tst-arm-mte bug: PSTATE.TCO is cleared on exceptions

[Szabolcs Nagy]

i'm using the branch at

https://github.com/rth7680/qemu/tree/tgt-arm-mte

to test armv8.5-a mte and hope this is ok to report bugs here.

i'm doing tests in qemu-system-aarch64 with linux userspace
code and it seems TCO bit gets cleared after syscalls or other
kernel entry, but PSTATE is expected to be restored, so i
suspect it is a qemu bug.

i think the architecture saves/restores PSTATE using SPSR_ELx
on exceptions.

i used the linux branch
https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/log/?h=devel/mte-v2

attached a reproducer that segfaults in qemu but should work.

thanks.

bug.c
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