On Tue, Feb 18, 2025 at 9:20 AM Maciej Wieczor-Retman <maciej.wieczor-retman@xxxxxxxxx> wrote: > > Make CONFIG_KASAN_SW_TAGS available for x86 machines if they have > ADDRESS_MASKING enabled (LAM) as that works similarly to Top-Byte Ignore > (TBI) that allows the software tag-based mode on arm64 platform. > > Set scale macro based on KASAN mode: in software tag-based mode 32 bytes > of memory map to one shadow byte and 16 in generic mode. These should be 16 and 8. > > Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@xxxxxxxxx> > --- > Changelog v2: > - Remove KASAN dense code. > > arch/x86/Kconfig | 6 ++++++ > arch/x86/boot/compressed/misc.h | 1 + > arch/x86/include/asm/kasan.h | 2 +- > arch/x86/kernel/setup.c | 2 ++ > 4 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index f4ef64bf824a..dc48eb5b664f 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -195,6 +195,7 @@ config X86 > select HAVE_ARCH_JUMP_LABEL_RELATIVE > select HAVE_ARCH_KASAN if X86_64 > select HAVE_ARCH_KASAN_VMALLOC if X86_64 > + select HAVE_ARCH_KASAN_SW_TAGS if ADDRESS_MASKING > select HAVE_ARCH_KFENCE > select HAVE_ARCH_KMSAN if X86_64 > select HAVE_ARCH_KGDB > @@ -402,6 +403,11 @@ config KASAN_SHADOW_OFFSET > hex > default 0xdffffc0000000000 if KASAN_GENERIC > > +config KASAN_SHADOW_SCALE_SHIFT > + int > + default 4 if KASAN_SW_TAGS > + default 3 What's the purpose of this config option? I think we can just change the value of the KASAN_SHADOW_SCALE_SHIFT define when KASAN_SW_TAGS is enabled. > + > config HAVE_INTEL_TXT > def_bool y > depends on INTEL_IOMMU && ACPI > diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h > index dd8d1a85f671..f6a87e9ad200 100644 > --- a/arch/x86/boot/compressed/misc.h > +++ b/arch/x86/boot/compressed/misc.h > @@ -13,6 +13,7 @@ > #undef CONFIG_PARAVIRT_SPINLOCKS > #undef CONFIG_KASAN > #undef CONFIG_KASAN_GENERIC > +#undef CONFIG_KASAN_SW_TAGS > > #define __NO_FORTIFY > > diff --git a/arch/x86/include/asm/kasan.h b/arch/x86/include/asm/kasan.h > index 4bfd3641af84..cfc31e4a2f70 100644 > --- a/arch/x86/include/asm/kasan.h > +++ b/arch/x86/include/asm/kasan.h > @@ -6,7 +6,7 @@ > #include <linux/kasan-tags.h> > #include <linux/types.h> > > -#define KASAN_SHADOW_SCALE_SHIFT 3 > +#define KASAN_SHADOW_SCALE_SHIFT CONFIG_KASAN_SHADOW_SCALE_SHIFT > > /* > * Compiler uses shadow offset assuming that addresses start > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index cebee310e200..768990c573ea 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -1124,6 +1124,8 @@ void __init setup_arch(char **cmdline_p) > > kasan_init(); > > + kasan_init_sw_tags(); > + > /* > * Sync back kernel address range. > * > -- > 2.47.1 >
