[v3,0/8] Memory tagging support

  This is the third iteration of the patch set to enable memory tagging
in glibc's malloc code.  It mainly addresses the following issues raised
during the previous review:

 - Clean up/add some internal API documentation
 - Remove ROUND_UP_ALLOCATION_SIZE and use some conditionalized code
   in checked_request2size instead.
 - Support MALLOC_CHECK_ in conjuction with _MTAG_ENABLE.

The first two issues are addressed in patch 4 of this series, and the
third in patch 5.  I intend to merge patches 3, 4 and 5 into a single
update to the malloc code before the final commit; I've kept them
separate for now to (hopefully) simplify the review.

The patches have all been rebased against master as of 2020/11/20.

I spent quite a bit of time while working on these looking at whether
the code could be refactored in order to reduce the places where
SIZE_SZ was being added (in different multiples) to various pointers.
I eventually concluded that this wasn't significantly improving the
readability of the code, but one change has survived - I've replaced
usage of 2 * SIZE_SZ with CHUNK_HDR_SZ when it is clear that this is
referring to the header block at the start of a chunk.

I've pushed a copy of this patch series to rearnsha/mte-v3.0, since I
understand some people want to try the patch series as a whole.

R.

Richard Earnshaw (8):
  config: Allow memory tagging to be enabled when configuring glibc
  elf: Add a tunable to control use of tagged memory
  malloc: Basic support for memory tagging in the malloc() family
  malloc: Clean up commentary
  malloc: support MALLOC_CHECK_ in conjunction with _MTAG_ENABLE.
  linux: Add compatibility definitions to sys/prctl.h for MTE
  aarch64: Add sysv specific enabling code for memory tagging
  aarch64: Add aarch64-specific files for memory tagging support

 INSTALL                                       |  14 +
 config.h.in                                   |   3 +
 config.make.in                                |   2 +
 configure                                     |  17 +
 configure.ac                                  |  10 +
 elf/dl-tunables.list                          |   9 +
 malloc/arena.c                                |  59 ++-
 malloc/hooks.c                                |  79 ++--
 malloc/malloc.c                               | 336 ++++++++++++++----
 malloc/malloc.h                               |   7 +
 manual/install.texi                           |  13 +
 manual/tunables.texi                          |  31 ++
 sysdeps/aarch64/Makefile                      |   5 +
 sysdeps/aarch64/__mtag_address_get_tag.S      |  31 ++
 sysdeps/aarch64/__mtag_memset_tag.S           |  46 +++
 sysdeps/aarch64/__mtag_new_tag.S              |  38 ++
 sysdeps/aarch64/__mtag_tag_region.S           |  44 +++
 sysdeps/aarch64/libc-mtag.h                   |  57 +++
 sysdeps/generic/libc-mtag.h                   |  52 +++
 sysdeps/unix/sysv/linux/aarch64/bits/hwcap.h  |   1 +
 sysdeps/unix/sysv/linux/aarch64/bits/mman.h   |   7 +
 .../unix/sysv/linux/aarch64/cpu-features.c    |  28 ++
 .../unix/sysv/linux/aarch64/cpu-features.h    |   1 +
 sysdeps/unix/sysv/linux/sys/prctl.h           |  18 +
 24 files changed, 811 insertions(+), 97 deletions(-)
 create mode 100644 sysdeps/aarch64/__mtag_address_get_tag.S
 create mode 100644 sysdeps/aarch64/__mtag_memset_tag.S
 create mode 100644 sysdeps/aarch64/__mtag_new_tag.S
 create mode 100644 sysdeps/aarch64/__mtag_tag_region.S
 create mode 100644 sysdeps/aarch64/libc-mtag.h
 create mode 100644 sysdeps/generic/libc-mtag.h