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remote+docs: software/hardware breakpoint traps
This adjusts target remote to tell the core whether a trap was caused by a breakpoint. To that end, the patch teaches GDB about new RSP stop reasons "T05 swbreak" and "T05 hwbreak", that remote targets report back to GDB, similarly to how "T05 watch" indicates a stop caused by a watchpoint. Because targets that can report these events are expected to themselves adjust the PC after a software breakpoint, these new stop reasons must only be reported if the stub is talking to a GDB that understands them. Because of that, the use of the new stop reasons needs to be handshaked on initial connection, using the qSupported mechanism. GDB simply sends "swbreak+" in its qSupports query, and the stub reports back "swbreak+" too. Because these new stop reasons are required to fix a fundamental non-stop mode problem, this commit extends the remote non-stop intro section in the manual, documenting the events as required. To be clear, GDB will still cope with remote targets that don't support these new stop reasons; it will behave just like today. Tested on x86-64 Fedora 20, native and gdbserver. gdb/ChangeLog: 2015-03-04 Pedro Alves <palves@redhat.com> * NEWS: Mention the new "swbreak" and "hwbreak" stop reasons. * remote.c (struct remote_state) <remote_stopped_by_watchpoint_p>: Delete field. <stop_reason>: New field. (PACKET_swbreak_feature, PACKET_hwbreak_feature): New enum values. (packet_set_cmd_state): New function. (remote_protocol_features): Register the "swbreak" and "hwbreak" features. (remote_query_supported): If not disabled with the corresponding "set remote foo-packet" command, report support for the swbreak and hwbreak features. (struct stop_reply) <remote_stopped_by_watchpoint_p>: Delete field. <stop_reason>: New field. (remote_parse_stop_reply): Handle "swbreak" and "hwbreak". (remote_wait_as): Adjust. (remote_stopped_by_sw_breakpoint) (remote_supports_stopped_by_sw_breakpoint) (remote_stopped_by_hw_breakpoint) (remote_supports_stopped_by_hw_breakpoint): New functions. (remote_stopped_by_watchpoint): New function. (init_remote_ops): Install them. (_initialize_remote): Register new "set/show remote swbreak-feature-packet" and "set/show remote swbreak-feature-packet" commands. gdb/doc/ChangeLog: 2015-03-04 Pedro Alves <palves@redhat.com> * gdb.texinfo (Remote Configuration): Document the "set/show remote swbreak-feature-packet" and "set/show remote hwbreak-feature-packet" commands. (Packets) <Z0>: Add cross link to the "swbreak" stop reason's decription. (Stop Reply Packets): Document the swbreak and hwbreak stop reasons. (General Query Packets): Document the swbreak and hwbreak qSupported features. (Remote Non-Stop): Explain that swbreak and hwbreak are required.
This commit is contained in:
Pedro Alves
parent
9e8915c6ce
commit
f7e6eed528
@ -1,3 +1,31 @@
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2015-03-04 Pedro Alves <palves@redhat.com>
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* NEWS: Mention the new "swbreak" and "hwbreak" stop reasons.
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* remote.c (struct remote_state) <remote_stopped_by_watchpoint_p>:
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Delete field.
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<stop_reason>: New field.
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(PACKET_swbreak_feature, PACKET_hwbreak_feature): New enum values.
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(packet_set_cmd_state): New function.
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(remote_protocol_features): Register the "swbreak" and "hwbreak"
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features.
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(remote_query_supported): If not disabled with the corresponding
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"set remote foo-packet" command, report support for the swbreak
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and hwbreak features.
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(struct stop_reply) <remote_stopped_by_watchpoint_p>: Delete
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field.
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<stop_reason>: New field.
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(remote_parse_stop_reply): Handle "swbreak" and "hwbreak".
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(remote_wait_as): Adjust.
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(remote_stopped_by_sw_breakpoint)
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(remote_supports_stopped_by_sw_breakpoint)
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(remote_stopped_by_hw_breakpoint)
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(remote_supports_stopped_by_hw_breakpoint): New functions.
