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linux/arch/avr32/mm/tlb.c
Haavard Skinnemoen b13d618b44 avr32: Clean up and optimize the TLB operations 
This and the following patches aim to optimize the code dealing with
page tables and TLB operations. Each patch reduces the time it takes
to gzip a 16 MB file slightly, but I expect things like fork() and
mmap() will improve somewhat more.

This patch deals with the low-level TLB operations:

  * Remove unused _TLBEHI_I define
  * Use gcc builtins instead of inline assembly
  * Remove a few unnecessary pipeline flushes and nops
  * Introduce NR_TLB_ENTRIES define and use it instead of hardcoding it
    to 32 a few places throughout the code.
  * Use sysreg bitops instead of hardcoded shifts and masks
  * Make a few needlessly global functions static

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
2008-07-02 11:01:28 +02:00

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/*
* AVR32 TLB operations
*
* Copyright (C) 2004-2006 Atmel Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/mm.h>
#include <asm/mmu_context.h>
/* TODO: Get the correct number from the CONFIG1 system register */
#define NR_TLB_ENTRIES 32
static void show_dtlb_entry(unsigned int index)
{
u32 tlbehi, tlbehi_save, tlbelo, mmucr, mmucr_save;
unsigned long flags;
local_irq_save(flags);
mmucr_save = sysreg_read(MMUCR);
tlbehi_save = sysreg_read(TLBEHI);
mmucr = SYSREG_BFINS(DRP, index, mmucr_save);
sysreg_write(MMUCR, mmucr);
__builtin_tlbr();
cpu_sync_pipeline();
tlbehi = sysreg_read(TLBEHI);
tlbelo = sysreg_read(TLBELO);
printk("%2u: %c %c %02x %05x %05x %o %o %c %c %c %c\n",
index,
SYSREG_BFEXT(TLBEHI_V, tlbehi) ? '1' : '0',
SYSREG_BFEXT(G, tlbelo) ? '1' : '0',
SYSREG_BFEXT(ASID, tlbehi),
SYSREG_BFEXT(VPN, tlbehi) >> 2,
SYSREG_BFEXT(PFN, tlbelo) >> 2,
SYSREG_BFEXT(AP, tlbelo),
SYSREG_BFEXT(SZ, tlbelo),
SYSREG_BFEXT(TLBELO_C, tlbelo) ? 'C' : ' ',
SYSREG_BFEXT(B, tlbelo) ? 'B' : ' ',
SYSREG_BFEXT(W, tlbelo) ? 'W' : ' ',
SYSREG_BFEXT(TLBELO_D, tlbelo) ? 'D' : ' ');
sysreg_write(MMUCR, mmucr_save);
sysreg_write(TLBEHI, tlbehi_save);
cpu_sync_pipeline();
local_irq_restore(flags);
}
void dump_dtlb(void)
{
unsigned int i;
printk("ID V G ASID VPN PFN AP SZ C B W D\n");
for (i = 0; i < NR_TLB_ENTRIES; i++)
show_dtlb_entry(i);
}
static void update_dtlb(unsigned long address, pte_t pte)
{
u32 tlbehi;
u32 mmucr;
/*
* We're not changing the ASID here, so no need to flush the
* pipeline.
