arm64: force CONFIG_SMP=y and remove redundant #ifdefs

Nobody seems to be producing !SMP systems anymore, so this is just becoming a source of kernel bugs, particularly if people want to use coherent DMA with non-shared pages. This patch forces CONFIG_SMP=y for arm64, removing a modest amount of code in the process. Signed-off-by: Will Deacon <will.deacon@arm.com>
torvalds · Jul 27, 2015 · 4b3dc96 · 4b3dc96
1 parent 52da443
commit 4b3dc96
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Showing 22 changed files with 8 additions and 153 deletions.
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
@@ -28,7 +28,7 @@ config ARM64
  select EDAC_SUPPORT
  select GENERIC_ALLOCATOR
  select GENERIC_CLOCKEVENTS
- select GENERIC_CLOCKEVENTS_BROADCAST if SMP
+ select GENERIC_CLOCKEVENTS_BROADCAST
  select GENERIC_CPU_AUTOPROBE
  select GENERIC_EARLY_IOREMAP
  select GENERIC_IRQ_PROBE
@@ -137,6 +137,9 @@ config NEED_DMA_MAP_STATE
 config NEED_SG_DMA_LENGTH
  def_bool y
 
+config SMP
+ def_bool y
+
 config SWIOTLB
  def_bool y
 
@@ -491,30 +494,15 @@ config CPU_BIG_ENDIAN
  help
  Say Y if you plan on running a kernel in big-endian mode.
 
-config SMP
- bool "Symmetric Multi-Processing"
- help
- This enables support for systems with more than one CPU. If
- you say N here, the kernel will run on single 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, single processor machines. On a single
- processor machine, the kernel will run faster if you say N
- here.
-
- If you don't know what to do here, say N.
-
 config SCHED_MC
  bool "Multi-core scheduler support"
- depends on SMP
  help
  Multi-core scheduler support improves the CPU scheduler's decision
  making when dealing with multi-core CPU chips at a cost of slightly
  increased overhead in some places. If unsure say N here.
 
 config SCHED_SMT
  bool "SMT scheduler support"
- depends on SMP
  help
  Improves the CPU scheduler's decision making when dealing with
  MultiThreading at a cost of slightly increased overhead in some
@@ -523,23 +511,17 @@ config SCHED_SMT
 config NR_CPUS
  int "Maximum number of CPUs (2-4096)"
  range 2 4096
- depends on SMP
  # These have to remain sorted largest to smallest
  default "64"
 
 config HOTPLUG_CPU
  bool "Support for hot-pluggable CPUs"
- depends on SMP
  help
  Say Y here to experiment with turning CPUs off and on. CPUs
  can be controlled through /sys/devices/system/cpu.
 
 source kernel/Kconfig.preempt
 
-config UP_LATE_INIT
- def_bool y
- depends on !SMP
-
 config HZ
  int
  default 100

diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
@@ -91,9 +91,7 @@
  * SMP data memory barrier
  */
  .macro smp_dmb, opt
-#ifdef CONFIG_SMP
  dmb \opt
-#endif
  .endm
 
 #define USER(l, x...) \

diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
@@ -35,28 +35,6 @@
 #define dma_rmb() dmb(oshld)
 #define dma_wmb() dmb(oshst)
 
-#ifndef CONFIG_SMP
-#define smp_mb() barrier()
-#define smp_rmb() barrier()
-#define smp_wmb() barrier()
-
-#define smp_store_release(p, v) \
-do { \
- compiletime_assert_atomic_type(*p); \
- barrier(); \
- ACCESS_ONCE(*p) = (v); \
-} while (0)
-
-#define smp_load_acquire(p) \
-({ \
- typeof(*p) ___p1 = ACCESS_ONCE(*p); \
- compiletime_assert_atomic_type(*p); \
- barrier(); \
- ___p1; \
-})
-
-#else
-
 #define smp_mb() dmb(ish)
 #define smp_rmb() dmb(ishld)
 #define smp_wmb() dmb(ishst)
@@ -109,8 +87,6 @@ do { \
  ___p1; \
 })
 
-#endif
-
 #define read_barrier_depends() do { } while(0)
 #define smp_read_barrier_depends() do { } while(0)
 

diff --git a/arch/arm64/include/asm/hardirq.h b/arch/arm64/include/asm/hardirq.h
@@ -24,20 +24,16 @@
 
 typedef struct {
  unsigned int __softirq_pending;
-#ifdef CONFIG_SMP
  unsigned int ipi_irqs[NR_IPI];
-#endif
 } ____cacheline_aligned irq_cpustat_t;
 
 #include <linux/irq_cpustat.h> /* Standard mappings for irq_cpustat_t above */
 
 #define __inc_irq_stat(cpu, member) __IRQ_STAT(cpu, member)++
 #define __get_irq_stat(cpu, member) __IRQ_STAT(cpu, member)
 
-#ifdef CONFIG_SMP
 u64 smp_irq_stat_cpu(unsigned int cpu);
 #define arch_irq_stat_cpu smp_irq_stat_cpu
-#endif
 
