From: Andrey Konovalov <andreyknvl@xxxxxxxxx> When KASAN support was being added to the Linux kernel, GCC did not yet support all of the KASAN-related compiler options. Thus, the KASAN Makefile had to probe the compiler for supported options. Nowadays, the Linux kernel GCC version requirement is 5.1+, and thus we don't need the probing of the -fasan-shadow-offset parameter: it exists in all 5.1+ GCCs. Simplify the KASAN Makefile to drop CFLAGS_KASAN_MINIMAL. Also add a few more comments and unify the indentation. Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxx> --- Changes v1->v2: - Comments fixes based on Miguel Ojeda's feedback. --- scripts/Makefile.kasan | 45 +++++++++++++++++++++--------------------- 1 file changed, 23 insertions(+), 22 deletions(-) diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan index 390658a2d5b74..aab4154af00a7 100644 --- a/scripts/Makefile.kasan +++ b/scripts/Makefile.kasan @@ -22,30 +22,31 @@ endif ifdef CONFIG_KASAN_GENERIC ifdef CONFIG_KASAN_INLINE + # When the number of memory accesses in a function is less than this + # call threshold number, the compiler will use inline instrumentation. + # 10000 is chosen offhand as a sufficiently large number to make all + # kernel functions to be instrumented inline. call_threshold := 10000 else call_threshold := 0 endif -CFLAGS_KASAN_MINIMAL := -fsanitize=kernel-address - -# -fasan-shadow-offset fails without -fsanitize -CFLAGS_KASAN_SHADOW := $(call cc-option, -fsanitize=kernel-address \ - -fasan-shadow-offset=$(KASAN_SHADOW_OFFSET), \ - $(call cc-option, -fsanitize=kernel-address \ - -mllvm -asan-mapping-offset=$(KASAN_SHADOW_OFFSET))) - -ifeq ($(strip $(CFLAGS_KASAN_SHADOW)),) - CFLAGS_KASAN := $(CFLAGS_KASAN_MINIMAL) -else - # Now add all the compiler specific options that are valid standalone - CFLAGS_KASAN := $(CFLAGS_KASAN_SHADOW) \ - $(call cc-param,asan-globals=1) \ - $(call cc-param,asan-instrumentation-with-call-threshold=$(call_threshold)) \ - $(call cc-param,asan-instrument-allocas=1) -endif - -CFLAGS_KASAN += $(call cc-param,asan-stack=$(stack_enable)) +# First, enable -fsanitize=kernel-address together with providing the shadow +# mapping offset, as for GCC, -fasan-shadow-offset fails without -fsanitize +# (GCC accepts the shadow mapping offset via -fasan-shadow-offset instead of +# a --param like the other KASAN parameters). +# Instead of ifdef-checking the compiler, rely on cc-option. +CFLAGS_KASAN := $(call cc-option, -fsanitize=kernel-address \ + -fasan-shadow-offset=$(KASAN_SHADOW_OFFSET), \ + $(call cc-option, -fsanitize=kernel-address \ + -mllvm -asan-mapping-offset=$(KASAN_SHADOW_OFFSET))) + +# Now, add other parameters enabled similarly in both GCC and Clang. +# As some of them are not supported by older compilers, use cc-param. +CFLAGS_KASAN += $(call cc-param,asan-instrumentation-with-call-threshold=$(call_threshold)) \ + $(call cc-param,asan-stack=$(stack_enable)) \ + $(call cc-param,asan-instrument-allocas=1) \ + $(call cc-param,asan-globals=1) # Instrument memcpy/memset/memmove calls by using instrumented __asan_mem*() # instead. With compilers that don't support this option, compiler-inserted @@ -57,9 +58,9 @@ endif # CONFIG_KASAN_GENERIC ifdef CONFIG_KASAN_SW_TAGS ifdef CONFIG_KASAN_INLINE - instrumentation_flags := $(call cc-param,hwasan-mapping-offset=$(KASAN_SHADOW_OFFSET)) + instrumentation_flags := $(call cc-param,hwasan-mapping-offset=$(KASAN_SHADOW_OFFSET)) else - instrumentation_flags := $(call cc-param,hwasan-instrument-with-calls=1) + instrumentation_flags := $(call cc-param,hwasan-instrument-with-calls=1) endif CFLAGS_KASAN := -fsanitize=kernel-hwaddress \ @@ -70,7 +71,7 @@ CFLAGS_KASAN := -fsanitize=kernel-hwaddress \ # Instrument memcpy/memset/memmove calls by using instrumented __hwasan_mem*(). ifeq ($(call clang-min-version, 150000)$(call gcc-min-version, 130000),y) -CFLAGS_KASAN += $(call cc-param,hwasan-kernel-mem-intrinsic-prefix=1) + CFLAGS_KASAN += $(call cc-param,hwasan-kernel-mem-intrinsic-prefix=1) endif endif # CONFIG_KASAN_SW_TAGS -- 2.25.1
