source: trunk/packages/xen-3.1/xen-3.1/linux-2.6-xen-sparse/include/asm-x86_64/mach-xen/asm/mmu_context.h @ 34

#ifndef __X86_64_MMU_CONTEXT_H
#define __X86_64_MMU_CONTEXT_H

#include <asm/desc.h>
#include <asm/atomic.h>
#include <asm/pgalloc.h>
#include <asm/page.h>
#include <asm/pda.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>

/*
 * possibly do the LDT unload here?
 */
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)
{
#if defined(CONFIG_SMP) && !defined(CONFIG_XEN)
        if (read_pda(mmu_state) == TLBSTATE_OK) 
                write_pda(mmu_state, TLBSTATE_LAZY);
#endif
}

#define prepare_arch_switch(next)       __prepare_arch_switch()

static inline void __prepare_arch_switch(void)
{
        /*
         * Save away %es, %ds, %fs and %gs. Must happen before reload
         * of cr3/ldt (i.e., not in __switch_to).
         */
        __asm__ __volatile__ (
                "mov %%es,%0 ; mov %%ds,%1 ; mov %%fs,%2 ; mov %%gs,%3"
                : "=m" (current->thread.es),
                  "=m" (current->thread.ds),
                  "=m" (current->thread.fsindex),
                  "=m" (current->thread.gsindex) );

        if (current->thread.ds)
                __asm__ __volatile__ ( "movl %0,%%ds" : : "r" (0) );

        if (current->thread.es)
                __asm__ __volatile__ ( "movl %0,%%es" : : "r" (0) );

        if (current->thread.fsindex) {
                __asm__ __volatile__ ( "movl %0,%%fs" : : "r" (0) );
                current->thread.fs = 0;
        }

        if (current->thread.gsindex) {
                load_gs_index(0);
                current->thread.gs = 0;
        }
}

extern void mm_pin(struct mm_struct *mm);
extern void mm_unpin(struct mm_struct *mm);
void mm_pin_all(void);

static inline void load_cr3(pgd_t *pgd)
{
        asm volatile("movq %0,%%cr3" :: "r" (phys_to_machine(__pa(pgd))) :
                     "memory");
}

static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, 
                             struct task_struct *tsk)
{
        unsigned cpu = smp_processor_id();
        struct mmuext_op _op[3], *op = _op;

        if (likely(prev != next)) {
                BUG_ON(!xen_feature(XENFEAT_writable_page_tables) &&
                       !next->context.pinned);

                /* stop flush ipis for the previous mm */
                cpu_clear(cpu, prev->cpu_vm_mask);
#if defined(CONFIG_SMP) && !defined(CONFIG_XEN)
                write_pda(mmu_state, TLBSTATE_OK);
                write_pda(active_mm, next);
#endif
                cpu_set(cpu, next->cpu_vm_mask);

                /* load_cr3(next->pgd) */
                op->cmd = MMUEXT_NEW_BASEPTR;
                op->arg1.mfn = pfn_to_mfn(__pa(next->pgd) >> PAGE_SHIFT);
                op++;

                /* xen_new_user_pt(__pa(__user_pgd(next->pgd))) */
                op->cmd = MMUEXT_NEW_USER_BASEPTR;
                op->arg1.mfn = pfn_to_mfn(__pa(__user_pgd(next->pgd)) >> PAGE_SHIFT);
                op++;
                
                if (unlikely(next->context.ldt != prev->context.ldt)) {
                        /* load_LDT_nolock(&next->context, cpu) */
                        op->cmd = MMUEXT_SET_LDT;
                        op->arg1.linear_addr = (unsigned long)next->context.ldt;
                        op->arg2.nr_ents     = next->context.size;
                        op++;
                }

                BUG_ON(HYPERVISOR_mmuext_op(_op, op-_op, NULL, DOMID_SELF));
        }
#if defined(CONFIG_SMP) && !defined(CONFIG_XEN)
        else {
                write_pda(mmu_state, TLBSTATE_OK);
                if (read_pda(active_mm) != next)
                        out_of_line_bug();
                if (!cpu_test_and_set(cpu, next->cpu_vm_mask)) {
                        /* 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);
                        xen_new_user_pt(__pa(__user_pgd(next->pgd)));           
                        load_LDT_nolock(&next->context, cpu);
                }
        }
#endif
}

#define deactivate_mm(tsk,mm)   do { \
        load_gs_index(0); \
        asm volatile("movl %0,%%fs"::"r"(0));  \
} while(0)

static inline void activate_mm(struct mm_struct *prev, struct mm_struct *next)
{
        if (!next->context.pinned)
                mm_pin(next);
        switch_mm(prev, next, NULL);
}

#endif