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>

12 files changed, 7 insertions, 95 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index e2e154051b07..bdf3b5fdea53 100644
--- a/arch/s390/Kconfig
+++ b/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.
diff --git a/arch/s390/include/asm/ctl_reg.h b/arch/s390/include/asm/ctl_reg.h
index 4600453536c2..a778a0825835 100644
--- a/arch/s390/include/asm/ctl_reg.h
+++ b/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 */
diff --git a/arch/s390/include/asm/percpu.h b/arch/s390/include/asm/percpu.h
index 0095ddb58ff6..50b4ce8cddfd 100644
--- a/arch/s390/include/asm/percpu.h
+++ b/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
 
diff --git a/arch/s390/include/asm/smp.h b/arch/s390/include/asm/smp.h
index 3907ead27ffa..30ba1a3f88de 100644
--- a/arch/s390/include/asm/smp.h
+++ b/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();
diff --git a/arch/s390/include/asm/spinlock.h b/arch/s390/include/asm/spinlock.h
index 0a29588aa00b..c02bff33f6c7 100644
--- a/arch/s390/include/asm/spinlock.h
+++ b/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
 
diff --git a/arch/s390/include/asm/tlbflush.h b/arch/s390/include/asm/tlbflush.h
index 8c840f0904f3..82703e03f35d 100644
--- a/arch/s390/include/asm/tlbflush.h
+++ b/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)
 {
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index b0478d01a0c5..0f255b54b051 100644
--- a/arch/s390/kernel/Makefile
+++ b/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
diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
index 9e87b68be21c..ac06c3949ab3 100644
--- a/arch/s390/kernel/dumpstack.c
+++ b/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");
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 3f4d272577d3..270d1d145761 100644
--- a/arch/s390/kernel/entry.S
+++ b/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)
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index f8544d517430..2b94b0ad3588 100644
--- a/arch/s390/kernel/setup.c
+++ b/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);
diff --git a/arch/s390/kernel/swsusp.S b/arch/s390/kernel/swsusp.S
index 19a3c427801a..a7baf0b5f818 100644
--- a/arch/s390/kernel/swsusp.S
+++ b/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:
diff --git a/arch/s390/lib/Makefile b/arch/s390/lib/Makefile
index 5418d10dc2a8..a1ec63abfb95 100644
--- a/arch/s390/lib/Makefile
+++ b/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