GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-06-28 17:41:50 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

kasan: docs: update HW_TAGS implementation details section

Browse source 
Update the "Implementation details" section for HW_TAGS KASAN:

 - Punctuation, readability, and other minor clean-ups.

Link: https://lkml.kernel.org/r/ee2caf4c138cc1fd239822c2abefd5af6c057744.1615559068.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrey Konovalov 2021-04-29 23:00:33 -07:00 • committed by Linus Torvalds
parent a6c18d4e76
commit bb48675e5a
1 changed files with 13 additions and 13 deletions
Download patch file Download diff file Expand all files Collapse all files

26
Documentation/dev-tools/kasan.rst
View file

@ -279,35 +279,35 @@ memory.
Hardware tag-based KASAN Hardware tag-based KASAN
~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~
Hardware tag-based KASAN is similar to the software mode in concept, but uses Hardware tag-based KASAN is similar to the software mode in concept but uses
hardware memory tagging support instead of compiler instrumentation and hardware memory tagging support instead of compiler instrumentation and
shadow memory. shadow memory.
Hardware tag-based KASAN is currently only implemented for arm64 architecture Hardware tag-based KASAN is currently only implemented for arm64 architecture
and based on both arm64 Memory Tagging Extension (MTE) introduced in ARMv8.5 and based on both arm64 Memory Tagging Extension (MTE) introduced in ARMv8.5
Instruction Set Architecture, and Top Byte Ignore (TBI). Instruction Set Architecture and Top Byte Ignore (TBI).
Special arm64 instructions are used to assign memory tags for each allocation. Special arm64 instructions are used to assign memory tags for each allocation.
Same tags are assigned to pointers to those allocations. On every memory Same tags are assigned to pointers to those allocations. On every memory
access, hardware makes sure that tag of the memory that is being accessed is access, hardware makes sure that the tag of the memory that is being accessed is
equal to tag of the pointer that is used to access this memory. In case of a equal to the tag of the pointer that is used to access this memory. In case of a
tag mismatch a fault is generated and a report is printed. tag mismatch, a fault is generated, and a report is printed.
Hardware tag-based KASAN uses 0xFF as a match-all pointer tag (accesses through Hardware tag-based KASAN uses 0xFF as a match-all pointer tag (accesses through
pointers with 0xFF pointer tag aren't checked). The value 0xFE is currently pointers with the 0xFF pointer tag are not checked). The value 0xFE is currently
reserved to tag freed memory regions. reserved to tag freed memory regions.
Hardware tag-based KASAN currently only supports tagging of Hardware tag-based KASAN currently only supports tagging of slab and page_alloc
kmem_cache_alloc/kmalloc and page_alloc memory. memory.
If the hardware doesn't support MTE (pre ARMv8.5), hardware tag-based KASAN If the hardware does not support MTE (pre ARMv8.5), hardware tag-based KASAN
won't be enabled. In this case all boot parameters are ignored. will not be enabled. In this case, all KASAN boot parameters are ignored.
Note, that enabling CONFIG_KASAN_HW_TAGS always results in in-kernel TBI being Note that enabling CONFIG_KASAN_HW_TAGS always results in in-kernel TBI being
enabled. Even when kasan.mode=off is provided, or when the hardware doesn't enabled. Even when ``kasan.mode=off`` is provided or when the hardware does not
support MTE (but supports TBI). support MTE (but supports TBI).
Hardware tag-based KASAN only reports the first found bug. After that MTE tag Hardware tag-based KASAN only reports the first found bug. After that, MTE tag
checking gets disabled. checking gets disabled.
Shadow memory Shadow memory