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SubjectRe: [RFC PATCH v3 13/13] kasan: introduce inline instrumentation
On Wed, Sep 24, 2014 at 5:44 AM, Andrey Ryabinin <a.ryabinin@samsung.com> wrote:
> This patch only demonstration how easy this could be achieved.
> GCC doesn't support this feature yet. Two patches required for this:
> https://gcc.gnu.org/ml/gcc-patches/2014-09/msg00452.html
> https://gcc.gnu.org/ml/gcc-patches/2014-09/msg00605.html
>
> In inline instrumentation mode compiler directly inserts code
> checking shadow memory instead of __asan_load/__asan_store
> calls.
> This is usually faster than outline. In some workloads inline is
> 2 times faster than outline instrumentation.
>
> The downside of inline instrumentation is bloated kernel's .text size:
>
> size noasan/vmlinux
> text data bss dec hex filename
> 11759720 1566560 946176 14272456 d9c7c8 noasan/vmlinux
>
> size outline/vmlinux
> text data bss dec hex filename
> 16553474 1602592 950272 19106338 1238a22 outline/vmlinux
>
> size inline/vmlinux
> text data bss dec hex filename
> 32064759 1598688 946176 34609623 21019d7 inline/vmlinux
>
> Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
> ---
> Makefile | 5 +++++
> lib/Kconfig.kasan | 24 ++++++++++++++++++++++++
> mm/kasan/report.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 74 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index 6cefe5e..fe7c534 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -773,6 +773,11 @@ KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
> endif
>
> ifdef CONFIG_KASAN
> +ifdef CONFIG_KASAN_INLINE
> +CFLAGS_KASAN += $(call cc-option, -fasan-shadow-offset=$(CONFIG_KASAN_SHADOW_OFFSET)) \
> + $(call cc-option, --param asan-instrumentation-with-call-threshold=10000)
> +endif
> +
> ifeq ($(CFLAGS_KASAN),)
> $(warning Cannot use CONFIG_KASAN: \
> -fsanitize=kernel-address not supported by compiler)
> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> index faddb0e..c4ac040 100644
> --- a/lib/Kconfig.kasan
> +++ b/lib/Kconfig.kasan
> @@ -27,4 +27,28 @@ config TEST_KASAN
> out of bounds accesses, use after free. It is usefull for testing
> kernel debugging features like kernel address sanitizer.
>
> +choice
> + prompt "Instrumentation type"
> + depends on KASAN
> + default KASAN_INLINE if X86_64
> +
> +config KASAN_OUTLINE
> + bool "Outline instrumentation"
> + help
> + Before every memory access compiler insert function call
> + __asan_load*/__asan_store*. These functions performs check
> + of shadow memory. This is slower than inline instrumentation,
> + however it doesn't bloat size of kernel's .text section so
> + much as inline does.
> +
> +config KASAN_INLINE
> + bool "Inline instrumentation"
> + help
> + Compiler directly inserts code checking shadow memory before
> + memory accesses. This is faster than outline (in some workloads
> + it gives about x2 boost over outline instrumentation), but
> + make kernel's .text size much bigger.
> +
> +endchoice
> +
> endif
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index c42f6ba..a9262f8 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -212,3 +212,48 @@ void kasan_report_user_access(struct access_info *info)
> "=================================\n");
> spin_unlock_irqrestore(&report_lock, flags);
> }
> +
> +#define CALL_KASAN_REPORT(__addr, __size, __is_write) \
> + struct access_info info; \
> + info.access_addr = __addr; \
> + info.access_size = __size; \
> + info.is_write = __is_write; \
> + info.ip = _RET_IP_; \
> + kasan_report_error(&info)
> +
> +#define DEFINE_ASAN_REPORT_LOAD(size) \
> +void __asan_report_recover_load##size(unsigned long addr) \
> +{ \
> + CALL_KASAN_REPORT(addr, size, false); \
> +} \
> +EXPORT_SYMBOL(__asan_report_recover_load##size)
> +
> +#define DEFINE_ASAN_REPORT_STORE(size) \
> +void __asan_report_recover_store##size(unsigned long addr) \
> +{ \
> + CALL_KASAN_REPORT(addr, size, true); \
> +} \
> +EXPORT_SYMBOL(__asan_report_recover_store##size)
> +
> +DEFINE_ASAN_REPORT_LOAD(1);
> +DEFINE_ASAN_REPORT_LOAD(2);
> +DEFINE_ASAN_REPORT_LOAD(4);
> +DEFINE_ASAN_REPORT_LOAD(8);
> +DEFINE_ASAN_REPORT_LOAD(16);
> +DEFINE_ASAN_REPORT_STORE(1);
> +DEFINE_ASAN_REPORT_STORE(2);
> +DEFINE_ASAN_REPORT_STORE(4);
> +DEFINE_ASAN_REPORT_STORE(8);
> +DEFINE_ASAN_REPORT_STORE(16);
> +
> +void __asan_report_recover_load_n(unsigned long addr, size_t size)
> +{
> + CALL_KASAN_REPORT(addr, size, false);
> +}
> +EXPORT_SYMBOL(__asan_report_recover_load_n);
> +
> +void __asan_report_recover_store_n(unsigned long addr, size_t size)
> +{
> + CALL_KASAN_REPORT(addr, size, true);
> +}
> +EXPORT_SYMBOL(__asan_report_recover_store_n);
> --
> 2.1.1
>



Yikes!
So this works during bootstrap, for user memory accesses, valloc
memory, etc, right?


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