[PATCH v3 19/19] btrace: honour scheduler-locking for all-stop targets

Markus Metzger
2015-09-17T14:10:26Z

In all-stop mode, record btrace maintains the old behaviour of an implicit
scheduler-locking on.

Now that we added a scheduler-locking mode to model this old behaviour, we
don't need the respective code in record btrace anymore. Remove it.

For all-stop targets, step inferior_ptid and continue other threads matching
the argument ptid. Assert that inferior_ptid matches the argument ptid.

This should make record btrace honour scheduler-locking.

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

gdb/
* record-btrace.c (record_btrace_resume): Honour scheduler-locking.

testsuite/
* gdb.btrace/multi-thread-step.exp: Test scheduler-locking on, step,
and replay.
---
gdb/record-btrace.c | 57 +++---
gdb/testsuite/gdb.btrace/multi-thread-step.exp | 233 +++++++++++++++++--------
2 files changed, 192 insertions(+), 98 deletions(-)

diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index 42195d1..d14e6cf 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -1888,33 +1888,18 @@ record_btrace_resume (struct target_ops *ops, ptid_t ptid, int step,
enum gdb_signal signal)
{
struct thread_info *tp;
- enum btrace_thread_flag flag;
- ptid_t orig_ptid;
+ enum btrace_thread_flag flag, cflag;

DEBUG ("resume %s: %s%s", target_pid_to_str (ptid),
execution_direction == EXEC_REVERSE ? "reverse-" : "",
step ? "step" : "cont");

- orig_ptid = ptid;
-
/* Store the execution direction of the last resume.

If there is more than one to_resume call, we have to rely on infrun
to not change the execution direction in-between. */
record_btrace_resume_exec_dir = execution_direction;

- /* For all-stop targets we pick the current thread when asked to resume an
- entire process or everything. */
- if (!target_is_non_stop_p ())
- {
- if (ptid_equal (minus_one_ptid, ptid) || ptid_is_pid (ptid))
- ptid = inferior_ptid;
-
- tp = find_thread_ptid (ptid);
- if (tp == NULL)
- error (_("Cannot find thread to resume."));
- }
-
/* As long as we're not replaying, just forward the request.

For non-stop targets this means that no thread is replaying. In order to
@@ -1924,20 +1909,44 @@ record_btrace_resume (struct target_ops *ops, ptid_t ptid, int step,
&& !record_btrace_is_replaying (ops, minus_one_ptid))
{
ops = ops->beneath;
- return ops->to_resume (ops, orig_ptid, step, signal);
+ return ops->to_resume (ops, ptid, step, signal);
}

/* Compute the btrace thread flag for the requested move. */
- if (step == 0)
- flag = execution_direction == EXEC_REVERSE ? BTHR_RCONT : BTHR_CONT;
+ if (execution_direction == EXEC_REVERSE)
+ {
+ flag = step == 0 ? BTHR_RCONT : BTHR_RSTEP;
+ cflag = BTHR_RCONT;
+ }
else
- flag = execution_direction == EXEC_REVERSE ? BTHR_RSTEP : BTHR_STEP;
+ {
+ flag = step == 0 ? BTHR_CONT : BTHR_STEP;
+ cflag = BTHR_CONT;
+ }

/* We just indicate the resume intent here. The actual stepping happens in
- record_btrace_wait below. */
- ALL_NON_EXITED_THREADS (tp)
- if (ptid_match (tp->ptid, ptid))
- record_btrace_resume_thread (tp, flag);
+ record_btrace_wait below.
+
+ For all-stop targets, we only step INFERIOR_PTID and continue others. */
+ if (!target_is_non_stop_p ())
+ {
+ gdb_assert (ptid_match (inferior_ptid, ptid));
+
+ ALL_NON_EXITED_THREADS (tp)
+ if (ptid_match (tp->ptid, ptid))
+ {
+ if (ptid_match (tp->ptid, inferior_ptid))
+ record_btrace_resume_thread (tp, flag);
+ else
+ record_btrace_resume_thread (tp, cflag);
+ }
+ }
+ else
+ {
+ ALL_NON_EXITED_THREADS (tp)
+ if (ptid_match (tp->ptid, ptid))
+ record_btrace_resume_thread (tp, flag);
+ }

