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Support clone events in the remote protocol

Browse Source 
The previous patch taught GDB about a new
TARGET_WAITKIND_THREAD_CLONED event kind, and made the Linux target
report clone events.

A following patch will teach Linux GDBserver to do the same thing.

But before we get there, we need to teach the remote protocol about
TARGET_WAITKIND_THREAD_CLONED.  That's what this patch does.  Clone is
very similar to vfork and fork, and the new stop reply is likewise
handled similarly.  The stub reports "T05clone:...".

GDBserver core is taught to handle TARGET_WAITKIND_THREAD_CLONED and
forward it to GDB in this patch, but no backend actually emits it yet.
That will be done in a following patch.

Documentation for this new remote protocol feature is included in a
documentation patch later in the series.

Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: If271f20320d864f074d8ac0d531cc1a323da847f
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=19675
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27830
This commit is contained in:
Pedro Alves 2021-11-23 20:35:12 +00:00
parent 0d36baa9af
commit 53de5394f7
3 changed files with 89 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

98
gdb/remote.c
View File

@ -1019,6 +1019,7 @@ public:
const struct btrace_config *btrace_conf (const struct btrace_target_info *) override;
bool augmented_libraries_svr4_read () override;
void follow_fork (inferior *, ptid_t, target_waitkind, bool, bool) override;
void follow_clone (ptid_t child_ptid) override;
void follow_exec (inferior *, ptid_t, const char *) override;
int insert_fork_catchpoint (int) override;
int remove_fork_catchpoint (int) override;
@ -1112,7 +1113,7 @@ public: /* Remote specific methods. */
void remote_btrace_maybe_reopen ();
void remove_new_fork_children (threads_listing_context *context);
void remove_new_children (threads_listing_context *context);
void kill_new_fork_children (inferior *inf);
void discard_pending_stop_replies (struct inferior *inf);
int stop_reply_queue_length ();
@ -2792,10 +2793,8 @@ remote_target::remote_add_thread (ptid_t ptid, bool running, bool executing,
else
thread = add_thread (this, ptid);
/* We start by assuming threads are resumed. That state then gets updated
when we process a matching stop reply. */
get_remote_thread_info (thread)->set_resumed ();
if (executing)
get_remote_thread_info (thread)->set_resumed ();
set_executing (this, ptid, executing);
set_running (this, ptid, running);
@ -4194,10 +4193,11 @@ remote_target::update_thread_list ()
}
}
/* Remove any unreported fork child threads from CONTEXT so
that we don't interfere with follow fork, which is where
creation of such threads is handled. */
remove_new_fork_children (&context);
/* Remove any unreported fork/vfork/clone child threads from
CONTEXT so that we don't interfere with follow
fork/vfork/clone, which is where creation of such threads is
handled. */
remove_new_children (&context);
/* And now add threads we don't know about yet to our list. */
for (thread_item &item : context.items)
@ -5161,6 +5161,8 @@ remote_target::start_remote_1 (int from_tty, int extended_p)
}
else
switch_to_thread (this->find_thread (curr_thread));
get_remote_thread_info (inferior_thread ())->set_resumed ();
}
/* init_wait_for_inferior should be called before get_offsets in order
@ -6120,16 +6122,25 @@ is_fork_status (target_waitkind kind)
|| kind == TARGET_WAITKIND_VFORKED);
}
/* Return THREAD's pending status if it is a pending fork parent, else
return nullptr. */
/* Return a reference to the field where a pending child status, if
there's one, is recorded. If there's no child event pending, the
returned waitstatus has TARGET_WAITKIND_IGNORE kind. */
static const target_waitstatus &
thread_pending_status (struct thread_info *thread)
{
return (thread->has_pending_waitstatus ()
? thread->pending_waitstatus ()
: thread->pending_follow);
}
/* Return THREAD's pending status if it is a pending fork/vfork (but
not clone) parent, else return nullptr. */
static const target_waitstatus *
thread_pending_fork_status (struct thread_info *thread)
{
const target_waitstatus &ws
= (thread->has_pending_waitstatus ()
? thread->pending_waitstatus ()
: thread->pending_follow);
const target_waitstatus &ws = thread_pending_status (thread);
if (!is_fork_status (ws.kind ()))
return nullptr;
@ -6137,6 +6148,20 @@ thread_pending_fork_status (struct thread_info *thread)
return &ws;
}
/* Return THREAD's pending status if is is a pending fork/vfork/clone
event, else return nullptr. */
static const target_waitstatus *
thread_pending_child_status (thread_info *thread)
{
const target_waitstatus &ws = thread_pending_status (thread);
if (!is_new_child_status (ws.kind ()))
return nullptr;
return &ws;
}
/* Detach the specified process. */
void
@ -6327,6 +6352,12 @@ remote_target::follow_fork (inferior *child_inf, ptid_t child_ptid,
}
}
void
remote_target::follow_clone (ptid_t child_ptid)
{
remote_add_thread (child_ptid, false, false, false);
}
/* Target follow-exec function for remote targets. Save EXECD_PATHNAME
in the program space of the new inferior. */
@ -7054,10 +7085,10 @@ remote_target::commit_resumed ()
if (priv->get_resume_state () == resume_state::RESUMED_PENDING_VCONT)
any_pending_vcont_resume = true;
/* If a thread is the parent of an unfollowed fork, then we
can't do a global wildcard, as that would resume the fork
child. */
if (thread_pending_fork_status (tp) != nullptr)
/* If a thread is the parent of an unfollowed fork/vfork/clone,
then we can't do a global wildcard, as that would resume the
pending child. */
if (thread_pending_child_status (tp) != nullptr)
may_global_wildcard_vcont = false;
}
@ -7517,22 +7548,22 @@ const notif_client notif_client_stop =
REMOTE_NOTIF_STOP,
};
/* If CONTEXT contains any fork child threads that have not been
reported yet, remove them from the CONTEXT list. If such a
thread exists it is because we are stopped at a fork catchpoint
and have not yet called follow_fork, which will set up the
host-side data structures for the new process. */
/* If CONTEXT contains any fork/vfork/clone child threads that have
not been reported yet, remove them from the CONTEXT list. If such
a thread exists it is because we are stopped at a fork/vfork/clone
catchpoint and have not yet called follow_fork/follow_clone, which
will set up the host-side data structures for the new child. */
void
remote_target::remove_new_fork_children (threads_listing_context *context)
remote_target::remove_new_children (threads_listing_context *context)
{
const notif_client *notif = &notif_client_stop;
/* For any threads stopped at a fork event, remove the corresponding
fork child threads from the CONTEXT list. */
/* For any threads stopped at a (v)fork/clone event, remove the
corresponding child threads from the CONTEXT list. */
for (thread_info *thread : all_non_exited_threads (this))
{
const target_waitstatus *ws = thread_pending_fork_status (thread);
const target_waitstatus *ws = thread_pending_child_status (thread);
if (ws == nullptr)
continue;
@ -7540,13 +7571,12 @@ remote_target::remove_new_fork_children (threads_listing_context *context)
context->remove_thread (ws->child_ptid ());
}
/* Check for any pending fork events (not reported or processed yet)
in process PID and remove those fork child threads from the
CONTEXT list as well. */
/* Check for any pending (v)fork/clone events (not reported or
processed yet) in process PID and remove those child threads from
the CONTEXT list as well. */
remote_notif_get_pending_events (notif);
for (auto &event : get_remote_state ()->stop_reply_queue)
if (event->ws.kind () == TARGET_WAITKIND_FORKED
|| event->ws.kind () == TARGET_WAITKIND_VFORKED)
if (is_new_child_status (event->ws.kind ()))
context->remove_thread (event->ws.child_ptid ());
else if (event->ws.kind () == TARGET_WAITKIND_THREAD_EXITED)
context->remove_thread (event->ptid);
@ -7877,6 +7907,8 @@ Packet: '%s'\n"),
event->ws.set_forked (read_ptid (++p1, &p));
else if (strprefix (p, p1, "vfork"))
event->ws.set_vforked (read_ptid (++p1, &p));
else if (strprefix (p, p1, "clone"))
event->ws.set_thread_cloned (read_ptid (++p1, &p));
else if (strprefix (p, p1, "vforkdone"))
{
event->ws.set_vfork_done ();