 #define __ARCH_IRQ_EXIT_IRQS_DISABLED 1
 

diff --git a/arch/arm64/include/asm/irq_work.h b/arch/arm64/include/asm/irq_work.h
@@ -1,22 +1,11 @@
 #ifndef __ASM_IRQ_WORK_H
 #define __ASM_IRQ_WORK_H
 
-#ifdef CONFIG_SMP
-
 #include <asm/smp.h>
 
 static inline bool arch_irq_work_has_interrupt(void)
 {
  return !!__smp_cross_call;
 }
 
-#else
-
-static inline bool arch_irq_work_has_interrupt(void)
-{
- return false;
-}
-
-#endif
-
 #endif /* __ASM_IRQ_WORK_H */
diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h
@@ -16,8 +16,6 @@
 #ifndef __ASM_PERCPU_H
 #define __ASM_PERCPU_H
 
-#ifdef CONFIG_SMP
-
 static inline void set_my_cpu_offset(unsigned long off)
 {
  asm volatile("msr tpidr_el1, %0" :: "r" (off) : "memory");
@@ -38,12 +36,6 @@ static inline unsigned long __my_cpu_offset(void)
 }
 #define __my_cpu_offset __my_cpu_offset()
 
-#else /* !CONFIG_SMP */
-
-#define set_my_cpu_offset(x) do { } while (0)
-
-#endif /* CONFIG_SMP */
-
 #define PERCPU_OP(op, asm_op) \
 static inline unsigned long __percpu_##op(void *ptr, \
  unsigned long val, int size) \

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
@@ -61,13 +61,8 @@ extern void __pmd_error(const char *file, int line, unsigned long val);
 extern void __pud_error(const char *file, int line, unsigned long val);
 extern void __pgd_error(const char *file, int line, unsigned long val);
 
-#ifdef CONFIG_SMP
 #define PROT_DEFAULT (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
 #define PROT_SECT_DEFAULT (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
-#else
-#define PROT_DEFAULT (PTE_TYPE_PAGE | PTE_AF)
-#define PROT_SECT_DEFAULT (PMD_TYPE_SECT | PMD_SECT_AF)
-#endif
 
 #define PROT_DEVICE_nGnRE (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_ATTRINDX(MT_DEVICE_nGnRE))
 #define PROT_NORMAL_NC (PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_ATTRINDX(MT_NORMAL_NC))

diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
@@ -183,11 +183,7 @@ static inline int valid_user_regs(struct user_pt_regs *regs)
 
 #define instruction_pointer(regs) ((unsigned long)(regs)->pc)
 
-#ifdef CONFIG_SMP
 extern unsigned long profile_pc(struct pt_regs *regs);
-#else
-#define profile_pc(regs) instruction_pointer(regs)
-#endif
 
 #endif /* __ASSEMBLY__ */
 #endif
diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
@@ -20,10 +20,6 @@
 #include <linux/cpumask.h>
 #include <linux/thread_info.h>
 
-#ifndef CONFIG_SMP
-# error "<asm/smp.h> included in non-SMP build"
-#endif
-
 #define raw_smp_processor_id() (current_thread_info()->cpu)
 
 struct seq_file;

diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
@@ -1,8 +1,6 @@
 #ifndef __ASM_TOPOLOGY_H
 #define __ASM_TOPOLOGY_H
 
-#ifdef CONFIG_SMP
-
 #include <linux/cpumask.h>
 
 struct cpu_topology {
@@ -24,13 +22,6 @@ void init_cpu_topology(void);
 void store_cpu_topology(unsigned int cpuid);
 const struct cpumask *cpu_coregroup_mask(int cpu);
 
-#else
-
-static inline void init_cpu_topology(void) { }
-static inline void store_cpu_topology(unsigned int cpuid) { }
-
-#endif
-
 #include <asm-generic/topology.h>
 
 #endif /* _ASM_ARM_TOPOLOGY_H */
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
@@ -17,16 +17,17 @@ arm64-obj-y := debug-monitors.o entry.o irq.o fpsimd.o \
  sys.o stacktrace.o time.o traps.o io.o vdso.o \
  hyp-stub.o psci.o psci-call.o cpu_ops.o insn.o \
  return_address.o cpuinfo.o cpu_errata.o \
- cpufeature.o alternative.o cacheinfo.o
+ cpufeature.o alternative.o cacheinfo.o \
+ smp.o smp_spin_table.o topology.o
 
 arm64-obj-$(CONFIG_COMPAT) += sys32.o kuser32.o signal32.o \
  sys_compat.o entry32.o \
  ../../arm/kernel/opcodes.o
 arm64-obj-$(CONFIG_FUNCTION_TRACER) += ftrace.o entry-ftrace.o
 arm64-obj-$(CONFIG_MODULES) += arm64ksyms.o module.o
 arm64-obj-$(CONFIG_SMP) += smp.o smp_spin_table.o topology.o
-arm64-obj-$(CONFIG_PERF_EVENTS) += perf_regs.o perf_callchain.o
-arm64-obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o
+arm64-obj-$(CONFIG_PERF_EVENTS) += perf_regs.o
+arm64-obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o perf_callchain.o
 arm64-obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
 arm64-obj-$(CONFIG_CPU_PM) += sleep.o suspend.o
 arm64-obj-$(CONFIG_CPU_IDLE) += cpuidle.o

