Re: [PATCH V2 07/10] kasan: Make INLINE KASan support arch selectable

From: Aneesh Kumar K.V
Date: Sun Aug 30 2015 - 08:50:53 EST


Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx> writes:

> 2015-08-26 11:26 GMT+03:00 Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>:
>> 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 <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
>> ---
>> 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

>
>> 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
>
>> 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.
>
>
>> endif
>> endif
>>

-aneesh

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