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Commit 4b3dc967 authored by Will Deacon's avatar Will Deacon
Browse files

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: default avatarWill Deacon <will.deacon@arm.com>
parent 52da443e

arch/arm64/Kconfig

+4 −22
Original line number Diff line number Diff line
@@ -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
@@ -491,22 +494,8 @@ 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
@@ -514,7 +503,6 @@ config SCHED_MC 


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

arch/arm64/include/asm/assembler.h

+0 −2
Original line number Diff line number Diff line
@@ -91,9 +91,7 @@ 
 * SMP data memory barrier

 */

	.macro	smp_dmb, opt

#ifdef CONFIG_SMP

	dmb	\opt

#endif

	.endm



#define USER(l, x...)				\

arch/arm64/include/asm/barrier.h

+0 −24
Original line number Diff line number Diff line
@@ -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)

arch/arm64/include/asm/hardirq.h

+0 −4
Original line number Diff line number Diff line
@@ -24,9 +24,7 @@ 


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 */
@@ -34,10 +32,8 @@ typedef struct { 
#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

arch/arm64/include/asm/irq_work.h

+0 −11
Original line number Diff line number Diff line 
#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)
@@ -10,13 +8,4 @@ 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 */