To allow us to select a different platform based on where the process is
running, plumb the process host architecture through platform selection.
This patch is in preparation for D121444 which needs this functionality
to tell apart iOS binaries running on Apple Silicon vs on a remote iOS
device.
Differential revision: https://reviews.llvm.org/D121484
All current callers set the argument to false. monitor_signals=true used
to be used in the Process plugins (which needed to know when the
debugged process gets a signal), but this implementation has several
serious issues, which means that individual process plugins now
orchestrate the monitoring of debugged processes themselves.
This allows us to simplify the implementation (no need to play with
process groups), and the interface (we only catch fatal events, so the
callback is always called just once).
Differential Revision: https://reviews.llvm.org/D120425
The race is between these two pieces of code that are executed in two separate
lldb-vscode threads (the first is in the main thread and another is in the
event-handling thread):
```
// lldb-vscode.cpp
g_vsc.debugger.SetAsync(false);
g_vsc.target.Launch(launch_info, error);
g_vsc.debugger.SetAsync(true);
```
```
// Target.cpp
bool old_async = debugger.GetAsyncExecution();
debugger.SetAsyncExecution(true);
debugger.GetCommandInterpreter().HandleCommands(GetCommands(), exc_ctx,
options, result);
debugger.SetAsyncExecution(old_async);
```
The sequence that leads to the bug is this one:
1. Main thread enables synchronous mode and launches the process.
2. When the process is launched, it generates the first stop event.
3. This stop event is catched by the event-handling thread and DoOnRemoval
is invoked.
4. Inside DoOnRemoval, this thread runs stop hooks. And before running stop
hooks, the current synchronization mode is stored into old_async (and
right now it is equal to "false").
5. The main thread finishes the launch and returns to lldb-vscode, the
synchronization mode is restored to asynchronous by lldb-vscode.
6. Event-handling thread finishes stop hooks processing and restores the
synchronization mode according to old_async (i.e. makes the mode synchronous)
7. And now the mode is synchronous while lldb-vscode expects it to be
asynchronous. Synchronous mode forbids the process to broadcast public stop
events, so, VS Code just hangs because lldb-vscode doesn't notify it about
stops.
So, this diff makes the target intercept the first stop event if the process is
launched in the synchronous mode, thus preventing stop hooks execution.
The bug is only present on Windows because other platforms already
intercept this event using their own hijacking listeners.
So, this diff also fixes some problems with lldb-vscode tests on Windows to make
it possible to run the related test. Other tests still can't be enabled because
the debugged program prints something into stdout and LLDB can't intercept this
output and redirect it to lldb-vscode properly.
Reviewed By: jingham
Differential Revision: https://reviews.llvm.org/D119548
Most of our code was including Log.h even though that is not where the
"lldb" log channel is defined (Log.h defines the generic logging
infrastructure). This worked because Log.h included Logging.h, even
though it should.
After the recent refactor, it became impossible the two files include
each other in this direction (the opposite inclusion is needed), so this
patch removes the workaround that was put in place and cleans up all
files to include the right thing. It also renames the file to LLDBLog to
better reflect its purpose.
Both serve the same purpose (finding shared libraries) and allow one to
launch a dynamically linked executable by just specifying the platform
sysroot.
This small patch adds two useful improvements:
- allows one to specify the emulator path as a bare filename, and have
it be looked up in the PATH
- allows one to leave the path empty and have the filename be derived
from the architecture.
This setting is for variables we want to pass to the emulator only --
then will be automatically removed from the target environment by our
environment diffing code. This variable can be used to pass various
QEMU_*** variables (although most of these can be passed through
emulator-args as well), as well as any other variables that can affect
the operation of the emulator (e.g. LD_LIBRARY_PATH).
The test for this functionality was failing on the darwin bot, because
the entries came out in opposite order. While this does not impact
functionality, and the algorithm that produces it is technically
deterministic (the nondeterminism comes from the contents of the host
environment), it seems like it would be more user-friendly if the
entries came out in a more predictible order.
Therefore I am adding the sort call to the actual code instead of
relaxing test expectations.
Qemu normally forwards its (host) environment variables to the emulated
process. While this works fine for most variables, there are some (few, but
fairly important) variables where this is not possible. LD_LIBRARY_PATH
is the probably the most important of those -- we don't want the library
search path for the emulated libraries to interfere with the libraries
that the emulator itself needs.
