arm64: mte: Document the core dump file format

Add the program header definition and data layout for the
PT_ARM_MEMTAG_MTE segments.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Luis Machado <luis.machado@linaro.org>
Link: https://lore.kernel.org/r/20220131165456.2160675-6-catalin.marinas@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Catalin Marinas 2022-01-31 16:54:56 +00:00 committed by Will Deacon
parent 6dd8b1a0b6
commit 731451ab3c

View File

@ -213,6 +213,29 @@ address ABI control and MTE configuration of a process as per the
Documentation/arm64/tagged-address-abi.rst and above. The corresponding
``regset`` is 1 element of 8 bytes (``sizeof(long))``).
Core dump support
-----------------
The allocation tags for user memory mapped with ``PROT_MTE`` are dumped
in the core file as additional ``PT_ARM_MEMTAG_MTE`` segments. The
program header for such segment is defined as:
:``p_type``: ``PT_ARM_MEMTAG_MTE``
:``p_flags``: 0
:``p_offset``: segment file offset
:``p_vaddr``: segment virtual address, same as the corresponding
``PT_LOAD`` segment
:``p_paddr``: 0
:``p_filesz``: segment size in file, calculated as ``p_mem_sz / 32``
(two 4-bit tags cover 32 bytes of memory)
:``p_memsz``: segment size in memory, same as the corresponding
``PT_LOAD`` segment
:``p_align``: 0
The tags are stored in the core file at ``p_offset`` as two 4-bit tags
in a byte. With the tag granule of 16 bytes, a 4K page requires 128
bytes in the core file.
Example of correct usage
========================