Andrey Ryabinin [off-list ref] writes:

2015-08-26 11:26 GMT+03:00 Aneesh Kumar K.V [off-list ref]:

quoted

Some of the archs, may find it difficult to support inline KASan
mode. Add HAVE_ARCH_KASAN_INLINE so that we can disable inline
support at config time.

Signed-off-by: Aneesh Kumar K.V <redacted>
---
 arch/x86/Kconfig       |  1 +
 lib/Kconfig.kasan      |  2 ++
 scripts/Makefile.kasan | 28 ++++++++++++++--------------
 3 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b3a1a5d77d92..4416f80580fb 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig

@@ -78,6 +78,7 @@ config X86
        select HAVE_ARCH_HUGE_VMAP              if X86_64 || X86_PAE
        select HAVE_ARCH_JUMP_LABEL
        select HAVE_ARCH_KASAN                  if X86_64 && SPARSEMEM_VMEMMAP
+       select HAVE_ARCH_KASAN_INLINE                   if X86_64 && SPARSEMEM_VMEMMAP

This will not work because config HAVE_ARCH_KASAN_INLINE is not defined.
Instead of you can just add following in this file:

config HAVE_ARCH_KASAN_INLINE
          def_bool y
          depends on KASAN

Missed cherry-pick

diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index e9d1bb1175b8..5dba03bc3f01 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan

@@ -1,6 +1,9 @@
 config HAVE_ARCH_KASAN
 	bool
 
+config HAVE_ARCH_KASAN_INLINE
+	bool
+
 if HAVE_ARCH_KASAN
 
 config KASAN

quoted

        select HAVE_ARCH_KGDB
        select HAVE_ARCH_KMEMCHECK
        select HAVE_ARCH_SECCOMP_FILTER

diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index 39f24d6721e5..e9d1bb1175b8 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan

@@ -32,6 +32,7 @@ config KASAN_OUTLINE
          however it doesn't bloat size of kernel's .text section so
          much as inline does.

+if HAVE_ARCH_KASAN_INLINE
 config KASAN_INLINE
        bool "Inline instrumentation"

 depends on HAVE_ARCH_KASAN_INLINE

quoted

        help

@@ -40,6 +41,7 @@ config KASAN_INLINE
          it gives about x2 boost over outline instrumentation), but
          make kernel's .text size much bigger.
          This requires a gcc version of 5.0 or later.
+endif

 endchoice

diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
index 3f874d24234f..c1c06e9e107a 100644
--- a/scripts/Makefile.kasan
+++ b/scripts/Makefile.kasan

@@ -1,29 +1,29 @@
 ifdef CONFIG_KASAN
-ifdef CONFIG_KASAN_INLINE
-       call_threshold := 10000
-else
-       call_threshold := 0
-endif
-
-CFLAGS_KASAN_MINIMAL := -fsanitize=kernel-address

 CFLAGS_KASAN := $(call cc-option, -fsanitize=kernel-address \
-               -fasan-shadow-offset=$(CONFIG_KASAN_SHADOW_OFFSET) \
-               --param asan-stack=1 --param asan-globals=1 \
-               --param asan-instrumentation-with-call-threshold=$(call_threshold))
-
-ifeq ($(call cc-option, $(CFLAGS_KASAN_MINIMAL) -Werror),)
+                   --param asan-instrumentation-with-call-threshold=0)
+ifeq ($(CFLAGS_KASAN),)
    ifneq ($(CONFIG_COMPILE_TEST),y)
         $(warning Cannot use CONFIG_KASAN: \
             -fsanitize=kernel-address is not supported by compiler)
    endif
 else
-    ifeq ($(CFLAGS_KASAN),)
+
+   ifdef CONFIG_KASAN_INLINE
+   CFLAGS_KASAN_INLINE := $(call cc-option, -fsanitize=kernel-address \
+                        -fasan-shadow-offset=$(CONFIG_KASAN_SHADOW_OFFSET) \
+                        --param asan-stack=1 --param asan-globals=1 \
+                        --param asan-instrumentation-with-call-threshold=10000)
+
+    ifeq ($(CFLAGS_KASAN_INLINE),)
         ifneq ($(CONFIG_COMPILE_TEST),y)
             $(warning CONFIG_KASAN: compiler does not support all options.\
                 Trying minimal configuration)
         endif
-        CFLAGS_KASAN := $(CFLAGS_KASAN_MINIMAL)
+    else
+        CFLAGS_KASAN := $(CFLAGS_KASAN_INLINE)
     endif
+    endif
+

This removes stack and globals for CONFIG_KASAN_OUTLINE=y. Why?
Those are completely separate features. So this patch shouldn't touch
this Makefile at all.
Depends on HAVE_ARCH_KASAN_INLINE in CONFIG_KASAN_INLINE should be enough.

Correct. I have changes that will make kasan_global and kasan_stack as
config items. I didn't add it as part of this series because I still
haven't got outline global and stack work on ppc64. Right now the split
config only applies to ppc64. Hence didn't want to make the patch more
complicated. 

But you need to disable 'asan-stack' and 'asan-globals' for pcc64.
I'd suggest to introduce CFLAGS_ARCH_KASAN.
Define it in ppc64 Makefile:

CFLAGS_ARCH_KASAN := --param asan-globals=0 --param asan-stack=0

and add these flags to CFLAGS_KASAN_MINIMAL and CFLAGS_KASAN in Makefile.kasan.

quoted

 endif
 endif

-aneesh