gdb/process-stratum-target.h

   1 /* Abstract base class inherited by all process_stratum targets
   2
   3    Copyright (C) 2018-2023 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 returns the inferior's address
  55      space.  */
  56   struct address_space *thread_address_space (ptid_t ptid) override;
  57
  58   /* This default implementation always returns target_gdbarch ().  */
  59   struct gdbarch *thread_architecture (ptid_t ptid) override;
  60
  61   /* Default implementations for process_stratum targets.  Return true
  62      if there's a selected inferior, false otherwise.  */
  63   bool has_all_memory () override;
  64   bool has_memory () override;
  65   bool has_stack () override;
  66   bool has_registers () override;
  67   bool has_execution (inferior *inf) override;
  68
  69   /* Default implementation of follow_exec.
  70
  71      If the current inferior and FOLLOW_INF are different (execution continues
  72      in a new inferior), push this process target to FOLLOW_INF's target stack
  73      and add an initial thread to FOLLOW_INF.  */
  74   void follow_exec (inferior *follow_inf, ptid_t ptid,
  75                     const char *execd_pathname) override;
  76
  77   /* Default implementation of follow_fork.
  78
  79      If a child inferior was created by infrun while following the fork
  80      (CHILD_INF is non-nullptr), push this target on CHILD_INF's target stack
  81      and add an initial thread with ptid CHILD_PTID.  */
  82   void follow_fork (inferior *child_inf, ptid_t child_ptid,
  83                     target_waitkind fork_kind, bool follow_child,
  84                     bool detach_on_fork) override;
  85
  86   /* True if any thread is, or may be executing.  We need to track
  87      this separately because until we fully sync the thread list, we
  88      won't know whether the target is fully stopped, even if we see
  89      stop events for all known threads, because any of those threads
  90      may have spawned new threads we haven't heard of yet.  */
  91   bool threads_executing = false;
  92
  93   /* If THREAD is resumed and has a pending wait status, add it to the
  94      target's "resumed with pending wait status" list.  */
  95   void maybe_add_resumed_with_pending_wait_status (thread_info *thread);
  96
  97   /* If THREAD is resumed and has a pending wait status, remove it from the
  98      target's "resumed with pending wait status" list.  */
  99   void maybe_remove_resumed_with_pending_wait_status (thread_info *thread);
 100
 101   /* Return true if this target has at least one resumed thread with a pending
 102      wait status.  */
 103   bool has_resumed_with_pending_wait_status () const
 104   { return !m_resumed_with_pending_wait_status.empty (); }
 105
 106   /* Return a random resumed thread with pending wait status belonging to INF
 107      and matching FILTER_PTID.  */
 108   thread_info *random_resumed_with_pending_wait_status
 109     (inferior *inf, ptid_t filter_ptid);
 110
 111   /* Search function to lookup a (non-exited) thread by 'ptid'.  */
 112   thread_info *find_thread (ptid_t ptid);
 113
 114   /* The connection number.  Visible in "info connections".  */
 115   int connection_number = 0;
 116
 117   /* Whether resumed threads must be committed to the target.
 118
 119      When true, resumed threads must be committed to the execution
 120      target.
 121
 122      When false, the target may leave resumed threads stopped when
 123      it's convenient or efficient to do so.  When the core requires
 124      resumed threads to be committed again, this is set back to true
 125      and calls the `commit_resumed` method to allow the target to do
 126      so.
 127
 128      To simplify the implementation of targets, the following methods
 129      are guaranteed to be called with COMMIT_RESUMED_STATE set to
 130      false:
 131
 132        - resume
 133        - stop
 134        - wait
 135
 136      Knowing this, the target doesn't need to implement different
 137      behaviors depending on the COMMIT_RESUMED_STATE, and can simply
 138      assume that it is false.
 139
 140      Targets can take advantage of this to batch resumption requests,
 141      for example.  In that case, the target doesn't actually resume in
 142      its `resume` implementation.  Instead, it takes note of the
 143      resumption intent in `resume` and defers the actual resumption to
 144      `commit_resumed`.  For example, the remote target uses this to
 145      coalesce multiple resumption requests in a single vCont
 146      packet.  */
 147   bool commit_resumed_state = false;
 148
 149 private:
 150   /* List of threads managed by this target which simultaneously are resumed
 151      and have a pending wait status.
 152
 153      This is done for optimization reasons, it would be possible to walk the
 154      inferior thread lists to find these threads.  But since this is something
 155      we need to do quite frequently in the hot path, maintaining this list
 156      avoids walking the thread lists repeatedly.  */
 157   thread_info_resumed_with_pending_wait_status_list
 158     m_resumed_with_pending_wait_status;
 159 };
 160
 161 /* Downcast TARGET to process_stratum_target.  */
 162
 163 static inline process_stratum_target *
 164 as_process_stratum_target (target_ops *target)
 165 {
 166   gdb_assert (target->stratum () == process_stratum);
 167   return gdb::checked_static_cast<process_stratum_target *> (target);
 168 }
 169
 170 /* Return a collection of targets that have non-exited inferiors.  */
 171
 172 extern std::set<process_stratum_target *> all_non_exited_process_targets ();
 173
 174 /* Switch to the first inferior (and program space) of TARGET, and
 175    switch to no thread selected.  */
 176
 177 extern void switch_to_target_no_thread (process_stratum_target *target);
 178
 179 #endif /* !defined (PROCESS_STRATUM_TARGET_H) */