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(remote_stopped_by_watchpoint): New function.
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(init_remote_ops): Install them.
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(_initialize_remote): Register new "set/show remote
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swbreak-feature-packet" and "set/show remote
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swbreak-feature-packet" commands.
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2015-03-04 Pedro Alves <palves@redhat.com>
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* btrace.h: Include target/waitstatus.h.
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10
gdb/NEWS
10
gdb/NEWS
@ -63,6 +63,16 @@ qXfer:btrace-conf:read
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Qbtrace-conf:bts:size
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Set the requested ring buffer size for branch tracing in BTS format.
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swbreak stop reason
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Indicates a memory breakpoint instruction was executed, irrespective
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of whether it was GDB that planted the breakpoint or the breakpoint
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is hardcoded in the program. This is required for correct non-stop
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mode operation.
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hwbreak stop reason
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Indicates the target stopped for a hardware breakpoint. This is
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required for correct non-stop mode operation.
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* The info record command now shows the recording format and the
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branch tracing configuration for the current thread when using
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the btrace record target.
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@ -1,3 +1,16 @@
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2015-03-04 Pedro Alves <palves@redhat.com>
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* gdb.texinfo (Remote Configuration): Document the "set/show
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remote swbreak-feature-packet" and "set/show remote
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hwbreak-feature-packet" commands.
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(Packets) <Z0>: Add cross link to the "swbreak" stop reason's
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decription.
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(Stop Reply Packets): Document the swbreak and hwbreak stop
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reasons.
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(General Query Packets): Document the swbreak and hwbreak
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qSupported features.
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(Remote Non-Stop): Explain that swbreak and hwbreak are required.
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2015-03-03 Philippe Proulx eeppeliteloop@gmail.com
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* gdb.texinfo (gdb/mi Async Records): Fix duplicate syscall-entry
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@ -19783,6 +19783,15 @@ are:
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@item @code{conditional-breakpoints-packet}
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@tab @code{Z0 and Z1}
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@tab @code{Support for target-side breakpoint condition evaluation}
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@item @code{swbreak-feature}
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@tab @code{swbreak stop reason}
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@tab @code{break}
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@item @code{hwbreak-feature}
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@tab @code{hwbreak stop reason}
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@tab @code{hbreak}
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@end multitable
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@node Remote Stub
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@ -34985,6 +34994,9 @@ form that should be evaluated on the target's side. These are the
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conditions that should be taken into consideration when deciding if
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the breakpoint trigger should be reported back to @var{GDBN}.
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See also the @samp{swbreak} stop reason (@pxref{swbreak stop reason})
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for how to best report a memory breakpoint event to @value{GDBN}.
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The @var{cond_list} parameter is comprised of a series of expressions,
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concatenated without separators. Each expression has the following form:
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@ -35188,6 +35200,34 @@ logged execution events, because it has reached the end (or the
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beginning when executing backward) of the log. The value of @var{r}
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will be either @samp{begin} or @samp{end}. @xref{Reverse Execution},
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for more information.
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@item swbreak
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@anchor{swbreak stop reason}
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The packet indicates a memory breakpoint instruction was executed,
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irrespective of whether it was @value{GDBN} that planted the
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breakpoint or the breakpoint is hardcoded in the program. The @var{r}
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part must be left empty.
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On some architectures, such as x86, at the architecture level, when a
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breakpoint instruction executes the program counter points at the
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breakpoint address plus an offset. On such targets, the stub is
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responsible for adjusting the PC to point back at the breakpoint
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address.
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This packet should not be sent by default; older @value{GDBN} versions
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did not support it. @value{GDBN} requests it, by supplying an
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appropriate @samp{qSupported} feature (@pxref{qSupported}). The
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remote stub must also supply the appropriate @samp{qSupported} feature
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indicating support.
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This packet is required for correct non-stop mode operation.
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@item hwbreak
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The packet indicates the target stopped for a hardware breakpoint.