*/
tlbehi = sysreg_read(TLBEHI);
tlbehi = SYSREG_BF(ASID, SYSREG_BFEXT(ASID, tlbehi));
tlbehi |= address & MMU_VPN_MASK;
tlbehi |= SYSREG_BIT(TLBEHI_V);
sysreg_write(TLBEHI, tlbehi);
/* Does this mapping already exist? */
__builtin_tlbs();
mmucr = sysreg_read(MMUCR);
if (mmucr & SYSREG_BIT(MMUCR_N)) {
/* Not found -- pick a not-recently-accessed entry */
unsigned int rp;
u32 tlbar = sysreg_read(TLBARLO);
rp = 32 - fls(tlbar);
if (rp == 32) {
rp = 0;
sysreg_write(TLBARLO, -1L);
}
mmucr = SYSREG_BFINS(DRP, rp, mmucr);
sysreg_write(MMUCR, mmucr);
}
sysreg_write(TLBELO, pte_val(pte) & _PAGE_FLAGS_HARDWARE_MASK);
/* Let's go */
__builtin_tlbw();
}
void update_mmu_cache(struct vm_area_struct *vma,
unsigned long address, pte_t pte)
{
unsigned long flags;
/* ptrace may call this routine */
if (vma && current->active_mm != vma->vm_mm)
return;
local_irq_save(flags);
update_dtlb(address, pte);
local_irq_restore(flags);
}
static void __flush_tlb_page(unsigned long asid, unsigned long page)
{
u32 mmucr, tlbehi;
/*
* Caller is responsible for masking out non-PFN bits in page
* and changing the current ASID if necessary. This means that
* we don't need to flush the pipeline after writing TLBEHI.
*/
tlbehi = page | asid;
sysreg_write(TLBEHI, tlbehi);
__builtin_tlbs();
mmucr = sysreg_read(MMUCR);
if (!(mmucr & SYSREG_BIT(MMUCR_N))) {
unsigned int entry;
u32 tlbarlo;
/* Clear the "valid" bit */
sysreg_write(TLBEHI, tlbehi);
/* mark the entry as "not accessed" */
entry = SYSREG_BFEXT(DRP, mmucr);
tlbarlo = sysreg_read(TLBARLO);
tlbarlo |= (0x80000000UL >> entry);
sysreg_write(TLBARLO, tlbarlo);
/* update the entry with valid bit clear */
__builtin_tlbw();
}
}
void flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
{
if (vma->vm_mm && vma->vm_mm->context != NO_CONTEXT) {
unsigned long flags, asid;
unsigned long saved_asid = MMU_NO_ASID;
asid = vma->vm_mm->context & MMU_CONTEXT_ASID_MASK;
page &= PAGE_MASK;
local_irq_save(flags);
if (vma->vm_mm != current->mm) {
saved_asid = get_asid();
set_asid(asid);
}
__flush_tlb_page(asid, page);
if (saved_asid != MMU_NO_ASID)
set_asid(saved_asid);
local_irq_restore(flags);
}
}
void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
unsigned long end)
{
struct mm_struct *mm = vma->vm_mm;
if (mm->context != NO_CONTEXT) {
unsigned long flags;
int size;
local_irq_save(flags);
size = (end - start + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
if (size > (MMU_DTLB_ENTRIES / 4)) { /* Too many entries to flush */
mm->context = NO_CONTEXT;
if (mm == current->mm)
activate_context(mm);
} else {
unsigned long asid;
unsigned long saved_asid;
asid = mm->context & MMU_CONTEXT_ASID_MASK;
saved_asid = MMU_NO_ASID;
start &= PAGE_MASK;
end += (PAGE_SIZE - 1);
end &= PAGE_MASK;
if (mm != current->mm) {
saved_asid = get_asid();
set_asid(asid);
}
while (start < end) {
__flush_tlb_page(asid, start);
start += PAGE_SIZE;
}
if (saved_asid != MMU_NO_ASID)
set_asid(saved_asid);
}
local_irq_restore(flags);
}
}
/*
* This function depends on the pages to be flushed having the G
* (global) bit set in their pte. This is true for all
* PAGE_KERNEL(_RO) pages.
