btrace: control memory access during replay
The btrace record target does not trace data. We therefore do not allow accessing read-write memory during replay. In some cases, this might be useful to advanced users, though, who we assume to know what they are doing. Add a set|show command pair to turn this memory access restriction off. * record-btrace.c (record_btrace_allow_memory_access): Remove. (replay_memory_access_read_only, replay_memory_access_read_write) (replay_memory_access_types, replay_memory_access) (set_record_btrace_cmdlist, show_record_btrace_cmdlist) (cmd_set_record_btrace, cmd_show_record_btrace) (cmd_show_replay_memory_access): New. (record_btrace_xfer_partial, record_btrace_insert_breakpoint) (record_btrace_remove_breakpoint): Replace record_btrace_allow_memory_access with replay_memory_access. (_initialize_record_btrace): Add commands. * NEWS: Announce it. testsuite/ * gdb.btrace/data.exp: Test it. doc/ * gdb.texinfo (Process Record and Replay): Document it.
This commit is contained in:
Markus Metzger
parent
4c6bdb4026
commit
67b5c0c1a4
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@ -1,3 +1,17 @@
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2014-05-23 Markus Metzger <markus.t.metzger@intel.com>
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* record-btrace.c (record_btrace_allow_memory_access): Remove.
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(replay_memory_access_read_only, replay_memory_access_read_write)
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(replay_memory_access_types, replay_memory_access)
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(set_record_btrace_cmdlist, show_record_btrace_cmdlist)
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(cmd_set_record_btrace, cmd_show_record_btrace)
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(cmd_show_replay_memory_access): New.
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(record_btrace_xfer_partial, record_btrace_insert_breakpoint)
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(record_btrace_remove_breakpoint): Replace
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record_btrace_allow_memory_access with replay_memory_access.
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(_initialize_record_btrace): Add commands.
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* NEWS: Announce it.
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2014-05-22 Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>
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* aarch64-linux-nat.c (asm/ptrace.h): Include.
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4
gdb/NEWS
4
gdb/NEWS
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@ -67,6 +67,10 @@ set auto-connect-native-target
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native target for the run, attach, etc. commands when not connected
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to any target yet. See also "target native" below.
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set record btrace replay-memory-access (read-only|read-write)
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show record btrace replay-memory-access
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Control what memory accesses are allowed during replay.
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* New features in the GDB remote stub, GDBserver
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** New option --debug-format=option1[,option2,...] allows one to add
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@ -1,3 +1,8 @@
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2014-05-23 Markus Metzger <markus.t.metzger@intel.com>
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* gdb.texinfo (Process Record and Replay): Document "set/show btrace
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replay-memory-access".
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2014-05-21 Pedro Alves <palves@redhat.com>
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* gdb.texinfo (Starting): Document "set/show
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@ -6451,6 +6451,28 @@ results.
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@item show record full memory-query
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Show the current setting of @code{memory-query}.
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@kindex set record btrace
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The @code{btrace} record target does not trace data. As a
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convenience, when replaying, @value{GDBN} reads read-only memory off
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the live program directly, assuming that the addresses of the
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read-only areas don't change. This for example makes it possible to
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disassemble code while replaying, but not to print variables.
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In some cases, being able to inspect variables might be useful.
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You can use the following command for that:
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@item set record btrace replay-memory-access
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Control the behavior of the @code{btrace} recording method when
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accessing memory during replay. If @code{read-only} (the default),
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@value{GDBN} will only allow accesses to read-only memory.
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If @code{read-write}, @value{GDBN} will allow accesses to read-only
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and to read-write memory. Beware that the accessed memory corresponds
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to the live target and not necessarily to the current replay
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position.
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@kindex show record btrace
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@item show record btrace replay-memory-access
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Show the current setting of @code{replay-memory-access}.
