gdb/process-stratum-target.h

   1 /* Abstract base class inherited by all process_stratum targets
   2
   3    Copyright (C) 2018-2024 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 "gdbsupport/gdb-checked-static-cast.h"
  27 #include "gdbthread.h"
  28
  29 /* Abstract base class inherited by all process_stratum targets.  */
  30
  31 class process_stratum_target : public target_ops
  32 {
  33 public:
  34   ~process_stratum_target () override = 0;
  35
  36   strata stratum () const final override { return process_stratum; }
  37
  38   /* Return a string representation of this target's open connection.
  39      This string is used to distinguish different instances of a given
  40      target type.  For example, when remote debugging, the target is
  41      called "remote", but since we may have more than one remote
  42      target open, connection_string() returns the connection serial
  43      connection name, e.g., "localhost:10001", "192.168.0.1:20000",
  44      etc.  This string is shown in several places, e.g., in "info
  45      connections" and "info inferiors".  */
  46   virtual const char *connection_string () { return nullptr; }
  47
  48   /* We must default these because they must be implemented by any
  49      target that can run.  */
  50   bool can_async_p () override { return false; }
  51   bool supports_non_stop () override { return false; }
  52   bool supports_disable_randomization () override { return false; }
  53
  54   /* This default implementation always returns the current inferior's
  55      gdbarch.  */
  56   struct gdbarch *thread_architecture (ptid_t ptid) override;
  57
  58   /* Default implementations for process_stratum targets.  Return true
  59      if there's a selected inferior, false otherwise.  */
  60   bool has_all_memory () override;
  61   bool has_memory () override;
  62   bool has_stack () override;
  63   bool has_registers () override;
  64   bool has_execution (inferior *inf) override;
  65
  66   /* Default implementation of follow_exec.
  67
  68      If the current inferior and FOLLOW_INF are different (execution continues
  69      in a new inferior), push this process target to FOLLOW_INF's target stack
  70      and add an initial thread to FOLLOW_INF.  */
  71   void follow_exec (inferior *follow_inf, ptid_t ptid,
  72                     const char *execd_pathname) override;
  73
  74   /* Default implementation of follow_fork.
  75
  76      If a child inferior was created by infrun while following the fork
  77      (CHILD_INF is non-nullptr), push this target on CHILD_INF's target stack
  78      and add an initial thread with ptid CHILD_PTID.  */
  79   void follow_fork (inferior *child_inf, ptid_t child_ptid,
  80                     target_waitkind fork_kind, bool follow_child,
  81                     bool detach_on_fork) override;
  82
  83   /* True if any thread is, or may be executing.  We need to track
  84      this separately because until we fully sync the thread list, we
  85      won't know whether the target is fully stopped, even if we see
  86      stop events for all known threads, because any of those threads
  87      may have spawned new threads we haven't heard of yet.  */
  88   bool threads_executing = false;
  89
  90   /* If THREAD is resumed and has a pending wait status, add it to the
  91      target's "resumed with pending wait status" list.  */
  92   void maybe_add_resumed_with_pending_wait_status (thread_info *thread);
  93
  94   /* If THREAD is resumed and has a pending wait status, remove it from the
  95      target's "resumed with pending wait status" list.  */
  96   void maybe_remove_resumed_with_pending_wait_status (thread_info *thread);
  97
  98   /* Return true if this target has at least one resumed thread with a pending
  99      wait status.  */
 100   bool has_resumed_with_pending_wait_status () const
 101   { return !m_resumed_with_pending_wait_status.empty (); }
 102
 103   /* Return a random resumed thread with pending wait status belonging to INF
 104      and matching FILTER_PTID.  */
 105   thread_info *random_resumed_with_pending_wait_status
 106     (inferior *inf, ptid_t filter_ptid);
 107
 108   /* Search function to lookup a (non-exited) thread by 'ptid'.  */
 109   thread_info *find_thread (ptid_t ptid);
 110
 111   /* The connection number.  Visible in "info connections".  */
 112   int connection_number = 0;
 113
 114   /* Whether resumed threads must be committed to the target.
 115
 116      When true, resumed threads must be committed to the execution
 117      target.
 118
 119      When false, the target may leave resumed threads stopped when
 120      it's convenient or efficient to do so.  When the core requires
 121      resumed threads to be committed again, this is set back to true
 122      and calls the `commit_resumed` method to allow the target to do
 123      so.
 124
 125      To simplify the implementation of targets, the following methods
 126      are guaranteed to be called with COMMIT_RESUMED_STATE set to
 127      false:
 128
 129        - resume
 130        - stop
 131        - wait
 132
 133      Knowing this, the target doesn't need to implement different
 134      behaviors depending on the COMMIT_RESUMED_STATE, and can simply
 135      assume that it is false.
 136
 137      Targets can take advantage of this to batch resumption requests,
 138      for example.  In that case, the target doesn't actually resume in
 139      its `resume` implementation.  Instead, it takes note of the
 140      resumption intent in `resume` and defers the actual resumption to
 141      `commit_resumed`.  For example, the remote target uses this to
 142      coalesce multiple resumption requests in a single vCont
 143      packet.  */
 144   bool commit_resumed_state = false;
 145
 146 private:
 147   /* List of threads managed by this target which simultaneously are resumed
 148      and have a pending wait status.
 149
 150      This is done for optimization reasons, it would be possible to walk the
 151      inferior thread lists to find these threads.  But since this is something
 152      we need to do quite frequently in the hot path, maintaining this list
 153      avoids walking the thread lists repeatedly.  */
 154   thread_info_resumed_with_pending_wait_status_list
 155     m_resumed_with_pending_wait_status;
 156 };
 157
 158 /* Downcast TARGET to process_stratum_target.  */
 159
 160 static inline process_stratum_target *
 161 as_process_stratum_target (target_ops *target)
 162 {
 163   gdb_assert (target->stratum () == process_stratum);
 164   return gdb::checked_static_cast<process_stratum_target *> (target);
 165 }
 166
 167 /* Return a collection of targets that have non-exited inferiors.  */
 168
 169 extern std::set<process_stratum_target *> all_non_exited_process_targets ();
 170
 171 /* Switch to the first inferior (and program space) of TARGET, and
 172    switch to no thread selected.  */
 173
 174 extern void switch_to_target_no_thread (process_stratum_target *target);
 175
 176 #endif /* !defined (PROCESS_STRATUM_TARGET_H) */