s390/entry: Unify save_area_sync and save_area_async

In the past two save areas existed because interrupt handlers
and system call / program check handlers where entered with
interrupts enabled. To prevent a handler from overwriting the
save areas from the previous handler, interrupts used the async
save area, while system call and program check handler used the
sync save area.

Since the removal of critical section cleanup from entry.S, handlers are
entered with interrupts disabled. When the interrupts are re-enabled,
the save area is no longer need. Therefore merge both save areas into one.

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

4 files changed, 16 insertions, 17 deletions

diff --git a/arch/s390/boot/head.S b/arch/s390/boot/head.S
index 637c29c3f6e3..0a47b16f6412 100644
--- a/arch/s390/boot/head.S
+++ b/arch/s390/boot/head.S
@@ -299,11 +299,11 @@ SYM_CODE_END(startup_normal)
 # the save area and does disabled wait with a faulty address.
 #
 SYM_CODE_START_LOCAL(startup_pgm_check_handler)
-	stmg	%r8,%r15,__LC_SAVE_AREA_SYNC
+	stmg	%r8,%r15,__LC_SAVE_AREA
 	la	%r8,4095
 	stctg	%c0,%c15,__LC_CREGS_SAVE_AREA-4095(%r8)
 	stmg	%r0,%r7,__LC_GPREGS_SAVE_AREA-4095(%r8)
-	mvc	__LC_GPREGS_SAVE_AREA-4095+64(64,%r8),__LC_SAVE_AREA_SYNC
+	mvc	__LC_GPREGS_SAVE_AREA-4095+64(64,%r8),__LC_SAVE_AREA
 	mvc	__LC_PSW_SAVE_AREA-4095(16,%r8),__LC_PGM_OLD_PSW
 	mvc	__LC_RETURN_PSW(16),__LC_PGM_OLD_PSW
 	ni	__LC_RETURN_PSW,0xfc	# remove IO and EX bits
diff --git a/arch/s390/include/asm/lowcore.h b/arch/s390/include/asm/lowcore.h
index 183ac29afaf8..48c64716d1f2 100644
--- a/arch/s390/include/asm/lowcore.h
+++ b/arch/s390/include/asm/lowcore.h
@@ -98,8 +98,8 @@ struct lowcore {
 	psw_t	io_new_psw;			/* 0x01f0 */
 
 	/* Save areas. */
-	__u64	save_area_sync[8];		/* 0x0200 */
-	__u64	save_area_async[8];		/* 0x0240 */
+	__u64	save_area[8];			/* 0x0200 */
+	__u8	pad_0x0240[0x0280-0x0240];	/* 0x0240 */
 	__u64	save_area_restart[1];		/* 0x0280 */
 
 	__u64	pcpu;				/* 0x0288 */
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index ffa0dd2dbaac..5529248d84fb 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -112,8 +112,7 @@ int main(void)
 	OFFSET(__LC_MCK_NEW_PSW, lowcore, mcck_new_psw);
 	OFFSET(__LC_IO_NEW_PSW, lowcore, io_new_psw);
 	/* software defined lowcore locations 0x200 - 0xdff*/
-	OFFSET(__LC_SAVE_AREA_SYNC, lowcore, save_area_sync);
-	OFFSET(__LC_SAVE_AREA_ASYNC, lowcore, save_area_async);
+	OFFSET(__LC_SAVE_AREA, lowcore, save_area);
 	OFFSET(__LC_SAVE_AREA_RESTART, lowcore, save_area_restart);
 	OFFSET(__LC_PCPU, lowcore, pcpu);
 	OFFSET(__LC_RETURN_PSW, lowcore, return_psw);
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 36424e53d63b..42ac4145dfe0 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -264,7 +264,7 @@ EXPORT_SYMBOL(sie_exit)
  */
 
 SYM_CODE_START(system_call)
-	STMG_LC	%r8,%r15,__LC_SAVE_AREA_SYNC
+	STMG_LC	%r8,%r15,__LC_SAVE_AREA
 	GET_LC	%r13
 	stpt	__LC_SYS_ENTER_TIMER(%r13)
 	BPOFF
@@ -287,7 +287,7 @@ SYM_CODE_START(system_call)
 	xgr	%r10,%r10
 	xgr	%r11,%r11
 	la	%r2,STACK_FRAME_OVERHEAD(%r15)	# pointer to pt_regs
-	mvc	__PT_R8(64,%r2),__LC_SAVE_AREA_SYNC(%r13)
+	mvc	__PT_R8(64,%r2),__LC_SAVE_AREA(%r13)
 	MBEAR	%r2,%r13
 	lgr	%r3,%r14
 	brasl	%r14,__do_syscall
@@ -323,7 +323,7 @@ SYM_CODE_END(ret_from_fork)
  */
 
