If MAP_32BIT was failing then we weren't checking error result
correctly.
This was causing us to crash.
Now add a helper function for checking syscall results since it is easy
to mess up.
Replaces the few cases where we were manually checking with the helper.
Fixes a Dota: Underlords crash
This isn't quite a 100% clean sweep of IWYU.
There are some false positives where clang fails.
Additionally there are still a few missed in the frontend side of things
that I didn't get to
The allocator functions don't return -1 on error, instead return the actual error.
This was setup to match the syscall behaviour rather than the glibc/errno behaviour
The vast majoirty of syscalls don't need anything in thread or frame.
So lets save an indirection for all those syscalls.
Most of the syscalls which do need Thread (or CTX via
Thread are in Thread.cpp or Memory.cpp
These have all been modifiy to fetch Thread from Frame
This was partially implemented before but it had some bugs still.
This fixes those bugs and also implements mremap, shmat, and shmdt.
This now works well enough for 32bit graphical applications
Sadly these things can't be split without breaking functionality so it
turns in to a bit of a mess.
SyscallHandler is very much something that is a Linux only construct and
shouldn't be in FEXCore itself. Lets the frontend register a
Syscallhandler with FEXCore. FEXCore itself is then aware of the current
syscall ABI and handles the ABI in an optimal fashion.
So it is not a 100% clean break otherwise we would lose performance.
The SignalDelegator then needs to move to the frontend since the
SyscallHandler requires it for signal based syscalls.
The CPU backend signal handling still needs to happen in FEXCore because
it is a very tight coupling with the CPU backend.
Once we need to support more Signal handling we can give the backends
cleaner support to select which specific OS handler to handle.
