From 3a00c80277a54abe0b286a6e8babc8fe50120205 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Wed, 13 Apr 2016 14:34:00 +0100 Subject: [PATCH] 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 3223143295b5 (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 PR remote/19840 * remote.c (struct remote_state) : 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. --- gdb/ChangeLog | 12 ++++++++++++ gdb/remote.c | 20 ++++++++++++++++++++ 2 files changed, 32 insertions(+) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 63e7caa..d03d5ae 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,15 @@ +2016-04-13 Pedro Alves + + PR remote/19840 + * remote.c (struct remote_state) : 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 * common/common-exceptions.h (GDB_XCPT_TRY): Update comment. diff --git a/gdb/remote.c b/gdb/remote.c index b7ff7bf..4c18b4f 100644 --- a/gdb/remote.c +++ b/gdb/remote.c @@ -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 -- 2.7.4