Move gdbserver to top level

This patch moves gdbserver to the top level.

This patch is as close to a pure move as possible -- gdbserver still
builds its own variant of gnulib and gdbsupport.  Changing this will
be done in a separate patch.

[v2] Note that, per Simon's review comment, this patch changes the
tree so that gdbserver is not built for or1k or score.  This makes
sense, because there is apparently not actually a gdbserver port here.

[v3] This version of the patch also splits out some configury into a
new file, gdbserver/configure.host, so that the top-level configure
script can simply rely on it in order to decide whether gdbserver
should be built.

[v4] This version adds documentation and removes some unnecessary
top-level dependencies.

[v5] Update docs to mention "make all-gdbserver" and change how
top-level configure decides whether to build gdbserver, switching to a
single, shared script.

Tested by the buildbot.

ChangeLog
2020-02-07  Tom Tromey  <tom@tromey.com>
	    Pedro Alves  <palves@redhat.com>

	* src-release.sh (GDB_SUPPORT_DIRS): Add gdbserver.
	* gdbserver: New directory, moved from gdb/gdbserver.
	* configure.ac (host_tools): Add gdbserver.
	Only build gdbserver on certain systems.
	* Makefile.in, configure: Rebuild.
	* Makefile.def (host_modules, dependencies): Add gdbserver.
	* MAINTAINERS: Add gdbserver.

gdb/ChangeLog
2020-02-07  Tom Tromey  <tom@tromey.com>

	* README: Update gdbserver documentation.
	* gdbserver: Move to top level.
	* configure.tgt (build_gdbserver): Remove.
	* configure.ac: Remove --enable-gdbserver.
	* configure: Rebuild.
	* Makefile.in (distclean): Don't mention gdbserver.

