s390: enforce CONFIG_SMP

There never have been distributions that shiped with CONFIG_SMP=n for
s390. In addition the kernel currently doesn't even compile with
CONFIG_SMP=n for s390. Most likely it wouldn't even work, even if we
fix the compile error, since nobody tests it, since there is no use
case that I can think of.
Therefore simply enforce CONFIG_SMP and get rid of some more or
less unused code.
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

arch/s390/Kconfig

@@ -30,7 +30,7 @@ config GENERIC_BUG_RELATIVE_POINTERS
 	def_bool y
 
 config GENERIC_LOCKBREAK
-	def_bool y if SMP && PREEMPT
+	def_bool y if PREEMPT
 
 config PGSTE
 	def_bool y if KVM
@@ -113,7 +113,6 @@ config S390
 	select DYNAMIC_FTRACE if FUNCTION_TRACER
 	select GENERIC_CLOCKEVENTS
 	select GENERIC_CPU_AUTOPROBE
-	select GENERIC_CPU_DEVICES if !SMP
 	select GENERIC_CPU_VULNERABILITIES
 	select GENERIC_FIND_FIRST_BIT
 	select GENERIC_SMP_IDLE_THREAD
@@ -399,27 +398,10 @@ config SYSVIPC_COMPAT
 
 config SMP
 	def_bool y
-	prompt "Symmetric multi-processing support"
-	---help---
-	  This enables support for systems with more than one CPU. If you have
-	  a system with only one CPU, like most personal computers, say N. If
-	  you have a system with more than one CPU, say Y.
-
-	  If you say N here, the kernel will run on uni- and multiprocessor
-	  machines, but will use only one CPU of a multiprocessor machine. If
-	  you say Y here, the kernel will run on many, but not all,
-	  uniprocessor machines. On a uniprocessor machine, the kernel
-	  will run faster if you say N here.
-
-	  See also the SMP-HOWTO available at
-	  <http://www.tldp.org/docs.html#howto>.
-
-	  Even if you don't know what to do here, say Y.
 
 config NR_CPUS
 	int "Maximum number of CPUs (2-512)"
 	range 2 512
-	depends on SMP
 	default "64"
 	help
 	  This allows you to specify the maximum number of CPUs which this
@@ -432,7 +414,6 @@ config NR_CPUS
 config HOTPLUG_CPU
 	def_bool y
 	prompt "Support for hot-pluggable CPUs"
-	depends on SMP
 	help
 	  Say Y here to be able to turn CPUs off and on. CPUs
 	  can be controlled through /sys/devices/system/cpu/cpu#.
@@ -448,7 +429,7 @@ config NODES_SPAN_OTHER_NODES
 
 config NUMA
 	bool "NUMA support"
-	depends on SMP && SCHED_TOPOLOGY
+	depends on SCHED_TOPOLOGY
 	default n
 	help
 	  Enable NUMA support
@@ -523,7 +504,6 @@ config SCHED_DRAWER
 config SCHED_TOPOLOGY
 	def_bool y
 	prompt "Topology scheduler support"
-	depends on SMP
 	select SCHED_SMT
 	select SCHED_MC
 	select SCHED_BOOK
@@ -829,7 +809,6 @@ menu "Dump support"
 
 config CRASH_DUMP
 	bool "kernel crash dumps"
-	depends on SMP
 	select KEXEC
 	help
 	  Generate crash dump after being started by kexec.

arch/s390/include/asm/ctl_reg.h

@@ -112,13 +112,8 @@ union ctlreg2 {
 	};
 };
 
-#ifdef CONFIG_SMP
-# define ctl_set_bit(cr, bit) smp_ctl_set_bit(cr, bit)
-# define ctl_clear_bit(cr, bit) smp_ctl_clear_bit(cr, bit)
-#else
-# define ctl_set_bit(cr, bit) __ctl_set_bit(cr, bit)
-# define ctl_clear_bit(cr, bit) __ctl_clear_bit(cr, bit)
-#endif
+#define ctl_set_bit(cr, bit) smp_ctl_set_bit(cr, bit)
+#define ctl_clear_bit(cr, bit) smp_ctl_clear_bit(cr, bit)
 
