s390/base: pass pt_regs to early program check handler

Pass pt_regs to early program check handler like it is done for every
other interrupt and exception handler.

Also the passed pt_regs can be changed by the called function and the
changes register contents and psw contents will be taken into account
when returning. In addition the return psw will not be copied to the
program check old psw in lowcore, but to the usual return psw
location, like it is also done by the regular program check handler.
This allows also to get rid of the code that disabled lowcore
protection when changing the return address.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

1 files changed, 3 insertions, 11 deletions

diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 9d151808d03e..5715d1aab173 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -149,22 +149,14 @@ static __init void setup_topology(void)
 	topology_max_mnest = max_mnest;
 }
 
-static void early_pgm_check_handler(void)
+static void early_pgm_check_handler(struct pt_regs *regs)
 {
 	const struct exception_table_entry *fixup;
-	unsigned long cr0, cr0_new;
-	unsigned long addr;
 
-	addr = S390_lowcore.program_old_psw.addr;
-	fixup = s390_search_extables(addr);
+	fixup = s390_search_extables(regs->psw.addr);
 	if (!fixup)
 		disabled_wait();
-	/* Disable low address protection before storing into lowcore. */
-	__ctl_store(cr0, 0, 0);
-	cr0_new = cr0 & ~(1UL << 28);
-	__ctl_load(cr0_new, 0, 0);
-	S390_lowcore.program_old_psw.addr = extable_fixup(fixup);
-	__ctl_load(cr0, 0, 0);
+	regs->psw.addr = extable_fixup(fixup);
 }
 
 static noinline __init void setup_lowcore_early(void)