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x86: further cpa largepage-split cleanups 

further cpa largepage-split cleanups: make the splitup isolated
functionality, without leaking details back into __change_page_attr().

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Ingo Molnar 2008-01-30 13:33:56 +01:00
parent 97f99fedf2
commit bb5c2dbd57
1 changed files with 49 additions and 40 deletions
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89
arch/x86/mm/pageattr_32.c
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@ -37,33 +37,6 @@ pte_t *lookup_address(unsigned long address, int *level)
return pte_offset_kernel(pmd, address);
}
static struct page *
split_large_page(unsigned long address, pgprot_t ref_prot)
{
unsigned long addr;
struct page *base;
pte_t *pbase;
int i;
base = alloc_pages(GFP_KERNEL, 0);
if (!base)
return NULL;
/*
* page_private is used to track the number of entries in
* the page table page that have non standard attributes.
*/
address = __pa(address);
addr = address & LARGE_PAGE_MASK;
pbase = (pte_t *)page_address(base);
paravirt_alloc_pt(&init_mm, page_to_pfn(base));
for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE)
set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT, ref_prot));
return base;
}
static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
{
unsigned long flags;
@ -88,14 +61,58 @@ static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
spin_unlock_irqrestore(&pgd_lock, flags);
}
static int
split_large_page(pte_t *kpte, unsigned long address, pgprot_t ref_prot)
{
int i, level;
unsigned long addr;
pte_t *pbase, *tmp;
struct page *base;
base = alloc_pages(GFP_KERNEL, 0);
if (!base)
return -ENOMEM;
down_write(&init_mm.mmap_sem);
/*
* Check for races, another CPU might have split this page
* up for us already:
*/
tmp = lookup_address(address, &level);
if (tmp != kpte)
goto out_unlock;
address = __pa(address);
addr = address & LARGE_PAGE_MASK;
pbase = (pte_t *)page_address(base);
paravirt_alloc_pt(&init_mm, page_to_pfn(base));
for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE)
set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT, ref_prot));
/*
* Install the new, split up pagetable:
*/
set_pmd_pte(kpte, address, mk_pte(base, ref_prot));
base = NULL;
out_unlock:
up_write(&init_mm.mmap_sem);
if (base)
__free_pages(base, 0);
return 0;
}
static int __change_page_attr(struct page *page, pgprot_t prot)
{
pgprot_t ref_prot = PAGE_KERNEL;
struct page *kpte_page;
unsigned long address;
int level, err = 0;
pgprot_t oldprot;
pte_t *kpte;
int level;
BUG_ON(PageHighMem(page));
address = (unsigned long)page_address(page);
@ -127,19 +144,11 @@ repeat:
if (level == 3) {
set_pte_atomic(kpte, mk_pte(page, prot));
} else {
struct page *split;
split = split_large_page(address, ref_prot);
if (!split)
return -ENOMEM;
/*
* There's a small window here to waste a bit of RAM:
*/
set_pmd_pte(kpte, address, mk_pte(split, ref_prot));
goto repeat;
err = split_large_page(kpte, address, ref_prot);
if (!err)
goto repeat;
}
return 0;
return err;
}
/*