/* Async support. */
if (target_can_async_p ())
diff --git a/gdb/testsuite/gdb.btrace/multi-thread-step.exp b/gdb/testsuite/gdb.btrace/multi-thread-step.exp
index 2295f71..c8f55d0 100644
--- a/gdb/testsuite/gdb.btrace/multi-thread-step.exp
+++ b/gdb/testsuite/gdb.btrace/multi-thread-step.exp
@@ -37,9 +37,29 @@ set bp_2 [gdb_get_line_number "bp.2" $srcfile]
set bp_3 [gdb_get_line_number "bp.3" $srcfile]

proc gdb_cont_to_line { line } {
- gdb_breakpoint $line
- gdb_continue_to_breakpoint "cont to $line" ".*$line\r\n.*"
- delete_breakpoints
+ gdb_breakpoint $line
+ gdb_continue_to_breakpoint "cont to $line" ".*$line\r\n.*"
+ delete_breakpoints
+}
+
+proc check_replay_insn { thread insn } {
+ gdb_test "thread apply $thread info record" \
+ "Replay in progress\. At instruction $insn\."
+}
+
+proc check_not_replaying { thread } {
+ global gdb_prompt
+
+ set test "thread $thread not replaying"
+
+ gdb_test_multiple "thread apply $thread info record" $test {
+ -re "Replay in progress" {
+ fail $test
+ }
+ -re "$gdb_prompt $" {
+ pass $test
+ }
+ }
}

# trace the code between the two breakpoints
@@ -50,86 +70,151 @@ gdb_test "info threads" ".*"
gdb_test_no_output "record btrace"
gdb_cont_to_line $srcfile:$bp_2

-# navigate in the trace history for both threads
-with_test_prefix "navigate" {
- gdb_test "thread 1" ".*"
- with_test_prefix "thread 1" {
- gdb_test "record goto begin" ".*"
- gdb_test "info record" ".*Replay in progress\. At instruction 1\."
- }
- gdb_test "thread 2" ".*"
- with_test_prefix "thread 2" {
- gdb_test "record goto begin" ".*"
- gdb_test "info record" ".*Replay in progress\. At instruction 1\."
- }
+proc test_navigate {} {
+ with_test_prefix "navigate" {
+ gdb_test "thread 1" ".*"
+ with_test_prefix "thread 1" {
+ gdb_test "record goto begin" ".*"
+
+ check_replay_insn 1 1
+ check_not_replaying 2
+ }
+ gdb_test "thread 2" ".*"
+ with_test_prefix "thread 2" {
+ gdb_test "record goto begin" ".*"
+
+ check_replay_insn 1 1
+ check_replay_insn 2 1
+ }
+ }
+}
+
+proc test_step {} {
+ with_test_prefix "step" {
+ gdb_test "thread 1" ".*"
+ with_test_prefix "thread 1" {
+ gdb_test "stepi" ".*"
+
+ check_replay_insn 1 2
+ check_replay_insn 2 1
+ }
+ gdb_test "thread 2" ".*"
+ with_test_prefix "thread 2" {
+ gdb_test "stepi" ".*"
+
+ check_replay_insn 1 2
+ check_replay_insn 2 2
+ }
+ }
+}
+
+proc test_cont {} {
+ with_test_prefix "cont" {
+ gdb_test "thread 1" ".*"
+ with_test_prefix "thread 1" {
+ gdb_test "continue" "No more reverse-execution history.*"
+
+ check_not_replaying 1
+ check_replay_insn 2 2
+ }
+ gdb_test "thread 2" ".*"
+ with_test_prefix "thread 2" {
+ gdb_test "continue" "No more reverse-execution history.*"
+
+ check_not_replaying 1
+ check_not_replaying 2
+ }
+ }
}

