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/*
* linux/arch/cris/arch-v10/mm/tlb.c
*
* Low level TLB handling
*
*
* Copyright (C) 2000-2007 Axis Communications AB
*
* Authors: Bjorn Wesen (bjornw@axis.com)
*
*/
#include <asm/tlb.h>
#include <asm/mmu_context.h>
#include <arch/svinto.h>
#define D(x)
/* The TLB can host up to 64 different mm contexts at the same time.
* The running context is R_MMU_CONTEXT, and each TLB entry contains a
* page_id that has to match to give a hit. In page_id_map, we keep track
* of which mm's we have assigned which page_id's, so that we know when
* to invalidate TLB entries.
*
* The last page_id is never running - it is used as an invalid page_id
* so we can make TLB entries that will never match.
*
* Notice that we need to make the flushes atomic, otherwise an interrupt
* handler that uses vmalloced memory might cause a TLB load in the middle
* of a flush causing.
*/
/* invalidate all TLB entries */
void
flush_tlb_all(void)
{
int i;
unsigned long flags;
/* the vpn of i & 0xf is so we dont write similar TLB entries
* in the same 4-way entry group. details...
*/
local_irq_save(flags);
for(i = 0; i < NUM_TLB_ENTRIES; i++) {
*R_TLB_SELECT = ( IO_FIELD(R_TLB_SELECT, index, i) );
*R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
IO_FIELD(R_TLB_HI, vpn, i & 0xf ) );
*R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no ) |
IO_STATE(R_TLB_LO, valid, no ) |
IO_STATE(R_TLB_LO, kernel,no ) |
IO_STATE(R_TLB_LO, we, no ) |
IO_FIELD(R_TLB_LO, pfn, 0 ) );
}
local_irq_restore(flags);
D(printk("tlb: flushed all\n"));
}
/* invalidate the selected mm context only */
void
flush_tlb_mm(struct mm_struct *mm)
{
int i;
int page_id = mm->context.page_id;
unsigned long flags;
D(printk("tlb: flush mm context %d (%p)\n", page_id, mm));
if(page_id == NO_CONTEXT)
return;
/* mark the TLB entries that match the page_id as invalid.
* here we could also check the _PAGE_GLOBAL bit and NOT flush
* global pages. is it worth the extra I/O ?
*/
local_irq_save(flags);
for(i = 0; i < NUM_TLB_ENTRIES; i++) {
*R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
if (IO_EXTRACT(R_TLB_HI, page_id, *R_TLB_HI) == page_id) {
*R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
IO_FIELD(R_TLB_HI, vpn, i & 0xf ) );
*R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no ) |
IO_STATE(R_TLB_LO, valid, no ) |
IO_STATE(R_TLB_LO, kernel,no ) |
IO_STATE(R_TLB_LO, we, no ) |
IO_FIELD(R_TLB_LO, pfn, 0 ) );
}
}
local_irq_restore(flags);
}
/* invalidate a single page */
void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
{
struct mm_struct *mm = vma->vm_mm;
int page_id = mm->context.page_id;
int i;
unsigned long flags;
D(printk("tlb: flush page %p in context %d (%p)\n", addr, page_id, mm));
if(page_id == NO_CONTEXT)
return;
addr &= PAGE_MASK; /* perhaps not necessary */
/* invalidate those TLB entries that match both the mm context
* and the virtual address requested
*/
local_irq_save(flags);
for(i = 0; i < NUM_TLB_ENTRIES; i++) {
unsigned long tlb_hi;
*R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
tlb_hi = *R_TLB_HI;
if (IO_EXTRACT(R_TLB_HI, page_id, tlb_hi) == page_id &&
(tlb_hi & PAGE_MASK) == addr) {
*R_TLB_HI = IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
addr; /* same addr as before works. */
*R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no ) |
IO_STATE(R_TLB_LO, valid, no ) |
IO_STATE(R_TLB_LO, kernel,no ) |
IO_STATE(R_TLB_LO, we, no ) |
IO_FIELD(R_TLB_LO, pfn, 0 ) );
}
}
local_irq_restore(flags);
}
/*
* Initialize the context related info for a new mm_struct
* instance.
*/
int
init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
mm->context.page_id = NO_CONTEXT;
return 0;
}
/* called in schedule() just before actually doing the switch_to */
void switch_mm(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
if (prev != next) {
/* make sure we have a context */
get_mmu_context(next);
/* remember the pgd for the fault handlers
* this is similar to the pgd register in some other CPU's.
* we need our own copy of it because current and active_mm
* might be invalid at points where we still need to derefer
* the pgd.
*/
per_cpu(current_pgd, smp_processor_id()) = next->pgd;
/* switch context in the MMU */
D(printk(KERN_DEBUG "switching mmu_context to %d (%p)\n",
next->context, next));
*R_MMU_CONTEXT = IO_FIELD(R_MMU_CONTEXT,
page_id, next->context.page_id);
}
}
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