X-Git-Url: http://drtracing.org/?a=blobdiff_plain;f=gdb%2Fravenscar-thread.c;h=72253188c716ec94ff6831a02507fc3e72c11682;hb=48e9cc84058771da089a2e8e652f70ac20a8fac0;hp=ddbaea69903f0d2357b83b31b0628725950b5a1c;hpb=25abf4decf405891fa9ad0d5ad138e021a5a872b;p=deliverable%2Fbinutils-gdb.git

diff --git a/gdb/ravenscar-thread.c b/gdb/ravenscar-thread.c
index ddbaea6990..72253188c7 100644
--- a/gdb/ravenscar-thread.c
+++ b/gdb/ravenscar-thread.c
@@ -1,6 +1,6 @@
 /* Ada Ravenscar thread support.
 
-   Copyright 2004, 2009-2012 Free Software Foundation, Inc.
+   Copyright (C) 2004-2020 Free Software Foundation, Inc.
 
    This file is part of GDB.
 
@@ -25,79 +25,227 @@
 #include "inferior.h"
 #include "command.h"
 #include "ravenscar-thread.h"
-#include "observer.h"
-#include "gdb_string.h"
+#include "observable.h"
 #include "gdbcmd.h"
 #include "top.h"
 #include "regcache.h"
+#include "objfiles.h"
+
+/* This module provides support for "Ravenscar" tasks (Ada) when
+   debugging on bare-metal targets.
+
+   The typical situation is when debugging a bare-metal target over
+   the remote protocol. In that situation, the system does not know
+   about high-level concepts such as threads, only about some code
+   running on one or more CPUs. And since the remote protocol does not
+   provide any handling for CPUs, the de facto standard for handling
+   them is to have one thread per CPU, where the thread's ptid has
+   its lwp field set to the CPU number (eg: 1 for the first CPU,
+   2 for the second one, etc).  This module will make that assumption.
+
+   This module then creates and maintains the list of threads based
+   on the list of Ada tasks, with one thread per Ada task. The convention
+   is that threads corresponding to the CPUs (see assumption above)
+   have a ptid_t of the form (PID, LWP, 0), while threads corresponding
+   to our Ada tasks have a ptid_t of the form (PID, 0, TID) where TID
+   is the Ada task's ID as extracted from Ada runtime information.
+
+   Switching to a given Ada task (or its underlying thread) is performed
+   by fetching the registers of that task from the memory area where
+   the registers were saved.  For any of the other operations, the
+   operation is performed by first finding the CPU on which the task
+   is running, switching to its corresponding ptid, and then performing
+   the operation on that ptid using the target beneath us.  */
+
+/* If true, ravenscar task support is enabled.  */
+static bool ravenscar_task_support = true;
 
-/* If non-null, ravenscar task support is enabled.  */
-static int ravenscar_task_support = 1;
+static const char running_thread_name[] = "__gnat_running_thread_table";
 
-/* This module's target-specific operations.  */
-static struct target_ops ravenscar_ops;
+static const char known_tasks_name[] = "system__tasking__debug__known_tasks";
+static const char first_task_name[] = "system__tasking__debug__first_task";
 
-/* Some base target uses a special value for the null PID (exempli gratia
-   remote).  */
-static ptid_t base_magic_null_ptid;
+static const char ravenscar_runtime_initializer[]
+  = "system__bb__threads__initialize";
 
-/* Ptid of the inferior as seen by the process stratum.  */
-static ptid_t base_ptid;
+static const target_info ravenscar_target_info = {
+  "ravenscar",
+  N_("Ravenscar tasks."),
+  N_("Ravenscar tasks support.")
+};
 
-static const char running_thread_name[] = "__gnat_running_thread_table";
+struct ravenscar_thread_target final : public target_ops
+{
+  ravenscar_thread_target ()
+    : m_base_ptid (inferior_ptid)
+  {
+    thread_info *thr = add_active_thread ();
+    if (thr != nullptr)
+      switch_to_thread (thr);
+  }
 
-static const char known_tasks_name[] = "system__tasking__debug__known_tasks";
-static const char first_task_name[] = "system__tasking__debug__first_task";
+  const target_info &info () const override
+  { return ravenscar_target_info; }
 
