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This implementation uses 7-bit tags, so it is compatible with either hardware mode. Patch 4 adds supports for KASAN_SW_TAGS with tag widths other than 8 bits. Pointer masking is an optional ISA extension, and it must be enabled using an SBI call to firmware on each CPU. If the SBI call fails on the boot CPU, KASAN is globally disabled. Patch 2 adds support for boot-time disabling of KASAN_SW_TAGS, and patch 3 adds support for runtime control of stack tagging. Patch 1 is an optimization that could be applied separately. It is included here because it affects the selection of KASAN_SHADOW_OFFSET. This implementation currently passes the KASAN KUnit test suite: # kasan: pass:64 fail:0 skip:9 total:73 # Totals: pass:64 fail:0 skip:9 total:73 ok 1 kasan One workaround is required to pass the vmalloc_percpu test. I have to shrink the initial percpu area to force the use of a KASAN-tagged percpu area in the test (depending on .config, this workaround is also needed on arm64 without this series applied, so it is not a new issue): masking, the kernel still boots successfully: kasan: test: Can't run KASAN tests with KASAN disabled # kasan: # failed to initialize (-1) not ok 1 kasan This series can be tested by applying patch series to LLVM[2] and QEMU[3], and using the master branch of OpenSBI[4]. [1]: https://github.com/riscv/riscv-j-extension/raw/d70011dde6c2/zjpm-spec.pdf [2]: https://github.com/SiFiveHolland/llvm-project/commits/up/riscv64-kernel-hwasan [3]: https://lore.kernel.org/qemu-devel/20240511101053.1875596-1-me@deliversmonkey.space/ [4]: https://github.com/riscv-software-src/opensbi/commit/1cb234b1c9ed Changes in v2: - Improve the explanation for how KASAN_SHADOW_END is derived - Update the range check in kasan_non_canonical_hook() - Split the generic and RISC-V parts of stack tag generation control to avoid breaking bisectability - Add a patch to call kasan_non_canonical_hook() on riscv - Fix build error with KASAN_GENERIC - Use symbolic definitons for SBI firmware features call - Update indentation in scripts/Makefile.kasan - Use kasan_params to set hwasan-generate-tags-with-calls=1 Clément Léger (1): riscv: Add SBI Firmware Features extension definitions Samuel Holland (8): kasan: sw_tags: Use arithmetic shift for shadow computation kasan: sw_tags: Check kasan_flag_enabled at runtime kasan: sw_tags: Support outline stack tag generation kasan: sw_tags: Support tag widths less than 8 bits riscv: mm: Log potential KASAN shadow alias riscv: Do not rely on KASAN to define the memory layout riscv: Align the sv39 linear map to 16 GiB riscv: Implement KASAN_SW_TAGS Documentation/arch/riscv/vm-layout.rst | 10 ++--- Documentation/dev-tools/kasan.rst | 14 +++--- arch/arm64/Kconfig | 10 ++--- arch/arm64/include/asm/kasan.h | 6 ++- arch/arm64/include/asm/memory.h | 17 ++++++- arch/arm64/include/asm/uaccess.h | 1 + arch/arm64/mm/kasan_init.c | 7 ++- arch/riscv/Kconfig | 4 +- arch/riscv/include/asm/cache.h | 4 ++ arch/riscv/include/asm/kasan.h | 29 +++++++++++- arch/riscv/include/asm/page.h | 21 +++++++-- arch/riscv/include/asm/pgtable.h | 6 +++ arch/riscv/include/asm/sbi.h | 28 ++++++++++++ arch/riscv/include/asm/tlbflush.h | 4 +- arch/riscv/kernel/setup.c | 6 +++ arch/riscv/kernel/smpboot.c | 8 +++- arch/riscv/lib/Makefile | 2 + arch/riscv/lib/kasan_sw_tags.S | 61 ++++++++++++++++++++++++++ arch/riscv/mm/fault.c | 3 ++ arch/riscv/mm/init.c | 2 +- arch/riscv/mm/kasan_init.c | 32 +++++++++++++- arch/riscv/mm/physaddr.c | 4 ++ include/linux/kasan-enabled.h | 15 +++---- include/linux/kasan-tags.h | 13 +++--- include/linux/kasan.h | 10 ++++- mm/kasan/hw_tags.c | 10 ----- mm/kasan/kasan.h | 2 + mm/kasan/report.c | 22 ++++++++-- mm/kasan/sw_tags.c | 9 ++++ mm/kasan/tags.c | 10 +++++ scripts/Makefile.kasan | 5 +++ scripts/gdb/linux/mm.py | 5 ++- 32 files changed, 313 insertions(+), 67 deletions(-) create mode 100644 arch/riscv/lib/kasan_sw_tags.S diff --git a/include/linux/percpu.h b/include/linux/percpu.h index b6321fc49159..26b97c79ad7c 100644 --- a/include/linux/percpu.h +++ b/include/linux/percpu.h @@ -43,7 +43,7 @@ #ifdef CONFIG_RANDOM_KMALLOC_CACHES #define PERCPU_DYNAMIC_SIZE_SHIFT 12 #else -#define PERCPU_DYNAMIC_SIZE_SHIFT 10 +#define PERCPU_DYNAMIC_SIZE_SHIFT 8 #endif When running with hardware or firmware that doesn't support pointer