s390/entry: Make early program check handler relocated lowcore aware

Add the missing pieces so the early program check handler also works
with a relocated lowcore. Right now the result of an early program
check in case of a relocated lowcore would be a program check loop.

Fixes: 8f1e70ad ("s390/boot: Add cmdline option to relocate lowcore")
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/kernel/early.c

@@ -183,12 +183,15 @@ void __do_early_pgm_check(struct pt_regs *regs)
 
 static noinline __init void setup_lowcore_early(void)
 {
+	struct lowcore *lc = get_lowcore();
 	psw_t psw;
 
 	psw.addr = (unsigned long)early_pgm_check_handler;
 	psw.mask = PSW_KERNEL_BITS;
-	get_lowcore()->program_new_psw = psw;
-	get_lowcore()->preempt_count = INIT_PREEMPT_COUNT;
+	lc->program_new_psw = psw;
+	lc->preempt_count = INIT_PREEMPT_COUNT;
+	lc->return_lpswe = gen_lpswe(__LC_RETURN_PSW);
+	lc->return_mcck_lpswe = gen_lpswe(__LC_RETURN_MCCK_PSW);
 }
 
 static __init void detect_diag9c(void)

arch/s390/kernel/entry.S

@@ -600,18 +600,19 @@ SYM_CODE_START(restart_int_handler)
 SYM_CODE_END(restart_int_handler)
 
 SYM_CODE_START(early_pgm_check_handler)
-	stmg	%r8,%r15,__LC_SAVE_AREA_SYNC
+	STMG_LC %r8,%r15,__LC_SAVE_AREA_SYNC
+	GET_LC	%r13
 	aghi	%r15,-(STACK_FRAME_OVERHEAD+__PT_SIZE)
 	la	%r11,STACK_FRAME_OVERHEAD(%r15)
 	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
 	stmg	%r0,%r7,__PT_R0(%r11)
-	mvc	__PT_PSW(16,%r11),__LC_PGM_OLD_PSW
-	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA_SYNC
+	mvc	__PT_PSW(16,%r11),__LC_PGM_OLD_PSW(%r13)
+	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA_SYNC(%r13)
 	lgr	%r2,%r11
 	brasl	%r14,__do_early_pgm_check
-	mvc	__LC_RETURN_PSW(16),STACK_FRAME_OVERHEAD+__PT_PSW(%r15)
+	mvc	__LC_RETURN_PSW(16,%r13),STACK_FRAME_OVERHEAD+__PT_PSW(%r15)
 	lmg	%r0,%r15,STACK_FRAME_OVERHEAD+__PT_R0(%r15)
-	lpswe	__LC_RETURN_PSW
+	LPSWEY	__LC_RETURN_PSW,__LC_RETURN_LPSWE
 SYM_CODE_END(early_pgm_check_handler)
 
 	.section .kprobes.text, "ax"