bb85fb5803
During context switch, switch_mm() sets our current CPU in mm_cpumask. We can avoid this atomic sequence in most cases by checking before setting the bit. Testing on a POWER8 using our context switch microbenchmark: tools/testing/selftests/powerpc/benchmarks/context_switch \ --process --no-fp --no-altivec --no-vector Performance improves 2%. Signed-off-by: Anton Blanchard <anton@samba.org> Acked-by: Balbir Singh <bsingharora@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
172 lines
5.1 KiB
C
172 lines
5.1 KiB
C
#ifndef __ASM_POWERPC_MMU_CONTEXT_H
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#define __ASM_POWERPC_MMU_CONTEXT_H
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#ifdef __KERNEL__
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/spinlock.h>
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#include <asm/mmu.h>
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#include <asm/cputable.h>
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#include <asm/cputhreads.h>
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/*
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* Most if the context management is out of line
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*/
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extern int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
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extern void destroy_context(struct mm_struct *mm);
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#ifdef CONFIG_SPAPR_TCE_IOMMU
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struct mm_iommu_table_group_mem_t;
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extern int isolate_lru_page(struct page *page); /* from internal.h */
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extern bool mm_iommu_preregistered(void);
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extern long mm_iommu_get(unsigned long ua, unsigned long entries,
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struct mm_iommu_table_group_mem_t **pmem);
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extern long mm_iommu_put(struct mm_iommu_table_group_mem_t *mem);
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extern void mm_iommu_init(mm_context_t *ctx);
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extern void mm_iommu_cleanup(mm_context_t *ctx);
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extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup(unsigned long ua,
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unsigned long size);
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extern struct mm_iommu_table_group_mem_t *mm_iommu_find(unsigned long ua,
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unsigned long entries);
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extern long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
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unsigned long ua, unsigned long *hpa);
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extern long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem);
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extern void mm_iommu_mapped_dec(struct mm_iommu_table_group_mem_t *mem);
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#endif
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extern void switch_slb(struct task_struct *tsk, struct mm_struct *mm);
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extern void set_context(unsigned long id, pgd_t *pgd);
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#ifdef CONFIG_PPC_BOOK3S_64
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extern void radix__switch_mmu_context(struct mm_struct *prev,
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struct mm_struct *next);
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static inline void switch_mmu_context(struct mm_struct *prev,
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struct mm_struct *next,
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struct task_struct *tsk)
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{
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if (radix_enabled())
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return radix__switch_mmu_context(prev, next);
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return switch_slb(tsk, next);
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}
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extern int __init_new_context(void);
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extern void __destroy_context(int context_id);
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static inline void mmu_context_init(void) { }
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#else
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extern void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next,
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struct task_struct *tsk);
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extern unsigned long __init_new_context(void);
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extern void __destroy_context(unsigned long context_id);
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extern void mmu_context_init(void);
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#endif
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extern void switch_cop(struct mm_struct *next);
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extern int use_cop(unsigned long acop, struct mm_struct *mm);
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extern void drop_cop(unsigned long acop, struct mm_struct *mm);
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/*
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* switch_mm is the entry point called from the architecture independent
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* code in kernel/sched/core.c
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*/
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static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
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struct task_struct *tsk)
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{
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/* Mark this context has been used on the new CPU */
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if (!cpumask_test_cpu(smp_processor_id(), mm_cpumask(next)))
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cpumask_set_cpu(smp_processor_id(), mm_cpumask(next));
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/* 32-bit keeps track of the current PGDIR in the thread struct */
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#ifdef CONFIG_PPC32
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tsk->thread.pgdir = next->pgd;
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#endif /* CONFIG_PPC32 */
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/* 64-bit Book3E keeps track of current PGD in the PACA */
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#ifdef CONFIG_PPC_BOOK3E_64
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get_paca()->pgd = next->pgd;
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#endif
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/* Nothing else to do if we aren't actually switching */
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if (prev == next)
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return;
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#ifdef CONFIG_PPC_ICSWX
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/* Switch coprocessor context only if prev or next uses a coprocessor */
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if (prev->context.acop || next->context.acop)
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switch_cop(next);
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#endif /* CONFIG_PPC_ICSWX */
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/* We must stop all altivec streams before changing the HW
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* context
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*/
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#ifdef CONFIG_ALTIVEC
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if (cpu_has_feature(CPU_FTR_ALTIVEC))
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asm volatile ("dssall");
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#endif /* CONFIG_ALTIVEC */
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/*
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* The actual HW switching method differs between the various
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* sub architectures. Out of line for now
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*/
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switch_mmu_context(prev, next, tsk);
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}
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#define deactivate_mm(tsk,mm) do { } while (0)
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/*
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* After we have set current->mm to a new value, this activates
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* the context for the new mm so we see the new mappings.
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*/
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static inline void activate_mm(struct mm_struct *prev, struct mm_struct *next)
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{
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unsigned long flags;
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local_irq_save(flags);
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switch_mm(prev, next, current);
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local_irq_restore(flags);
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}
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/* We don't currently use enter_lazy_tlb() for anything */
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static inline void enter_lazy_tlb(struct mm_struct *mm,
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struct task_struct *tsk)
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{
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/* 64-bit Book3E keeps track of current PGD in the PACA */
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#ifdef CONFIG_PPC_BOOK3E_64
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get_paca()->pgd = NULL;
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#endif
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}
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static inline void arch_dup_mmap(struct mm_struct *oldmm,
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struct mm_struct *mm)
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{
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}
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static inline void arch_exit_mmap(struct mm_struct *mm)
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{
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}
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static inline void arch_unmap(struct mm_struct *mm,
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struct vm_area_struct *vma,
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unsigned long start, unsigned long end)
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{
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if (start <= mm->context.vdso_base && mm->context.vdso_base < end)
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mm->context.vdso_base = 0;
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}
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static inline void arch_bprm_mm_init(struct mm_struct *mm,
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struct vm_area_struct *vma)
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{
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}
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static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
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bool write, bool execute, bool foreign)
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{
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/* by default, allow everything */
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return true;
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}
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static inline bool arch_pte_access_permitted(pte_t pte, bool write)
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{
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/* by default, allow everything */
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return true;
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}
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#endif /* __KERNEL__ */
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#endif /* __ASM_POWERPC_MMU_CONTEXT_H */
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