Hi Marco, On Fri, Feb 24, 2023 at 09:59:39AM +0100, Marco Elver wrote: > Clang 15 provides an option to prefix memcpy/memset/memmove calls with > __asan_/__hwasan_ in instrumented functions: https://reviews.llvm.org/D122724 > > GCC will add support in future: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108777 > > Use it to regain KASAN instrumentation of memcpy/memset/memmove on > architectures that require noinstr to be really free from instrumented > mem*() functions (all GENERIC_ENTRY architectures). > > Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions") > Signed-off-by: Marco Elver <elver@xxxxxxxxxx> > Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> > Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx> > Tested-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx> > Tested-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> [...] > diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan > index b9e94c5e7097..fa9f836f8039 100644 > --- a/scripts/Makefile.kasan > +++ b/scripts/Makefile.kasan > @@ -38,6 +38,11 @@ endif > > CFLAGS_KASAN += $(call cc-param,asan-stack=$(stack_enable)) > > +# Instrument memcpy/memset/memmove calls by using instrumented __asan_mem*() > +# instead. With compilers that don't support this option, compiler-inserted > +# memintrinsics won't be checked by KASAN on GENERIC_ENTRY architectures. > +CFLAGS_KASAN += $(call cc-param,asan-kernel-mem-intrinsic-prefix=1) > + > endif # CONFIG_KASAN_GENERIC > > ifdef CONFIG_KASAN_SW_TAGS > @@ -54,6 +59,9 @@ CFLAGS_KASAN := -fsanitize=kernel-hwaddress \ > $(call cc-param,hwasan-inline-all-checks=0) \ > $(instrumentation_flags) > > +# Instrument memcpy/memset/memmove calls by using instrumented __hwasan_mem*(). > +CFLAGS_KASAN += $(call cc-param,hwasan-kernel-mem-intrinsic-prefix=1) This patch breaks the arm64 kernel builds with KASAN_SW_TAGS enabled and clang prior to version 15. Those prior clang versions don't like the '-mllvm -hwasan-kernel-mem-intrinsic-prefix=1' option, end up printing the help text instead of generating the object. Do we need some combination of cc-option and cc-param? Or at least disable this instrumentation if earlier clang versions are used. It's already in mainline as commit 51287dcb00cc715c27bf6a6b4dbd431621c5b65a. Thanks. -- Catalin
