root/arch/sparc/include/asm/mmu_context_64.h

INCLUDED FROM

DEFINITIONS

1. enter_lazy_tlb
2. tsb_context_switch_ctx
3. switch_mm
4. arch_start_context_switch
5. finish_arch_post_lock_switch

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __SPARC64_MMU_CONTEXT_H
   3 #define __SPARC64_MMU_CONTEXT_H
   4 
   5 /* Derived heavily from Linus's Alpha/AXP ASN code... */
   6 
   7 #ifndef __ASSEMBLY__
   8 
   9 #include <linux/spinlock.h>
  10 #include <linux/mm_types.h>
  11 #include <linux/smp.h>
  12 #include <linux/sched.h>
  13 
  14 #include <asm/spitfire.h>
  15 #include <asm/adi_64.h>
  16 #include <asm-generic/mm_hooks.h>
  17 #include <asm/percpu.h>
  18 
  19 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
  20 {
  21 }
  22 
  23 extern spinlock_t ctx_alloc_lock;
  24 extern unsigned long tlb_context_cache;
  25 extern unsigned long mmu_context_bmap[];
  26 
  27 DECLARE_PER_CPU(struct mm_struct *, per_cpu_secondary_mm);
  28 void get_new_mmu_context(struct mm_struct *mm);
  29 int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
  30 void destroy_context(struct mm_struct *mm);
  31 
  32 void __tsb_context_switch(unsigned long pgd_pa,
  33                           struct tsb_config *tsb_base,
  34                           struct tsb_config *tsb_huge,
  35                           unsigned long tsb_descr_pa,
  36                           unsigned long secondary_ctx);
  37 
  38 static inline void tsb_context_switch_ctx(struct mm_struct *mm,
  39                                           unsigned long ctx)
  40 {
  41         __tsb_context_switch(__pa(mm->pgd),
  42                              &mm->context.tsb_block[MM_TSB_BASE],
  43 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
  44                              (mm->context.tsb_block[MM_TSB_HUGE].tsb ?
  45                               &mm->context.tsb_block[MM_TSB_HUGE] :
  46                               NULL)
  47 #else
  48                              NULL
  49 #endif
  50                              , __pa(&mm->context.tsb_descr[MM_TSB_BASE]),
  51                              ctx);
  52 }
  53 
  54 #define tsb_context_switch(X) tsb_context_switch_ctx(X, 0)
  55 
  56 void tsb_grow(struct mm_struct *mm,
  57               unsigned long tsb_index,
  58               unsigned long mm_rss);
  59 #ifdef CONFIG_SMP
  60 void smp_tsb_sync(struct mm_struct *mm);
  61 #else
  62 #define smp_tsb_sync(__mm) do { } while (0)
  63 #endif
  64 
  65 /* Set MMU context in the actual hardware. */
  66 #define load_secondary_context(__mm) \
  67         __asm__ __volatile__( \
  68         "\n661: stxa            %0, [%1] %2\n" \
  69         "       .section        .sun4v_1insn_patch, \"ax\"\n" \
  70         "       .word           661b\n" \
  71         "       stxa            %0, [%1] %3\n" \
  72         "       .previous\n" \
  73         "       flush           %%g6\n" \
  74         : /* No outputs */ \
  75         : "r" (CTX_HWBITS((__mm)->context)), \
  76           "r" (SECONDARY_CONTEXT), "i" (ASI_DMMU), "i" (ASI_MMU))
  77 
  78 void __flush_tlb_mm(unsigned long, unsigned long);
  79 
  80 /* Switch the current MM context. */
  81 static inline void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm, struct task_struct *tsk)
  82 {
  83         unsigned long ctx_valid, flags;
  84         int cpu = smp_processor_id();
  85 
  86         per_cpu(per_cpu_secondary_mm, cpu) = mm;
  87         if (unlikely(mm == &init_mm))
  88                 return;
  89 
  90         spin_lock_irqsave(&mm->context.lock, flags);
  91         ctx_valid = CTX_VALID(mm->context);
  92         if (!ctx_valid)
  93                 get_new_mmu_context(mm);
  94 
  95         /* We have to be extremely careful here or else we will miss
  96          * a TSB grow if we switch back and forth between a kernel
  97          * thread and an address space which has it's TSB size increased
  98          * on another processor.
  99          *
 100          * It is possible to play some games in order to optimize the
