build: Add option KERNEL_KASAN_SW_TAGS and HW_TAGS

Currently KASAN is supported but only the generic one. SW-tag and HW-tag
based KASAN have less impact on memory footprint or performance, and are
worth supporting.

Add choice menu for software and hardware Tag-Based KASAN, in addition
to the generic one.

Signed-off-by: Zhen XIN <zhen.xin@nokia-sbell.com>
[Restructure commit message]
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

diff --git a/config/Config-kernel.in b/config/Config-kernel.in
index 76b0395f3735c690245689777d8c05a5e0979933..0c9e00d11fe5edf5bd7275ae118e2545c0ca466f 100644 (file)
--- a/config/Config-kernel.in
+++ b/config/Config-kernel.in
@@ -184,16 +184,73 @@ config KERNEL_KASAN_VMALLOC
          will have no effect.
 
 if KERNEL_KASAN
-       config KERNEL_KASAN_GENERIC
-       def_bool y
+choice
+       prompt "KASAN mode"
+       depends on KERNEL_KASAN
+       default KERNEL_KASAN_GENERIC
+       help
+         KASAN has three modes:
+
+         1. Generic KASAN (supported by many architectures, enabled with
+            CONFIG_KASAN_GENERIC, similar to userspace ASan),
+         2. Software Tag-Based KASAN (arm64 only, based on software memory
+            tagging, enabled with CONFIG_KASAN_SW_TAGS, similar to userspace
+            HWASan), and
+         3. Hardware Tag-Based KASAN (arm64 only, based on hardware memory
+            tagging, enabled with CONFIG_KASAN_HW_TAGS).
+
+config KERNEL_KASAN_GENERIC
+       bool "Generic KASAN"
+       select KERNEL_SLUB_DEBUG
+       help
+         Enables Generic KASAN.
+
+         Consumes about 1/8th of available memory at kernel start and adds an
+         overhead of ~50% for dynamic allocations.
+         The performance slowdown is ~x3.
+
+config KERNEL_KASAN_SW_TAGS
+       bool "Software Tag-Based KASAN"
+       depends on aarch64
+       select KERNEL_SLUB_DEBUG
+       help
+         Enables Software Tag-Based KASAN.
+
+         Supported only on arm64 CPUs and relies on Top Byte Ignore.
+
+         Consumes about 1/16th of available memory at kernel start and
+         add an overhead of ~20% for dynamic allocations.
+
+         May potentially introduce problems related to pointer casting and
+         comparison, as it embeds a tag into the top byte of each pointer.
+
+config KERNEL_KASAN_HW_TAGS
+       bool "Hardware Tag-Based KASAN"
+       depends on aarch64
+       select KERNEL_SLUB_DEBUG
+       select KERNEL_ARM64_MTE
+       help
+         Enables Hardware Tag-Based KASAN.
+
+         Supported only on arm64 CPUs starting from ARMv8.5 and relies on
+         Memory Tagging Extension and Top Byte Ignore.
+
+         Consumes about 1/32nd of available memory.
+
+         May potentially introduce problems related to pointer casting and
+         comparison, as it embeds a tag into the top byte of each pointer.
+
+endchoice
+
+       config KERNEL_ARM64_MTE
+               def_bool n
 
-       config KERNEL_KASAN_SW_TAGS
-       def_bool n
 endif
 
 choice
        prompt "Instrumentation type"
        depends on KERNEL_KASAN
+       depends on !KERNEL_KASAN_HW_TAGS
        default KERNEL_KASAN_OUTLINE
 
 config KERNEL_KASAN_OUTLINE