On Wed, 14 Aug 2024 at 18:11, <andrey.konovalov@xxxxxxxxx> wrote: > > 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> Acked-by: Marco Elver <elver@xxxxxxxxxx> Just in case, did you test SW and HW tags modes as well? > --- > > 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 >
