We are required in our syscall emulation to handle cases where pointers
are invalid. This means we need to pessimistically assume a memcpy will
fault when reading application memory.
This implements a signal handler based approach to catching the SIGSEGV
on memcpy and returning an EFAULT if it faults.
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.
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