diff --git a/arch/arm64/kernel/cpu_ops.c b/arch/arm64/kernel/cpu_ops.c
@@ -30,9 +30,7 @@ extern const struct cpu_operations cpu_psci_ops;
 const struct cpu_operations *cpu_ops[NR_CPUS];
 
 static const struct cpu_operations *supported_cpu_ops[] __initconst = {
-#ifdef CONFIG_SMP
  &smp_spin_table_ops,
-#endif
  &cpu_psci_ops,
  NULL,
 };

diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
@@ -62,13 +62,8 @@
 /*
  * Initial memory map attributes.
  */
-#ifndef CONFIG_SMP
-#define PTE_FLAGS PTE_TYPE_PAGE | PTE_AF
-#define PMD_FLAGS PMD_TYPE_SECT | PMD_SECT_AF
-#else
 #define PTE_FLAGS PTE_TYPE_PAGE | PTE_AF | PTE_SHARED
 #define PMD_FLAGS PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S
-#endif
 
 #ifdef CONFIG_ARM64_64K_PAGES
 #define MM_MMUFLAGS PTE_ATTRINDX(MT_NORMAL) | PTE_FLAGS
@@ -574,7 +569,6 @@ ENTRY(__boot_cpu_mode)
  .long BOOT_CPU_MODE_EL1
  .popsection
 
-#ifdef CONFIG_SMP
  /*
  * This provides a "holding pen" for platforms to hold all secondary
  * cores are held until we're ready for them to initialise.
@@ -622,7 +616,6 @@ ENTRY(__secondary_switched)
  mov x29, #0
  b secondary_start_kernel
 ENDPROC(__secondary_switched)
-#endif /* CONFIG_SMP */
 
 /*
  * Enable the MMU.

diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
@@ -33,9 +33,7 @@ unsigned long irq_err_count;
 
 int arch_show_interrupts(struct seq_file *p, int prec)
 {
-#ifdef CONFIG_SMP
  show_ipi_list(p, prec);
-#endif
  seq_printf(p, "%*s: %10lu\n", prec, "Err", irq_err_count);
  return 0;
 }

diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
@@ -462,8 +462,6 @@ int __init psci_acpi_init(void)
 }
 #endif
 
-#ifdef CONFIG_SMP
-
 static int __init cpu_psci_cpu_init(unsigned int cpu)
 {
  return 0;
@@ -550,7 +548,6 @@ static int cpu_psci_cpu_kill(unsigned int cpu)
  return -ETIMEDOUT;
 }
 #endif
-#endif
 
 static int psci_suspend_finisher(unsigned long index)
 {
@@ -585,7 +582,6 @@ const struct cpu_operations cpu_psci_ops = {
  .cpu_init_idle = cpu_psci_cpu_init_idle,
  .cpu_suspend = cpu_psci_cpu_suspend,
 #endif
-#ifdef CONFIG_SMP
  .cpu_init = cpu_psci_cpu_init,
  .cpu_prepare = cpu_psci_cpu_prepare,
  .cpu_boot = cpu_psci_cpu_boot,
@@ -594,6 +590,5 @@ const struct cpu_operations cpu_psci_ops = {
  .cpu_die = cpu_psci_cpu_die,
  .cpu_kill = cpu_psci_cpu_kill,
 #endif
-#endif
 };
 
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
@@ -131,7 +131,6 @@ bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
 }
 
 struct mpidr_hash mpidr_hash;
-#ifdef CONFIG_SMP
 /**
  * smp_build_mpidr_hash - Pre-compute shifts required at each affinity
  * level in order to build a linear index from an
@@ -197,7 +196,6 @@ static void __init smp_build_mpidr_hash(void)
  pr_warn("Large number of MPIDR hash buckets detected\n");
  __flush_dcache_area(&mpidr_hash, sizeof(struct mpidr_hash));
 }
-#endif
 
 static void __init hyp_mode_check(void)
 {
@@ -405,10 +403,8 @@ void __init setup_arch(char **cmdline_p)
  xen_early_init();
 
  cpu_read_bootcpu_ops();
-#ifdef CONFIG_SMP
  smp_init_cpus();
  smp_build_mpidr_hash();
-#endif
 
 #ifdef CONFIG_VT
 #if defined(CONFIG_VGA_CONSOLE)
@@ -508,9 +504,7 @@ static int c_show(struct seq_file *m, void *v)
  * online processors, looking for lines beginning with
  * "processor". Give glibc what it expects.
  */
-#ifdef CONFIG_SMP
  seq_printf(m, "processor\t: %d\n", i);
-#endif
 
  /*
  * Dump out the common processor features in a single line.