-static const char ravenscar_runtime_initializer[] =
-  "system__bb__threads__initialize";
-
-static struct observer *update_target_observer = NULL;
-
-/* Architecture-specific hooks.  */
-static struct ravenscar_arch_ops* current_arch_ops;
-
-static void ravenscar_find_new_threads (struct target_ops *ops);
-static ptid_t ravenscar_running_thread (void);
-static char *ravenscar_extra_thread_info (struct thread_info *tp);
-static int ravenscar_thread_alive (struct target_ops *ops, ptid_t ptid);
-static void ravenscar_fetch_registers (struct target_ops *ops,
-                                       struct regcache *regcache, int regnum);
-static void ravenscar_store_registers (struct target_ops *ops,
-                                       struct regcache *regcache, int regnum);
-static void ravenscar_prepare_to_store (struct regcache *regcache);
-static void ravenscar_resume (struct target_ops *ops, ptid_t ptid, int step,
-			      enum gdb_signal siggnal);
-static void ravenscar_mourn_inferior (struct target_ops *ops);
-static void ravenscar_update_inferior_ptid (void);
-static int has_ravenscar_runtime (void);
-static int ravenscar_runtime_initialized (void);
-static void ravenscar_inferior_created (struct target_ops *target,
-					int from_tty);
-
-/* Fetch the ravenscar running thread from target memory and
-   update inferior_ptid accordingly.  */
+  strata stratum () const override { return thread_stratum; }
 
-static void
-ravenscar_update_inferior_ptid (void)
+  ptid_t wait (ptid_t, struct target_waitstatus *, int) override;
+  void resume (ptid_t, int, enum gdb_signal) override;
+
+  void fetch_registers (struct regcache *, int) override;
+  void store_registers (struct regcache *, int) override;
+
+  void prepare_to_store (struct regcache *) override;
+
+  bool stopped_by_sw_breakpoint () override;
+
+  bool stopped_by_hw_breakpoint () override;
+
+  bool stopped_by_watchpoint () override;
+
+  bool stopped_data_address (CORE_ADDR *) override;
+
+  bool thread_alive (ptid_t ptid) override;
+
+  int core_of_thread (ptid_t ptid) override;
+
+  void update_thread_list () override;
+
+  const char *extra_thread_info (struct thread_info *) override;
+
+  std::string pid_to_str (ptid_t) override;
+
+  ptid_t get_ada_task_ptid (long lwp, long thread) override;
+
+  void mourn_inferior () override;
+
+  void close () override
+  {
+    delete this;
+  }
+
+private:
+
+  /* PTID of the last thread that received an event.
+     This can be useful to determine the associated task that received
+     the event, to make it the current task.  */
+  ptid_t m_base_ptid;
+
+  thread_info *add_active_thread ();
+  ptid_t active_task (int cpu);
+  bool task_is_currently_active (ptid_t ptid);
+  bool runtime_initialized ();
+};
+
+/* Return true iff PTID corresponds to a ravenscar task.  */
+
+static bool
+is_ravenscar_task (ptid_t ptid)
 {
-  base_ptid = inferior_ptid;
+  /* By construction, ravenscar tasks have their LWP set to zero.
+     Also make sure that the TID is nonzero, as some remotes, when
+     asked for the list of threads, will return the first thread
+     as having its TID set to zero.  For instance, TSIM version
+     2.0.48 for LEON3 sends 'm0' as a reply to the 'qfThreadInfo'
+     query, which the remote protocol layer then treats as a thread
+     whose TID is 0.  This is obviously not a ravenscar task.  */
+  return ptid.lwp () == 0 && ptid.tid () != 0;
+}
 
