The patch titled
Subject: kasan: simplify and clarify Makefile
has been added to the -mm mm-unstable branch. Its filename is
kasan-simplify-and-clarify-makefile.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kasan-simplify-and-clarify-makefile.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Subject: kasan: simplify and clarify Makefile
Date: Wed, 14 Aug 2024 00:40:27 +0200
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.
Link: https://lkml.kernel.org/r/20240813224027.84503-1-andrey.konovalov@xxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Matthew Maurer <mmaurer@xxxxxxxxxx>
Cc: Miguel Ojeda <ojeda@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
scripts/Makefile.kasan | 43 +++++++++++++++++++--------------------
1 file changed, 21 insertions(+), 22 deletions(-)
--- a/scripts/Makefile.kasan~kasan-simplify-and-clarify-makefile
+++ a/scripts/Makefile.kasan
@@ -22,30 +22,29 @@ 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 normal --param). 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 in a similar way with GCC and Clang.
+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 +56,9 @@ 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 := $(call cc-param,hwasan-instrument-with-calls=1)
endif
CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
@@ -70,7 +69,7 @@ CFLAGS_KASAN := -fsanitize=kernel-hwaddr
# Instrument memcpy/memset/memmove calls by using instrumented __hwasan_mem*().
ifeq ($(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
_
Patches currently in -mm which might be from andreyknvl@xxxxxxxxx are
kasan-simplify-and-clarify-makefile.patch
kcov-dont-instrument-lib-find_bitc.patch
