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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2008-02-08 12:22:04 (GMT)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-08 17:22:42 (GMT)
commit2f569afd9ced9ebec9a6eb3dbf6f83429be0a7b4 (patch)
tree23a31763887d9505e62e9d7cc8ec2fa4b86bd380 /arch
parent13214adf738abc92b0a00c0763fd3be79eebaa7c (diff)
downloadlinux-2f569afd9ced9ebec9a6eb3dbf6f83429be0a7b4.tar.xz
CONFIG_HIGHPTE vs. sub-page page tables.
Background: I've implemented 1K/2K page tables for s390. These sub-page page tables are required to properly support the s390 virtualization instruction with KVM. The SIE instruction requires that the page tables have 256 page table entries (pte) followed by 256 page status table entries (pgste). The pgstes are only required if the process is using the SIE instruction. The pgstes are updated by the hardware and by the hypervisor for a number of reasons, one of them is dirty and reference bit tracking. To avoid wasting memory the standard pte table allocation should return 1K/2K (31/64 bit) and 2K/4K if the process is using SIE. Problem: Page size on s390 is 4K, page table size is 1K or 2K. That means the s390 version for pte_alloc_one cannot return a pointer to a struct page. Trouble is that with the CONFIG_HIGHPTE feature on x86 pte_alloc_one cannot return a pointer to a pte either, since that would require more than 32 bit for the return value of pte_alloc_one (and the pte * would not be accessible since its not kmapped). Solution: The only solution I found to this dilemma is a new typedef: a pgtable_t. For s390 pgtable_t will be a (pte *) - to be introduced with a later patch. For everybody else it will be a (struct page *). The additional problem with the initialization of the ptl lock and the NR_PAGETABLE accounting is solved with a constructor pgtable_page_ctor and a destructor pgtable_page_dtor. The page table allocation and free functions need to call these two whenever a page table page is allocated or freed. pmd_populate will get a pgtable_t instead of a struct page pointer. To get the pgtable_t back from a pmd entry that has been installed with pmd_populate a new function pmd_pgtable is added. It replaces the pmd_page call in free_pte_range and apply_to_pte_range. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/frv/mm/pgalloc.c8
-rw-r--r--arch/powerpc/mm/pgtable_32.c14
-rw-r--r--arch/ppc/mm/pgtable.c9
-rw-r--r--arch/s390/mm/pgtable.c2
-rw-r--r--arch/sparc/mm/srmmu.c10
-rw-r--r--arch/sparc/mm/sun4c.c14
-rw-r--r--arch/um/kernel/mem.c4
-rw-r--r--arch/x86/mm/pgtable_32.c5
8 files changed, 45 insertions, 21 deletions
diff --git a/arch/frv/mm/pgalloc.c b/arch/frv/mm/pgalloc.c
index 1a2e5c8..66f616f 100644
--- a/arch/frv/mm/pgalloc.c
+++ b/arch/frv/mm/pgalloc.c
@@ -28,7 +28,7 @@ pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
return pte;
}
-struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
+pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
struct page *page;
@@ -37,9 +37,11 @@ struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
#else
page = alloc_pages(GFP_KERNEL|__GFP_REPEAT, 0);
#endif
- if (page)
+ if (page) {
clear_highpage(page);
- flush_dcache_page(page);
+ pgtable_page_ctor(page);
+ flush_dcache_page(page);
+ }
return page;
}
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index f80f90c..ac3390f 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -107,19 +107,20 @@ __init_refok pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long add
return pte;
}
-struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
+pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
struct page *ptepage;
#ifdef CONFIG_HIGHPTE
- gfp_t flags = GFP_KERNEL | __GFP_HIGHMEM | __GFP_REPEAT;
+ gfp_t flags = GFP_KERNEL | __GFP_HIGHMEM | __GFP_REPEAT | __GFP_ZERO;
#else
- gfp_t flags = GFP_KERNEL | __GFP_REPEAT;
+ gfp_t flags = GFP_KERNEL | __GFP_REPEAT | __GFP_ZERO;
#endif
ptepage = alloc_pages(flags, 0);
- if (ptepage)
- clear_highpage(ptepage);
+ if (!ptepage)
+ return NULL;
+ pgtable_page_ctor(ptepage);
return ptepage;
}
@@ -131,11 +132,12 @@ void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
free_page((unsigned long)pte);
}
-void pte_free(struct mm_struct *mm, struct page *ptepage)
+void pte_free(struct mm_struct *mm, pgtable_t ptepage)
{
#ifdef CONFIG_SMP
hash_page_sync();
#endif
+ pgtable_page_dtor(ptepage);
__free_page(ptepage);
}
diff --git a/arch/ppc/mm/pgtable.c b/arch/ppc/mm/pgtable.c
index 409fcaa..03a79bf 100644
--- a/arch/ppc/mm/pgtable.c
+++ b/arch/ppc/mm/pgtable.c
@@ -95,7 +95,7 @@ __init_refok pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long add
return pte;
}
-struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
+pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
struct page *ptepage;
@@ -106,8 +106,10 @@ struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
#endif
ptepage = alloc_pages(flags, 0);
- if (ptepage)
+ if (ptepage) {
clear_highpage(ptepage);
+ pgtable_page_ctor(ptepage);
+ }
return ptepage;
}
@@ -119,11 +121,12 @@ void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
free_page((unsigned long)pte);
}
-void pte_free(struct mm_struct *mm, struct page *ptepage)
+void pte_free(struct mm_struct *mm, pgtable_t ptepage)
{
#ifdef CONFIG_SMP
hash_page_sync();
#endif
+ pgtable_page_dtor(ptepage);
__free_page(ptepage);
}
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index e60e0ae..019f518 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -78,6 +78,7 @@ unsigned long *page_table_alloc(int noexec)
clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE);
page->index = (addr_t) table;
}
+ pgtable_page_ctor(page);
table = (unsigned long *) page_to_phys(page);
clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE);
return table;
@@ -87,6 +88,7 @@ void page_table_free(unsigned long *table)
{
unsigned long *shadow = get_shadow_pte(table);
+ pgtable_page_dtor(virt_to_page(table));
if (shadow)
free_page((unsigned long) shadow);
free_page((unsigned long) table);
diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c
index dc98e38..23d3291 100644
--- a/arch/sparc/mm/srmmu.c
+++ b/arch/sparc/mm/srmmu.c
@@ -489,14 +489,17 @@ srmmu_pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
return (pte_t *)srmmu_get_nocache(PTE_SIZE, PTE_SIZE);
}
-static struct page *
+static pgtable_t
srmmu_pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
unsigned long pte;
+ struct page *page;
if ((pte = (unsigned long)srmmu_pte_alloc_one_kernel(mm, address)) == 0)
return NULL;
- return pfn_to_page( __nocache_pa(pte) >> PAGE_SHIFT );
+ page = pfn_to_page( __nocache_pa(pte) >> PAGE_SHIFT );
+ pgtable_page_ctor(page);
+ return page;
}
static void srmmu_free_pte_fast(pte_t *pte)
@@ -504,10 +507,11 @@ static void srmmu_free_pte_fast(pte_t *pte)
srmmu_free_nocache((unsigned long)pte, PTE_SIZE);
}
-static void srmmu_pte_free(struct page *pte)
+static void srmmu_pte_free(pgtable_t pte)
{
unsigned long p;
+ pgtable_page_dtor(pte);
p = (unsigned long)page_address(pte); /* Cached address (for test) */
if (p == 0)
BUG();
diff --git a/arch/sparc/mm/sun4c.c b/arch/sparc/mm/sun4c.c
index 0729305..c0442e8 100644
--- a/arch/sparc/mm/sun4c.c
+++ b/arch/sparc/mm/sun4c.c
@@ -1947,12 +1947,17 @@ static pte_t *sun4c_pte_alloc_one_kernel(struct mm_struct *mm, unsigned long add
return pte;
}
-static struct page *sun4c_pte_alloc_one(struct mm_struct *mm, unsigned long address)
+static pgtable_t sun4c_pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
- pte_t *pte = sun4c_pte_alloc_one_kernel(mm, address);
+ pte_t *pte;
+ struct page *page;
+
+ pte = sun4c_pte_alloc_one_kernel(mm, address);
if (pte == NULL)
return NULL;
- return virt_to_page(pte);
+ page = virt_to_page(pte);
+ pgtable_page_ctor(page);
+ return page;
}
static inline void sun4c_free_pte_fast(pte_t *pte)
@@ -1962,8 +1967,9 @@ static inline void sun4c_free_pte_fast(pte_t *pte)
pgtable_cache_size++;
}
-static void sun4c_pte_free(struct page *pte)
+static void sun4c_pte_free(pgtable_t pte)
{
+ pgtable_page_dtor(pte);
sun4c_free_pte_fast(page_address(pte));
}
diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index d872fdc..2627ce8 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -354,11 +354,13 @@ pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
return pte;
}
-struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
+pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
struct page *pte;
pte = alloc_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
+ if (pte)
+ pgtable_page_ctor(pte);
return pte;
}
diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c
index 6c19146..73aba71 100644
--- a/arch/x86/mm/pgtable_32.c
+++ b/arch/x86/mm/pgtable_32.c
@@ -183,7 +183,7 @@ pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
return (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
}
-struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
+pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
struct page *pte;
@@ -192,6 +192,8 @@ struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
#else
pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO, 0);
#endif
+ if (pte)
+ pgtable_page_ctor(pte);
return pte;
}
@@ -365,6 +367,7 @@ void check_pgt_cache(void)
void __pte_free_tlb(struct mmu_gather *tlb, struct page *pte)
{
+ pgtable_page_dtor(pte);
paravirt_release_pt(page_to_pfn(pte));
tlb_remove_page(tlb, pte);
}