nptl_db/td_ta_thr_iter.c

   1 /* Iterate over a process's threads.
   2    Copyright (C) 1999-2023 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    <https://www.gnu.org/licenses/>.  */
  18
  19 #include "thread_dbP.h"
  20
  21
  22 static td_err_e
  23 iterate_thread_list (td_thragent_t *ta, td_thr_iter_f *callback,
  24                      void *cbdata_p, td_thr_state_e state, int ti_pri,
  25                      psaddr_t head, bool fake_empty)
  26 {
  27   td_err_e err;
  28   psaddr_t next, ofs;
  29   void *copy;
  30
  31   /* Test the state.
  32      XXX This is incomplete.  Normally this test should be in the loop.  */
  33   if (state != TD_THR_ANY_STATE)
  34     return TD_OK;
  35
  36   err = DB_GET_FIELD (next, ta, head, list_t, next, 0);
  37   if (err != TD_OK)
  38     return err;
  39
  40   if (next == 0 && fake_empty)
  41     {
  42       /* __pthread_initialize_minimal has not run.  There is just the main
  43          thread to return.  We cannot rely on its thread register.  They
  44          sometimes contain garbage that would confuse us, left by the
  45          kernel at exec.  So if it looks like initialization is incomplete,
  46          we only fake a special descriptor for the initial thread.  */
  47       td_thrhandle_t th = { ta, 0 };
  48       return callback (&th, cbdata_p) != 0 ? TD_DBERR : TD_OK;
  49     }
  50
  51   /* Cache the offset from struct pthread to its list_t member.  */
  52   err = DB_GET_FIELD_ADDRESS (ofs, ta, 0, pthread, list, 0);
  53   if (err != TD_OK)
  54     return err;
  55
  56   if (ta->ta_sizeof_pthread == 0)
  57     {
  58       err = _td_check_sizeof (ta, &ta->ta_sizeof_pthread, SYM_SIZEOF_pthread);
  59       if (err != TD_OK)
  60         return err;
  61     }
  62   copy = __alloca (ta->ta_sizeof_pthread);
  63
  64   while (next != head)
  65     {
  66       psaddr_t addr, schedpolicy, schedprio;
  67
  68       addr = next - (ofs - (psaddr_t) 0);
  69       if (next == 0 || addr == 0) /* Sanity check.  */
  70         return TD_DBERR;
  71
  72       /* Copy the whole descriptor in once so we can access the several
  73          fields locally.  Excess copying in one go is much better than
  74          multiple ps_pdread calls.  */
  75       if (ps_pdread (ta->ph, addr, copy, ta->ta_sizeof_pthread) != PS_OK)
  76         return TD_ERR;
  77
  78       err = DB_GET_FIELD_LOCAL (schedpolicy, ta, copy, pthread,
  79                                 schedpolicy, 0);
  80       if (err != TD_OK)
  81         break;
  82       err = DB_GET_FIELD_LOCAL (schedprio, ta, copy, pthread,
  83                                 schedparam_sched_priority, 0);
  84       if (err != TD_OK)
  85         break;
  86
  87       /* Now test whether this thread matches the specified conditions.  */
  88
  89       /* Only if the priority level is as high or higher.  */
  90       int descr_pri = ((uintptr_t) schedpolicy == SCHED_OTHER
  91                        ? 0 : (uintptr_t) schedprio);
  92       if (descr_pri >= ti_pri)
  93         {
  94           /* Yep, it matches.  Call the callback function.  */
  95           td_thrhandle_t th;
  96           th.th_ta_p = (td_thragent_t *) ta;
  97           th.th_unique = addr;
  98           if (callback (&th, cbdata_p) != 0)
  99             return TD_DBERR;
 100         }
 101
 102       /* Get the pointer to the next element.  */
 103       err = DB_GET_FIELD_LOCAL (next, ta, copy + (ofs - (psaddr_t) 0), list_t,
 104                                 next, 0);
 105       if (err != TD_OK)
 106         break;
 107     }
 108
 109   return err;
 110 }
 111
 112
 113 td_err_e
 114 td_ta_thr_iter (const td_thragent_t *ta_arg, td_thr_iter_f *callback,
 115                 void *cbdata_p, td_thr_state_e state, int ti_pri,
 116                 sigset_t *ti_sigmask_p, unsigned int ti_user_flags)
 117 {
 118   td_thragent_t *const ta = (td_thragent_t *) ta_arg;
 119   td_err_e err;
 120   psaddr_t list = 0;
 121
 122   LOG ("td_ta_thr_iter");
 123
 124   /* Test whether the TA parameter is ok.  */
 125   if (! ta_ok (ta))
 126     return TD_BADTA;
 127
 128   /* The thread library keeps two lists for the running threads.  One
 129      list contains the thread which are using user-provided stacks
 130      (this includes the main thread) and the other includes the
 131      threads for which the thread library allocated the stacks.  We
 132      have to iterate over both lists separately.  We start with the
 133      list of threads with user-defined stacks.  */
 134
 135   err = __td_ta_stack_user (ta, &list);
 136   if (err == TD_OK)
 137     err = iterate_thread_list (ta, callback, cbdata_p, state, ti_pri,
 138                                list, true);
 139
 140   /* And the threads with stacks allocated by the implementation.  */
 141   if (err == TD_OK)
 142     err = __td_ta_stack_used (ta, &list);
 143   if (err == TD_OK)
 144     err = iterate_thread_list (ta, callback, cbdata_p, state, ti_pri,
 145                                list, false);
 146
 147   return err;
 148 }