-  /* If the runtime has not been initialized yet, the inferior_ptid is
-     the only ptid that there is.  */
-  if (!ravenscar_runtime_initialized ())
-    return;
+/* Given PTID, which can be either a ravenscar task or a CPU thread,
+   return which CPU that ptid is running on.
+
+   This assume that PTID is a valid ptid_t.  Otherwise, a gdb_assert
+   will be triggered.  */
+
+static int
+ravenscar_get_thread_base_cpu (ptid_t ptid)
+{
+  int base_cpu;
+
+  if (is_ravenscar_task (ptid))
+    {
+      struct ada_task_info *task_info = ada_get_task_info_from_ptid (ptid);
+
+      gdb_assert (task_info != NULL);
+      base_cpu = task_info->base_cpu;
+    }
+  else
+    {
+      /* We assume that the LWP of the PTID is equal to the CPU number.  */
+      base_cpu = ptid.lwp ();
+    }
+
+  return base_cpu;
+}
+
+/* Given a ravenscar task (identified by its ptid_t PTID), return true
+   if this task is the currently active task on the cpu that task is
+   running on.
+
+   In other words, this function determine which CPU this task is
+   currently running on, and then return nonzero if the CPU in question
+   is executing the code for that task.  If that's the case, then
+   that task's registers are in the CPU bank.  Otherwise, the task
+   is currently suspended, and its registers have been saved in memory.  */
+
+bool
+ravenscar_thread_target::task_is_currently_active (ptid_t ptid)
+{
+  ptid_t active_task_ptid
+    = active_task (ravenscar_get_thread_base_cpu (ptid));
+
+  return ptid == active_task_ptid;
+}
+
+/* Return the CPU thread (as a ptid_t) on which the given ravenscar
+   task is running.
+
+   This is the thread that corresponds to the CPU on which the task
+   is running.  */
+
+static ptid_t
+get_base_thread_from_ravenscar_task (ptid_t ptid)
+{
+  int base_cpu;
+
+  if (!is_ravenscar_task (ptid))
+    return ptid;
+
+  base_cpu = ravenscar_get_thread_base_cpu (ptid);
+  return ptid_t (ptid.pid (), base_cpu, 0);
+}
+
+/* Fetch the ravenscar running thread from target memory, make sure
+   there's a corresponding thread in the thread list, and return it.
+   If the runtime is not initialized, return NULL.  */
+
+thread_info *
+ravenscar_thread_target::add_active_thread ()
+{
+  process_stratum_target *proc_target
+    = as_process_stratum_target (this->beneath ());
+
+  int base_cpu;
+
+  gdb_assert (!is_ravenscar_task (m_base_ptid));
+  base_cpu = ravenscar_get_thread_base_cpu (m_base_ptid);
+
+  if (!runtime_initialized ())
+    return nullptr;
 
-  /* Make sure we set base_ptid before calling ravenscar_running_thread
+  /* Make sure we set m_base_ptid before calling active_task
      as the latter relies on it.  */
-  inferior_ptid = ravenscar_running_thread ();
-  gdb_assert (!ptid_equal (inferior_ptid, null_ptid));
+  ptid_t active_ptid = active_task (base_cpu);
+  gdb_assert (active_ptid != null_ptid);
 
   /* The running thread may not have been added to
-     system.tasking.debug's list yet; so ravenscar_find_new_threads
+     system.tasking.debug's list yet; so ravenscar_update_thread_list
      may not always add it to the thread list.  Add it here.  */
-  if (!find_thread_ptid (inferior_ptid))
-    add_thread (inferior_ptid);
+  thread_info *active_thr = find_thread_ptid (proc_target, active_ptid);
+  if (active_thr == nullptr)
+    active_thr = add_thread (proc_target, active_ptid);
+  return active_thr;
 }
 
 /* The Ravenscar Runtime exports a symbol which contains the ID of
@@ -105,13 +253,13 @@ ravenscar_update_inferior_ptid (void)
    and return its associated minimal symbol.
    Return NULL if not found.  */
 
-static struct minimal_symbol *
-get_running_thread_msymbol (void)
+static struct bound_minimal_symbol
+get_running_thread_msymbol ()
 {
-  struct minimal_symbol *msym;
+  struct bound_minimal_symbol msym;
 
   msym = lookup_minimal_symbol (running_thread_name, NULL, NULL);
-  if (!msym)
+  if (!msym.minsym)
     /* Older versions of the GNAT runtime were using a different
        (less ideal) name for the symbol where the active thread ID
        is stored.  If we couldn't find the symbol using the latest
@@ -124,77 +272,84 @@ get_running_thread_msymbol (void)
 /* Return True if the Ada Ravenscar run-time can be found in the
    application.  */
 