 101          * switch, but the safest thing to do is to unconditionally
 102          * perform the secondary context load and the TSB context switch.
 103          *
 104          * For reference the bad case is, for address space "A":
 105          *
 106          *              CPU 0                   CPU 1
 107          *      run address space A
 108          *      set cpu0's bits in cpu_vm_mask
 109          *      switch to kernel thread, borrow
 110          *      address space A via entry_lazy_tlb
 111          *                                      run address space A
 112          *                                      set cpu1's bit in cpu_vm_mask
 113          *                                      flush_tlb_pending()
 114          *                                      reset cpu_vm_mask to just cpu1
 115          *                                      TSB grow
 116          *      run address space A
 117          *      context was valid, so skip
 118          *      TSB context switch
 119          *
 120          * At that point cpu0 continues to use a stale TSB, the one from
 121          * before the TSB grow performed on cpu1.  cpu1 did not cross-call
 122          * cpu0 to update it's TSB because at that point the cpu_vm_mask
 123          * only had cpu1 set in it.
 124          */
 125         tsb_context_switch_ctx(mm, CTX_HWBITS(mm->context));
 126 
 127         /* Any time a processor runs a context on an address space
 128          * for the first time, we must flush that context out of the
 129          * local TLB.
 130          */
 131         if (!ctx_valid || !cpumask_test_cpu(cpu, mm_cpumask(mm))) {
 132                 cpumask_set_cpu(cpu, mm_cpumask(mm));
 133                 __flush_tlb_mm(CTX_HWBITS(mm->context),
 134                                SECONDARY_CONTEXT);
 135         }
 136         spin_unlock_irqrestore(&mm->context.lock, flags);
 137 }
 138 
 139 #define deactivate_mm(tsk,mm)   do { } while (0)
 140 #define activate_mm(active_mm, mm) switch_mm(active_mm, mm, NULL)
 141 
 142 #define  __HAVE_ARCH_START_CONTEXT_SWITCH
 143 static inline void arch_start_context_switch(struct task_struct *prev)
 144 {
 145         /* Save the current state of MCDPER register for the process
 146          * we are switching from
 147          */
 148         if (adi_capable()) {
 149                 register unsigned long tmp_mcdper;
 150 
 151                 __asm__ __volatile__(
 152                         ".word 0x83438000\n\t"  /* rd  %mcdper, %g1 */
 153                         "mov %%g1, %0\n\t"
 154                         : "=r" (tmp_mcdper)
 155                         :
 156                         : "g1");
 157                 if (tmp_mcdper)
 158                         set_tsk_thread_flag(prev, TIF_MCDPER);
 159                 else
 160                         clear_tsk_thread_flag(prev, TIF_MCDPER);
 161         }
 162 }
 163 
 164 #define finish_arch_post_lock_switch    finish_arch_post_lock_switch
 165 static inline void finish_arch_post_lock_switch(void)
 166 {
 167         /* Restore the state of MCDPER register for the new process
 168          * just switched to.
 169          */
 170         if (adi_capable()) {
 171                 register unsigned long tmp_mcdper;
 172 
 173                 tmp_mcdper = test_thread_flag(TIF_MCDPER);
 174                 __asm__ __volatile__(
 175                         "mov %0, %%g1\n\t"
 176                         ".word 0x9d800001\n\t"  /* wr %g0, %g1, %mcdper" */
 177                         ".word 0xaf902001\n\t"  /* wrpr %g0, 1, %pmcdper */
 178                         :
 179                         : "ir" (tmp_mcdper)
 180                         : "g1");
 181                 if (current && current->mm && current->mm->context.adi) {
 182                         struct pt_regs *regs;
 183 
 184                         regs = task_pt_regs(current);
 185                         regs->tstate |= TSTATE_MCDE;
 186                 }
 187         }
 188 }
 189 
 190 #endif /* !(__ASSEMBLY__) */
 191 
 192 #endif /* !(__SPARC64_MMU_CONTEXT_H) */