Enumerate Linear Address Masking and provide defines for CR3 and CR4 flags. The new CONFIG_ADDRESS_MASKING option enables the feature support in kernel. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Tested-by: Alexander Potapenko <glider@xxxxxxxxxx> --- arch/x86/Kconfig | 11 +++++++++++ arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/processor-flags.h | 2 ++ arch/x86/include/uapi/asm/processor-flags.h | 6 ++++++ 4 files changed, 20 insertions(+) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index a825bf031f49..aa9f73f5d670 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -2290,6 +2290,17 @@ config RANDOMIZE_MEMORY_PHYSICAL_PADDING If unsure, leave at the default value. +config ADDRESS_MASKING + bool "Linear Address Masking support" + depends on X86_64 + help + Linear Address Masking (LAM) modifies the checking that is applied + to 64-bit linear addresses, allowing software to use of the + untranslated address bits for metadata. + + The capability can be used for efficient address sanitizers (ASAN) + implementation and for optimizations in JITs. + config HOTPLUG_CPU def_bool y depends on SMP diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index 73c9672c123b..353b054812de 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -321,6 +321,7 @@ #define X86_FEATURE_LKGS (12*32+18) /* "" Load "kernel" (userspace) GS */ #define X86_FEATURE_AMX_FP16 (12*32+21) /* "" AMX fp16 Support */ #define X86_FEATURE_AVX_IFMA (12*32+23) /* "" Support for VPMADD52[H,L]UQ */ +#define X86_FEATURE_LAM (12*32+26) /* Linear Address Masking */ /* AMD-defined CPU features, CPUID level 0x80000008 (EBX), word 13 */ #define X86_FEATURE_CLZERO (13*32+ 0) /* CLZERO instruction */ diff --git a/arch/x86/include/asm/processor-flags.h b/arch/x86/include/asm/processor-flags.h index a7f3d9100adb..d8cccadc83a6 100644 --- a/arch/x86/include/asm/processor-flags.h +++ b/arch/x86/include/asm/processor-flags.h @@ -28,6 +28,8 @@ * On systems with SME, one bit (in a variable position!) is stolen to indicate * that the top-level paging structure is encrypted. * + * On systemms with LAM, bits 61 and 62 are used to indicate LAM mode. + * * All of the remaining bits indicate the physical address of the top-level * paging structure. * diff --git a/arch/x86/include/uapi/asm/processor-flags.h b/arch/x86/include/uapi/asm/processor-flags.h index c47cc7f2feeb..d898432947ff 100644 --- a/arch/x86/include/uapi/asm/processor-flags.h +++ b/arch/x86/include/uapi/asm/processor-flags.h @@ -82,6 +82,10 @@ #define X86_CR3_PCID_BITS 12 #define X86_CR3_PCID_MASK (_AC((1UL << X86_CR3_PCID_BITS) - 1, UL)) +#define X86_CR3_LAM_U57_BIT 61 /* Activate LAM for userspace, 62:57 bits masked */ +#define X86_CR3_LAM_U57 _BITULL(X86_CR3_LAM_U57_BIT) +#define X86_CR3_LAM_U48_BIT 62 /* Activate LAM for userspace, 62:48 bits masked */ +#define X86_CR3_LAM_U48 _BITULL(X86_CR3_LAM_U48_BIT) #define X86_CR3_PCID_NOFLUSH_BIT 63 /* Preserve old PCID */ #define X86_CR3_PCID_NOFLUSH _BITULL(X86_CR3_PCID_NOFLUSH_BIT) @@ -132,6 +136,8 @@ #define X86_CR4_PKE _BITUL(X86_CR4_PKE_BIT) #define X86_CR4_CET_BIT 23 /* enable Control-flow Enforcement Technology */ #define X86_CR4_CET _BITUL(X86_CR4_CET_BIT) +#define X86_CR4_LAM_SUP_BIT 28 /* LAM for supervisor pointers */ +#define X86_CR4_LAM_SUP _BITUL(X86_CR4_LAM_SUP_BIT) /* * x86-64 Task Priority Register, CR8 -- 2.39.2
