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/*
* linux/arch/cris/mm/tlb.c
*
* Copyright (C) 2000, 2001 Axis Communications AB
*
* Authors: Bjorn Wesen (bjornw@axis.com)
*
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <asm/system.h>
#include <asm/segment.h>
#include <asm/pgtable.h>
#include <asm/svinto.h>
#include <asm/mmu_context.h>
#define D(x)
/* CRIS in Etrax100LX TLB */
#define NUM_TLB_ENTRIES 64
#define NUM_PAGEID 64
#define INVALID_PAGEID 63
#define NO_CONTEXT -1
/* 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.
*/
struct mm_struct *page_id_map[NUM_PAGEID];
static int map_replace_ptr = 1; /* which page_id_map entry to replace next */
/* 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..
*/
save_and_cli(flags); /* flush needs to be atomic */
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 ) );
}
restore_flags(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;
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 ?
*/
save_and_cli(flags); /* flush needs to be atomic */
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 ) );
}
}
restore_flags(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;
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
*/
save_and_cli(flags); /* flush needs to be atomic */
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 ) );
}
}
restore_flags(flags);
}
/* invalidate a page range */
void
flush_tlb_range(struct mm_struct *mm,
unsigned long start,
unsigned long end)
{
int page_id = mm->context;
int i;
unsigned long flags;
D(printk("tlb: flush range %p<->%p in context %d (%p)\n",
start, end, page_id, mm));
if(page_id == NO_CONTEXT)
return;
start &= PAGE_MASK; /* probably not necessary */
end &= PAGE_MASK; /* dito */
/* invalidate those TLB entries that match both the mm context
* and the virtual address range
*/
save_and_cli(flags); /* flush needs to be atomic */
for(i = 0; i < NUM_TLB_ENTRIES; i++) {
unsigned long tlb_hi, vpn;
*R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
tlb_hi = *R_TLB_HI;
vpn = tlb_hi & PAGE_MASK;
if (IO_EXTRACT(R_TLB_HI, page_id, tlb_hi) == page_id &&
vpn >= start && vpn < end) {
*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 ) );
}
}
restore_flags(flags);
}
/* dump the entire TLB for debug purposes */
#if 0
void
dump_tlb_all(void)
{
int i;
unsigned long flags;
printk("TLB dump. LO is: pfn | reserved | global | valid | kernel | we |\n");
save_and_cli(flags);
for(i = 0; i < NUM_TLB_ENTRIES; i++) {
*R_TLB_SELECT = ( IO_FIELD(R_TLB_SELECT, index, i) );
printk("Entry %d: HI 0x%08lx, LO 0x%08lx\n",
i, *R_TLB_HI, *R_TLB_LO);
}
restore_flags(flags);
}
#endif
/*
* 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 = NO_CONTEXT;
return 0;
}
/* the following functions are similar to those used in the PPC port */
static inline void
alloc_context(struct mm_struct *mm)
{
struct mm_struct *old_mm;
D(printk("tlb: alloc context %d (%p)\n", map_replace_ptr, mm));
/* did we replace an mm ? */
old_mm = page_id_map[map_replace_ptr];
if(old_mm) {
/* throw out any TLB entries belonging to the mm we replace
* in the map
*/
flush_tlb_mm(old_mm);
old_mm->context = NO_CONTEXT;
}
/* insert it into the page_id_map */
mm->context = map_replace_ptr;
page_id_map[map_replace_ptr] = mm;
map_replace_ptr++;
if(map_replace_ptr == INVALID_PAGEID)
map_replace_ptr = 0; /* wrap around */
}
/*
* if needed, get a new MMU context for the mm. otherwise nothing is done.
*/
void
get_mmu_context(struct mm_struct *mm)
{
if(mm->context == NO_CONTEXT)
alloc_context(mm);
}
/* 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, int cpu)
{
/* 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.
*/
current_pgd = next->pgd;
/* switch context in the MMU */
D(printk("switching mmu_context to %d (%p)\n", next->context, next));
*R_MMU_CONTEXT = IO_FIELD(R_MMU_CONTEXT, page_id, next->context);
}
/* called by __exit_mm to destroy the used MMU context if any before
* destroying the mm itself. this is only called when the last user of the mm
* drops it.
*
* the only thing we really need to do here is mark the used PID slot
* as empty.
*/
void
destroy_context(struct mm_struct *mm)
{
if(mm->context != NO_CONTEXT) {
D(printk("destroy_context %d (%p)\n", mm->context, mm));
flush_tlb_mm(mm); /* TODO this might be redundant ? */
page_id_map[mm->context] = NULL;
/* mm->context = NO_CONTEXT; redundant.. mm will be freed */
}
}
/* called once during VM initialization, from init.c */
void __init
tlb_init(void)
{
int i;
/* clear the page_id map */
for (i = 1; i < sizeof (page_id_map) / sizeof (page_id_map[0]); i++)
page_id_map[i] = NULL;
/* invalidate the entire TLB */
flush_tlb_all();
/* the init_mm has context 0 from the boot */
page_id_map[0] = &init_mm;
}
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