 SYM_CODE_START(pgm_check_handler)
-	STMG_LC	%r8,%r15,__LC_SAVE_AREA_SYNC
+	STMG_LC	%r8,%r15,__LC_SAVE_AREA
 	GET_LC	%r13
 	stpt	__LC_SYS_ENTER_TIMER(%r13)
 	BPOFF
@@ -338,16 +338,16 @@ SYM_CODE_START(pgm_check_handler)
 	jnz	2f			# -> enabled, can't be a double fault
 	tm	__LC_PGM_ILC+3(%r13),0x80	# check for per exception
 	jnz	.Lpgm_svcper		# -> single stepped svc
-2:	CHECK_STACK __LC_SAVE_AREA_SYNC,%r13
+2:	CHECK_STACK __LC_SAVE_AREA,%r13
 	aghi	%r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE)
 	# CHECK_VMAP_STACK branches to stack_overflow or 4f
-	CHECK_VMAP_STACK __LC_SAVE_AREA_SYNC,%r13,4f
+	CHECK_VMAP_STACK __LC_SAVE_AREA,%r13,4f
 3:	lg	%r15,__LC_KERNEL_STACK(%r13)
 4:	la	%r11,STACK_FRAME_OVERHEAD(%r15)
 	xc	__PT_FLAGS(8,%r11),__PT_FLAGS(%r11)
 	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
 	stmg	%r0,%r7,__PT_R0(%r11)
-	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA_SYNC(%r13)
+	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA(%r13)
 	mvc	__PT_LAST_BREAK(8,%r11),__LC_PGM_LAST_BREAK(%r13)
 	stctg	%c1,%c1,__PT_CR1(%r11)
 #if IS_ENABLED(CONFIG_KVM)
@@ -398,7 +398,7 @@ SYM_CODE_END(pgm_check_handler)
  */
 .macro INT_HANDLER name,lc_old_psw,handler
 SYM_CODE_START(\name)
-	STMG_LC	%r8,%r15,__LC_SAVE_AREA_ASYNC
+	STMG_LC	%r8,%r15,__LC_SAVE_AREA
 	GET_LC	%r13
 	stckf	__LC_INT_CLOCK(%r13)
 	stpt	__LC_SYS_ENTER_TIMER(%r13)
@@ -414,7 +414,7 @@ SYM_CODE_START(\name)
 	BPENTER	__SF_SIE_FLAGS(%r15),_TIF_ISOLATE_BP_GUEST
 	SIEEXIT __SF_SIE_CONTROL(%r15),%r13
 #endif
-0:	CHECK_STACK __LC_SAVE_AREA_ASYNC,%r13
+0:	CHECK_STACK __LC_SAVE_AREA,%r13
 	aghi	%r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE)
 	j	2f
 1:	lctlg	%c1,%c1,__LC_KERNEL_ASCE(%r13)
@@ -432,7 +432,7 @@ SYM_CODE_START(\name)
 	xgr	%r7,%r7
 	xgr	%r10,%r10
 	xc	__PT_FLAGS(8,%r11),__PT_FLAGS(%r11)
-	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA_ASYNC(%r13)
+	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA(%r13)
 	MBEAR	%r11,%r13
 	stmg	%r8,%r9,__PT_PSW(%r11)
 	lgr	%r2,%r11		# pass pointer to pt_regs
@@ -601,14 +601,14 @@ SYM_CODE_END(restart_int_handler)
 
 	__INIT
 SYM_CODE_START(early_pgm_check_handler)
-	STMG_LC %r8,%r15,__LC_SAVE_AREA_SYNC
+	STMG_LC %r8,%r15,__LC_SAVE_AREA
 	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(%r13)
-	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA_SYNC(%r13)
+	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA(%r13)
 	lgr	%r2,%r11
 	brasl	%r14,__do_early_pgm_check
 	mvc	__LC_RETURN_PSW(16,%r13),STACK_FRAME_OVERHEAD+__PT_PSW(%r15)