kernel-aes67/arch/i386/mm/pageattr.c
Zachary Amsden c9b02a2413 [PATCH] i386: use set_pte macros in a couple places where they were missing
Also, setting PDPEs in PAE mode does not require atomic operations, since the
PDPEs are cached by the processor, and only reloaded on an explicit or
implicit reload of CR3.

Since the four PDPEs must always be present in an active root, and the kernel
PDPE is never updated, we are safe even from SMIs and interrupts / NMIs using
task gates (which reload CR3).  Actually, much of this is moot, since the user
PDPEs are never updated either, and the only usage of task gates is by the
doublefault handler.  It appears the only place PGDs get updated in PAE mode
is in init_low_mappings() / zap_low_mapping() for initial page table creation
and recovery from ACPI sleep state, and these sites are safe by inspection.
Getting rid of the cmpxchg8b saves code space and 720 cycles in pgd_alloc on
P4.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-05 00:06:12 -07:00

223 lines
5.5 KiB
C

/*
* 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>
#include <asm/pgalloc.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) {
set_pte(&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)
wbinvd();
/* 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);