Currently no functional change but public API breaks should come early.
The thread state object will be used for looking up thread specific
codebuffers in the future when we support MDWE with code mirrors.
Previously we were only storing the 32-bit base address which isn't
actually how segment descriptors work.
In reality segment descriptors are 64-bit descriptors that are laid out
in a particular layout depending on the 4-bit type value. In reality we
only care about code and data segment layouts since the rest are
bonkers.
Describe these descriptors correctly and setup a default code descriptor
for the operating mode that FEX is starting in.
Lots going on here.
This moves OS thread object lifetime management and internal thread
state lifetime management to the frontend. This causes a bunch of thread
handling to move from the FEXCore Context to the frontend.
Looking at `FEXCore/include/FEXCore/Core/Context.h` really shows how
much of the API has moved to the frontend that FEXCore no longer needs
to manage. Primarily this makes FEXCore itself no longer need to care
about most of the management of the emulation state.
A large amount of the behaviour moved wholesale from Core.cpp to
LinuxEmulation's ThreadManager.cpp. Which this manages the lifetimes of
both the OS threads and the FEXCore thread state objects.
One feature lost was the instruction capability, but this was already
buggy and is going to be rewritten/fixed when gdbserver work continues.
Now that all of this management is moved to the frontend, the gdbserver
can start improving since it can start managing all thread state
directly.
FEX was incorrectly invalidating RBX and RBP when a new
thread/clone/fork was created. Only RAX should be set to zero to
signify that it is the child process.
I tried to find some reference as to why this was being done in FEX, and
I seem to recall some code somewhere that was setting up this state.
Sadly I can't seem to find any reference to this being required now by
the linux kernel when it creates new processes, so maybe I was just
gaslighting myself.
Fixes crash in bubblewrap where it was expecting a valid RBP to exist
after it does a clone syscall.
I have unit tests coming for this but it is uncovering some more bugs in
FEX's thread handling. Some of which are getting fixed with the current
PRs that are moving the thread handling to the frontend.
But since proton is broken now, this needs to get in.
This was left over and was using the wrong argument.
This would cause the stack for the child thread/process to be at the
start instead of the end.
Fixes a crash in bubblewrap.
Similar to #3284 but works around some of the bugs that one introduced.
This is the minimal amount of changes to move the ownership from FEXCore
to the frontend. Since the frontends don't yet have a full thread state
tracking, there is an opaque pointer that needs to be managed.
In the followup commits this will be changed to have the syscall handler
to be the thread object manager.
Which requires moving LinuxEmulation to its own independent folder as
well. Since both IRLoader and FEXLoader rely on it.
No functional change, just moves the the code around.
Ryan Houdek