
 132       /* Some hosts don't have this call and this case won't be used.  */
 133 # pragma weak ps_get_thread_area
 134       if (&ps_get_thread_area == NULL)
 135         return TD_NOCAPAB;
 136
 137       /* A la x86-64, there is a magic index for get_thread_area.  */
 138       if (ps_get_thread_area (ta->ph, lwpid,
 139                               ta->ta_howto_data.const_thread_area,
 140                               &th->th_unique) != PS_OK)
 141         return TD_ERR;  /* XXX Other error value?  */
 142       break;
 143
 144     case ta_howto_reg_thread_area:
 145       if (&ps_get_thread_area == NULL)
 146         return TD_NOCAPAB;
 147
 148       /* A la i386, a register holds the index for get_thread_area.  */
 149       if (ps_lgetregs (ta->ph, lwpid, regs) != PS_OK)
 150         return TD_ERR;
 151       terr = _td_fetch_value_local (ta, ta->ta_howto_data.reg_thread_area,
 152                                     -1, 0, regs, &addr);
 153       if (terr != TD_OK)
 154         return terr;
 155       /* In this descriptor the nelem word is overloaded as scale factor.  */
 156       if (ps_get_thread_area
 157           (ta->ph, lwpid,
 158            ((addr - (psaddr_t) 0)
 159             >> DB_DESC_NELEM (ta->ta_howto_data.reg_thread_area)),
 160            &th->th_unique) != PS_OK)
 161         return TD_ERR;  /* XXX Other error value?  */
 162       break;
 163     }
 164
 165   /* Found it.  Now complete the `td_thrhandle_t' object.  */
 166   th->th_ta_p = ta;
 167
 168   return TD_OK;
 169 }
 170
 171 td_err_e
 172 td_ta_map_lwp2thr (const td_thragent_t *ta_arg,
 173                    lwpid_t lwpid, td_thrhandle_t *th)
 174 {
 175   td_thragent_t *const ta = (td_thragent_t *) ta_arg;
 176
 177   LOG ("td_ta_map_lwp2thr");
 178
 179   /* Test whether the TA parameter is ok.  */
 180   if (! ta_ok (ta))
 181     return TD_BADTA;
 182
 183   /* We cannot rely on thread registers and such information at all
 184      before __pthread_initialize_minimal has gotten far enough.  They
 185      sometimes contain garbage that would confuse us, left by the kernel
 186      at exec.  So if it looks like initialization is incomplete, we only
 187      fake a special descriptor for the initial thread.  */
 188
 189   psaddr_t list;
 190   td_err_e err = DB_GET_SYMBOL (list, ta, __stack_user);
 191   if (err != TD_OK)
 192     return err;
 193
 194   err = DB_GET_FIELD (list, ta, list, list_t, next, 0);
 195   if (err != TD_OK)
 196     return err;
 197
 198   if (list == 0)
 199     {
 200       if (ps_getpid (ta->ph) != lwpid)
 201         return TD_ERR;
 202       th->th_ta_p = ta;
 203       th->th_unique = 0;
 204       return TD_OK;
 205     }
 206
 207   return __td_ta_lookup_th_unique (ta_arg, lwpid, th);
 208 }