-static int
-has_ravenscar_runtime (void)
+static bool
+has_ravenscar_runtime ()
 {
-  struct minimal_symbol *msym_ravenscar_runtime_initializer =
-    lookup_minimal_symbol (ravenscar_runtime_initializer, NULL, NULL);
-  struct minimal_symbol *msym_known_tasks =
-    lookup_minimal_symbol (known_tasks_name, NULL, NULL);
-  struct minimal_symbol *msym_first_task =
-    lookup_minimal_symbol (first_task_name, NULL, NULL);
-  struct minimal_symbol *msym_running_thread = get_running_thread_msymbol ();
-
-  return (msym_ravenscar_runtime_initializer
-	  && (msym_known_tasks || msym_first_task)
-	  && msym_running_thread);
+  struct bound_minimal_symbol msym_ravenscar_runtime_initializer
+    = lookup_minimal_symbol (ravenscar_runtime_initializer, NULL, NULL);
+  struct bound_minimal_symbol msym_known_tasks
+    = lookup_minimal_symbol (known_tasks_name, NULL, NULL);
+  struct bound_minimal_symbol msym_first_task
+    = lookup_minimal_symbol (first_task_name, NULL, NULL);
+  struct bound_minimal_symbol msym_running_thread
+    = get_running_thread_msymbol ();
+
+  return (msym_ravenscar_runtime_initializer.minsym
+	  && (msym_known_tasks.minsym || msym_first_task.minsym)
+	  && msym_running_thread.minsym);
 }
 
 /* Return True if the Ada Ravenscar run-time can be found in the
    application, and if it has been initialized on target.  */
 
-static int
-ravenscar_runtime_initialized (void)
+bool
+ravenscar_thread_target::runtime_initialized ()
 {
-  return (!(ptid_equal (ravenscar_running_thread (), null_ptid)));
+  return active_task (1) != null_ptid;
 }
 
 /* Return the ID of the thread that is currently running.
    Return 0 if the ID could not be determined.  */
 
 static CORE_ADDR
-get_running_thread_id (void)
+get_running_thread_id (int cpu)
 {
-  const struct minimal_symbol *object_msym = get_running_thread_msymbol ();
+  struct bound_minimal_symbol object_msym = get_running_thread_msymbol ();
   int object_size;
   int buf_size;
-  char *buf;
+  gdb_byte *buf;
   CORE_ADDR object_addr;
-  struct type *builtin_type_void_data_ptr =
-    builtin_type (target_gdbarch ())->builtin_data_ptr;
+  struct type *builtin_type_void_data_ptr
+    = builtin_type (target_gdbarch ())->builtin_data_ptr;
 
-  if (!object_msym)
+  if (!object_msym.minsym)
     return 0;
 
-  object_addr = SYMBOL_VALUE_ADDRESS (object_msym);
   object_size = TYPE_LENGTH (builtin_type_void_data_ptr);
+  object_addr = (BMSYMBOL_VALUE_ADDRESS (object_msym)
+		 + (cpu - 1) * object_size);
   buf_size = object_size;
-  buf = alloca (buf_size);
+  buf = (gdb_byte *) alloca (buf_size);
   read_memory (object_addr, buf, buf_size);
   return extract_typed_address (buf, builtin_type_void_data_ptr);
 }
 
-static void
-ravenscar_resume (struct target_ops *ops, ptid_t ptid, int step,
-		  enum gdb_signal siggnal)
+void
+ravenscar_thread_target::resume (ptid_t ptid, int step,
+				 enum gdb_signal siggnal)
 {
-  struct target_ops *beneath = find_target_beneath (ops);
-
-  inferior_ptid = base_ptid;
-  beneath->to_resume (beneath, base_ptid, step, siggnal);
+  /* If we see a wildcard resume, we simply pass that on.  Otherwise,
+     arrange to resume the base ptid.  */
+  inferior_ptid = m_base_ptid;
+  if (ptid != minus_one_ptid)
+    ptid = m_base_ptid;
+  beneath ()->resume (ptid, step, siggnal);
 }
 
