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/*
* Copyright 2002 Andi Kleen, SuSE Labs.
* Thanks to Ben LaHaise for precious feedback.
*/
#include <linux/config.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/highmem.h>
#include <linux/module.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
/* Should move most of this stuff into the appropiate includes */
#define LARGE_PAGE_MASK (~(LARGE_PAGE_SIZE-1))
#define LARGE_PAGE_SIZE (1UL << PMD_SHIFT)
static inline pte_t *lookup_address(unsigned long address)
{
pmd_t *pmd;
pgd_t *pgd = pgd_offset(&init_mm, address);
if (pgd_none(*pgd))
return NULL;
if (pgd_val(*pgd) & _PAGE_PSE)
return (pte_t *)pgd;
pmd = pmd_offset(pgd, address);
if (pmd_none(*pmd))
return NULL;
if (pmd_val(*pmd) & _PAGE_PSE)
return (pte_t *)pmd;
return pte_offset(pmd, address);
}
static struct page *split_large_page(unsigned long address, pgprot_t prot)
{
int i;
unsigned long addr;
struct page *base = alloc_pages(GFP_KERNEL, 0);
pte_t *pbase;
if (!base)
return NULL;
address = __pa(address);
addr = address & LARGE_PAGE_MASK;
pbase = (pte_t *)page_address(base);
for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
pbase[i] = mk_pte_phys(addr,
addr == address ? prot : PAGE_KERNEL);
}
return base;
}
static void flush_kernel_map(void * address)
{
if (!test_bit(X86_FEATURE_SELFSNOOP, boot_cpu_data.x86_capability)) {
/* Could use CLFLUSH here if the CPU supports it (Hammer,P4) */
if (boot_cpu_data.x86_model >= 4)
asm volatile("wbinvd":::"memory");
}
/* Do global flush here to work around large page flushing errata
in some early Athlons */
__flush_tlb_all();
}
static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
{
set_pte_atomic(kpte, pte); /* change init_mm */
#ifndef CONFIG_X86_PAE
{
struct list_head *l;
spin_lock(&mmlist_lock);
list_for_each(l, &init_mm.mmlist) {
struct mm_struct *mm = list_entry(l, struct mm_struct, mmlist);
pmd_t *pmd = pmd_offset(pgd_offset(mm, address), address);
set_pte_atomic((pte_t *)pmd, pte);
}
spin_unlock(&mmlist_lock);
}
#endif
}
/* no more special protections in this 2/4MB area - revert to a
large page again. */
static inline void revert_page(struct page *kpte_page, unsigned long address)
{
pte_t *linear = (pte_t *)
pmd_offset(pgd_offset(&init_mm, address), address);
set_pmd_pte(linear, address,
mk_pte_phys(__pa(address & LARGE_PAGE_MASK),
MAKE_GLOBAL(_KERNPG_TABLE|_PAGE_PSE)));
}
/*
* Change the page attributes of an page in the linear mapping.
*
* This should be used when a page is mapped with a different caching policy
* than write-back somewhere - some CPUs do not like it when mappings with
* different caching policies exist. This changes the page attributes of the
* in kernel linear mapping too.
*
* The caller needs to ensure that there are no conflicting mappings elsewhere.
* This function only deals with the kernel linear map.
* When page is in highmem it must never be kmap'ed.
*/
static int
__change_page_attr(struct page *page, pgprot_t prot, struct page **oldpage)
{
pte_t *kpte;
unsigned long address;
struct page *kpte_page;
#ifdef CONFIG_HIGHMEM
if (page >= highmem_start_page)
BUG();
#endif
address = (unsigned long)page_address(page);
kpte = lookup_address(address);
if (!kpte)
return -EINVAL;
kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) {
if ((pte_val(*kpte) & _PAGE_PSE) == 0) {
pte_t old = *kpte;
pte_t standard = mk_pte(page, PAGE_KERNEL);
set_pte_atomic(kpte, mk_pte(page, prot));
if (pte_same(old,standard))
atomic_inc(&kpte_page->count);
} else {
struct page *split = split_large_page(address, prot);
if (!split)
return -ENOMEM;
atomic_inc(&kpte_page->count);
set_pmd_pte(kpte,address,mk_pte(split, PAGE_KERNEL));
}
} else if ((pte_val(*kpte) & _PAGE_PSE) == 0) {
set_pte_atomic(kpte, mk_pte(page, PAGE_KERNEL));
atomic_dec(&kpte_page->count);
}
if (cpu_has_pse && (atomic_read(&kpte_page->count) == 1)) {
*oldpage = kpte_page;
revert_page(kpte_page, address);
}
return 0;
}
int change_page_attr(struct page *page, int numpages, pgprot_t prot)
{
int err = 0;
struct page *fpage;
int i;
down_write(&init_mm.mmap_sem);
for (i = 0; i < numpages; i++, page++) {
fpage = NULL;
err = __change_page_attr(page, prot, &fpage);
if (err)
break;
if (fpage || i == numpages-1) {
void *address = page_address(page);
#ifdef CONFIG_SMP
smp_call_function(flush_kernel_map, address, 1, 1);
#endif
flush_kernel_map(address);
if (fpage)
__free_page(fpage);
}
}
up_write(&init_mm.mmap_sem);
return err;
}
EXPORT_SYMBOL(change_page_attr);
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