mmu_context.h

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#ifndef _ASM_X86_MMU_CONTEXT_H
#define _ASM_X86_MMU_CONTEXT_H

#include <asm/desc.h>
#include <linux/atomic.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/paravirt.h>
#ifndef CONFIG_PARAVIRT
#include <asm-generic/mm_hooks.h>

static inline void paravirt_activate_mm(struct mm_struct *prev,
                    struct mm_struct *next)
{
}
#endif  /* !CONFIG_PARAVIRT */

/*
 * Used for LDT copy/destruction.
 */
int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
void destroy_context(struct mm_struct *mm);


static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
{
#ifdef CONFIG_SMP
    if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK)
        this_cpu_write(cpu_tlbstate.state, TLBSTATE_LAZY);
#endif
}

static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
                 struct task_struct *tsk)
{
    unsigned cpu = smp_processor_id();

    if (likely(prev != next)) {
#ifdef CONFIG_SMP
        this_cpu_write(cpu_tlbstate.state, TLBSTATE_OK);
        this_cpu_write(cpu_tlbstate.active_mm, next);
#endif
        cpumask_set_cpu(cpu, mm_cpumask(next));

        /* Re-load page tables */
        load_cr3(next->pgd);

        /* stop flush ipis for the previous mm */
        cpumask_clear_cpu(cpu, mm_cpumask(prev));

        /*
         * load the LDT, if the LDT is different:
         */
        if (unlikely(prev->context.ldt != next->context.ldt))
            load_LDT_nolock(&next->context);
    }
#ifdef CONFIG_SMP
    else {
        this_cpu_write(cpu_tlbstate.state, TLBSTATE_OK);
        BUG_ON(this_cpu_read(cpu_tlbstate.active_mm) != next);

        if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next))) {
            /* We were in lazy tlb mode and leave_mm disabled
             * tlb flush IPI delivery. We must reload CR3
             * to make sure to use no freed page tables.
             */
            load_cr3(next->pgd);
            load_LDT_nolock(&next->context);
        }
    }
#endif
}

#define activate_mm(prev, next)         \
do {                        \
    paravirt_activate_mm((prev), (next));   \
    switch_mm((prev), (next), NULL);    \
} while (0);

#ifdef CONFIG_X86_32
#define deactivate_mm(tsk, mm)          \
do {                        \
    lazy_load_gs(0);            \
} while (0)
#else
#define deactivate_mm(tsk, mm)          \
do {                        \
    load_gs_index(0);           \
    loadsegment(fs, 0);         \
} while (0)
#endif

#endif /* _ASM_X86_MMU_CONTEXT_H */