arch/sparc/include/asm/mmu_context_64.h

   1 #ifndef __SPARC64_MMU_CONTEXT_H
   2 #define __SPARC64_MMU_CONTEXT_H
   3
   4 /* Derived heavily from Linus's Alpha/AXP ASN code... */
   5
   6 #ifndef __ASSEMBLY__
   7
   8 #include <linux/spinlock.h>
   9 #include <linux/mm_types.h>
  10 #include <linux/smp.h>
  11
  12 #include <asm/spitfire.h>
  13 #include <asm-generic/mm_hooks.h>
  14 #include <asm/percpu.h>
  15
  16 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
  17 {
  18 }
  19
  20 extern spinlock_t ctx_alloc_lock;
  21 extern unsigned long tlb_context_cache;
  22 extern unsigned long mmu_context_bmap[];
  23
  24 DECLARE_PER_CPU(struct mm_struct *, per_cpu_secondary_mm);
  25 void get_new_mmu_context(struct mm_struct *mm);
  26 int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
  27 void destroy_context(struct mm_struct *mm);
  28
  29 void __tsb_context_switch(unsigned long pgd_pa,
  30                           struct tsb_config *tsb_base,
  31                           struct tsb_config *tsb_huge,
  32                           unsigned long tsb_descr_pa,
  33                           unsigned long secondary_ctx);
  34
  35 static inline void tsb_context_switch_ctx(struct mm_struct *mm,
  36                                           unsigned long ctx)
  37 {
  38         __tsb_context_switch(__pa(mm->pgd),
  39                              &mm->context.tsb_block[MM_TSB_BASE],
  40 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
  41                              (mm->context.tsb_block[MM_TSB_HUGE].tsb ?
  42                               &mm->context.tsb_block[MM_TSB_HUGE] :
  43                               NULL)
  44 #else
  45                              NULL
  46 #endif
  47                              , __pa(&mm->context.tsb_descr[MM_TSB_BASE]),
  48                              ctx);
  49 }
  50
  51 #define tsb_context_switch(X) tsb_context_switch_ctx(X, 0)
  52
  53 void tsb_grow(struct mm_struct *mm,
  54               unsigned long tsb_index,
  55               unsigned long mm_rss);
  56 #ifdef CONFIG_SMP
  57 void smp_tsb_sync(struct mm_struct *mm);
  58 #else
  59 #define smp_tsb_sync(__mm) do { } while (0)
  60 #endif
  61
  62 /* Set MMU context in the actual hardware. */
  63 #define load_secondary_context(__mm) \
  64         __asm__ __volatile__( \
  65         "\n661: stxa            %0, [%1] %2\n" \
  66         "       .section        .sun4v_1insn_patch, \"ax\"\n" \
  67         "       .word           661b\n" \
  68         "       stxa            %0, [%1] %3\n" \
  69         "       .previous\n" \
  70         "       flush           %%g6\n" \
  71         : /* No outputs */ \
  72         : "r" (CTX_HWBITS((__mm)->context)), \
  73           "r" (SECONDARY_CONTEXT), "i" (ASI_DMMU), "i" (ASI_MMU))
  74
  75 void __flush_tlb_mm(unsigned long, unsigned long);
  76
  77 /* Switch the current MM context. */
  78 static inline void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm, struct task_struct *tsk)
  79 {
  80         unsigned long ctx_valid, flags;
  81         int cpu = smp_processor_id();
  82
  83         per_cpu(per_cpu_secondary_mm, cpu) = mm;
  84         if (unlikely(mm == &init_mm))
  85                 return;
  86
  87         spin_lock_irqsave(&mm->context.lock, flags);
  88         ctx_valid = CTX_VALID(mm->context);
  89         if (!ctx_valid)
  90                 get_new_mmu_context(mm);
  91
  92         /* We have to be extremely careful here or else we will miss
  93          * a TSB grow if we switch back and forth between a kernel
  94          * thread and an address space which has it's TSB size increased
  95          * on another processor.
  96          *
  97          * It is possible to play some games in order to optimize the
  98          * switch, but the safest thing to do is to unconditionally
  99          * perform the secondary context load and the TSB context switch.
 100          *
 101          * For reference the bad case is, for address space "A":
 102          *
 103          *              CPU 0                   CPU 1
 104          *      run address space A
 105          *      set cpu0's bits in cpu_vm_mask
 106          *      switch to kernel thread, borrow
 107          *      address space A via entry_lazy_tlb
 108          *                                      run address space A
 109          *                                      set cpu1's bit in cpu_vm_mask
 110          *                                      flush_tlb_pending()
 111          *                                      reset cpu_vm_mask to just cpu1
 112          *                                      TSB grow
 113          *      run address space A
 114          *      context was valid, so skip
 115          *      TSB context switch
 116          *
 117          * At that point cpu0 continues to use a stale TSB, the one from
 118          * before the TSB grow performed on cpu1.  cpu1 did not cross-call
 119          * cpu0 to update it's TSB because at that point the cpu_vm_mask
 120          * only had cpu1 set in it.
 121          */
 122         tsb_context_switch_ctx(mm, CTX_HWBITS(mm->context));
 123
 124         /* Any time a processor runs a context on an address space
 125          * for the first time, we must flush that context out of the
 126          * local TLB.
 127          */
 128         if (!ctx_valid || !cpumask_test_cpu(cpu, mm_cpumask(mm))) {
 129                 cpumask_set_cpu(cpu, mm_cpumask(mm));
 130                 __flush_tlb_mm(CTX_HWBITS(mm->context),
 131                                SECONDARY_CONTEXT);
 132         }
 133         spin_unlock_irqrestore(&mm->context.lock, flags);
 134 }
 135
 136 #define deactivate_mm(tsk,mm)   do { } while (0)
 137 #define activate_mm(active_mm, mm) switch_mm(active_mm, mm, NULL)
 138 #endif /* !(__ASSEMBLY__) */
 139
 140 #endif /* !(__SPARC64_MMU_CONTEXT_H) */