Two bug fixes here.
- We weren't reporting a correctl ErrorRegister. Needs to contain
PF_INSTR at least.
- We weren't setting siginfo->si_addr in the case of `FaultToTopAndGeneratedException`
Fixes Mafia 2 (Classic)
We need to read the current x87 TOP location and rotate the values when
saving and restoring the context state on Linux. Wasn't visible in the
ASM tests since we read the FEX's CPU state directly there.
Effectively NFC today while we don't allow installing LDT entries, but
is required to have signal handlers execute in the correct bitness if
32-bit code segments are enabled.
Nothing too crazy, just that four segments are stuffed in to the
`REG_CSGSFS` data value, and then CS/SS gets restored on restore.
FS and GS are ignored in this instance because edge case behaviour where
those don't get reset on signal entry, so if they get changed then it is
on the userspace application to fix it.
Gets another change out of my stashes.
Taking this very slowly because this is very fickle code. The frontend
needs to manage GDT and LDT, but before we get there, we need to
actually add support for LDT in the backend. Split the segments to two
arrays so the JIT can actually update their cached values correctly.
Still treats GDT and LDT as mirrors like how the JIT previously did (By
it ignoring the selector's TI bit).
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.
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>
Since the frontend has changed to informing the backend if AVX is
supported, there is no reason to feed that configuration back in to
SignalDelegator from the backend.
Instead inform the SignalDelegator directly in the frontend instead of
this now weird round-about path.
No functional change, just moving the code.
This is entirely freestanding from the rest of the signal delegator
handling and mostly gets in the way when I'm working with the rest of
the signal handling. Separate it out to improve readability.
Ryan Houdek