1# SPDX-License-Identifier: GPL-2.0 2 3ifdef CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX 4# Safe for compiler to generate meminstrinsic calls in uninstrumented files. 5CFLAGS_KASAN_NOSANITIZE := 6else 7# Don't let compiler generate memintrinsic calls in uninstrumented files 8# because they are instrumented. 9CFLAGS_KASAN_NOSANITIZE := -fno-builtin 10endif 11 12KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET) 13 14cc-param = $(call cc-option, -mllvm -$(1), $(call cc-option, --param $(1))) 15rustc-param = $(call rustc-option, -Cllvm-args=-$(1),) 16 17check-args = $(foreach arg,$(2),$(call $(1),$(arg))) 18 19kasan_params := 20 21ifdef CONFIG_KASAN_STACK 22 stack_enable := 1 23else 24 stack_enable := 0 25endif 26 27ifdef CONFIG_KASAN_GENERIC 28 29ifdef CONFIG_KASAN_INLINE 30 # When the number of memory accesses in a function is less than this 31 # call threshold number, the compiler will use inline instrumentation. 32 # 10000 is chosen offhand as a sufficiently large number to make all 33 # kernel functions to be instrumented inline. 34 call_threshold := 10000 35else 36 call_threshold := 0 37endif 38 39# First, enable -fsanitize=kernel-address together with providing the shadow 40# mapping offset, as for GCC, -fasan-shadow-offset fails without -fsanitize 41# (GCC accepts the shadow mapping offset via -fasan-shadow-offset instead of 42# a --param like the other KASAN parameters). 43# Instead of ifdef-checking the compiler, rely on cc-option. 44CFLAGS_KASAN := $(call cc-option, -fsanitize=kernel-address \ 45 -fasan-shadow-offset=$(KASAN_SHADOW_OFFSET), \ 46 $(call cc-option, -fsanitize=kernel-address \ 47 -mllvm -asan-mapping-offset=$(KASAN_SHADOW_OFFSET))) 48 49# The minimum supported `rustc` version has a minimum supported LLVM 50# version late enough that we can assume support for -asan-mapping-offset. 51RUSTFLAGS_KASAN := -Zsanitizer=kernel-address \ 52 -Zsanitizer-recover=kernel-address \ 53 -Cllvm-args=-asan-mapping-offset=$(KASAN_SHADOW_OFFSET) 54 55# Now, add other parameters enabled similarly in GCC, Clang, and rustc. 56# As some of them are not supported by older compilers, these will be filtered 57# through `cc-param` or `rust-param` as applicable. 58kasan_params += asan-instrumentation-with-call-threshold=$(call_threshold) \ 59 asan-stack=$(stack_enable) \ 60 asan-instrument-allocas=1 \ 61 asan-globals=1 62 63# Instrument memcpy/memset/memmove calls by using instrumented __asan_mem*() 64# instead. With compilers that don't support this option, compiler-inserted 65# memintrinsics won't be checked by KASAN on GENERIC_ENTRY architectures. 66kasan_params += asan-kernel-mem-intrinsic-prefix=1 67 68endif # CONFIG_KASAN_GENERIC 69 70ifdef CONFIG_KASAN_SW_TAGS 71 72CFLAGS_KASAN := -fsanitize=kernel-hwaddress 73 74# This sets flags that will enable SW_TAGS KASAN once enabled in Rust. These 75# will not work today, and is guarded against in dependencies for CONFIG_RUST. 76RUSTFLAGS_KASAN := -Zsanitizer=kernel-hwaddress \ 77 -Zsanitizer-recover=kernel-hwaddress 78 79ifdef CONFIG_KASAN_INLINE 80 kasan_params += hwasan-mapping-offset=$(KASAN_SHADOW_OFFSET) 81else 82 kasan_params += hwasan-instrument-with-calls=1 83endif 84 85kasan_params += hwasan-instrument-stack=$(stack_enable) \ 86 hwasan-use-short-granules=0 \ 87 hwasan-inline-all-checks=0 88 89# Instrument memcpy/memset/memmove calls by using instrumented __hwasan_mem*(). 90ifeq ($(call clang-min-version, 150000)$(call gcc-min-version, 130000),y) 91 kasan_params += hwasan-kernel-mem-intrinsic-prefix=1 92endif 93 94endif # CONFIG_KASAN_SW_TAGS 95 96# Add all as-supported KASAN LLVM parameters requested by the configuration. 97CFLAGS_KASAN += $(call check-args, cc-param, $(kasan_params)) 98 99ifdef CONFIG_RUST 100 # Avoid calling `rustc-param` unless Rust is enabled. 101 RUSTFLAGS_KASAN += $(call check-args, rustc-param, $(kasan_params)) 102endif # CONFIG_RUST 103 104export CFLAGS_KASAN CFLAGS_KASAN_NOSANITIZE RUSTFLAGS_KASAN 105