-static ptid_t
-ravenscar_wait (struct target_ops *ops, ptid_t ptid,
-                struct target_waitstatus *status,
-                int options)
+ptid_t
+ravenscar_thread_target::wait (ptid_t ptid,
+			       struct target_waitstatus *status,
+			       int options)
 {
-  struct target_ops *beneath = find_target_beneath (ops);
+  process_stratum_target *beneath
+    = as_process_stratum_target (this->beneath ());
+  ptid_t event_ptid;
 
-  inferior_ptid = base_ptid;
-  beneath->to_wait (beneath, base_ptid, status, 0);
-  /* Find any new threads that might have been created, and update
-     inferior_ptid to the active thread.
+  if (ptid != minus_one_ptid)
+    ptid = m_base_ptid;
+  event_ptid = beneath->wait (ptid, status, 0);
+  /* Find any new threads that might have been created, and return the
+     active thread.
 
      Only do it if the program is still alive, though.  Otherwise,
      this causes problems when debugging through the remote protocol,
@@ -203,10 +358,11 @@ ravenscar_wait (struct target_ops *ops, ptid_t ptid,
   if (status->kind != TARGET_WAITKIND_EXITED
       && status->kind != TARGET_WAITKIND_SIGNALLED)
     {
-      ravenscar_find_new_threads (ops);
-      ravenscar_update_inferior_ptid ();
+      m_base_ptid = event_ptid;
+      this->update_thread_list ();
+      return this->add_active_thread ()->ptid;
     }
-  return inferior_ptid;
+  return m_base_ptid;
 }
 
 /* Add the thread associated to the given TASK to the thread list
@@ -215,185 +371,197 @@ ravenscar_wait (struct target_ops *ops, ptid_t ptid,
 static void
 ravenscar_add_thread (struct ada_task_info *task)
 {
-  if (find_thread_ptid (task->ptid) == NULL)
-    add_thread (task->ptid);
+  if (find_thread_ptid (current_inferior (), task->ptid) == NULL)
+    add_thread (current_inferior ()->process_target (), task->ptid);
 }
 
-static void
-ravenscar_find_new_threads (struct target_ops *ops)
+void
+ravenscar_thread_target::update_thread_list ()
 {
-  ada_build_task_list ();
-
   /* Do not clear the thread list before adding the Ada task, to keep
      the thread that the process stratum has included into it
-     (base_ptid) and the running thread, that may not have been included
+     (m_base_ptid) and the running thread, that may not have been included
      to system.tasking.debug's list yet.  */
 
   iterate_over_live_ada_tasks (ravenscar_add_thread);
 }
 
-static ptid_t
-ravenscar_running_thread (void)
+ptid_t
+ravenscar_thread_target::active_task (int cpu)
 {
-  CORE_ADDR tid = get_running_thread_id ();
+  CORE_ADDR tid = get_running_thread_id (cpu);
 
   if (tid == 0)
     return null_ptid;
   else
-    return ptid_build (ptid_get_pid (base_ptid), 0, tid);
+    return ptid_t (m_base_ptid.pid (), 0, tid);
 }
 
-static char *
-ravenscar_extra_thread_info (struct thread_info *tp)
+const char *
+ravenscar_thread_target::extra_thread_info (thread_info *tp)
 {
   return "Ravenscar task";
 }
 
-static int
-ravenscar_thread_alive (struct target_ops *ops, ptid_t ptid)
+bool
+ravenscar_thread_target::thread_alive (ptid_t ptid)
 {
   /* Ravenscar tasks are non-terminating.  */
-  return 1;
+  return true;
 }
 
-static char *
-ravenscar_pid_to_str (struct target_ops *ops, ptid_t ptid)
+std::string
+ravenscar_thread_target::pid_to_str (ptid_t ptid)
 {
-  static char buf[30];
-
-  snprintf (buf, sizeof (buf), "Thread %#x", (int) ptid_get_tid (ptid));
-  return buf;
+  return string_printf ("Thread %#x", (int) ptid.tid ());
 }
 
