[PATCH v5 5/6] aarch64: Add sysv specific enabling code for memory tagging

[Richard Earnshaw]

Add various defines and stubs for enabling MTE on AArch64 sysv-like
systems such as Linux.  The HWCAP feature bit is copied over in the
same way as other feature bits.  Similarly we add a new wrapper header
for mman.h to define the PROT_MTE flag that can be used with mmap and
related functions.

We add a new field to struct cpu_features that can be used, for
example, to check whether or not certain ifunc'd routines should be
bound to MTE-safe versions.

Finally, if we detect that MTE should be enabled (ie via the glibc
tunable); we enable MTE during startup as required.

Support in the Linux kernel was added in version 5.10.

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
---
 sysdeps/unix/sysv/linux/aarch64/bits/hwcap.h  |  1 +
 sysdeps/unix/sysv/linux/aarch64/bits/mman.h   |  1 +
 .../unix/sysv/linux/aarch64/cpu-features.c    | 30 +++++++++++++++++++
 .../unix/sysv/linux/aarch64/cpu-features.h    |  2 ++
 4 files changed, 34 insertions(+)

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