This is a test for GDB reverse debugging commands: reverse step and reverse continue.
Every test in this suite consists of two phases: record and replay.
Recording saves the execution of some instructions and makes an initial
VM snapshot to allow reverse execution.
Replay saves the order of the first instructions and then checks that they
are executed backwards in the correct order.
After that the execution is replayed to the end, and reverse continue
command is checked by setting several breakpoints, and asserting
that the execution is stopped at the last of them.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>

--

v5:
 - disabled (as some other tests) when running on gitlab
   due to the unidentified timeout problem
Message-Id: <160174524678.12451.13258942849173670277.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

When record/replay does not uses overlays for storing the snapshots,
user is not capable of issuing reverse debugging commands.
This patch adds creation of the VM snapshot on the temporary
overlay image, when the debugger connects to QEMU.
Therefore the execution can be rewind to the moment
of the debugger connection while debugging the virtual machine.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>

--

v6:
 - dropped unused error processing (suggested by Philippe Mathieu-Daudé)
Message-Id: <160174524096.12451.11651270339216758643.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch updates the documentation and describes usage of the reverse
debugging in QEMU+GDB.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

--

v4 changes:
 - added an example of the command line for reverse debugging of
   the diskless machine
Message-Id: <160174523509.12451.1409905901920738979.stgit@pasha-ThinkPad-X280>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch adds support of the reverse continue operation for gdbstub.
Reverse continue finds the last breakpoint that would happen in normal
execution from the beginning to the current moment.
Implementation of the reverse continue replays the execution twice:
to find the breakpoints that were hit and to seek to the last breakpoint.
Reverse continue loads the previous snapshot and tries to find the breakpoint
since that moment. If there are no such breakpoints, it proceeds to
the earlier snapshot, and so on. When no breakpoints or watchpoints were
hit at all, execution stops at the beginning of the replay log.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Message-Id: <160174522930.12451.6994758004725016836.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

GDB remote protocol supports two reverse debugging commands:
reverse step and reverse continue.
This patch adds support of the first one to the gdbstub.
Reverse step is intended to step one instruction in the backwards
direction. This is not possible in regular execution.
But replayed execution is deterministic, therefore we can load one of
the prior snapshots and proceed to the desired step. It is equivalent
to stepping one instruction back.
There should be at least one snapshot preceding the debugged part of
the replay log.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

--

v4 changes:
 - inverted condition in cpu_handle_guest_debug (suggested by Alex Bennée)
Message-Id: <160174522341.12451.1498758422543765253.stgit@pasha-ThinkPad-X280>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Non-empty record/replay queue prevents saving and loading the VM state,
because it includes pending bottom halves and block coroutines.
But when the new VM state is loaded, we don't have to preserve the consistency
of the current state anymore. Therefore this patch just flushes the queue
allowing the coroutines to finish and removes checking for empty rr queue
for load_snapshot function.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <160174521762.12451.15752448887893855757.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch adds hmp/qmp commands replay_seek/replay-seek that proceed
the execution to the specified instruction count.
The command automatically loads nearest snapshot and replays the execution
to find the desired instruction count.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Acked-by: Markus Armbruster <armbru@redhat.com>

--

v4 changes:
 - fixed HMP command description indent
 - removed useless error_free call
Message-Id: <160174521180.12451.14033112911009278753.stgit@pasha-ThinkPad-X280>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch introduces replay_break, replay_delete_break
qmp and hmp commands.
These commands allow stopping at the specified instruction.
It may be useful for debugging when there are some known
events that should be investigated.
replay_break command has one argument - number of instructions
executed since the start of the replay.
replay_delete_break removes previously set breakpoint.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Acked-by: Markus Armbruster <armbru@redhat.com>

--

v4 changes:
 - removed useless error_free call
Message-Id: <160174520606.12451.7056879546045599378.stgit@pasha-ThinkPad-X280>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch introduces 'info replay' monitor command and
corresponding qmp request.
These commands request the current record/replay mode, replay log file
name, and the instruction count (number of recorded/replayed
instructions).  The instruction count can be used with the
replay_seek/replay_break commands added in the next two patches.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <160174520026.12451.13112161947433306561.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch adds replay.json file. It will be
used for adding record/replay-related data structures and commands.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <160174519444.12451.3472949430004845434.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Saving icount as a parameters of the snapshot allows navigation between
them in the execution replay scenario.
This information can be used for finding a specific snapshot for proceeding
the recorded execution to the specific moment of the time.
E.g., 'reverse step' action (introduced in one of the following patches)
needs to load the nearest snapshot which is prior to the current moment
of time.
This patch also updates snapshot test which verifies qemu monitor output.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Acked-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Kevin Wolf <kwolf@redhat.com>