-static void
-ravenscar_fetch_registers (struct target_ops *ops,
-                           struct regcache *regcache, int regnum)
+void
+ravenscar_thread_target::fetch_registers (struct regcache *regcache, int regnum)
 {
-  struct target_ops *beneath = find_target_beneath (ops);
+  ptid_t ptid = regcache->ptid ();
+
+  if (runtime_initialized ()
+      && is_ravenscar_task (ptid)
+      && !task_is_currently_active (ptid))
+    {
+      struct gdbarch *gdbarch = regcache->arch ();
+      struct ravenscar_arch_ops *arch_ops
+	= gdbarch_ravenscar_ops (gdbarch);
 
-  if (!ravenscar_runtime_initialized ()
-      || ptid_equal (inferior_ptid, base_magic_null_ptid)
-      || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
-    beneath->to_fetch_registers (beneath, regcache, regnum);
+      arch_ops->fetch_registers (regcache, regnum);
+    }
   else
-    current_arch_ops->to_fetch_registers (regcache, regnum);
+    beneath ()->fetch_registers (regcache, regnum);
 }
 
-static void
-ravenscar_store_registers (struct target_ops *ops,
-                           struct regcache *regcache, int regnum)
+void
+ravenscar_thread_target::store_registers (struct regcache *regcache,
+					  int regnum)
 {
-  struct target_ops *beneath = find_target_beneath (ops);
+  ptid_t ptid = regcache->ptid ();
+
+  if (runtime_initialized ()
+      && is_ravenscar_task (ptid)
+      && !task_is_currently_active (ptid))
+    {
+      struct gdbarch *gdbarch = regcache->arch ();
+      struct ravenscar_arch_ops *arch_ops
+	= gdbarch_ravenscar_ops (gdbarch);
 
-  if (!ravenscar_runtime_initialized ()
-      || ptid_equal (inferior_ptid, base_magic_null_ptid)
-      || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
-    beneath->to_store_registers (beneath, regcache, regnum);
+      arch_ops->store_registers (regcache, regnum);
+    }
   else
-    current_arch_ops->to_store_registers (regcache, regnum);
+    beneath ()->store_registers (regcache, regnum);
 }
 
-static void
-ravenscar_prepare_to_store (struct regcache *regcache)
+void
+ravenscar_thread_target::prepare_to_store (struct regcache *regcache)
 {
-  struct target_ops *beneath = find_target_beneath (&ravenscar_ops);
+  ptid_t ptid = regcache->ptid ();
 
-  if (!ravenscar_runtime_initialized ()
-      || ptid_equal (inferior_ptid, base_magic_null_ptid)
-      || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
-    beneath->to_prepare_to_store (regcache);
+  if (runtime_initialized ()
+      && is_ravenscar_task (ptid)
+      && !task_is_currently_active (ptid))
+    {
+      /* Nothing.  */
+    }
   else
-    current_arch_ops->to_prepare_to_store (regcache);
+    beneath ()->prepare_to_store (regcache);
 }
 
-static void
-ravenscar_mourn_inferior (struct target_ops *ops)
+/* Implement the to_stopped_by_sw_breakpoint target_ops "method".  */
+
+bool
+ravenscar_thread_target::stopped_by_sw_breakpoint ()
 {
-  struct target_ops *beneath = find_target_beneath (&ravenscar_ops);
+  scoped_restore save_ptid = make_scoped_restore (&inferior_ptid);
+  inferior_ptid = get_base_thread_from_ravenscar_task (inferior_ptid);
+  return beneath ()->stopped_by_sw_breakpoint ();
+}
+
+/* Implement the to_stopped_by_hw_breakpoint target_ops "method".  */
 
-  base_ptid = null_ptid;
-  beneath->to_mourn_inferior (beneath);
-  unpush_target (&ravenscar_ops);
+bool
+ravenscar_thread_target::stopped_by_hw_breakpoint ()
+{
+  scoped_restore save_ptid = make_scoped_restore (&inferior_ptid);
+  inferior_ptid = get_base_thread_from_ravenscar_task (inferior_ptid);
+  return beneath ()->stopped_by_hw_breakpoint ();
 }
 
