On Wed, Sep 24, 2014 at 5:44 AM, Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx> 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@xxxxxxxxxxx> > --- > 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? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>