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Fix PR remote/19840: gdb crashes on reverse-stepi 

Reverse debugging against a remote target that does reverse debugging
itself (with the bs/bc packets) always trips on:

 (gdb) target remote localhost:...
 (gdb) reverse-stepi
 ../../gdb/target.c:602: internal-error: default_execution_direction: to_execution_direction must be implemented for reverse async

I missed adding a to_execution_direction method to remote.c in commit
3223143295 (Adds target_execution_direction to make record targets
support async mode), GDB 7.4 time.  Later, GDB 7.8 switched to
target-async on by default, making the regression user-visible by
default too.

Fix is simply to add the missing to_execution_direction implementation
to target remote.

Tested by Andi Kleen against Simics.

gdb/ChangeLog:
2016-04-13  Pedro Alves  <palves@redhat.com>

	PR remote/19840
	* remote.c (struct remote_state) <last_resume_exec_dir>: New
	field.
	(new_remote_state): Default last_resume_exec_dir to EXEC_FORWARD.
	(remote_open_1): Reset last_resume_exec_dir to EXEC_FORWARD.
	(remote_resume): Store the last execution direction.
	(remote_execution_direction): New function.
	(init_remote_ops): Install it as to_execution_direction target_ops
	method.
This commit is contained in:
Pedro Alves 2016-04-13 14:34:00 +01:00
parent e26b7e4165
commit 3a00c80277
2 changed files with 32 additions and 0 deletions
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12
gdb/ChangeLog
View File

@ -1,3 +1,15 @@
2016-04-13 Pedro Alves <palves@redhat.com>
PR remote/19840
* remote.c (struct remote_state) <last_resume_exec_dir>: New
field.
(new_remote_state): Default last_resume_exec_dir to EXEC_FORWARD.
(remote_open_1): Reset last_resume_exec_dir to EXEC_FORWARD.
(remote_resume): Store the last execution direction.
(remote_execution_direction): New function.
(init_remote_ops): Install it as to_execution_direction target_ops
method.
2016-04-12 Pedro Alves <palves@redhat.com>
* common/common-exceptions.h (GDB_XCPT_TRY): Update comment.

20
gdb/remote.c
View File

@ -393,6 +393,9 @@ struct remote_state
int last_sent_step;
/* The execution direction of the last resume we got. */
enum exec_direction_kind last_resume_exec_dir;
char *finished_object;
char *finished_annex;
ULONGEST finished_offset;
@ -481,6 +484,7 @@ new_remote_state (void)
result->buf = (char *) xmalloc (result->buf_size);
result->remote_traceframe_number = -1;
result->last_sent_signal = GDB_SIGNAL_0;
result->last_resume_exec_dir = EXEC_FORWARD;
result->fs_pid = -1;
return result;
@ -4999,6 +5003,8 @@ remote_open_1 (const char *name, int from_tty,
rs->continue_thread = not_sent_ptid;
rs->remote_traceframe_number = -1;
rs->last_resume_exec_dir = EXEC_FORWARD;
/* Probe for ability to use "ThreadInfo" query, as required. */
rs->use_threadinfo_query = 1;
rs->use_threadextra_query = 1;
@ -5634,6 +5640,8 @@ remote_resume (struct target_ops *ops,
rs->last_sent_signal = siggnal;
rs->last_sent_step = step;
rs->last_resume_exec_dir = execution_direction;
/* The vCont packet doesn't need to specify threads via Hc. */
/* No reverse support (yet) for vCont. */
if (execution_direction != EXEC_REVERSE)
@ -12985,6 +12993,17 @@ remote_can_do_single_step (struct target_ops *ops)
return 0;
}
/* Implementation of the to_execution_direction method for the remote
target. */
static enum exec_direction_kind
remote_execution_direction (struct target_ops *self)
{
struct remote_state *rs = get_remote_state ();
return rs->last_resume_exec_dir;
}
static void
init_remote_ops (void)
{
@ -13130,6 +13149,7 @@ Specify the serial device it is connected to\n\
remote_ops.to_remove_vfork_catchpoint = remote_remove_vfork_catchpoint;
remote_ops.to_insert_exec_catchpoint = remote_insert_exec_catchpoint;
remote_ops.to_remove_exec_catchpoint = remote_remove_exec_catchpoint;
remote_ops.to_execution_direction = remote_execution_direction;
}
/* Set up the extended remote vector by making a copy of the standard