[PATCH v2 00/11] kasan: unify kasan_arch_is_ready with kasan_enabled
Sabyrzhan Tasbolatov
snovitoll at gmail.com
Fri Jun 27 01:31:36 AEST 2025
This patch series unifies the kasan_arch_is_ready() and kasan_enabled()
interfaces by extending the existing kasan_enabled() infrastructure to
work consistently across all KASAN modes (Generic, SW_TAGS, HW_TAGS).
Currently, kasan_enabled() only works for HW_TAGS mode using a static key,
while other modes either return IS_ENABLED(CONFIG_KASAN) (compile-time
constant) or rely on architecture-specific kasan_arch_is_ready()
implementations with custom static keys and global variables.
This leads to:
- Code duplication across architectures
- Inconsistent runtime behavior between KASAN modes
- Architecture-specific readiness tracking
After this series:
- All KASAN modes use the same kasan_flag_enabled static key
- Consistent runtime enable/disable behavior across modes
- Simplified architecture code with unified kasan_init_generic() calls
- Elimination of arch specific kasan_arch_is_ready() implementations
- Unified vmalloc integration using kasan_enabled() checks
This addresses the bugzilla issue [1] about making
kasan_flag_enabled and kasan_enabled() work for Generic mode,
and extends it to provide true unification across all modes.
[1] https://bugzilla.kernel.org/show_bug.cgi?id=217049
=== Current mainline KUnit status
To see if there is any regression, I've tested first on the following
commit 739a6c93cc75 ("Merge tag 'nfsd-6.16-1' of
git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux").
Tested via compiling a kernel with CONFIG_KASAN_KUNIT_TEST and running
QEMU VM. There are failing tests in SW_TAGS and GENERIC modes in arm64:
arm64 CONFIG_KASAN_HW_TAGS:
# kasan: pass:62 fail:0 skip:13 total:75
# Totals: pass:62 fail:0 skip:13 total:75
ok 1 kasan
arm64 CONFIG_KASAN_SW_TAGS=y:
# kasan: pass:65 fail:1 skip:9 total:75
# Totals: pass:65 fail:1 skip:9 total:75
not ok 1 kasan
# kasan_strings: EXPECTATION FAILED at mm/kasan/kasan_test_c.c:1598
KASAN failure expected in "strscpy(ptr, src + KASAN_GRANULE_SIZE, KASAN_GRANULE_SIZE)", but none occurred
arm64 CONFIG_KASAN_GENERIC=y, CONFIG_KASAN_OUTLINE=y:
# kasan: pass:61 fail:1 skip:13 total:75
# Totals: pass:61 fail:1 skip:13 total:75
not ok 1 kasan
# same failure as above
x86_64 CONFIG_KASAN_GENERIC=y:
# kasan: pass:58 fail:0 skip:17 total:75
# Totals: pass:58 fail:0 skip:17 total:75
ok 1 kasan
=== Testing with patches
Testing in v2:
- Compiled every affected arch with no errors:
$ make CC=clang LD=ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip \
OBJCOPY=llvm-objcopy OBJDUMP=llvm-objdump READELF=llvm-readelf \
HOSTCC=clang HOSTCXX=clang++ HOSTAR=llvm-ar HOSTLD=ld.lld \
ARCH=$ARCH
$ clang --version
ClangBuiltLinux clang version 19.1.4
Target: x86_64-unknown-linux-gnu
Thread model: posix
- make ARCH=um produces the warning during compiling:
MODPOST Module.symvers
WARNING: modpost: vmlinux: section mismatch in reference: \
kasan_init+0x43 (section: .ltext) -> \
kasan_init_generic (section: .init.text)
AFAIU, it's due to the code in arch/um/kernel/mem.c, where kasan_init()
is placed in own section ".kasan_init", which calls kasan_init_generic()
which is marked with "__init".
- Booting via qemu-system- and running KUnit tests:
* arm64 (GENERIC, HW_TAGS, SW_TAGS): no regression, same above results.
* x86_64 (GENERIC): no regression, no errors
=== NB
I haven't tested the kernel boot on the following arch. due to the absence
of qemu-system- support on those arch on my machine, so I defer this to
relevant arch people to test KASAN initialization:
- loongarch
- s390
- um
- xtensa
- powerpc
- riscv
Code changes in v2:
- Replace the order of patches. Move "kasan: replace kasan_arch_is_ready
with kasan_enabled" at the end to keep the compatibility.
- arch/arm, arch/riscv: add 2 arch. missed in v1
- arch/powerpc: add kasan_init_generic() in other kasan_init() calls:
arch/powerpc/mm/kasan/init_32.c
arch/powerpc/mm/kasan/init_book3e_64.c
- arch/um: add the proper header `#include <linux/kasan.h>`. Tested
via compiling with no errors. In the v1 arch/um changes were acked-by
Johannes Berg, though I don't include it due to the changed code in v2.
- arch/powerpc: add back `#ifdef CONFIG_KASAN` deleted in v1 and tested
the compilation.
- arch/loongarch: update git commit message about non-standard flow of
calling kasan_init_generic()
Sabyrzhan Tasbolatov (11):
kasan: unify static kasan_flag_enabled across modes
kasan/arm64: call kasan_init_generic in kasan_init
kasan/arm: call kasan_init_generic in kasan_init
kasan/xtensa: call kasan_init_generic in kasan_init
kasan/loongarch: call kasan_init_generic in kasan_init
kasan/um: call kasan_init_generic in kasan_init
kasan/x86: call kasan_init_generic in kasan_init
kasan/s390: call kasan_init_generic in kasan_init
kasan/powerpc: call kasan_init_generic in kasan_init
kasan/riscv: call kasan_init_generic in kasan_init
kasan: replace kasan_arch_is_ready with kasan_enabled
arch/arm/mm/kasan_init.c | 2 +-
arch/arm64/mm/kasan_init.c | 4 +---
arch/loongarch/include/asm/kasan.h | 7 -------
arch/loongarch/mm/kasan_init.c | 7 ++-----
arch/powerpc/include/asm/kasan.h | 13 -------------
arch/powerpc/mm/kasan/init_32.c | 2 +-
arch/powerpc/mm/kasan/init_book3e_64.c | 2 +-
arch/powerpc/mm/kasan/init_book3s_64.c | 6 +-----
arch/riscv/mm/kasan_init.c | 1 +
arch/s390/kernel/early.c | 3 ++-
arch/um/include/asm/kasan.h | 5 -----
arch/um/kernel/mem.c | 4 ++--
arch/x86/mm/kasan_init_64.c | 2 +-
arch/xtensa/mm/kasan_init.c | 2 +-
include/linux/kasan-enabled.h | 22 ++++++++++++++++------
include/linux/kasan.h | 6 ++++++
mm/kasan/common.c | 15 +++++++++++----
mm/kasan/generic.c | 17 ++++++++++++++---
mm/kasan/hw_tags.c | 7 -------
mm/kasan/kasan.h | 6 ------
mm/kasan/shadow.c | 15 +++------------
mm/kasan/sw_tags.c | 2 ++
22 files changed, 66 insertions(+), 84 deletions(-)
--
2.34.1
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