root/arch/x86/include/asm/mmu_context.h

DEFINITIONS

1. paravirt_activate_mm
2. enter_lazy_tlb
3. switch_mm

#ifndef _ASM_X86_MMU_CONTEXT_H
#define _ASM_X86_MMU_CONTEXT_H

#include <asm/desc.h>
#include <linux/atomic.h>
#include <linux/mm_types.h>

#include <trace/events/tlb.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);
                trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);

                /* 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_cpu(cpu, mm_cpumask(next))) {
                        /*
                         * On established mms, the mm_cpumask is only changed
                         * from irq context, from ptep_clear_flush() while in
                         * lazy tlb mode, and here. Irqs are blocked during
                         * schedule, protecting us from simultaneous changes.
                         */
                        cpumask_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);
                        trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
                        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 */