[PATCH v6 12/44] kmsan: disable instrumentation of unsupported common kernel code

Alexander Potapenko
2022-09-05T12:27:04Z

EFI stub cannot be linked with KMSAN runtime, so we disable
instrumentation for it.

Instrumenting kcov, stackdepot or lockdep leads to infinite recursion
caused by instrumentation hooks calling instrumented code again.

Signed-off-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Marco Elver <elver@google.com>
---
v4:
-- This patch was previously part of "kmsan: disable KMSAN
instrumentation for certain kernel parts", but was split away per
Mark Rutland's request.

v5:
-- remove unnecessary comment belonging to another patch

Link: https://linux-review.googlesource.com/id/I41ae706bd3474f074f6a870bfc3f0f90e9c720f7
---
drivers/firmware/efi/libstub/Makefile | 1 +
kernel/Makefile | 1 +
kernel/locking/Makefile | 3 ++-
lib/Makefile | 3 +++
4 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index d0537573501e9..81432d0c904b1 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -46,6 +46,7 @@ GCOV_PROFILE := n
# Sanitizer runtimes are unavailable and cannot be linked here.
KASAN_SANITIZE := n
KCSAN_SANITIZE := n
+KMSAN_SANITIZE := n
UBSAN_SANITIZE := n
OBJECT_FILES_NON_STANDARD := y

diff --git a/kernel/Makefile b/kernel/Makefile
index 318789c728d32..d754e0be1176d 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -38,6 +38,7 @@ KCOV_INSTRUMENT_kcov.o := n
KASAN_SANITIZE_kcov.o := n
KCSAN_SANITIZE_kcov.o := n
UBSAN_SANITIZE_kcov.o := n
+KMSAN_SANITIZE_kcov.o := n
CFLAGS_kcov.o := $(call cc-option, -fno-conserve-stack) -fno-stack-protector

# Don't instrument error handlers
diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
index d51cabf28f382..ea925731fa40f 100644
--- a/kernel/locking/Makefile
+++ b/kernel/locking/Makefile
@@ -5,8 +5,9 @@ KCOV_INSTRUMENT := n

obj-y += mutex.o semaphore.o rwsem.o percpu-rwsem.o

-# Avoid recursion lockdep -> KCSAN -> ... -> lockdep.
+# Avoid recursion lockdep -> sanitizer -> ... -> lockdep.
KCSAN_SANITIZE_lockdep.o := n
+KMSAN_SANITIZE_lockdep.o := n

ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_lockdep.o = $(CC_FLAGS_FTRACE)
diff --git a/lib/Makefile b/lib/Makefile
index ffabc30a27d4e..fcebece0f5b6f 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -275,6 +275,9 @@ obj-$(CONFIG_POLYNOMIAL) += polynomial.o
CFLAGS_stackdepot.o += -fno-builtin
obj-$(CONFIG_STACKDEPOT) += stackdepot.o
KASAN_SANITIZE_stackdepot.o := n
+# In particular, instrumenting stackdepot.c with KMSAN will result in infinite
+# recursion.
+KMSAN_SANITIZE_stackdepot.o := n
KCOV_INSTRUMENT_stackdepot.o := n

obj-$(CONFIG_REF_TRACKER) += ref_tracker.o
--
2.37.2.789.g6183377224-goog