This patch adds a configuration option for a new KASAN mode called hardware tag-based KASAN. This mode uses the memory tagging approach like the software tag-based mode, but relies on arm64 Memory Tagging Extension feature for tag management and access checking. Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> Reviewed-by: Marco Elver <elver@xxxxxxxxxx> --- Change-Id: I246c2def9fffa6563278db1bddfbe742ca7bdefe --- lib/Kconfig.kasan | 56 +++++++++++++++++++++++++++++++++-------------- 1 file changed, 39 insertions(+), 17 deletions(-) diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index f73d5979575a..516d3a24f7d7 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -6,7 +6,10 @@ config HAVE_ARCH_KASAN config HAVE_ARCH_KASAN_SW_TAGS bool -config HAVE_ARCH_KASAN_VMALLOC +config HAVE_ARCH_KASAN_HW_TAGS + bool + +config HAVE_ARCH_KASAN_VMALLOC bool config CC_HAS_KASAN_GENERIC @@ -20,10 +23,11 @@ config CC_HAS_WORKING_NOSANITIZE_ADDRESS menuconfig KASAN bool "KASAN: runtime memory debugger" - depends on (HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC) || \ - (HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS) + depends on (((HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC) || \ + (HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS)) && \ + CC_HAS_WORKING_NOSANITIZE_ADDRESS) || \ + HAVE_ARCH_KASAN_HW_TAGS depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB) - depends on CC_HAS_WORKING_NOSANITIZE_ADDRESS select CONSTRUCTORS select STACKDEPOT help @@ -37,13 +41,18 @@ choice prompt "KASAN mode" default KASAN_GENERIC help - KASAN has two modes: generic KASAN (similar to userspace ASan, - x86_64/arm64/xtensa, enabled with CONFIG_KASAN_GENERIC) and - software tag-based KASAN (a version based on software memory - tagging, arm64 only, similar to userspace HWASan, enabled with - CONFIG_KASAN_SW_TAGS). + KASAN has three modes: + 1. generic KASAN (similar to userspace ASan, + x86_64/arm64/xtensa, enabled with CONFIG_KASAN_GENERIC), + 2. software tag-based KASAN (arm64 only, based on software + memory tagging (similar to userspace HWASan), enabled with + CONFIG_KASAN_SW_TAGS), and + 3. hardware tag-based KASAN (arm64 only, based on hardware + memory tagging, enabled with CONFIG_KASAN_HW_TAGS). + + All KASAN modes are strictly debugging features. - Both generic and tag-based KASAN are strictly debugging features. + For better error reports enable CONFIG_STACKTRACE. config KASAN_GENERIC bool "Generic mode" @@ -61,8 +70,6 @@ config KASAN_GENERIC and introduces an overhead of ~x1.5 for the rest of the allocations. The performance slowdown is ~x3. - For better error detection enable CONFIG_STACKTRACE. - Currently CONFIG_KASAN_GENERIC doesn't work with CONFIG_DEBUG_SLAB (the resulting kernel does not boot). @@ -73,9 +80,11 @@ config KASAN_SW_TAGS help Enables software tag-based KASAN mode. - This mode requires Top Byte Ignore support by the CPU and therefore - is only supported for arm64. This mode requires Clang version 7.0.0 - or later. + This mode require software memory tagging support in the form of + HWASan-like compiler instrumentation. + + Currently this mode is only implemented for arm64 CPUs and relies on + Top Byte Ignore. This mode requires Clang version 7.0.0 or later. This mode consumes about 1/16th of available memory at kernel start and introduces an overhead of ~20% for the rest of the allocations. @@ -83,15 +92,27 @@ config KASAN_SW_TAGS casting and comparison, as it embeds tags into the top byte of each pointer. - For better error detection enable CONFIG_STACKTRACE. - Currently CONFIG_KASAN_SW_TAGS doesn't work with CONFIG_DEBUG_SLAB (the resulting kernel does not boot). +config KASAN_HW_TAGS + bool "Hardware tag-based mode" + depends on HAVE_ARCH_KASAN_HW_TAGS + depends on SLUB + help + Enables hardware tag-based KASAN mode. + + This mode requires hardware memory tagging support, and can be used + by any architecture that provides it. + + Currently this mode is only implemented for arm64 CPUs starting from + ARMv8.5 and relies on Memory Tagging Extension and Top Byte Ignore. + endchoice choice prompt "Instrumentation type" + depends on KASAN_GENERIC || KASAN_SW_TAGS default KASAN_OUTLINE config KASAN_OUTLINE @@ -115,6 +136,7 @@ endchoice config KASAN_STACK_ENABLE bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST + depends on KASAN_GENERIC || KASAN_SW_TAGS help The LLVM stack address sanitizer has a know problem that causes excessive stack usage in a lot of functions, see -- 2.28.0.1011.ga647a8990f-goog