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The @var{r} part must be left empty.
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The same remarks about @samp{qSupported} and non-stop mode above
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apply.
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@end table
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@item W @var{AA}
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@ -35772,6 +35812,14 @@ description.
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This feature indicates whether @value{GDBN} supports the
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@samp{qRelocInsn} packet (@pxref{Tracepoint Packets,,Relocate
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instruction reply packet}).
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@item swbreak
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This feature indicates whether @value{GDBN} supports the swbreak stop
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reason in stop replies. @xref{swbreak stop reason}, for details.
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@item hwbreak
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This feature indicates whether @value{GDBN} supports the hwbreak stop
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reason in stop replies. @xref{swbreak stop reason}, for details.
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@end table
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Stubs should ignore any unknown values for
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@ -36000,6 +36048,16 @@ These are the currently defined stub features and their properties:
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@tab @samp{-}
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@tab No
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@item @samp{swbreak}
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@tab No
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@tab @samp{-}
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@tab No
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@item @samp{hwbreak}
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@tab No
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@tab @samp{-}
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@tab No
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@end multitable
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These are the currently defined stub features, in more detail:
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@ -36180,6 +36238,14 @@ The remote stub understands the @samp{Qbtrace:bts} packet.
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@item Qbtrace-conf:bts:size
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The remote stub understands the @samp{Qbtrace-conf:bts:size} packet.
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@item swbreak
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The remote stub reports the @samp{swbreak} stop reason for memory
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breakpoints.
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@item hwbreak
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The remote stub reports the @samp{hwbreak} stop reason for hardware
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breakpoints.
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@end table
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@item qSymbol::
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@ -37565,6 +37631,20 @@ If all threads are running when the target receives the @samp{?} packet,
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or if the target is not attached to any process, it shall respond
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@samp{OK}.
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If the stub supports non-stop mode, it should also support the
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@samp{swbreak} stop reason if software breakpoints are supported, and
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the @samp{hwbreak} stop reason if hardware breakpoints are supported
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(@pxref{swbreak stop reason}). This is because given the asynchronous
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nature of non-stop mode, between the time a thread hits a breakpoint
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and the time the event is finally processed by @value{GDBN}, the
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breakpoint may have already been removed from the target. Due to
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this, @value{GDBN} needs to be able to tell whether a trap stop was
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caused by a delayed breakpoint event, which should be ignored, as
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opposed to a random trap signal, which should be reported to the user.
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Note the @samp{swbreak} feature implies that the target is responsible
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for adjusting the PC when a software breakpoint triggers, if
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necessary, such as on the x86 architecture.
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@node Packet Acknowledgment
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@section Packet Acknowledgment
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119
gdb/remote.c
119
gdb/remote.c
@ -364,8 +364,8 @@ struct remote_state
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to stop for a watchpoint. */
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CORE_ADDR remote_watch_data_address;
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/* This is non-zero if target stopped for a watchpoint. */
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int remote_stopped_by_watchpoint_p;
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/* Whether the target stopped for a breakpoint/watchpoint. */
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enum target_stop_reason stop_reason;
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threadref echo_nextthread;
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threadref nextthread;
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@ -1338,11 +1338,26 @@ enum {
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/* Support for the Qbtrace-conf:bts:size packet. */
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PACKET_Qbtrace_conf_bts_size,
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/* Support for swbreak+ feature. */
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PACKET_swbreak_feature,
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/* Support for hwbreak+ feature. */
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PACKET_hwbreak_feature,
