mbox series

[v3,0/4] LoongArch: Add kernel address sanitizer support

Message ID 20230512015731.23787-1-zhangqing@loongson.cn
Headers
Series LoongArch: Add kernel address sanitizer support |

Message

Qing Zhang May 12, 2023, 1:57 a.m. UTC 
  1/8 of kernel addresses reserved for shadow memory. But for LoongArch,
There are a lot of holes between different segments and valid address
space (256T available) is insufficient to map all these segments to kasan
shadow memory with the common formula provided by kasan core, saying
(addr >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET

So LoongArch has a arch-specific mapping formula, different segments are
mapped individually, and only limited space lengths of these specific
segments are mapped to shadow.

At early boot stage the whole shadow region populated with just one
physical page (kasan_early_shadow_page). Later, this page is reused as
readonly zero shadow for some memory that kasan currently don't track.
After mapping the physical memory, pages for shadow memory are allocated
and mapped.

Functions like memset()/memcpy()/memmove() do a lot of memory accesses.
If bad pointer passed to one of these function it is important to be
caught. Compiler's instrumentation cannot do this since these functions
are written in assembly.

KASan replaces memory functions with manually instrumented variants.
Original functions declared as weak symbols so strong definitions in
mm/kasan/kasan.c could replace them. Original functions have aliases
with '__' prefix in names, so we could call non-instrumented variant
if needed.

Changes v2 -> v3:
- Rebased on 6.4-rc1
- Add Makefile ``KASAN_SANITIZE`` annotation for tlb related files
  to adapt to multiple cores.

Changes v1 -> v2:
Suggested by Andrey:
- Make two separate patches for changes to public files.
- Removes unnecessary judgments in check_region_inline.
- Add pud/pmd_init __weak define.
- Add Empty function kasan_(early)_init when CONFIG_KASAN turned off.
Suggested by Huacai:
- Split the simplified relocation patch.
Suggested by Youling:
- Add ARCH_HAS_FORTIFY_SOURCE in Kconfig and split into separate patches.
- update `Documentation/translations/zh_CN/dev-tools/kasan.rst`.
- Use macros to avoid using magic values directly.
- Modify patch sequence.
- Remove redundant tab.
- Modify submission information.

Qing Zhang (4):
  kasan: Add __HAVE_ARCH_SHADOW_MAP to support arch specific mapping
  kasan: Add (pmd|pud)_init for LoongArch zero_(pud|p4d)_populate
    process
  LoongArch: Simplify the processing of jumping new kernel for KASLR
  LoongArch: Add kernel address sanitizer support

 Documentation/dev-tools/kasan.rst             |   4 +-
 .../features/debug/KASAN/arch-support.txt     |   2 +-
 .../translations/zh_CN/dev-tools/kasan.rst    |   2 +-
 arch/loongarch/Kconfig                        |   7 +
 arch/loongarch/include/asm/kasan.h            | 120 +++++++++
 arch/loongarch/include/asm/pgtable.h          |   7 +
 arch/loongarch/include/asm/setup.h            |   2 +-
 arch/loongarch/include/asm/string.h           |  20 ++
 arch/loongarch/kernel/Makefile                |   6 +
 arch/loongarch/kernel/head.S                  |  13 +-
 arch/loongarch/kernel/relocate.c              |   8 +-
 arch/loongarch/kernel/setup.c                 |   4 +
 arch/loongarch/lib/memcpy.S                   |   4 +-
 arch/loongarch/lib/memmove.S                  |  16 +-
 arch/loongarch/lib/memset.S                   |   4 +-
 arch/loongarch/mm/Makefile                    |   2 +
 arch/loongarch/mm/kasan_init.c                | 255 ++++++++++++++++++
 arch/loongarch/vdso/Makefile                  |   4 +
 include/linux/kasan.h                         |   2 +
 mm/kasan/init.c                               |  18 +-
 mm/kasan/kasan.h                              |   6 +
 21 files changed, 478 insertions(+), 28 deletions(-)
 create mode 100644 arch/loongarch/include/asm/kasan.h
 create mode 100644 arch/loongarch/mm/kasan_init.c