*/
void flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
unsigned long flags;
int size;
size = (end - start + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
if (size > (MMU_DTLB_ENTRIES / 4)) { /* Too many entries to flush */
flush_tlb_all();
} else {
unsigned long asid;
local_irq_save(flags);
asid = get_asid();
start &= PAGE_MASK;
end += (PAGE_SIZE - 1);
end &= PAGE_MASK;
while (start < end) {
__flush_tlb_page(asid, start);
start += PAGE_SIZE;
}
local_irq_restore(flags);
}
}
void flush_tlb_mm(struct mm_struct *mm)
{
/* Invalidate all TLB entries of this process by getting a new ASID */
if (mm->context != NO_CONTEXT) {
unsigned long flags;
local_irq_save(flags);
mm->context = NO_CONTEXT;
if (mm == current->mm)
activate_context(mm);
local_irq_restore(flags);
}
}
void flush_tlb_all(void)
{
unsigned long flags;
local_irq_save(flags);
sysreg_write(MMUCR, sysreg_read(MMUCR) | SYSREG_BIT(MMUCR_I));
local_irq_restore(flags);
}
#ifdef CONFIG_PROC_FS
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
static void *tlb_start(struct seq_file *tlb, loff_t *pos)
{
static unsigned long tlb_index;
if (*pos >= NR_TLB_ENTRIES)
return NULL;
tlb_index = 0;
return &tlb_index;
}
static void *tlb_next(struct seq_file *tlb, void *v, loff_t *pos)
{
unsigned long *index = v;
if (*index >= NR_TLB_ENTRIES - 1)
return NULL;
++*pos;
++*index;
return index;
}
static void tlb_stop(struct seq_file *tlb, void *v)
{
}
static int tlb_show(struct seq_file *tlb, void *v)
{
unsigned int tlbehi, tlbehi_save, tlbelo, mmucr, mmucr_save;
unsigned long flags;
unsigned long *index = v;
if (*index == 0)
seq_puts(tlb, "ID V G ASID VPN PFN AP SZ C B W D\n");
BUG_ON(*index >= NR_TLB_ENTRIES);
local_irq_save(flags);
mmucr_save = sysreg_read(MMUCR);
tlbehi_save = sysreg_read(TLBEHI);
mmucr = SYSREG_BFINS(DRP, *index, mmucr_save);
sysreg_write(MMUCR, mmucr);
/* TLBR might change the ASID */
__builtin_tlbr();
cpu_sync_pipeline();
tlbehi = sysreg_read(TLBEHI);
tlbelo = sysreg_read(TLBELO);
sysreg_write(MMUCR, mmucr_save);
sysreg_write(TLBEHI, tlbehi_save);
cpu_sync_pipeline();
local_irq_restore(flags);
seq_printf(tlb, "%2lu: %c %c %02x %05x %05x %o %o %c %c %c %c\n",
*index,
SYSREG_BFEXT(TLBEHI_V, tlbehi) ? '1' : '0',
SYSREG_BFEXT(G, tlbelo) ? '1' : '0',
SYSREG_BFEXT(ASID, tlbehi),
SYSREG_BFEXT(VPN, tlbehi) >> 2,
SYSREG_BFEXT(PFN, tlbelo) >> 2,
SYSREG_BFEXT(AP, tlbelo),
SYSREG_BFEXT(SZ, tlbelo),
SYSREG_BFEXT(TLBELO_C, tlbelo) ? '1' : '0',
SYSREG_BFEXT(B, tlbelo) ? '1' : '0',
SYSREG_BFEXT(W, tlbelo) ? '1' : '0',
SYSREG_BFEXT(TLBELO_D, tlbelo) ? '1' : '0');
return 0;
}
static const struct seq_operations tlb_ops = {
.start = tlb_start,
.next = tlb_next,
.stop = tlb_stop,
.show = tlb_show,
};
static int tlb_open(struct inode *inode, struct file *file)
{
return seq_open(file, &tlb_ops);
}
static const struct file_operations proc_tlb_operations = {
.open = tlb_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
static int __init proctlb_init(void)
{
proc_create("tlb", 0, NULL, &proc_tlb_operations);
return 0;
}
late_initcall(proctlb_init);
#endif /* CONFIG_PROC_FS */
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