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PACKET_MAX
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};
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static struct packet_config remote_protocol_packets[PACKET_MAX];
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/* Returns the packet's corresponding "set remote foo-packet" command
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state. See struct packet_config for more details. */
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static enum auto_boolean
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packet_set_cmd_state (int packet)
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{
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return remote_protocol_packets[packet].detect;
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}
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/* Returns whether a given packet or feature is supported. This takes
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into account the state of the corresponding "set remote foo-packet"
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command, which may be used to bypass auto-detection. */
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@ -4025,7 +4040,9 @@ static const struct protocol_feature remote_protocol_features[] = {
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{ "qXfer:btrace-conf:read", PACKET_DISABLE, remote_supported_packet,
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PACKET_qXfer_btrace_conf },
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{ "Qbtrace-conf:bts:size", PACKET_DISABLE, remote_supported_packet,
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PACKET_Qbtrace_conf_bts_size }
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PACKET_Qbtrace_conf_bts_size },
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{ "swbreak", PACKET_DISABLE, remote_supported_packet, PACKET_swbreak_feature },
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{ "hwbreak", PACKET_DISABLE, remote_supported_packet, PACKET_hwbreak_feature }
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};
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static char *remote_support_xml;
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@ -4094,6 +4111,11 @@ remote_query_supported (void)
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q = remote_query_supported_append (q, "multiprocess+");
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if (packet_set_cmd_state (PACKET_swbreak_feature) != AUTO_BOOLEAN_FALSE)
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q = remote_query_supported_append (q, "swbreak+");
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if (packet_set_cmd_state (PACKET_hwbreak_feature) != AUTO_BOOLEAN_FALSE)
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q = remote_query_supported_append (q, "hwbreak+");
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if (remote_support_xml)
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q = remote_query_supported_append (q, remote_support_xml);
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@ -5202,7 +5224,8 @@ typedef struct stop_reply
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fetch them is avoided). */
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VEC(cached_reg_t) *regcache;
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int stopped_by_watchpoint_p;
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enum target_stop_reason stop_reason;
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CORE_ADDR watch_data_address;
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int core;
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@ -5513,7 +5536,7 @@ remote_parse_stop_reply (char *buf, struct stop_reply *event)
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event->rs = get_remote_state ();
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event->ws.kind = TARGET_WAITKIND_IGNORE;
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event->ws.value.integer = 0;
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event->stopped_by_watchpoint_p = 0;
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event->stop_reason = TARGET_STOPPED_BY_NO_REASON;
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event->regcache = NULL;
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event->core = -1;
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@ -5556,10 +5579,36 @@ Packet: '%s'\n"),
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|| (strncmp (p, "rwatch", p1 - p) == 0)
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|| (strncmp (p, "awatch", p1 - p) == 0))
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{
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event->stopped_by_watchpoint_p = 1;
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event->stop_reason = TARGET_STOPPED_BY_WATCHPOINT;
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p = unpack_varlen_hex (++p1, &addr);
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event->watch_data_address = (CORE_ADDR) addr;
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}
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else if (strncmp (p, "swbreak", p1 - p) == 0)
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{
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event->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT;
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/* Make sure the stub doesn't forget to indicate support
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with qSupported. */
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if (packet_support (PACKET_swbreak_feature) != PACKET_ENABLE)
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error (_("Unexpected swbreak stop reason"));
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/* The value part is documented as "must be empty",
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though we ignore it, in case we ever decide to make
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use of it in a backward compatible way. */
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p = skip_to_semicolon (p1 + 1);
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}
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else if (strncmp (p, "hwbreak", p1 - p) == 0)
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{
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event->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT;
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/* Make sure the stub doesn't forget to indicate support
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with qSupported. */
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if (packet_support (PACKET_hwbreak_feature) != PACKET_ENABLE)
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error (_("Unexpected hwbreak stop reason"));
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/* See above. */
