[PATCH early RFC 2/4] kbuild: kasan: refactor open coded cflags for kasan test

[Jann Horn <jannh@google.com>]

In the Makefile for mm/kasan/, KASAN is broadly disabled to prevent the
KASAN runtime from recursing into itself; but the KASAN tests must be
exempt from that.

This is currently implemented by duplicating the same logic that is also
in scripts/Makefile.lib. In preparation for changing that logic,
refactor away the duplicate logic - we already have infrastructure for
opting in specific files inside directories that are opted out.

Signed-off-by: Jann Horn <jannh@google.com>
---
 mm/kasan/Makefile | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
index dd93ae8a6beb..922b2e6f6d14 100644
--- a/mm/kasan/Makefile
+++ b/mm/kasan/Makefile
@@ -35,18 +35,10 @@ CFLAGS_shadow.o := $(CC_FLAGS_KASAN_RUNTIME)
 CFLAGS_hw_tags.o := $(CC_FLAGS_KASAN_RUNTIME)
 CFLAGS_sw_tags.o := $(CC_FLAGS_KASAN_RUNTIME)
 
-CFLAGS_KASAN_TEST := $(CFLAGS_KASAN)
-ifndef CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX
-# If compiler instruments memintrinsics by prefixing them with __asan/__hwasan,
-# we need to treat them normally (as builtins), otherwise the compiler won't
-# recognize them as instrumentable. If it doesn't instrument them, we need to
-# pass -fno-builtin, so the compiler doesn't inline them.
-CFLAGS_KASAN_TEST += -fno-builtin
-endif
+KASAN_SANITIZE_kasan_test_c.o := y
+KASAN_SANITIZE_kasan_test_rust.o := y
 
 CFLAGS_REMOVE_kasan_test_c.o += $(call cc-option, -Wvla-larger-than=1)
-CFLAGS_kasan_test_c.o := $(CFLAGS_KASAN_TEST)
-RUSTFLAGS_kasan_test_rust.o := $(RUSTFLAGS_KASAN)
 
 obj-y := common.o report.o
 obj-$(CONFIG_KASAN_GENERIC) += init.o generic.o report_generic.o shadow.o quarantine.o

-- 
2.50.1.565.gc32cd1483b-goog