-/* Observer on inferior_created: push ravenscar thread stratum if needed.  */
+/* Implement the to_stopped_by_watchpoint target_ops "method".  */
 
-static void
-ravenscar_inferior_created (struct target_ops *target, int from_tty)
+bool
+ravenscar_thread_target::stopped_by_watchpoint ()
 {
-  if (!ravenscar_task_support || !has_ravenscar_runtime ())
-    return;
+  scoped_restore save_ptid = make_scoped_restore (&inferior_ptid);
+  inferior_ptid = get_base_thread_from_ravenscar_task (inferior_ptid);
+  return beneath ()->stopped_by_watchpoint ();
+}
+
+/* Implement the to_stopped_data_address target_ops "method".  */
 
-  base_magic_null_ptid = inferior_ptid;
-  ravenscar_update_inferior_ptid ();
-  push_target (&ravenscar_ops);
+bool
+ravenscar_thread_target::stopped_data_address (CORE_ADDR *addr_p)
+{
+  scoped_restore save_ptid = make_scoped_restore (&inferior_ptid);
+  inferior_ptid = get_base_thread_from_ravenscar_task (inferior_ptid);
+  return beneath ()->stopped_data_address (addr_p);
 }
 
 void
-ravenscar_register_arch_ops (struct ravenscar_arch_ops *ops)
+ravenscar_thread_target::mourn_inferior ()
 {
-  /* FIXME: To be clean, we would need to handle a list of
-     architectures, just like in remote-wtx-hw.c.  However, for now the
-     only Ravenscar run-time for bare board that is implemented in
-     GNAT is for only one architecture: erc32-elf.  So no need to care about
-     that for now...  */
-  current_arch_ops = ops;
+  m_base_ptid = null_ptid;
+  target_ops *beneath = this->beneath ();
+  unpush_target (this);
+  beneath->mourn_inferior ();
 }
 
-static ptid_t
-ravenscar_get_ada_task_ptid (long lwp, long thread)
+/* Implement the to_core_of_thread target_ops "method".  */
+
+int
+ravenscar_thread_target::core_of_thread (ptid_t ptid)
 {
-  return ptid_build (ptid_get_pid (base_ptid), 0, thread);
+  scoped_restore save_ptid = make_scoped_restore (&inferior_ptid);
+  inferior_ptid = get_base_thread_from_ravenscar_task (inferior_ptid);
+  return beneath ()->core_of_thread (inferior_ptid);
 }
 
+/* Observer on inferior_created: push ravenscar thread stratum if needed.  */
+
 static void
-init_ravenscar_thread_ops (void)
+ravenscar_inferior_created (struct target_ops *target, int from_tty)
 {
-  ravenscar_ops.to_shortname = "ravenscar";
-  ravenscar_ops.to_longname = "Ravenscar tasks.";
-  ravenscar_ops.to_doc = "Ravenscar tasks support.";
-  ravenscar_ops.to_resume = ravenscar_resume;
-  ravenscar_ops.to_wait = ravenscar_wait;
-  ravenscar_ops.to_fetch_registers = ravenscar_fetch_registers;
-  ravenscar_ops.to_store_registers = ravenscar_store_registers;
-  ravenscar_ops.to_prepare_to_store = ravenscar_prepare_to_store;
-  ravenscar_ops.to_thread_alive = ravenscar_thread_alive;
-  ravenscar_ops.to_find_new_threads = ravenscar_find_new_threads;
-  ravenscar_ops.to_pid_to_str = ravenscar_pid_to_str;
-  ravenscar_ops.to_extra_thread_info = ravenscar_extra_thread_info;
-  ravenscar_ops.to_get_ada_task_ptid = ravenscar_get_ada_task_ptid;
-  ravenscar_ops.to_mourn_inferior = ravenscar_mourn_inferior;
-  ravenscar_ops.to_has_all_memory = default_child_has_all_memory;
-  ravenscar_ops.to_has_memory = default_child_has_memory;
-  ravenscar_ops.to_has_stack = default_child_has_stack;
-  ravenscar_ops.to_has_registers = default_child_has_registers;
-  ravenscar_ops.to_has_execution = default_child_has_execution;
-  ravenscar_ops.to_stratum = thread_stratum;
-  ravenscar_ops.to_magic = OPS_MAGIC;
-}
+  const char *err_msg;
 
