KHWASAN uses the Top Byte Ignore feature of arm64 CPUs to store a pointer tag in the top byte of each pointer. This commit enables the TCR_TBI1 bit, which enables Top Byte Ignore for the kernel, when KHWASAN is used. Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> --- arch/arm64/include/asm/pgtable-hwdef.h | 1 + arch/arm64/mm/proc.S | 9 ++++++++- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h index cdfe3e657a9e..ae6b6405eacc 100644 --- a/arch/arm64/include/asm/pgtable-hwdef.h +++ b/arch/arm64/include/asm/pgtable-hwdef.h @@ -289,6 +289,7 @@ #define TCR_A1 (UL(1) << 22) #define TCR_ASID16 (UL(1) << 36) #define TCR_TBI0 (UL(1) << 37) +#define TCR_TBI1 (UL(1) << 38) #define TCR_HA (UL(1) << 39) #define TCR_HD (UL(1) << 40) diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index c0af47617299..d64ce2ea40ec 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -41,6 +41,12 @@ /* PTWs cacheable, inner/outer WBWA */ #define TCR_CACHE_FLAGS TCR_IRGN_WBWA | TCR_ORGN_WBWA +#ifdef CONFIG_KASAN_TAGS +#define KASAN_TCR_FLAGS TCR_TBI1 +#else +#define KASAN_TCR_FLAGS 0 +#endif + #define MAIR(attr, mt) ((attr) << ((mt) * 8)) /* @@ -432,7 +438,8 @@ ENTRY(__cpu_setup) * both user and kernel. */ ldr x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \ - TCR_TG_FLAGS | TCR_ASID16 | TCR_TBI0 | TCR_A1 + TCR_TG_FLAGS | TCR_ASID16 | TCR_TBI0 | TCR_A1 | \ + KASAN_TCR_FLAGS tcr_set_idmap_t0sz x10, x9 /* -- 2.17.0.rc0.231.g781580f067-goog