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p = skip_to_semicolon (p1 + 1);
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}
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else if (strncmp (p, "library", p1 - p) == 0)
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{
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event->ws.kind = TARGET_WAITKIND_LOADED;
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@ -5817,7 +5866,7 @@ process_stop_reply (struct stop_reply *stop_reply,
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VEC_free (cached_reg_t, stop_reply->regcache);
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}
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rs->remote_stopped_by_watchpoint_p = stop_reply->stopped_by_watchpoint_p;
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rs->stop_reason = stop_reply->stop_reason;
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rs->remote_watch_data_address = stop_reply->watch_data_address;
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remote_notice_new_inferior (ptid, 0);
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@ -5944,7 +5993,7 @@ remote_wait_as (ptid_t ptid, struct target_waitstatus *status, int options)
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buf = rs->buf;
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rs->remote_stopped_by_watchpoint_p = 0;
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rs->stop_reason = TARGET_STOPPED_BY_NO_REASON;
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/* We got something. */
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rs->waiting_for_stop_reply = 0;
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@ -8421,12 +8470,54 @@ remote_check_watch_resources (struct target_ops *self,
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return -1;
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}
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/* The to_stopped_by_sw_breakpoint method of target remote. */
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static int
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remote_stopped_by_sw_breakpoint (struct target_ops *ops)
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{
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struct remote_state *rs = get_remote_state ();
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return rs->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT;
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}
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/* The to_supports_stopped_by_sw_breakpoint method of target
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remote. */
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static int
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remote_supports_stopped_by_sw_breakpoint (struct target_ops *ops)
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{
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struct remote_state *rs = get_remote_state ();
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return (packet_support (PACKET_swbreak_feature) == PACKET_ENABLE);
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}
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/* The to_stopped_by_hw_breakpoint method of target remote. */
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static int
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remote_stopped_by_hw_breakpoint (struct target_ops *ops)
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{
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struct remote_state *rs = get_remote_state ();
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return rs->stop_reason == TARGET_STOPPED_BY_HW_BREAKPOINT;
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}
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/* The to_supports_stopped_by_hw_breakpoint method of target
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remote. */
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static int
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remote_supports_stopped_by_hw_breakpoint (struct target_ops *ops)
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{
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struct remote_state *rs = get_remote_state ();
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return (packet_support (PACKET_hwbreak_feature) == PACKET_ENABLE);
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}
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static int
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remote_stopped_by_watchpoint (struct target_ops *ops)
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{
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struct remote_state *rs = get_remote_state ();
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return rs->remote_stopped_by_watchpoint_p;
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return rs->stop_reason == TARGET_STOPPED_BY_WATCHPOINT;
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}
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static int
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@ -11617,6 +11708,10 @@ Specify the serial device it is connected to\n\
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remote_ops.to_files_info = remote_files_info;
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remote_ops.to_insert_breakpoint = remote_insert_breakpoint;
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remote_ops.to_remove_breakpoint = remote_remove_breakpoint;
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remote_ops.to_stopped_by_sw_breakpoint = remote_stopped_by_sw_breakpoint;
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remote_ops.to_supports_stopped_by_sw_breakpoint = remote_supports_stopped_by_sw_breakpoint;
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remote_ops.to_stopped_by_hw_breakpoint = remote_stopped_by_hw_breakpoint;
|
||||
remote_ops.to_supports_stopped_by_hw_breakpoint = remote_supports_stopped_by_hw_breakpoint;
|
||||
remote_ops.to_stopped_by_watchpoint = remote_stopped_by_watchpoint;
|
||||
remote_ops.to_stopped_data_address = remote_stopped_data_address;
|
||||
remote_ops.to_watchpoint_addr_within_range =
|
||||
@ -12322,6 +12417,12 @@ Show the maximum size of the address (in bits) in a memory packet."), NULL,
|
||||
add_packet_config_cmd (&remote_protocol_packets[PACKET_Qbtrace_conf_bts_size],
|
||||
"Qbtrace-conf:bts:size", "btrace-conf-bts-size", 0);
|
||||
|
||||
add_packet_config_cmd (&remote_protocol_packets[PACKET_swbreak_feature],
|
||||
"swbreak-feature", "swbreak-feature", 0);
|
||||
|
||||
add_packet_config_cmd (&remote_protocol_packets[PACKET_hwbreak_feature],
|
||||
"hwbreak-feature", "hwbreak-feature", 0);
|
||||
|
||||
/* Assert that we've registered commands for all packet configs. */
|
||||
{
|
||||
int i;
|
||||
|
||||
Loading…
Reference in New Issue
Block a user