kasan, arm64: enable top byte ignore for the kernel

Tag-based KASAN 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 tag-based
KASAN is used.

Link: http://lkml.kernel.org/r/1ed03d53ee679cba52ba7118d2acbef948d21fcc.1543337629.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index 1d7d8da2ef9b301dec85e80fe1825b95f71aa54b..d43b870c39b37b7acb389a8ec96e329a8cdedbf3 100644 (file)
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -291,6 +291,7 @@
 #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)
 #define TCR_NFD1               (UL(1) << 54)

diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 2c75b0b903ae2f043f74273d23dd4f0f7a8e94a4..d861f208eeb1a74cc3c37344556339723903c751 100644 (file)
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -47,6 +47,12 @@
 /* PTWs cacheable, inner/outer WBWA */
 #define TCR_CACHE_FLAGS        TCR_IRGN_WBWA | TCR_ORGN_WBWA
 
+#ifdef CONFIG_KASAN_SW_TAGS
+#define TCR_KASAN_FLAGS TCR_TBI1
+#else
+#define TCR_KASAN_FLAGS 0
+#endif
+
 #define MAIR(attr, mt) ((attr) << ((mt) * 8))
 
 /*
@@ -445,7 +451,7 @@ ENTRY(__cpu_setup)
         */
        ldr     x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
                        TCR_TG_FLAGS | TCR_KASLR_FLAGS | TCR_ASID16 | \
-                       TCR_TBI0 | TCR_A1
+                       TCR_TBI0 | TCR_A1 | TCR_KASAN_FLAGS
        tcr_set_idmap_t0sz      x10, x9
 
        /*