--

v4 changes:
 - squashed format update with test output update
v7 changes:
 - introduced the spaces between the fields in snapshot info output
 - updated the test to match new field widths
Message-Id: <160174518865.12451.14327573383978752463.stgit@pasha-ThinkPad-X280>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch introduces the icount field for saving within the snapshot.
It is required for navigation between the snapshots in record/replay mode.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Acked-by: Kevin Wolf <kwolf@redhat.com>

--

v7 changes:
 - also fix the test which checks qcow2 snapshot extra data
Message-Id: <160174518284.12451.2301137308458777398.stgit@pasha-ThinkPad-X280>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch adds an accessor function for the name of the record/replay
log file. Adding an accessor instead of making variable global,
prevents accidental modification of this variable by other modules.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <160174517710.12451.17645787545733927488.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Interrupt poll is not a real interrupt event. It is needed only for
thread safety. This interrupt is used for i386 and converted
to hardware interrupt by cpu_handle_interrupt function.
Therefore it is not needed to be recorded, because hardware
interrupt will be recorded after converting.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

--

v4 changes:
 - Condition check refactoring (suggested by Alex Bennée)
Message-Id: <160174517124.12451.12983410242461131737.stgit@pasha-ThinkPad-X280>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Unlike other OSs it is not possible for gdb to temporarily disable ASLR when
debugging executables on Windows which causes gdb to fail with memory access
errors when trying to debug QEMU.

Keep ASLR enabled by default on Windows via the --dynamicbase compiler flag
except for --enable-debug builds when there is a clear expectation that a
functioning gdb is expected at the cost of slightly less security.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20201005133434.12614-1-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Environment variables like CFLAGS are easy to accidentally change.  Meson
warns if that happens, but in a project with a lot of configuration that
is easy to lose.  It is also surprising behavior since meson caches -D
options and remembers those on reconfiguration (which we rely on,
since configure options become -D options).

By placing the user-provided CFLAGS, CXXFLAGS and LDFLAGS in the
cross file, we at least get consistent behavior.  These environment
variables are still ugly and not really recommended, but there are
distros that rely on them.  For the gory details, refer to
https://github.com/mesonbuild/meson/issues/4664

.

Tested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200923092617.1593722-5-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

If the CFLAGS, CXXFLAGS or LDFLAGS variables are present in the environment,
any modification made within the configure script is passed down to Meson.
This is particularly undesirable for the "-pie" option, since it overrides
"-shared" and thus messes up the linker flags for shared modules.

Using a separate variable therefore fixes the bug, while clarifying that
the scope of these CFLAGS is just the configure script.

We also do not need to pass those variables in config-host.mak; they
were only used for printing the summary now that all submodules are
built with handwritten Meson rules).  For now synthesize CFLAGS in the
configuration summary, the next patch will also pass them in a cleaner
way using the cross file.

Reported-by: Frederic Bezies
Analyzed-by: Toolybird
Tested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200923092617.1593722-4-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Build the library via the main meson.build just like for capstone.
This improves the current state of affairs in that we will re-link
the qemu executables against a changed libfdt.a, which we wouldn't
do before-hand, and lets us remove the whole recursive make machinery.

Tested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

SLIRP uses Meson so it could become a subproject in the future,
but our choice of configure options is not yet supported in Meson
(https://github.com/mesonbuild/meson/pull/7740

).

For now, build the library via the main meson.build just like for
capstone.

This improves the current state of affairs in that we will re-link
the qemu executables against a changed libslirp.a, which we wouldn't
do before-hand.

Tested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

current_machine is always set before accelerators are initialized,
so use that instead of MACHINE(qdev_get_machine()).

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Clean up the error handling in kvm_init_vcpu so we can see what went
wrong more easily.

Make it take an Error ** and fill it out with what failed, including
the cpu id, so you can tell if it only fails at a given ID.

Replace the remaining DPRINTF by a trace.