Change-Id: I826b7565b54604711dc7a11edea0499cd51ff39e

1 files changed, 227 insertions, 0 deletions

diff --git a/gdbserver/gdbthread.h b/gdbserver/gdbthread.h
new file mode 100644
index 00000000000..68762517c98
--- /dev/null
+++ b/gdbserver/gdbthread.h
@@ -0,0 +1,227 @@
+/* Multi-thread control defs for remote server for GDB.
+   Copyright (C) 1993-2020 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef GDBSERVER_GDBTHREAD_H
+#define GDBSERVER_GDBTHREAD_H
+
+#include "gdbsupport/common-gdbthread.h"
+#include "inferiors.h"
+
+#include <list>
+
+struct btrace_target_info;
+struct regcache;
+
+struct thread_info
+{
+  /* The id of this thread.  */
+  ptid_t id;
+
+  void *target_data;
+  struct regcache *regcache_data;
+
+  /* The last resume GDB requested on this thread.  */
+  enum resume_kind last_resume_kind;
+
+  /* The last wait status reported for this thread.  */
+  struct target_waitstatus last_status;
+
+  /* True if LAST_STATUS hasn't been reported to GDB yet.  */
+  int status_pending_p;
+
+  /* Given `while-stepping', a thread may be collecting data for more
+     than one tracepoint simultaneously.  E.g.:
+
+    ff0001  INSN1 <-- TP1, while-stepping 10 collect $regs
+    ff0002  INSN2
+    ff0003  INSN3 <-- TP2, collect $regs
+    ff0004  INSN4 <-- TP3, while-stepping 10 collect $regs
+    ff0005  INSN5
+
+   Notice that when instruction INSN5 is reached, the while-stepping
+   actions of both TP1 and TP3 are still being collected, and that TP2
+   had been collected meanwhile.  The whole range of ff0001-ff0005
+   should be single-stepped, due to at least TP1's while-stepping
+   action covering the whole range.
+
+   On the other hand, the same tracepoint with a while-stepping action
+   may be hit by more than one thread simultaneously, hence we can't
+   keep the current step count in the tracepoint itself.
+
+   This is the head of the list of the states of `while-stepping'
+   tracepoint actions this thread is now collecting; NULL if empty.
+   Each item in the list holds the current step of the while-stepping
+   action.  */
+  struct wstep_state *while_stepping;
+
+  /* Branch trace target information for this thread.  */
+  struct btrace_target_info *btrace;
+};
+
+extern std::list<thread_info *> all_threads;
+
+void remove_thread (struct thread_info *thread);
+struct thread_info *add_thread (ptid_t ptid, void *target_data);
+
+/* Return a pointer to the first thread, or NULL if there isn't one.  */
+
+struct thread_info *get_first_thread (void);
+
+struct thread_info *find_thread_ptid (ptid_t ptid);
+
+/* Find any thread of the PID process.  Returns NULL if none is
+   found.  */
+struct thread_info *find_any_thread_of_pid (int pid);
+
+/* Find the first thread for which FUNC returns true.  Return NULL if no thread
+   satisfying FUNC is found.  */
+
+template <typename Func>
+static thread_info *
+find_thread (Func func)
+{
+  std::list<thread_info *>::iterator next, cur = all_threads.begin ();
+
+  while (cur != all_threads.end ())
+    {
+      next = cur;
+      next++;
+
+      if (func (*cur))
+	return *cur;
+
+      cur = next;
+    }
+
+  return NULL;
+}
+
+/* Like the above, but only consider threads with pid PID.  */
+
+template <typename Func>
+static thread_info *
+find_thread (int pid, Func func)
+{
+  return find_thread ([&] (thread_info *thread)
+    {
+      return thread->id.pid () == pid && func (thread);
+    });
+}
+
+/* Find the first thread that matches FILTER for which FUNC returns true.
+   Return NULL if no thread satisfying these conditions is found.  */
+
+template <typename Func>
+static thread_info *
+find_thread (ptid_t filter, Func func)
+{
+  return find_thread ([&] (thread_info *thread) {
+    return thread->id.matches (filter) && func (thread);
+  });
+}
+
+/* Invoke FUNC for each thread.  */
+
+template <typename Func>
+static void
+for_each_thread (Func func)
+{
+  std::list<thread_info *>::iterator next, cur = all_threads.begin ();
+
+  while (cur != all_threads.end ())
+    {
+      next = cur;
+      next++;
+      func (*cur);
+      cur = next;
+    }
+}
+
+/* Like the above, but only consider threads with pid PID.  */
+
+template <typename Func>
+static void
+for_each_thread (int pid, Func func)
+{
+  for_each_thread ([&] (thread_info *thread)
+    {
+      if (pid == thread->id.pid ())
+	func (thread);
+    });
+}
+
+/* Find the a random thread for which FUNC (THREAD) returns true.  If
+   no entry is found then return NULL.  */
+
+template <typename Func>
+static thread_info *
+find_thread_in_random (Func func)
+{
+  int count = 0;
+  int random_selector;
+
+  /* First count how many interesting entries we have.  */
+  for_each_thread ([&] (thread_info *thread) {
+    if (func (thread))
+      count++;
+  });
+
+  if (count == 0)
+    return NULL;
+
+  /* Now randomly pick an entry out of those.  */
+  random_selector = (int)
+    ((count * (double) rand ()) / (RAND_MAX + 1.0));
+
+  thread_info *thread = find_thread ([&] (thread_info *thr_arg) {
+    return func (thr_arg) && (random_selector-- == 0);
+  });
+
+  gdb_assert (thread != NULL);
+
+  return thread;
+}
+
+/* Get current thread ID (Linux task ID).  */
+#define current_ptid (current_thread->id)
+
+/* Get the ptid of THREAD.  */
+
+static inline ptid_t
+ptid_of (const thread_info *thread)
+{
+  return thread->id;
+}
+
+/* Get the pid of THREAD.  */
+
+static inline int
+pid_of (const thread_info *thread)
+{
+  return thread->id.pid ();
+}
+
+/* Get the lwp of THREAD.  */
+
+static inline long
+lwpid_of (const thread_info *thread)
+{
+  return thread->id.lwp ();
+}
+
+#endif /* GDBSERVER_GDBTHREAD_H */