s390/kvm: improve stack frame constants in entry.S

The code in sie64a uses the stack frame passed to the function to store
some temporary data in the empty1 array (see struct stack_frame in
asm/processor.h.

Replace the __SF_EMPTY+x constants with a properly defined offset:
s/__SF_EMPTY/__SF_SIE_CONTROL/, s/__SF_EMPTY+8/__SF_SIE_SAVEAREA/,
s/__SF_EMPTY+16/__SF_SIE_REASON/, s/__SF_EMPTY+24/__SF_SIE_FLAGS/.

Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/asm-offsets.c

@@ -63,6 +63,7 @@ int main(void)
 	OFFSET(__SF_SIE_CONTROL, stack_frame, empty1[0]);
 	OFFSET(__SF_SIE_SAVEAREA, stack_frame, empty1[1]);
 	OFFSET(__SF_SIE_REASON, stack_frame, empty1[2]);
+	OFFSET(__SF_SIE_FLAGS, stack_frame, empty1[3]);
 	BLANK();
 	/* timeval/timezone offsets for use by vdso */
 	OFFSET(__VDSO_UPD_COUNT, vdso_data, tb_update_count);

arch/s390/kernel/entry.S

@@ -297,10 +297,10 @@ ENTRY(__switch_to)
 ENTRY(sie64a)
 	stmg	%r6,%r14,__SF_GPRS(%r15)	# save kernel registers
 	lg	%r12,__LC_CURRENT
-	stg	%r2,__SF_EMPTY(%r15)		# save control block pointer
-	stg	%r3,__SF_EMPTY+8(%r15)		# save guest register save area
-	xc	__SF_EMPTY+16(8,%r15),__SF_EMPTY+16(%r15) # reason code = 0
-	mvc	__SF_EMPTY+24(8,%r15),__TI_flags(%r12) # copy thread flags
+	stg	%r2,__SF_SIE_CONTROL(%r15)	# save control block pointer
+	stg	%r3,__SF_SIE_SAVEAREA(%r15)	# save guest register save area
+	xc	__SF_SIE_REASON(8,%r15),__SF_SIE_REASON(%r15) # reason code = 0
+	mvc	__SF_SIE_FLAGS(8,%r15),__TI_flags(%r12) # copy thread flags
 	TSTMSK	__LC_CPU_FLAGS,_CIF_FPU		# load guest fp/vx registers ?
 	jno	.Lsie_load_guest_gprs
 	brasl	%r14,load_fpu_regs		# load guest fp/vx regs
@@ -311,18 +311,18 @@ ENTRY(sie64a)
 	jz	.Lsie_gmap
 	lctlg	%c1,%c1,__GMAP_ASCE(%r14)	# load primary asce
 .Lsie_gmap:
-	lg	%r14,__SF_EMPTY(%r15)		# get control block pointer
+	lg	%r14,__SF_SIE_CONTROL(%r15)	# get control block pointer
 	oi	__SIE_PROG0C+3(%r14),1		# we are going into SIE now
 	tm	__SIE_PROG20+3(%r14),3		# last exit...
 	jnz	.Lsie_skip
 	TSTMSK	__LC_CPU_FLAGS,_CIF_FPU
 	jo	.Lsie_skip			# exit if fp/vx regs changed
-	BPEXIT	__SF_EMPTY+24(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
+	BPEXIT	__SF_SIE_FLAGS(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
 .Lsie_entry:
 	sie	0(%r14)
 .Lsie_exit:
 	BPOFF
-	BPENTER	__SF_EMPTY+24(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
+	BPENTER	__SF_SIE_FLAGS(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
 .Lsie_skip:
 	ni	__SIE_PROG0C+3(%r14),0xfe	# no longer in SIE
 	lctlg	%c1,%c1,__LC_USER_ASCE		# load primary asce
@@ -341,7 +341,7 @@ ENTRY(sie64a)
 	nopr	7
 	.globl sie_exit
 sie_exit:
-	lg	%r14,__SF_EMPTY+8(%r15)		# load guest register save area
+	lg	%r14,__SF_SIE_SAVEAREA(%r15)	# load guest register save area
 	stmg	%r0,%r13,0(%r14)		# save guest gprs 0-13
 	xgr	%r0,%r0				# clear guest registers to
 	xgr	%r1,%r1				# prevent speculative use
@@ -350,11 +350,11 @@ sie_exit:
 	xgr	%r4,%r4
 	xgr	%r5,%r5
 	lmg	%r6,%r14,__SF_GPRS(%r15)	# restore kernel registers
-	lg	%r2,__SF_EMPTY+16(%r15)		# return exit reason code
+	lg	%r2,__SF_SIE_REASON(%r15)	# return exit reason code
 	BR_R1USE_R14
 .Lsie_fault:
 	lghi	%r14,-EFAULT
-	stg	%r14,__SF_EMPTY+16(%r15)	# set exit reason code
+	stg	%r14,__SF_SIE_REASON(%r15)	# set exit reason code
 	j	sie_exit
 
 	EX_TABLE(.Lrewind_pad6,.Lsie_fault)
@@ -643,7 +643,7 @@ ENTRY(pgm_check_handler)
 	slg	%r14,BASED(.Lsie_critical_start)
 	clg	%r14,BASED(.Lsie_critical_length)
 	jhe	0f
-	lg	%r14,__SF_EMPTY(%r15)		# get control block pointer
+	lg	%r14,__SF_SIE_CONTROL(%r15)	# get control block pointer
 	ni	__SIE_PROG0C+3(%r14),0xfe	# no longer in SIE
 	lctlg	%c1,%c1,__LC_USER_ASCE		# load primary asce
 	larl	%r9,sie_exit			# skip forward to sie_exit
@@ -1353,8 +1353,8 @@ cleanup_critical:
 	clg     %r9,BASED(.Lsie_crit_mcck_length)
 	jh      1f
 	oi      __LC_CPU_FLAGS+7, _CIF_MCCK_GUEST
-1:	BPENTER __SF_EMPTY+24(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
-	lg	%r9,__SF_EMPTY(%r15)		# get control block pointer
+1:	BPENTER __SF_SIE_FLAGS(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
+	lg	%r9,__SF_SIE_CONTROL(%r15)	# get control block pointer
 	ni	__SIE_PROG0C+3(%r9),0xfe	# no longer in SIE
 	lctlg	%c1,%c1,__LC_USER_ASCE		# load primary asce
 	larl	%r9,sie_exit			# skip forward to sie_exit