26
gdbserver/remote-utils.cc
View File

@ -1063,6 +1063,7 @@ prepare_resume_reply (char *buf, ptid_t ptid, const target_waitstatus &status)
case TARGET_WAITKIND_FORKED:
case TARGET_WAITKIND_VFORKED:
case TARGET_WAITKIND_VFORK_DONE:
case TARGET_WAITKIND_THREAD_CLONED:
case TARGET_WAITKIND_EXECD:
case TARGET_WAITKIND_THREAD_CREATED:
case TARGET_WAITKIND_SYSCALL_ENTRY:
@ -1071,13 +1072,30 @@ prepare_resume_reply (char *buf, ptid_t ptid, const target_waitstatus &status)
struct regcache *regcache;
char *buf_start = buf;
if ((status.kind () == TARGET_WAITKIND_FORKED && cs.report_fork_events)
if ((status.kind () == TARGET_WAITKIND_FORKED
&& cs.report_fork_events)
|| (status.kind () == TARGET_WAITKIND_VFORKED
&& cs.report_vfork_events))
&& cs.report_vfork_events)
|| status.kind () == TARGET_WAITKIND_THREAD_CLONED)
{
enum gdb_signal signal = GDB_SIGNAL_TRAP;
const char *event = (status.kind () == TARGET_WAITKIND_FORKED
? "fork" : "vfork");
auto kind_remote_str = [] (target_waitkind kind)
{
switch (kind)
{
case TARGET_WAITKIND_FORKED:
return "fork";
case TARGET_WAITKIND_VFORKED:
return "vfork";
case TARGET_WAITKIND_THREAD_CLONED:
return "clone";
default:
gdb_assert_not_reached ("unhandled kind");
}
};
const char *event = kind_remote_str (status.kind ());
sprintf (buf, "T%02x%s:", signal, event);
buf += strlen (buf);

3
gdbserver/server.cc
View File

@ -241,7 +241,8 @@ in_queued_stop_replies_ptid (struct notif_event *event, ptid_t filter_ptid)
/* Don't resume fork children that GDB does not know about yet. */
if ((vstop_event->status.kind () == TARGET_WAITKIND_FORKED
|| vstop_event->status.kind () == TARGET_WAITKIND_VFORKED)
|| vstop_event->status.kind () == TARGET_WAITKIND_VFORKED
|| vstop_event->status.kind () == TARGET_WAITKIND_THREAD_CLONED)
&& vstop_event->status.child_ptid ().matches (filter_ptid))
return true;