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/*
* Copyright 2002 Andi Kleen, SuSE Labs.
* Thanks to Ben LaHaise for precious feedback.
*/
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/highmem.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
#include <asm/tlbflush.h>
#include <asm/io.h>
static inline pte_t *lookup_address(unsigned long address)
{
pgd_t *pgd = pgd_offset_k(address);
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
if (pgd_none(*pgd))
return NULL;
pud = pud_offset(pgd, address);
if (!pud_present(*pud))
return NULL;
pmd = pmd_offset(pud, address);
if (!pmd_present(*pmd))
return NULL;
if (pmd_large(*pmd))
return (pte_t *)pmd;
pte = pte_offset_kernel(pmd, address);
if (pte && !pte_present(*pte))
pte = NULL;
return pte;
}
static struct page *split_large_page(unsigned long address, pgprot_t prot,
pgprot_t ref_prot)
{
int i;
unsigned long addr;
struct page *base = alloc_pages(GFP_KERNEL, 0);
pte_t *pbase;
if (!base)
return NULL;
/*
* page_private is used to track the number of entries in
* the page table page have non standard attributes.
*/
SetPagePrivate(base);
page_private(base) = 0;
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] = pfn_pte(addr >> PAGE_SHIFT,
addr == address ? prot : ref_prot);
}
return base;
}
static void cache_flush_page(void *adr)
{
int i;
for (i = 0; i < PAGE_SIZE; i += boot_cpu_data.x86_clflush_size)
asm volatile("clflush (%0)" :: "r" (adr + i));
}
static void flush_kernel_map(void *arg)
{
struct list_head *l = (struct list_head *)arg;
struct page *pg;
/* When clflush is available always use it because it is
much cheaper than WBINVD */
if (!cpu_has_clflush)
asm volatile("wbinvd" ::: "memory");
list_for_each_entry(pg, l, lru) {
void *adr = page_address(pg);
if (cpu_has_clflush)
cache_flush_page(adr);
}
__flush_tlb_all();
}
static inline void flush_map(struct list_head *l)
{
on_each_cpu(flush_kernel_map, l, 1, 1);
}
static LIST_HEAD(deferred_pages); /* protected by init_mm.mmap_sem */
static inline void save_page(struct page *fpage)
{
list_add(&fpage->lru, &deferred_pages);
}
/*
* No more special protections in this 2/4MB area - revert to a
* large page again.
*/
static void revert_page(unsigned long address, pgprot_t ref_prot)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t large_pte;
unsigned long pfn;
pgd = pgd_offset_k(address);
BUG_ON(pgd_none(*pgd));
pud = pud_offset(pgd,address);
BUG_ON(pud_none(*pud));
pmd = pmd_offset(pud, address);
BUG_ON(pmd_val(*pmd) & _PAGE_PSE);
pfn = (__pa(address) & LARGE_PAGE_MASK) >> PAGE_SHIFT;
large_pte = pfn_pte(pfn, ref_prot);
large_pte = pte_mkhuge(large_pte);
set_pte((pte_t *)pmd, large_pte);
}
static int
__change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot,
pgprot_t ref_prot)
{
pte_t *kpte;
struct page *kpte_page;
pgprot_t ref_prot2;
kpte = lookup_address(address);
if (!kpte) return 0;
kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
if (pgprot_val(prot) != pgprot_val(ref_prot)) {
if (!pte_huge(*kpte)) {
set_pte(kpte, pfn_pte(pfn, prot));
} else {
/*
* split_large_page will take the reference for this
* change_page_attr on the split page.
*/
struct page *split;
ref_prot2 = pte_pgprot(pte_clrhuge(*kpte));
split = split_large_page(address, prot, ref_prot2);
if (!split)
return -ENOMEM;
set_pte(kpte, mk_pte(split, ref_prot2));
kpte_page = split;
}
page_private(kpte_page)++;
} else if (!pte_huge(*kpte)) {
set_pte(kpte, pfn_pte(pfn, ref_prot));
BUG_ON(page_private(kpte_page) == 0);
page_private(kpte_page)--;
} else
BUG();
/* on x86-64 the direct mapping set at boot is not using 4k pages */
BUG_ON(PageReserved(kpte_page));
if (page_private(kpte_page) == 0) {
save_page(kpte_page);
revert_page(address, ref_prot);
}
return 0;
}
/*
* 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.
*
* Caller must call global_flush_tlb() after this.
*/
int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
{
int err = 0;
int i;
down_write(&init_mm.mmap_sem);
for (i = 0; i < numpages; i++, address += PAGE_SIZE) {
unsigned long pfn = __pa(address) >> PAGE_SHIFT;
err = __change_page_attr(address, pfn, prot, PAGE_KERNEL);
if (err)
break;
/* Handle kernel mapping too which aliases part of the
* lowmem */
if (__pa(address) < KERNEL_TEXT_SIZE) {
unsigned long addr2;
pgprot_t prot2;
addr2 = __START_KERNEL_map + __pa(address);
/* Make sure the kernel mappings stay executable */
prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot)));
err = __change_page_attr(addr2, pfn, prot2,
PAGE_KERNEL_EXEC);
}
}
up_write(&init_mm.mmap_sem);
return err;
}
/* Don't call this for MMIO areas that may not have a mem_map entry */
int change_page_attr(struct page *page, int numpages, pgprot_t prot)
{
unsigned long addr = (unsigned long)page_address(page);
return change_page_attr_addr(addr, numpages, prot);
}
void global_flush_tlb(void)
{
struct page *pg, *next;
struct list_head l;
down_read(&init_mm.mmap_sem);
list_replace_init(&deferred_pages, &l);
up_read(&init_mm.mmap_sem);
flush_map(&l);
list_for_each_entry_safe(pg, next, &l, lru) {
ClearPagePrivate(pg);
__free_page(pg);
}
}
EXPORT_SYMBOL(change_page_attr);
EXPORT_SYMBOL(global_flush_tlb);
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