This turns a:
kvm_init_vcpu failed: Invalid argument

into:
kvm_init_vcpu: kvm_get_vcpu failed (256): Invalid argument

and with the trace you then get to see:

19049@1595520414.310107:kvm_init_vcpu index: 169 id: 212
19050@1595520414.310635:kvm_init_vcpu index: 170 id: 256
qemu-system-x86_64: kvm_init_vcpu: kvm_get_vcpu failed (256): Invalid argument

which makes stuff a lot more obvious.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200723160915.129069-1-dgilbert@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

kvm: uses the generic handler
qtest: uses the generic handler
whpx: changed to use the generic handler (identical implementation)
hax: changed to use the generic handler (identical implementation)
hvf: changed to use the generic handler (identical implementation)
tcg: adapt tcg-cpus to point to the tcg-specific handler

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

now that all accelerators support the CpusAccel interface,
we can remove most checks for non-NULL cpus_accel,
we just add a sanity check/assert at vcpu creation.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

register a "CpusAccel" interface for HVF as well.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
[added const]
Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

register a "CpusAccel" interface for WHPX as well.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

register a "CpusAccel" interface for HAX as well.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

register a "CpusAccel" interface for KVM as well.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
[added const]
Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

register a "CpusAccel" interface for qtest as well.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

TCG is the first accelerator to register a "CpusAccel" interface
on initialization, providing functions for starting a vcpu,
kicking a vcpu, sychronizing state and getting virtual clock
and ticks.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
[added const]
Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

The new interface starts unused, will start being used by the
next patches.

It provides methods for each accelerator to start a vcpu, kick a vcpu,
synchronize state, get cpu virtual clock and elapsed ticks.

In qemu_wait_io_event, make it clear that APC is used only for HAX
on Windows.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

refactoring of cpus.c continues with cpu timer state extraction.

cpu-timers: responsible for the softmmu cpu timers state,
            including cpu clocks and ticks.

icount: counts the TCG instructions executed. As such it is specific to
the TCG accelerator. Therefore, it is built only under CONFIG_TCG.

One complication is due to qtest, which uses an icount field to warp time
as part of qtest (qtest_clock_warp).

In order to solve this problem, provide a separate counter for qtest.

This requires fixing assumptions scattered in the code that
qtest_enabled() implies icount_enabled(), checking each specific case.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
[remove redundant initialization with qemu_spice_init]
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
[fix lingering calls to icount_get]
Signed-off-by: Claudio Fontana <cfontana@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

* move target configuration to default-configs/targets (myself)
* Memory failure event (Zhenwei)

# gpg: Signature made Mon 05 Oct 2020 08:14:29 BST
# gpg:                using RSA key F13338574B662389866C7682BFFBD25F78C7AE83
# gpg:                issuer "pbonzini@redhat.com"
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>" [full]
# gpg:                 aka "Paolo Bonzini <pbonzini@redhat.com>" [full]
# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4  E2F7 7E15 100C CD36 69B1
#      Subkey fingerprint: F133 3857 4B66 2389 866C  7682 BFFB D25F 78C7 AE83

* remotes/bonzini-gitlab/tags/for-upstream:
  dockerfiles: add diffutils to Fedora
  tests: tcg: do not use implicit rules
  target-i386: post memory failure event to QMP
  qapi/run-state.json: introduce memory failure event
  target-i386: seperate MCIP & MCE_MASK error reason
  meson: move sparse detection to Meson and rewrite check_sparse.py
  default-configs: remove redundant keys
  default-configs: use TARGET_ARCH key
  configure: move OpenBSD W^X test to meson
  default-configs: remove default-configs/devices for user-mode targets
  configure: remove target configuration
  configure: remove useless config-target.mak symbols
  configure: compute derivatives of target name in meson
  configure: remove dead variable
  configure: move accelerator logic to meson
  configure: rewrite accelerator defaults as tests
  configure: convert accelerator variables to meson options
  default-configs: move files to default-configs/devices/
  travis: remove TCI test

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

# Conflicts:
#	configure

Update capstone submodule from v3.0.5 to v5 ("next").
Convert submodule build to meson.
Enable capstone disassembly for s390x.
Code cleanups in disas.c

# gpg: Signature made Sat 03 Oct 2020 10:33:44 BST
# gpg:                using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F
# gpg:                issuer "richard.henderson@linaro.org"
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>" [full]
# Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A  05C0 64DF 38E8 AF7E 215F

* remotes/rth-gitlab/tags/pull-cap-20201003:
  disas/capstone: Add skipdata hook for s390x
  disas: Enable capstone disassembly for s390x
  disas: Split out capstone code to disas/capstone.c
  disas: Configure capstone for aarch64 host without libvixl
  disas: Cleanup plugin_disas
  disas: Use qemu/bswap.h for bfd endian loads
  disas: Clean up CPUDebug initialization
  disas: Move host asm annotations to tb_gen_code
  capstone: Require version 4.0 from a system library
  capstone: Update to upstream "next" branch
  capstone: Convert Makefile bits to meson bits

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

For some reason diffutils is not included in the Fedora containers anymore,
causing the build to fail.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Neal Gompa <ngompa13@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20201003085054.332992-2-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>