From 008dead43d1e16b9849b388a47f7e3e647dd09ec Mon Sep 17 00:00:00 2001 From: Ilya Leoshkevich Date: Fri, 21 Jun 2024 13:35:08 +0200 Subject: [PATCH] s390/boot: add the KMSAN runtime stub It should be possible to have inline functions in the s390 header files, which call kmsan_unpoison_memory(). The problem is that these header files might be included by the decompressor, which does not contain KMSAN runtime, causing linker errors. Not compiling these calls if __SANITIZE_MEMORY__ is not defined - either by changing kmsan-checks.h or at the call sites - may cause unintended side effects, since calling these functions from an uninstrumented code that is linked into the kernel is valid use case. One might want to explicitly distinguish between the kernel and the decompressor. Checking for a decompressor-specific #define is quite heavy-handed, and will have to be done at all call sites. A more generic approach is to provide a dummy kmsan_unpoison_memory() definition. This produces some runtime overhead, but only when building with CONFIG_KMSAN. The benefit is that it does not disturb the existing KMSAN build logic and call sites don't need to be changed. Link: https://lkml.kernel.org/r/20240621113706.315500-25-iii@linux.ibm.com Signed-off-by: Ilya Leoshkevich Reviewed-by: Alexander Potapenko Cc: Alexander Gordeev Cc: Christian Borntraeger Cc: Christoph Lameter Cc: David Rientjes Cc: Dmitry Vyukov Cc: Heiko Carstens Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Joonsoo Kim Cc: Cc: Marco Elver Cc: Mark Rutland Cc: Masami Hiramatsu (Google) Cc: Pekka Enberg Cc: Roman Gushchin Cc: Steven Rostedt (Google) Cc: Sven Schnelle Cc: Vasily Gorbik Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- arch/s390/boot/Makefile | 1 + arch/s390/boot/kmsan.c | 6 ++++++ 2 files changed, 7 insertions(+) create mode 100644 arch/s390/boot/kmsan.c diff --git a/arch/s390/boot/Makefile b/arch/s390/boot/Makefile index 526ed20b9d31..e7658997452b 100644 --- a/arch/s390/boot/Makefile +++ b/arch/s390/boot/Makefile @@ -44,6 +44,7 @@ obj-$(findstring y, $(CONFIG_PROTECTED_VIRTUALIZATION_GUEST) $(CONFIG_PGSTE)) += obj-$(CONFIG_RANDOMIZE_BASE) += kaslr.o obj-y += $(if $(CONFIG_KERNEL_UNCOMPRESSED),,decompressor.o) info.o obj-$(CONFIG_KERNEL_ZSTD) += clz_ctz.o +obj-$(CONFIG_KMSAN) += kmsan.o obj-all := $(obj-y) piggy.o syms.o targets := bzImage section_cmp.boot.data section_cmp.boot.preserved.data $(obj-y) diff --git a/arch/s390/boot/kmsan.c b/arch/s390/boot/kmsan.c new file mode 100644 index 000000000000..e7b3ac48143e --- /dev/null +++ b/arch/s390/boot/kmsan.c @@ -0,0 +1,6 @@ +// SPDX-License-Identifier: GPL-2.0 +#include + +void kmsan_unpoison_memory(const void *address, size_t size) +{ +}