-/* Command-list for the "set/show ravenscar" prefix command.  */
-static struct cmd_list_element *set_ravenscar_list;
-static struct cmd_list_element *show_ravenscar_list;
+  if (!ravenscar_task_support
+      || gdbarch_ravenscar_ops (target_gdbarch ()) == NULL
+      || !has_ravenscar_runtime ())
+    return;
 
-/* Implement the "set ravenscar" prefix command.  */
+  err_msg = ada_get_tcb_types_info ();
+  if (err_msg != NULL)
+    {
+      warning (_("%s. Task/thread support disabled."), err_msg);
+      return;
+    }
 
-static void
-set_ravenscar_command (char *arg, int from_tty)
-{
-  printf_unfiltered (_(\
-"\"set ravenscar\" must be followed by the name of a setting.\n"));
-  help_list (set_ravenscar_list, "set ravenscar ", -1, gdb_stdout);
+  target_ops_up target_holder (new ravenscar_thread_target ());
+  push_target (std::move (target_holder));
 }
 
-/* Implement the "show ravenscar" prefix command.  */
-
-static void
-show_ravenscar_command (char *args, int from_tty)
+ptid_t
+ravenscar_thread_target::get_ada_task_ptid (long lwp, long thread)
 {
-  cmd_show_list (show_ravenscar_list, from_tty, "");
+  return ptid_t (m_base_ptid.pid (), 0, thread);
 }
 
+/* Command-list for the "set/show ravenscar" prefix command.  */
+static struct cmd_list_element *set_ravenscar_list;
+static struct cmd_list_element *show_ravenscar_list;
+
 /* Implement the "show ravenscar task-switching" command.  */
 
 static void
@@ -409,36 +577,29 @@ Support for Ravenscar task/thread switching is enabled\n"));
 Support for Ravenscar task/thread switching is disabled\n"));
 }
 
-/* Provide a prototype to silence -Wmissing-prototypes.  */
-extern void _initialize_ravenscar (void);
-
 /* Module startup initialization function, automagically called by
    init.c.  */
 
+void _initialize_ravenscar ();
 void
-_initialize_ravenscar (void)
+_initialize_ravenscar ()
 {
-  init_ravenscar_thread_ops ();
-  base_ptid = null_ptid;
-
   /* Notice when the inferior is created in order to push the
      ravenscar ops if needed.  */
-  observer_attach_inferior_created (ravenscar_inferior_created);
-
-  add_target (&ravenscar_ops);
+  gdb::observers::inferior_created.attach (ravenscar_inferior_created);
 
-  add_prefix_cmd ("ravenscar", no_class, set_ravenscar_command,
-                  _("Prefix command for changing Ravenscar-specific settings"),
-                  &set_ravenscar_list, "set ravenscar ", 0, &setlist);
+  add_basic_prefix_cmd ("ravenscar", no_class,
+			_("Prefix command for changing Ravenscar-specific settings."),
+			&set_ravenscar_list, "set ravenscar ", 0, &setlist);
 
-  add_prefix_cmd ("ravenscar", no_class, show_ravenscar_command,
-                  _("Prefix command for showing Ravenscar-specific settings"),
-                  &show_ravenscar_list, "show ravenscar ", 0, &showlist);
+  add_show_prefix_cmd ("ravenscar", no_class,
+		       _("Prefix command for showing Ravenscar-specific settings."),
+		       &show_ravenscar_list, "show ravenscar ", 0, &showlist);
 
   add_setshow_boolean_cmd ("task-switching", class_obscure,
                            &ravenscar_task_support, _("\
-Enable or disable support for GNAT Ravenscar tasks"), _("\
-Show whether support for GNAT Ravenscar tasks is enabled"),
+Enable or disable support for GNAT Ravenscar tasks."), _("\
+Show whether support for GNAT Ravenscar tasks is enabled."),
                            _("\
 Enable or disable support for task/thread switching with the GNAT\n\
 Ravenscar run-time library for bareboard configuration."),