| Message ID | b4ba65afa55f2fdfd2856fb03c5aba99c7a8bdd7.1535462971.git.andreyknvl@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | khwasan: kernel hardware assisted address sanitizer | expand |
On Wed, Aug 29, 2018 at 1:35 PM, Andrey Konovalov <andreyknvl@google.com> wrote: > KWHASAN uses 1 shadow byte for 16 bytes of kernel memory, so it requires > 1/16th of the kernel virtual address space for the shadow memory. > > This commit sets KASAN_SHADOW_SCALE_SHIFT to 4 when KHWASAN is enabled. > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> > --- > arch/arm64/Makefile | 2 +- > arch/arm64/include/asm/memory.h | 13 +++++++++---- > 2 files changed, 10 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > index 106039d25e2f..17047b8ab984 100644 > --- a/arch/arm64/Makefile > +++ b/arch/arm64/Makefile > @@ -94,7 +94,7 @@ endif > # KASAN_SHADOW_OFFSET = VA_START + (1 << (VA_BITS - KASAN_SHADOW_SCALE_SHIFT)) > # - (1 << (64 - KASAN_SHADOW_SCALE_SHIFT)) > # in 32-bit arithmetic > -KASAN_SHADOW_SCALE_SHIFT := 3 > +KASAN_SHADOW_SCALE_SHIFT := $(if $(CONFIG_KASAN_HW), 4, 3) > KASAN_SHADOW_OFFSET := $(shell printf "0x%08x00000000\n" $$(( \ > (0xffffffff & (-1 << ($(CONFIG_ARM64_VA_BITS) - 32))) \ > + (1 << ($(CONFIG_ARM64_VA_BITS) - 32 - $(KASAN_SHADOW_SCALE_SHIFT))) \ > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h > index b96442960aea..f5e262ee76c1 100644 > --- a/arch/arm64/include/asm/memory.h > +++ b/arch/arm64/include/asm/memory.h > @@ -74,12 +74,17 @@ > #define KERNEL_END _end > > /* > - * KASAN requires 1/8th of the kernel virtual address space for the shadow > - * region. KASAN can bloat the stack significantly, so double the (minimum) > - * stack size when KASAN is in use. > + * KASAN and KHWASAN require 1/8th and 1/16th of the kernel virtual address I am somewhat confused by the terminology. "KASAN" is not actually "CONFIG_KASAN" below, it is actually "CONFIG_KASAN_GENERIC". While "KHWASAN" translates to "KASAN_HW" few lines later. I think we need some consistent terminology for comments and config names until it's too late. > + * space for the shadow region respectively. They can bloat the stack > + * significantly, so double the (minimum) stack size when they are in use. > */ > -#ifdef CONFIG_KASAN > +#ifdef CONFIG_KASAN_GENERIC > #define KASAN_SHADOW_SCALE_SHIFT 3 > +#endif > +#ifdef CONFIG_KASAN_HW > +#define KASAN_SHADOW_SCALE_SHIFT 4 > +#endif > +#ifdef CONFIG_KASAN > #define KASAN_SHADOW_SIZE (UL(1) << (VA_BITS - KASAN_SHADOW_SCALE_SHIFT)) > #define KASAN_THREAD_SHIFT 1 > #else > -- > 2.19.0.rc0.228.g281dcd1b4d0-goog >
On Wed, Sep 12, 2018 at 4:54 PM, Dmitry Vyukov <dvyukov@google.com> wrote: > On Wed, Aug 29, 2018 at 1:35 PM, Andrey Konovalov <andreyknvl@google.com> wrote: >> /* >> - * KASAN requires 1/8th of the kernel virtual address space for the shadow >> - * region. KASAN can bloat the stack significantly, so double the (minimum) >> - * stack size when KASAN is in use. >> + * KASAN and KHWASAN require 1/8th and 1/16th of the kernel virtual address > > > I am somewhat confused by the terminology. > "KASAN" is not actually "CONFIG_KASAN" below, it is actually > "CONFIG_KASAN_GENERIC". While "KHWASAN" translates to "KASAN_HW" few > lines later. > I think we need some consistent terminology for comments and config > names until it's too late. > As per offline discussion will rename in v7.
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 106039d25e2f..17047b8ab984 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -94,7 +94,7 @@ endif # KASAN_SHADOW_OFFSET = VA_START + (1 << (VA_BITS - KASAN_SHADOW_SCALE_SHIFT)) # - (1 << (64 - KASAN_SHADOW_SCALE_SHIFT)) # in 32-bit arithmetic -KASAN_SHADOW_SCALE_SHIFT := 3 +KASAN_SHADOW_SCALE_SHIFT := $(if $(CONFIG_KASAN_HW), 4, 3) KASAN_SHADOW_OFFSET := $(shell printf "0x%08x00000000\n" $$(( \ (0xffffffff & (-1 << ($(CONFIG_ARM64_VA_BITS) - 32))) \ + (1 << ($(CONFIG_ARM64_VA_BITS) - 32 - $(KASAN_SHADOW_SCALE_SHIFT))) \ diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index b96442960aea..f5e262ee76c1 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -74,12 +74,17 @@ #define KERNEL_END _end /* - * KASAN requires 1/8th of the kernel virtual address space for the shadow - * region. KASAN can bloat the stack significantly, so double the (minimum) - * stack size when KASAN is in use. + * KASAN and KHWASAN require 1/8th and 1/16th of the kernel virtual address + * space for the shadow region respectively. They can bloat the stack + * significantly, so double the (minimum) stack size when they are in use. */ -#ifdef CONFIG_KASAN +#ifdef CONFIG_KASAN_GENERIC #define KASAN_SHADOW_SCALE_SHIFT 3 +#endif +#ifdef CONFIG_KASAN_HW +#define KASAN_SHADOW_SCALE_SHIFT 4 +#endif +#ifdef CONFIG_KASAN #define KASAN_SHADOW_SIZE (UL(1) << (VA_BITS - KASAN_SHADOW_SCALE_SHIFT)) #define KASAN_THREAD_SHIFT 1 #else
KWHASAN uses 1 shadow byte for 16 bytes of kernel memory, so it requires 1/16th of the kernel virtual address space for the shadow memory. This commit sets KASAN_SHADOW_SCALE_SHIFT to 4 when KHWASAN is enabled. Signed-off-by: Andrey Konovalov <andreyknvl@google.com> --- arch/arm64/Makefile | 2 +- arch/arm64/include/asm/memory.h | 13 +++++++++---- 2 files changed, 10 insertions(+), 5 deletions(-)