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@kindex info record
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@item info record
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Show various statistics about the recording depending on the recording
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@ -43,8 +43,22 @@ static struct target_ops record_btrace_ops;
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/* A new thread observer enabling branch tracing for the new thread. */
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static struct observer *record_btrace_thread_observer;
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/* Temporarily allow memory accesses. */
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static int record_btrace_allow_memory_access;
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/* Memory access types used in set/show record btrace replay-memory-access. */
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static const char replay_memory_access_read_only[] = "read-only";
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static const char replay_memory_access_read_write[] = "read-write";
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static const char *const replay_memory_access_types[] =
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{
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replay_memory_access_read_only,
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replay_memory_access_read_write,
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NULL
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};
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/* The currently allowed replay memory access type. */
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static const char *replay_memory_access = replay_memory_access_read_only;
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/* Command lists for "set/show record btrace". */
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static struct cmd_list_element *set_record_btrace_cmdlist;
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static struct cmd_list_element *show_record_btrace_cmdlist;
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/* Print a record-btrace debug message. Use do ... while (0) to avoid
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ambiguities when used in if statements. */
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@ -816,7 +830,8 @@ record_btrace_xfer_partial (struct target_ops *ops, enum target_object object,
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struct target_ops *t;
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/* Filter out requests that don't make sense during replay. */
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if (!record_btrace_allow_memory_access && record_btrace_is_replaying (ops))
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if (replay_memory_access == replay_memory_access_read_only
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&& record_btrace_is_replaying (ops))
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{
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switch (object)
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{
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@ -870,18 +885,19 @@ record_btrace_insert_breakpoint (struct target_ops *ops,
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struct bp_target_info *bp_tgt)
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{
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volatile struct gdb_exception except;
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int old, ret;
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const char *old;
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int ret;
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/* Inserting breakpoints requires accessing memory. Allow it for the
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duration of this function. */
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old = record_btrace_allow_memory_access;
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record_btrace_allow_memory_access = 1;
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old = replay_memory_access;
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replay_memory_access = replay_memory_access_read_write;
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ret = 0;
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TRY_CATCH (except, RETURN_MASK_ALL)
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ret = ops->beneath->to_insert_breakpoint (ops->beneath, gdbarch, bp_tgt);
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record_btrace_allow_memory_access = old;
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replay_memory_access = old;
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if (except.reason < 0)
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throw_exception (except);
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@ -897,18 +913,19 @@ record_btrace_remove_breakpoint (struct target_ops *ops,
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struct bp_target_info *bp_tgt)
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{
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volatile struct gdb_exception except;
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int old, ret;
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const char *old;
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int ret;
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/* Removing breakpoints requires accessing memory. Allow it for the
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duration of this function. */
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old = record_btrace_allow_memory_access;
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record_btrace_allow_memory_access = 1;
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old = replay_memory_access;
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replay_memory_access = replay_memory_access_read_write;
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ret = 0;
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TRY_CATCH (except, RETURN_MASK_ALL)
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ret = ops->beneath->to_remove_breakpoint (ops->beneath, gdbarch, bp_tgt);
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record_btrace_allow_memory_access = old;
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replay_memory_access = old;
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if (except.reason < 0)
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throw_exception (except);
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@ -1939,6 +1956,32 @@ cmd_record_btrace_start (char *args, int from_tty)
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execute_command ("target record-btrace", from_tty);
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}
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/* The "set record btrace" command. */
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static void
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cmd_set_record_btrace (char *args, int from_tty)
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{
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cmd_show_list (set_record_btrace_cmdlist, from_tty, "");
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}
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/* The "show record btrace" command. */
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static void
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cmd_show_record_btrace (char *args, int from_tty)
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{
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cmd_show_list (show_record_btrace_cmdlist, from_tty, "");
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}
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/* The "show record btrace replay-memory-access" command. */
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static void
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cmd_show_replay_memory_access (struct ui_file *file, int from_tty,
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struct cmd_list_element *c, const char *value)
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{
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fprintf_filtered (gdb_stdout, _("Replay memory access is %s.\n"),
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replay_memory_access);
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}
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void _initialize_record_btrace (void);
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/* Initialize btrace commands. */
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@ -1951,6 +1994,29 @@ _initialize_record_btrace (void)
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&record_cmdlist);
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add_alias_cmd ("b", "btrace", class_obscure, 1, &record_cmdlist);
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add_prefix_cmd ("btrace", class_support, cmd_set_record_btrace,
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_("Set record options"), &set_record_btrace_cmdlist,
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"set record btrace ", 0, &set_record_cmdlist);
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add_prefix_cmd ("btrace", class_support, cmd_show_record_btrace,
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_("Show record options"), &show_record_btrace_cmdlist,
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"show record btrace ", 0, &show_record_cmdlist);
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add_setshow_enum_cmd ("replay-memory-access", no_class,
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replay_memory_access_types, &replay_memory_access, _("\
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Set what memory accesses are allowed during replay."), _("\
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Show what memory accesses are allowed during replay."),
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_("Default is READ-ONLY.\n\n\
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The btrace record target does not trace data.\n\
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The memory therefore corresponds to the live target and not \
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to the current replay position.\n\n\
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When READ-ONLY, allow accesses to read-only memory during replay.\n\
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When READ-WRITE, allow accesses to read-only and read-write memory during \
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replay."),
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NULL, cmd_show_replay_memory_access,
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&set_record_btrace_cmdlist,
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&show_record_btrace_cmdlist);
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init_record_btrace_ops ();
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add_target (&record_btrace_ops);
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@ -1,3 +1,7 @@
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2014-05-23 Markus Metzger <markus.t.metzger@intel.com>
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* gdb.btrace/data.exp: Test memory access during btrace replay.
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2014-05-22 Simon Marchi <simon.marchi@ericsson.com>
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* lib/mi-support.exp (mi_run_cmd_full): Add comments.
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@ -40,6 +40,14 @@ gdb_test "reverse-step" ".*test\.4.*"
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gdb_test "print glob" "unavailable\[^\\\r\\\n\]*"
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gdb_test "print loc" "unavailable\[^\\\r\\\n\]*"
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# stop replaying and try again
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gdb_test "record goto end"
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# we can read memory if we explicitly allow it.
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gdb_test_no_output "set record btrace replay-memory-access read-write"
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gdb_test "print glob" "1"
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# we can't if we don't explicitly allow it.
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gdb_test_no_output "set record btrace replay-memory-access read-only"
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gdb_test "print glob" "unavailable\[^\\\r\\\n\]*"
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# stop replaying and try again
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gdb_test "record goto end" ".*main\.3.*"
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gdb_test "print glob" "1"
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