-# step both threads
-with_test_prefix "step" {
- gdb_test "thread 1" ".*"
- with_test_prefix "thread 1" {
- gdb_test "info record" ".*Replay in progress\. At instruction 1\."
- gdb_test "stepi" ".*"
- gdb_test "info record" ".*Replay in progress\. At instruction 2\."
- }
- gdb_test "thread 2" ".*"
- with_test_prefix "thread 2" {
- gdb_test "info record" ".*Replay in progress\. At instruction 1\."
- gdb_test "stepi" ".*"
- gdb_test "info record" ".*Replay in progress\. At instruction 2\."
- }
+proc test_cont_all {} {
+ with_test_prefix "cont-all" {
+ gdb_test "continue" "No more reverse-execution history.*"
+
+ # this works because we're lock-stepping threads that executed exactly
+ # the same code starting from the same instruction.
+
+ check_not_replaying 1
+ check_not_replaying 2
+ }
+}
+
+proc test_rstep {} {
+ with_test_prefix "reverse-step" {
+ gdb_test "thread apply all record goto 3"
+
+ gdb_test "thread 1" ".*"
+ with_test_prefix "thread 1" {
+ gdb_test "reverse-stepi" ".*"
+
+ check_replay_insn 1 2
+ check_replay_insn 2 3
+ }
+ gdb_test "thread 2" ".*"
+ with_test_prefix "thread 2" {
+ gdb_test "reverse-stepi" ".*"
+
+ check_replay_insn 1 2
+ check_replay_insn 2 2
+ }
+ }
}

-# run to the end of the history for both threads
-with_test_prefix "cont" {
- gdb_test "thread 1" ".*"
- with_test_prefix "thread 1" {
- gdb_test "info record" ".*Replay in progress\. At instruction 2\."
- gdb_test "continue" "No more reverse-execution history.*"
- }
- gdb_test "thread 2" ".*"
- with_test_prefix "thread 2" {
- gdb_test "info record" ".*Replay in progress\. At instruction 2\."
- gdb_test "continue" "No more reverse-execution history.*"
- }
+proc test_goto_end {} {
+ with_test_prefix "goto-end" {
+ gdb_test "thread apply all record goto end"
+
+ check_not_replaying 1
+ check_not_replaying 2
+ }
}

-# reverse-step both threads
-with_test_prefix "reverse-step" {
- gdb_test "thread 1" ".*"
- with_test_prefix "thread 1" {
- gdb_test "reverse-stepi" ".*"
- gdb_test "info record" ".*Replay in progress\..*"
- }
- gdb_test "thread 2" ".*"
- with_test_prefix "thread 2" {
- gdb_test "reverse-stepi" ".*"
- gdb_test "info record" ".*Replay in progress\..*"
- }
+foreach schedlock { "replay" "on" } {
+ with_test_prefix "schedlock-$schedlock" {
+ gdb_test_no_output "set scheduler-locking $schedlock"
+
+ test_navigate
+ test_step
+ test_cont
+ test_rstep
+ test_goto_end
+ }
}

-# both threads are still replaying
-with_test_prefix "check" {
- gdb_test "thread 1" ".*"
- with_test_prefix "thread 1" {
- gdb_test "info record" ".*Replay in progress\..*"
- }
- gdb_test "thread 2" ".*"
- with_test_prefix "thread 2" {
- gdb_test "info record" ".*Replay in progress\..*"
- }
+with_test_prefix "schedlock-step" {
+ gdb_test_no_output "set scheduler-locking step"
+
+ test_navigate
+ test_step
+ test_cont_all
+ test_rstep
+ test_goto_end
}

+# schedlock-off is difficult to test since we can't really say where the other
+# thread will be when the resumed thread stops.
+
# navigate back into the history for thread 1 and continue thread 2
-with_test_prefix "cont" {
- gdb_test "thread 1" ".*"
- with_test_prefix "thread 1" {
- gdb_test "record goto begin" ".*"
- gdb_test "info record" ".*Replay in progress\. At instruction 1\."
- }
- gdb_test "thread 2" ".*"
- with_test_prefix "thread 2" {
- gdb_test "record goto end" ".*"
- gdb_cont_to_line $srcfile:$bp_3
- }
+with_test_prefix "cont-to-end" {
+ # this test only works for scheduler-locking replay
+ gdb_test_no_output "set scheduler-locking replay"
+
+ gdb_test "thread 1" ".*"
+ with_test_prefix "thread 1" {
+ gdb_test "record goto begin" ".*"
+
+ check_replay_insn 1 1
+ }
+ gdb_test "thread 2" ".*"
+ with_test_prefix "thread 2" {
+ gdb_test "record goto end" ".*"
+
+ check_not_replaying 2
+
+ # if we reach the breakpoint, thread 2 terminated...
+ gdb_cont_to_line $srcfile:$bp_3
+
+ # and thread 1 stopped replaying
+ check_not_replaying 1
+ }
}
--
1.8.3.1