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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 <linux/slab.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
#include <asm/tlbflush.h>
static DEFINE_SPINLOCK(cpa_lock);
static struct list_head df_list = LIST_HEAD_INIT(df_list);
pte_t *lookup_address(unsigned long address)
{
pgd_t *pgd = pgd_offset_k(address);
pud_t *pud;
pmd_t *pmd;
if (pgd_none(*pgd))
return NULL;
pud = pud_offset(pgd, address);
if (pud_none(*pud))
return NULL;
pmd = pmd_offset(pud, address);
if (pmd_none(*pmd))
return NULL;
if (pmd_large(*pmd))
return (pte_t *)pmd;
return pte_offset_kernel(pmd, address);
}
static struct page *split_large_page(unsigned long address, pgprot_t prot)
{
int i;
unsigned long addr;
struct page *base;
pte_t *pbase;
spin_unlock_irq(&cpa_lock);
base = alloc_pages(GFP_KERNEL, 0);
spin_lock_irq(&cpa_lock);
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] = pfn_pte(addr >> PAGE_SHIFT,
addr == address ? prot : PAGE_KERNEL);
}
return base;
}
static void flush_kernel_map(void *dummy)
{
/* Could use CLFLUSH here if the CPU supports it (Hammer,P4) */
if (boot_cpu_data.x86_model >= 4)
asm volatile("wbinvd":::"memory");
/* Flush all to work around Errata in early athlons regarding
* large page flushing.
*/
__flush_tlb_all();
}
static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
{
struct page *page;
unsigned long flags;
set_pte_atomic(kpte, pte); /* change init_mm */
if (PTRS_PER_PMD > 1)
return;
spin_lock_irqsave(&pgd_lock, flags);
for (page = pgd_list; page; page = (struct page *)page->index) {
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pgd = (pgd_t *)page_address(page) + pgd_index(address);
pud = pud_offset(pgd, address);
pmd = pmd_offset(pud, address);
set_pte_atomic((pte_t *)pmd, pte);
}
spin_unlock_irqrestore(&pgd_lock, flags);
}
/*
* 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(pud_offset(pgd_offset_k(address), address), address);
set_pmd_pte(linear, address,
pfn_pte((__pa(address) & LARGE_PAGE_MASK) >> PAGE_SHIFT,
PAGE_KERNEL_LARGE));
}
static int
__change_page_attr(struct page *page, pgprot_t prot)
{
pte_t *kpte;
unsigned long address;
struct page *kpte_page;
BUG_ON(PageHighMem(page));
address = (unsigned long)page_address(page);
kpte = lookup_address(address);
if (!kpte)
return -EINVAL;
kpte_page = virt_to_page(kpte);
if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) {
if ((pte_val(*kpte) & _PAGE_PSE) == 0) {
set_pte_atomic(kpte, mk_pte(page, prot));
} else {
struct page *split = split_large_page(address, prot);
if (!split)
return -ENOMEM;
set_pmd_pte(kpte,address,mk_pte(split, PAGE_KERNEL));
kpte_page = split;
}
get_page(kpte_page);
} else if ((pte_val(*kpte) & _PAGE_PSE) == 0) {
set_pte_atomic(kpte, mk_pte(page, PAGE_KERNEL));
__put_page(kpte_page);
} else
BUG();
/*
* If the pte was reserved, it means it was created at boot
* time (not via split_large_page) and in turn we must not
* replace it with a largepage.
*/
if (!PageReserved(kpte_page)) {
/* memleak and potential failed 2M page regeneration */
BUG_ON(!page_count(kpte_page));
if (cpu_has_pse && (page_count(kpte_page) == 1)) {
list_add(&kpte_page->lru, &df_list);
revert_page(kpte_page, address);
}
}
return 0;
}
static inline void flush_map(void)
{
on_each_cpu(flush_kernel_map, NULL, 1, 1);
}
/*
* 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(struct page *page, int numpages, pgprot_t prot)
{
int err = 0;
int i;
unsigned long flags;
spin_lock_irqsave(&cpa_lock, flags);
for (i = 0; i < numpages; i++, page++) {
err = __change_page_attr(page, prot);
if (err)
break;
}
spin_unlock_irqrestore(&cpa_lock, flags);
return err;
}
void global_flush_tlb(void)
{
LIST_HEAD(l);
struct page *pg, *next;
BUG_ON(irqs_disabled());
spin_lock_irq(&cpa_lock);
list_splice_init(&df_list, &l);
spin_unlock_irq(&cpa_lock);
flush_map();
list_for_each_entry_safe(pg, next, &l, lru)
__free_page(pg);
}
#ifdef CONFIG_DEBUG_PAGEALLOC
void kernel_map_pages(struct page *page, int numpages, int enable)
{
if (PageHighMem(page))
return;
/* the return value is ignored - the calls cannot fail,
* large pages are disabled at boot time.
*/
change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
/* we should perform an IPI and flush all tlbs,
* but that can deadlock->flush only current cpu.
*/
__flush_tlb_all();
}
#endif
EXPORT_SYMBOL(change_page_attr);
EXPORT_SYMBOL(global_flush_tlb);
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