gdb/process-stratum-target.h

   1 /* Abstract base class inherited by all process_stratum targets
   2
   3    Copyright (C) 2018-2022 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef PROCESS_STRATUM_TARGET_H
  21 #define PROCESS_STRATUM_TARGET_H
  22
  23 #include "target.h"
  24 #include <set>
  25 #include "gdbsupport/intrusive_list.h"
  26 #include "gdbthread.h"
  27
  28 /* Abstract base class inherited by all process_stratum targets.  */
  29
  30 class process_stratum_target : public target_ops
  31 {
  32 public:
  33   ~process_stratum_target () override = 0;
  34
  35   strata stratum () const final override { return process_stratum; }
  36
  37   /* Return a string representation of this target's open connection.
  38      This string is used to distinguish different instances of a given
  39      target type.  For example, when remote debugging, the target is
  40      called "remote", but since we may have more than one remote
  41      target open, connection_string() returns the connection serial
  42      connection name, e.g., "localhost:10001", "192.168.0.1:20000",
  43      etc.  This string is shown in several places, e.g., in "info
  44      connections" and "info inferiors".  */
  45   virtual const char *connection_string () { return nullptr; }
  46
  47   /* We must default these because they must be implemented by any
  48      target that can run.  */
  49   bool can_async_p () override { return false; }
  50   bool supports_non_stop () override { return false; }
  51   bool supports_disable_randomization () override { return false; }
  52
  53   /* This default implementation returns the inferior's address
  54      space.  */
  55   struct address_space *thread_address_space (ptid_t ptid) override;
  56
  57   /* This default implementation always returns target_gdbarch ().  */
  58   struct gdbarch *thread_architecture (ptid_t ptid) override;
  59
  60   /* Default implementations for process_stratum targets.  Return true
  61      if there's a selected inferior, false otherwise.  */
  62   bool has_all_memory () override;
  63   bool has_memory () override;
  64   bool has_stack () override;
  65   bool has_registers () override;
  66   bool has_execution (inferior *inf) override;
  67
  68   /* Default implementation of follow_exec.
  69
  70      If the current inferior and FOLLOW_INF are different (execution continues
  71      in a new inferior), push this process target to FOLLOW_INF's target stack
  72      and add an initial thread to FOLLOW_INF.  */
  73   void follow_exec (inferior *follow_inf, ptid_t ptid,
  74                     const char *execd_pathname) override;
  75
  76   /* Default implementation of follow_fork.
  77
  78      If a child inferior was created by infrun while following the fork
  79      (CHILD_INF is non-nullptr), push this target on CHILD_INF's target stack
  80      and add an initial thread with ptid CHILD_PTID.  */
  81   void follow_fork (inferior *child_inf, ptid_t child_ptid,
  82                     target_waitkind fork_kind, bool follow_child,
  83                     bool detach_on_fork) override;
  84
  85   /* True if any thread is, or may be executing.  We need to track
  86      this separately because until we fully sync the thread list, we
  87      won't know whether the target is fully stopped, even if we see
  88      stop events for all known threads, because any of those threads
  89      may have spawned new threads we haven't heard of yet.  */
  90   bool threads_executing = false;
  91
  92   /* If THREAD is resumed and has a pending wait status, add it to the
  93      target's "resumed with pending wait status" list.  */
  94   void maybe_add_resumed_with_pending_wait_status (thread_info *thread);
  95
  96   /* If THREAD is resumed and has a pending wait status, remove it from the
  97      target's "resumed with pending wait status" list.  */
  98   void maybe_remove_resumed_with_pending_wait_status (thread_info *thread);
  99
 100   /* Return true if this target has at least one resumed thread with a pending
 101      wait status.  */
 102   bool has_resumed_with_pending_wait_status () const
 103   { return !m_resumed_with_pending_wait_status.empty (); }
 104
 105   /* Return a random resumed thread with pending wait status belonging to INF
 106      and matching FILTER_PTID.  */
 107   thread_info *random_resumed_with_pending_wait_status
 108     (inferior *inf, ptid_t filter_ptid);
 109
 110   /* The connection number.  Visible in "info connections".  */
 111   int connection_number = 0;
 112
 113   /* Whether resumed threads must be committed to the target.
 114
 115      When true, resumed threads must be committed to the execution
 116      target.
 117
 118      When false, the target may leave resumed threads stopped when
 119      it's convenient or efficient to do so.  When the core requires
 120      resumed threads to be committed again, this is set back to true
 121      and calls the `commit_resumed` method to allow the target to do
 122      so.
 123
 124      To simplify the implementation of targets, the following methods
 125      are guaranteed to be called with COMMIT_RESUMED_STATE set to
 126      false:
 127
 128        - resume
 129        - stop
 130        - wait
 131
 132      Knowing this, the target doesn't need to implement different
 133      behaviors depending on the COMMIT_RESUMED_STATE, and can simply
 134      assume that it is false.
 135
 136      Targets can take advantage of this to batch resumption requests,
 137      for example.  In that case, the target doesn't actually resume in
 138      its `resume` implementation.  Instead, it takes note of the
 139      resumption intent in `resume` and defers the actual resumption to
 140      `commit_resumed`.  For example, the remote target uses this to
 141      coalesce multiple resumption requests in a single vCont
 142      packet.  */
 143   bool commit_resumed_state = false;
 144
 145 private:
 146   /* List of threads managed by this target which simultaneously are resumed
 147      and have a pending wait status.
 148
 149      This is done for optimization reasons, it would be possible to walk the
 150      inferior thread lists to find these threads.  But since this is something
 151      we need to do quite frequently in the hot path, maintaining this list
 152      avoids walking the thread lists repeatedly.  */
 153   thread_info_resumed_with_pending_wait_status_list
 154     m_resumed_with_pending_wait_status;
 155 };
 156
 157 /* Downcast TARGET to process_stratum_target.  */
 158
 159 static inline process_stratum_target *
 160 as_process_stratum_target (target_ops *target)
 161 {
 162   gdb_assert (target->stratum () == process_stratum);
 163   return static_cast<process_stratum_target *> (target);
 164 }
 165
 166 /* Return a collection of targets that have non-exited inferiors.  */
 167
 168 extern std::set<process_stratum_target *> all_non_exited_process_targets ();
 169
 170 /* Switch to the first inferior (and program space) of TARGET, and
 171    switch to no thread selected.  */
 172
 173 extern void switch_to_target_no_thread (process_stratum_target *target);
 174
 175 #endif /* !defined (PROCESS_STRATUM_TARGET_H) */