[PATCH 0/5] arm64: mte: add core dump support

[Catalin Marinas]

Hi,

Add core dump support for MTE tags. When a core file is generated and
the user has mappings with PROT_MTE, segments with the PT_ARM_MEMTAG_MTE
type are dumped. These correspond to the PT_LOAD segments for the same
virtual addresses.

The last patch documents the core file format. The tags are dumped
packed, two tags per byte (unlike ptrace where we have one tag per byte)
and there is no header to define the format, it's all fixed for the
PT_ARM_MEMTAG_MTE type.

Below you can see the output of 'readelf -a core' for a program mapping
two regions with PROT_MTE, one 2-page and the other 4-page long. Half of
the first page in each range was filled with 0xa and 0xb tags
respectively.

Program Headers:
  Type             Offset   VirtAddr           PhysAddr           FileSiz  MemSiz   Flg Align
  ...
  LOAD             0x030000 0x0000ffff80034000 0x0000000000000000 0x000000 0x002000 RW  0x1000
  LOAD             0x030000 0x0000ffff80036000 0x0000000000000000 0x004000 0x004000 RW  0x1000
  ...
  LOPROC+0x5441470 0x05b000 0x0000ffff80034000 0x0000000000000000 0x000100 0x002000     0
  LOPROC+0x5441470 0x05b100 0x0000ffff80036000 0x0000000000000000 0x000200 0x004000     0

The relevant 'od -tx1 core' output:

05b000 bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
*
05b040 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
*
05b100 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
*
05b140 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
*
05b300

Catalin Marinas (5):
  elfcore: Replace CONFIG_{IA64,UML} checks with a new option
  elf: Introduce the ARM MTE ELF segment type
  arm64: mte: Define the number of bytes for storing the tags in a page
  arm64: mte: Dump the MTE tags in the core file
  arm64: mte: Document the core dump file format

 .../arm64/memory-tagging-extension.rst        |  22 ++++
 arch/arm64/Kconfig                            |   1 +
 arch/arm64/include/asm/mte-def.h              |   1 +
 arch/arm64/kernel/Makefile                    |   1 +
 arch/arm64/kernel/elfcore.c                   | 123 ++++++++++++++++++
 arch/arm64/lib/mte.S                          |   4 +-
 arch/arm64/mm/mteswap.c                       |   2 +-
 arch/ia64/Kconfig                             |   1 +
 arch/x86/um/Kconfig                           |   1 +
 fs/Kconfig.binfmt                             |   3 +
 include/linux/elfcore.h                       |   4 +-
 include/uapi/linux/elf.h                      |   3 +
 12 files changed, 161 insertions(+), 5 deletions(-)
 create mode 100644 arch/arm64/kernel/elfcore.c