This matches the systemd path, no more _32 and _64 versions, just
binfmt_misc.
Having a mixed install where one program does one architecture and
another is weird and unsupported anyway.
Allocate the stack with uncommited guard pages on either side, if
any faulting accesses to these occur then the call-ret SP value is
reset to the default and execution resumed.
Prevents invalidations being missed under the following circumstances:
Thread A JITs block A into the global codebuffer, adding the guest to host
mapping to its CodePages, thread A is then killed.
Thread B then performs SMC on block A. An exception will be triggered but
as CodePages was stored per-thread, and thread A is now killed when all
threads are iterated over by the frontend to perform invalidations it
will be missed.
The accumulator is introduced to handle the case where multiple threads
have the same code entry in their local caches but share the same codebuffer.
Consider a thread C in the above example that also has block A in its cache,
without an accumulator, when invalidating thread B the entrypoint of A is erased
from the shared guest to host map. So when C is invalidated, the local cache entry
for A is not removed since it was removed from CodePages when invalidating B.
Consider a page with two blocks in it, A and B. Block A performs SMC on B then A.
With the previous logic, the SMC write of B would unprotect the page and then
the inline SMC touching A would not be detected and a single-step would not be forced.
There is a ELF note for this but currently clang doesn't support a
`no-gcs` flag. The best we can do is check if the kernel has GCS enabled
for the current process and early exit.
Then continue to use the kernel's locking functionality to disable it if
the guest happens to try, ensuring safety.
Part of waitpkg is the TPAUSE instruction. This instruction gives an
RDTSC deadline to go in to a low power sleep mode with the CPU.
Semantically we can't implement umonitor and umwait with ARM's exclusive
monitor implementation, but a nop implementation is sane. Just need to
make sure to clear the pre-req flags.
This lowers power consumption of UE5 games since their job handler now
goes to a tpause based implementation instead of a `pause` spinloop
implementation.
Rather than relying on wine-specific alphabetical behaviour, that
has since been changed. Rely on their addresses being sorted which
is more stable behaviour also present in Windows.
FEX should only set fpx_sw_bytes.magic1 with FP_XSTATE_MAGIC when
avx is enabled. Otherwise it may cause segfault in ntdll::save_context,
which requires access to extended xstate info if magic1 equals FP_XSTATE_MAGIC.
Signed-off-by: Changwei Miao <chanthmiao@outlook.com>
Billy Laws