s390/kasan: fix early pgm check handler execution

[ Upstream commit 998f5bbe3dbdab81c1cfb1aef7c3892f5d24f6c7 ]

Currently if early_pgm_check_handler is called it ends up in pgm check
loop. The problem is that early_pgm_check_handler is instrumented by
KASAN but executed without DAT flag enabled which leads to addressing
exception when KASAN checks try to access shadow memory.

Fix that by executing early handlers with DAT flag on under KASAN as
expected.

Reported-and-tested-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 4ba5ad44a21a2ec860e35789c8da3816b9501612..73045142febf062b6857af4001bd40c0cfbf586f 100644 (file)
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -317,6 +317,8 @@ static noinline __init void setup_lowcore_early(void)
        psw_t psw;
 
        psw.mask = PSW_MASK_BASE | PSW_DEFAULT_KEY | PSW_MASK_EA | PSW_MASK_BA;
+       if (IS_ENABLED(CONFIG_KASAN))
+               psw.mask |= PSW_MASK_DAT;
        psw.addr = (unsigned long) s390_base_ext_handler;
        S390_lowcore.external_new_psw = psw;
        psw.addr = (unsigned long) s390_base_pgm_handler;