- It turns out that the optimised string routines merged in 5.14 are not
safe with in-kernel MTE (KASAN_HW_TAGS) because of reading beyond the
end of a string (strcmp, strncmp). Such reading may go across a 16
byte tag granule and cause a tag check fault. When KASAN_HW_TAGS is
enabled, use the generic strcmp/strncmp C implementation.
- An errata workaround for ThunderX relied on the CPU capabilities being
enabled in a specific order. This disappeared with the automatic
generation of the cpucaps.h file (sorted alphabetically). Fix it by
checking the current CPU only rather than the system-wide capability.
- Add system_supports_mte() checks on the kernel entry/exit path and
thread switching to avoid unnecessary barriers and function calls on
systems where MTE is not supported.
- kselftests: skip arm64 tests if the required features are missing.
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Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 fixes from Catalin Marinas:
- It turns out that the optimised string routines merged in 5.14 are
not safe with in-kernel MTE (KASAN_HW_TAGS) because of reading beyond
the end of a string (strcmp, strncmp). Such reading may go across a
16 byte tag granule and cause a tag check fault. When KASAN_HW_TAGS
is enabled, use the generic strcmp/strncmp C implementation.
- An errata workaround for ThunderX relied on the CPU capabilities
being enabled in a specific order. This disappeared with the
automatic generation of the cpucaps.h file (sorted alphabetically).
Fix it by checking the current CPU only rather than the system-wide
capability.
- Add system_supports_mte() checks on the kernel entry/exit path and
thread switching to avoid unnecessary barriers and function calls on
systems where MTE is not supported.
- kselftests: skip arm64 tests if the required features are missing.
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: Restore forced disabling of KPTI on ThunderX
kselftest/arm64: signal: Skip tests if required features are missing
arm64: Mitigate MTE issues with str{n}cmp()
arm64: add MTE supported check to thread switching and syscall entry/exit
1b7eaf5701