 #endif /* __ASSEMBLY__ */
 #endif /* __ASM_CTL_REG_H */

arch/s390/include/asm/percpu.h

@@ -16,7 +16,7 @@
  * per cpu area, use weak definitions to force the compiler to
  * generate external references.
  */
-#if defined(CONFIG_SMP) && defined(MODULE)
+#if defined(MODULE)
 #define ARCH_NEEDS_WEAK_PER_CPU
 #endif
 

arch/s390/include/asm/smp.h

@@ -9,9 +9,6 @@
 #define __ASM_SMP_H
 
 #include <asm/sigp.h>
-
-#ifdef CONFIG_SMP
-
 #include <asm/lowcore.h>
 
 #define raw_smp_processor_id()	(S390_lowcore.cpu_nr)
@@ -40,33 +37,6 @@ extern int smp_cpu_get_polarization(int cpu);
 extern void smp_fill_possible_mask(void);
 extern void smp_detect_cpus(void);
 
-#else /* CONFIG_SMP */
-
-#define smp_cpu_mtid	0
-
-static inline void smp_call_ipl_cpu(void (*func)(void *), void *data)
-{
-	func(data);
-}
-
-static inline void smp_call_online_cpu(void (*func)(void *), void *data)
-{
-	func(data);
-}
-
-static inline void smp_emergency_stop(void)
-{
-}
-
-static inline int smp_find_processor_id(u16 address) { return 0; }
-static inline int smp_store_status(int cpu) { return 0; }
-static inline int smp_vcpu_scheduled(int cpu) { return 1; }
-static inline void smp_yield_cpu(int cpu) { }
-static inline void smp_fill_possible_mask(void) { }
-static inline void smp_detect_cpus(void) { }
-
-#endif /* CONFIG_SMP */
-
 static inline void smp_stop_cpu(void)
 {
 	u16 pcpu = stap();

arch/s390/include/asm/spinlock.h

@@ -20,11 +20,7 @@
 
 extern int spin_retry;
 
-#ifndef CONFIG_SMP
-static inline bool arch_vcpu_is_preempted(int cpu) { return false; }
-#else
 bool arch_vcpu_is_preempted(int cpu);
-#endif
 
 #define vcpu_is_preempted arch_vcpu_is_preempted
 

arch/s390/include/asm/tlbflush.h

@@ -32,7 +32,6 @@ static inline void __tlb_flush_idte(unsigned long asce)
 		: : "a" (opt), "a" (asce) : "cc");
 }
 
-#ifdef CONFIG_SMP
 void smp_ptlb_all(void);
 
 /*
@@ -83,22 +82,6 @@ static inline void __tlb_flush_kernel(void)
 	else
 		__tlb_flush_global();
 }
-#else
-#define __tlb_flush_global()	__tlb_flush_local()
-
-/*
- * Flush TLB entries for a specific ASCE on all CPUs.
- */
-static inline void __tlb_flush_mm(struct mm_struct *mm)
-{
-	__tlb_flush_local();
-}
-
-static inline void __tlb_flush_kernel(void)
-{
-	__tlb_flush_local();
-}
-#endif
 
 static inline void __tlb_flush_mm_lazy(struct mm_struct * mm)
 {

arch/s390/kernel/Makefile

@@ -53,6 +53,7 @@ obj-y	+= sysinfo.o lgr.o os_info.o machine_kexec.o pgm_check.o
 obj-y	+= runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o sthyi.o
 obj-y	+= entry.o reipl.o relocate_kernel.o kdebugfs.o alternative.o
 obj-y	+= nospec-branch.o ipl_vmparm.o machine_kexec_reloc.o unwind_bc.o
+obj-y	+= smp.o
 
 extra-y				+= head64.o vmlinux.lds
 
@@ -60,7 +61,6 @@ obj-$(CONFIG_SYSFS)		+= nospec-sysfs.o
 CFLAGS_REMOVE_nospec-branch.o	+= $(CC_FLAGS_EXPOLINE)
 
 obj-$(CONFIG_MODULES)		+= module.o
-obj-$(CONFIG_SMP)		+= smp.o
 obj-$(CONFIG_SCHED_TOPOLOGY)	+= topology.o
 obj-$(CONFIG_HIBERNATION)	+= suspend.o swsusp.o
 obj-$(CONFIG_AUDIT)		+= audit.o

