[PATCH v3 02/19] btrace: support to_stop

Markus Metzger
2015-09-17T14:09:57Z

Add support for the to_stop target method to the btrace record target.

2015-09-17 Markus Metzger <markus.t.metzger@intel.com>

gdb/
* btrace.h (enum btrace_thread_flag) <BTHR_STOP>: New.
* record-btrace (record_btrace_resume_thread): Clear BTHR_STOP.
(record_btrace_find_thread_to_move): Also accept threads that have
BTHR_STOP set.
(btrace_step_stopped_on_request, record_btrace_stop): New.
(record_btrace_step_thread): Support BTHR_STOP.
(record_btrace_wait): Also clear BTHR_STOP when stopping other threads.
(init_record_btrace_ops): Initialize to_stop.
---
gdb/btrace.h | 5 ++++-
gdb/record-btrace.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 59 insertions(+), 9 deletions(-)

diff --git a/gdb/btrace.h b/gdb/btrace.h
index 756a778..f844df8 100644
--- a/gdb/btrace.h
+++ b/gdb/btrace.h
@@ -240,7 +240,10 @@ enum btrace_thread_flag
BTHR_RCONT = (1 << 3),

/* The thread is to be moved. */
- BTHR_MOVE = (BTHR_STEP | BTHR_RSTEP | BTHR_CONT | BTHR_RCONT)
+ BTHR_MOVE = (BTHR_STEP | BTHR_RSTEP | BTHR_CONT | BTHR_RCONT),
+
+ /* The thread is to be stopped. */
+ BTHR_STOP = (1 << 4)
};

#if defined (HAVE_LIBIPT)
diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index 2d8b20b..a9ed4b7 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -1677,6 +1677,8 @@ record_btrace_resume_thread (struct thread_info *tp,
/* Fetch the latest branch trace. */
btrace_fetch (tp);

+ /* A resume request overwrites a preceding stop request. */
+ btinfo->flags &= ~BTHR_STOP;
btinfo->flags |= flag;
}

@@ -1872,12 +1874,12 @@ record_btrace_find_thread_to_move (ptid_t ptid)

/* First check the parameter thread. */
tp = find_thread_ptid (ptid);
- if (tp != NULL && (tp->btrace.flags & BTHR_MOVE) != 0)
+ if (tp != NULL && (tp->btrace.flags & (BTHR_MOVE | BTHR_STOP)) != 0)
return tp;

/* Otherwise, find one other thread that has been resumed. */
ALL_NON_EXITED_THREADS (tp)
- if ((tp->btrace.flags & BTHR_MOVE) != 0)
+ if ((tp->btrace.flags & (BTHR_MOVE | BTHR_STOP)) != 0)
return tp;

return NULL;
@@ -1908,6 +1910,20 @@ btrace_step_stopped (void)
return status;
}

+/* Return a target_waitstatus indicating that a thread was stopped as
+ requested. */
+
+static struct target_waitstatus
+btrace_step_stopped_on_request (void)
+{
+ struct target_waitstatus status;
+
+ status.kind = TARGET_WAITKIND_STOPPED;
+ status.value.sig = GDB_SIGNAL_0;
+
+ return status;
+}
+
/* Clear the record histories. */

static void
@@ -1932,23 +1948,27 @@ record_btrace_step_thread (struct thread_info *tp)
enum btrace_thread_flag flags;
unsigned int steps;

- /* We can't step without an execution history. */
- if (btrace_is_empty (tp))
- return btrace_step_no_history ();

btinfo = &tp->btrace;
replay = btinfo->replay;

- flags = btinfo->flags & BTHR_MOVE;
- btinfo->flags &= ~BTHR_MOVE;
+ flags = btinfo->flags & (BTHR_MOVE | BTHR_STOP);
+ btinfo->flags &= ~(BTHR_MOVE | BTHR_STOP);

DEBUG ("stepping %d (%s): %u", tp->num, target_pid_to_str (tp->ptid), flags);

+ /* We can't step without an execution history. */
+ if ((flags & BTHR_MOVE) != 0 && btrace_is_empty (tp))
+ return btrace_step_no_history ();
+
switch (flags)
{
default:
internal_error (__FILE__, __LINE__, _("invalid stepping type."));

+ case BTHR_STOP:
+ return btrace_step_stopped_on_request ();
+
case BTHR_STEP:
/* We're done if we're not replaying. */
if (replay == NULL)
@@ -2106,7 +2126,7 @@ record_btrace_wait (struct target_ops *ops, ptid_t ptid,
/* Stop all other threads. */
if (!target_is_non_stop_p ())
ALL_NON_EXITED_THREADS (other)
- other->btrace.flags &= ~BTHR_MOVE;
+ other->btrace.flags &= ~(BTHR_MOVE | BTHR_STOP);

/* Start record histories anew from the current position. */
record_btrace_clear_histories (&tp->btrace);
@@ -2117,6 +2137,32 @@ record_btrace_wait (struct target_ops *ops, ptid_t ptid,
return tp->ptid;
}

+/* The to_stop method of target record-btrace. */
+
+static void
+record_btrace_stop (struct target_ops *ops, ptid_t ptid)
+{
+ DEBUG ("stop %s", target_pid_to_str (ptid));
+
+ /* As long as we're not replaying, just forward the request. */
+ if (!record_btrace_is_replaying (ops) && execution_direction != EXEC_REVERSE)
+ {
+ ops = ops->beneath;
+ ops->to_stop (ops, ptid);
+ }
+ else
+ {
+ struct thread_info *tp;
+
+ ALL_NON_EXITED_THREADS (tp)
+ if (ptid_match (tp->ptid, ptid))
+ {
+ tp->btrace.flags &= ~BTHR_MOVE;
+ tp->btrace.flags |= BTHR_STOP;
+ }
+ }
+ }
+
/* The to_can_execute_reverse method of target record-btrace. */

static int
@@ -2350,6 +2396,7 @@ init_record_btrace_ops (void)
ops->to_get_tailcall_unwinder = &record_btrace_to_get_tailcall_unwinder;
ops->to_resume = record_btrace_resume;
ops->to_wait = record_btrace_wait;
+ ops->to_stop = record_btrace_stop;
ops->to_update_thread_list = record_btrace_update_thread_list;
ops->to_thread_alive = record_btrace_thread_alive;
ops->to_goto_record_begin = record_btrace_goto_begin;
--
1.8.3.1