131 lines
3.6 KiB
C
131 lines
3.6 KiB
C
#ifndef _ASM_X86_MMU_CONTEXT_H
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#define _ASM_X86_MMU_CONTEXT_H
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#include <asm/desc.h>
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#include <linux/atomic.h>
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#include <asm/pgalloc.h>
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#include <asm/tlbflush.h>
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#include <asm/paravirt.h>
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#ifndef CONFIG_PARAVIRT
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#include <asm-generic/mm_hooks.h>
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static inline void paravirt_activate_mm(struct mm_struct *prev,
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struct mm_struct *next)
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{
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}
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#endif /* !CONFIG_PARAVIRT */
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/*
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* Used for LDT copy/destruction.
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*/
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int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
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void destroy_context(struct mm_struct *mm);
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static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
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{
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#ifdef CONFIG_SMP
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if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK)
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this_cpu_write(cpu_tlbstate.state, TLBSTATE_LAZY);
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#endif
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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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unsigned cpu = smp_processor_id();
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if (likely(prev != next)) {
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#ifdef CONFIG_SMP
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this_cpu_write(cpu_tlbstate.state, TLBSTATE_OK);
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this_cpu_write(cpu_tlbstate.active_mm, next);
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#endif
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cpumask_set_cpu(cpu, mm_cpumask(next));
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/*
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* Re-load page tables.
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*
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* This logic has an ordering constraint:
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*
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* CPU 0: Write to a PTE for 'next'
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* CPU 0: load bit 1 in mm_cpumask. if nonzero, send IPI.
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* CPU 1: set bit 1 in next's mm_cpumask
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* CPU 1: load from the PTE that CPU 0 writes (implicit)
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*
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* We need to prevent an outcome in which CPU 1 observes
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* the new PTE value and CPU 0 observes bit 1 clear in
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* mm_cpumask. (If that occurs, then the IPI will never
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* be sent, and CPU 0's TLB will contain a stale entry.)
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*
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* The bad outcome can occur if either CPU's load is
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* reordered before that CPU's store, so both CPUs must
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* execute full barriers to prevent this from happening.
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*
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* Thus, switch_mm needs a full barrier between the
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* store to mm_cpumask and any operation that could load
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* from next->pgd. TLB fills are special and can happen
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* due to instruction fetches or for no reason at all,
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* and neither LOCK nor MFENCE orders them.
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* Fortunately, load_cr3() is serializing and gives the
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* ordering guarantee we need.
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*
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*/
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load_cr3(next->pgd);
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/* Stop flush ipis for the previous mm */
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cpumask_clear_cpu(cpu, mm_cpumask(prev));
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/* Load the LDT, if the LDT is different: */
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if (unlikely(prev->context.ldt != next->context.ldt))
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load_LDT_nolock(&next->context);
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}
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#ifdef CONFIG_SMP
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else {
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this_cpu_write(cpu_tlbstate.state, TLBSTATE_OK);
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BUG_ON(this_cpu_read(cpu_tlbstate.active_mm) != next);
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if (!cpumask_test_cpu(cpu, mm_cpumask(next))) {
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/*
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* On established mms, the mm_cpumask is only changed
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* from irq context, from ptep_clear_flush() while in
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* lazy tlb mode, and here. Irqs are blocked during
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* schedule, protecting us from simultaneous changes.
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*/
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cpumask_set_cpu(cpu, mm_cpumask(next));
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/*
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* We were in lazy tlb mode and leave_mm disabled
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* tlb flush IPI delivery. We must reload CR3
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* to make sure to use no freed page tables.
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*
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* As above, load_cr3() is serializing and orders TLB
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* fills with respect to the mm_cpumask write.
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*/
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load_cr3(next->pgd);
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load_LDT_nolock(&next->context);
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}
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}
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#endif
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}
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#define activate_mm(prev, next) \
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do { \
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paravirt_activate_mm((prev), (next)); \
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switch_mm((prev), (next), NULL); \
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} while (0);
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#ifdef CONFIG_X86_32
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#define deactivate_mm(tsk, mm) \
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do { \
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lazy_load_gs(0); \
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} while (0)
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#else
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#define deactivate_mm(tsk, mm) \
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do { \
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load_gs_index(0); \
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loadsegment(fs, 0); \
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} while (0)
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#endif
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#endif /* _ASM_X86_MMU_CONTEXT_H */
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