Commit 49b3cf03 authored by Peter Collingbourne's avatar Peter Collingbourne Committed by Catalin Marinas
Browse files

kasan: arm64: set TCR_EL1.TBID1 when enabled 



On hardware supporting pointer authentication, we previously ended up
enabling TBI on instruction accesses when tag-based ASAN was enabled,
but this was costing us 8 bits of PAC entropy, which was unnecessary
since tag-based ASAN does not require TBI on instruction accesses. Get
them back by setting TCR_EL1.TBID1.

Signed-off-by: default avatarPeter Collingbourne <pcc@google.com>
Reviewed-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Link: https://linux-review.googlesource.com/id/I3dded7824be2e70ea64df0aabab9598d5aebfcc4
Link: https://lore.kernel.org/r/20f64e26fc8a1309caa446fffcb1b4e2fe9e229f.1605952129.git.pcc@google.com


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 739003c6

arch/arm64/include/asm/pgtable-hwdef.h

+1 −0
Original line number Diff line number Diff line
@@ -260,6 +260,7 @@ 
#define TCR_TBI1		(UL(1) << 38)

#define TCR_HA			(UL(1) << 39)

#define TCR_HD			(UL(1) << 40)

#define TCR_TBID1		(UL(1) << 52)

#define TCR_NFD0		(UL(1) << 53)

#define TCR_NFD1		(UL(1) << 54)

#define TCR_E0PD0		(UL(1) << 55)

arch/arm64/mm/proc.S

+1 −1
Original line number Diff line number Diff line
@@ -40,7 +40,7 @@ 
#define TCR_CACHE_FLAGS	TCR_IRGN_WBWA | TCR_ORGN_WBWA



#ifdef CONFIG_KASAN_SW_TAGS

#define TCR_KASAN_FLAGS TCR_TBI1

#define TCR_KASAN_FLAGS TCR_TBI1 | TCR_TBID1

#else

#define TCR_KASAN_FLAGS 0

#endif