For this reason, qemu provides a mechanism (QEMU_SET_ENV,
QEMU_UNSET_ENV) to set variables only for the emulated process. This
patch makes use of that functionality to pass any user-provided
variables to the emulated process. Since we're piggy-backing on the
normal lldb environment-handling mechanism, all the usual mechanism to
provide environment (target.env-vars setting, SBLaunchInfo, etc.) work
out-of-the-box, and the only thing we need to do is to properly
construct the qemu environment variables.
This patch also adds a new setting -- target-env-vars, which represents
environment variables which are added (on top of the host environment)
to the default launch environments of all (qemu) targets. The reason for
its existence is to enable the configuration (e.g., from a startup
script) of the default launch environment, before any target is created.
The idea is that this would contain the variables (like the
aforementioned LD_LIBRARY_PATH) common to all targets being debugged on
the given system. The user is, of course, free to customize the
environment for a particular target in the usual manner.
The reason I do not want to use/recommend the "global" version of the
target.env-vars setting for this purpose is that the setting would apply
to all targets, whereas the settings (their values) I have mentioned
would be specific to the given platform.
Differential Revision: https://reviews.llvm.org/D115246
This setting allows the user to pass additional arguments to the qemu instance.
While we may want to introduce dedicated settings for the most common qemu
arguments (-cpu, for one), having this setting allows us to avoid creating a
setting for every possible argument.
Differential Revision: https://reviews.llvm.org/D115151
Lldb uses a pty to read/write to the standard input and output of the
debugged process. For host processes this would be automatically set up
by Target::FinalizeFileActions. The Qemu platform is in a unique
position of not really being a host platform, but not being remote
either. It reports IsHost() = false, but it is sufficiently host-like
that we can use the usual pty mechanism.
This patch adds the necessary glue code to enable pty redirection. It
includes a small refactor of Target::FinalizeFileActions and
ProcessLaunchInfo::SetUpPtyRedirection to reduce the amount of
boilerplate that would need to be copied.
I will note that qemu is not able to separate output from the emulated
program from the output of the emulator itself, so the two will arrive
intertwined. Normally this should not be a problem since qemu should not
produce any output during regular operation, but some output can slip
through in case of errors. This situation should be pretty obvious (to a
human), and it is the best we can do anyway.
For testing purposes, and inspired by lldb-server tests, I have extended
the mock emulator with the ability "program" the behavior of the
"emulated" program via command-line arguments.
Differential Revision: https://reviews.llvm.org/D114796
This adds a new platform class, whose job is to enable running
(debugging) executables under qemu.
(For general information about qemu, I recommend reading the RFC thread
on lldb-dev
<https://lists.llvm.org/pipermail/lldb-dev/2021-October/017106.html>.)
This initial patch implements the necessary boilerplate as well as the
minimal amount of functionality needed to actually be able to do
something useful (which, in this case means debugging a fully statically
linked executable).
The knobs necessary to emulate dynamically linked programs, as well as
to control other aspects of qemu operation (the emulated cpu, for
instance) will be added in subsequent patches. Same goes for the ability
to automatically bind to the executables of the emulated architecture.
Currently only two settings are available:
- architecture: the architecture that we should emulate
- emulator-path: the path to the emulator
Even though this patch is relatively small, it doesn't lack subtleties
that are worth calling out explicitly:
- named sockets: qemu supports tcp and unix socket connections, both of
them in the "forward connect" mode (qemu listening, lldb connecting).
Forward TCP connections are impossible to realise in a race-free way.
This is the reason why I chose unix sockets as they have larger, more
structured names, which can guarantee that there are no collisions
between concurrent connection attempts.
- the above means that this code will not work on windows. I don't think
that's an issue since user mode qemu does not support windows anyway.
- Right now, I am leaving the code enabled for windows, but maybe it
would be better to disable it (otoh, disabling it means windows
developers can't check they don't break it)
- qemu-user also does not support macOS, so one could contemplate
disabling it there too. However, macOS does support named sockets, so
one can even run the (mock) qemu tests there, and I think it'd be a
shame to lose that.
Differential Revision: https://reviews.llvm.org/D114509
Jonas Devlieghere