arch/s390/kernel/dumpstack.c

@@ -199,9 +199,7 @@ void die(struct pt_regs *regs, const char *str)
 #ifdef CONFIG_PREEMPT
 	pr_cont("PREEMPT ");
 #endif
-#ifdef CONFIG_SMP
 	pr_cont("SMP ");
-#endif
 	if (debug_pagealloc_enabled())
 		pr_cont("DEBUG_PAGEALLOC");
 	pr_cont("\n");

arch/s390/kernel/entry.S

@@ -986,14 +986,12 @@ ENTRY(psw_idle)
 	stg	%r3,__SF_EMPTY(%r15)
 	larl	%r1,.Lpsw_idle_lpsw+4
 	stg	%r1,__SF_EMPTY+8(%r15)
-#ifdef CONFIG_SMP
 	larl	%r1,smp_cpu_mtid
 	llgf	%r1,0(%r1)
 	ltgr	%r1,%r1
 	jz	.Lpsw_idle_stcctm
 	.insn	rsy,0xeb0000000017,%r1,5,__SF_EMPTY+16(%r15)
 .Lpsw_idle_stcctm:
-#endif
 	oi	__LC_CPU_FLAGS+7,_CIF_ENABLED_WAIT
 	BPON
 	STCK	__CLOCK_IDLE_ENTER(%r2)
@@ -1468,7 +1466,6 @@ ENDPROC(cleanup_critical)
 	mvc	__CLOCK_IDLE_ENTER(8,%r2),__CLOCK_IDLE_EXIT(%r2)
 	mvc	__TIMER_IDLE_ENTER(8,%r2),__TIMER_IDLE_EXIT(%r2)
 1:	# calculate idle cycles
-#ifdef CONFIG_SMP
 	clg	%r9,BASED(.Lcleanup_idle_insn)
 	jl	3f
 	larl	%r1,smp_cpu_mtid
@@ -1486,7 +1483,6 @@ ENDPROC(cleanup_critical)
 	la	%r3,8(%r3)
 	la	%r4,8(%r4)
 	brct	%r1,2b
-#endif
 3:	# account system time going idle
 	lg	%r9,__LC_STEAL_TIMER
 	alg	%r9,__CLOCK_IDLE_ENTER(%r2)

arch/s390/kernel/setup.c

@@ -461,11 +461,9 @@ static void __init setup_lowcore_dat_off(void)
 	mem_assign_absolute(S390_lowcore.restart_source, lc->restart_source);
 	mem_assign_absolute(S390_lowcore.restart_psw, lc->restart_psw);
 
-#ifdef CONFIG_SMP
 	lc->spinlock_lockval = arch_spin_lockval(0);
 	lc->spinlock_index = 0;
 	arch_spin_lock_setup(0);
-#endif
 	lc->br_r1_trampoline = 0x07f1;	/* br %r1 */
 
 	set_prefix((u32)(unsigned long) lc);

arch/s390/kernel/swsusp.S

@@ -162,7 +162,6 @@ ENTRY(swsusp_arch_resume)
 	larl	%r1,__swsusp_reset_dma
 	lg	%r1,0(%r1)
 	BASR_EX	%r14,%r1
-#ifdef CONFIG_SMP
 	larl	%r1,smp_cpu_mt_shift
 	icm	%r1,15,0(%r1)
 	jz	smt_done
@@ -172,7 +171,6 @@ smt_loop:
 	brc	8,smt_done			/* accepted */
 	brc	2,smt_loop			/* busy, try again */
 smt_done:
-#endif
 	larl	%r1,.Lnew_pgm_check_psw
 	lpswe	0(%r1)
 pgm_check_entry:

arch/s390/lib/Makefile

@@ -3,9 +3,8 @@
 # Makefile for s390-specific library files..
 #
 
-lib-y += delay.o string.o uaccess.o find.o
+lib-y += delay.o string.o uaccess.o find.o spinlock.o
 obj-y += mem.o xor.o
-lib-$(CONFIG_SMP) += spinlock.o
 lib-$(CONFIG_KPROBES) += probes.o
 lib-$(CONFIG_UPROBES) += probes.o