ARM: implement highpte

Add the ARM implementation of highpte, which allows PTE tables to be
placed in highmem.  Unfortunately, we do not offer highpte support
when support for L2 cache is enabled.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index aef63c8..370f477 100644 (file)
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1054,6 +1054,11 @@ config HIGHMEM
 
          If unsure, say n.
 
+config HIGHPTE
+       bool "Allocate 2nd-level pagetables from highmem"
+       depends on HIGHMEM
+       depends on !OUTER_CACHE
+
 source "mm/Kconfig"
 
 config LEDS

diff --git a/arch/arm/include/asm/pgalloc.h b/arch/arm/include/asm/pgalloc.h
index 3dcd64b..b12cc98 100644 (file)
--- a/arch/arm/include/asm/pgalloc.h
+++ b/arch/arm/include/asm/pgalloc.h
@@ -36,6 +36,8 @@ extern void free_pgd_slow(struct mm_struct *mm, pgd_t *pgd);
 #define pgd_alloc(mm)                  get_pgd_slow(mm)
 #define pgd_free(mm, pgd)              free_pgd_slow(mm, pgd)
 
+#define PGALLOC_GFP    (GFP_KERNEL | __GFP_NOTRACK | __GFP_REPEAT | __GFP_ZERO)
+
 /*
  * Allocate one PTE table.
  *
@@ -57,7 +59,7 @@ pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr)
 {
        pte_t *pte;
 
-       pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
+       pte = (pte_t *)__get_free_page(PGALLOC_GFP);
        if (pte) {
                clean_dcache_area(pte, sizeof(pte_t) * PTRS_PER_PTE);
                pte += PTRS_PER_PTE;
@@ -71,10 +73,16 @@ pte_alloc_one(struct mm_struct *mm, unsigned long addr)
 {
        struct page *pte;
 
-       pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO, 0);
+#ifdef CONFIG_HIGHPTE
+       pte = alloc_pages(PGALLOC_GFP | __GFP_HIGHMEM, 0);
+#else
+       pte = alloc_pages(PGALLOC_GFP, 0);
+#endif
        if (pte) {
-               void *page = page_address(pte);
-               clean_dcache_area(page, sizeof(pte_t) * PTRS_PER_PTE);
+               if (!PageHighMem(pte)) {
+                       void *page = page_address(pte);
+                       clean_dcache_area(page, sizeof(pte_t) * PTRS_PER_PTE);
+               }
                pgtable_page_ctor(pte);
        }
 

diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 9655bce..201ccaa 100644 (file)
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -262,10 +262,19 @@ extern struct page *empty_zero_page;
 #define pte_clear(mm,addr,ptep)        set_pte_ext(ptep, __pte(0), 0)
 #define pte_page(pte)          (pfn_to_page(pte_pfn(pte)))
 #define pte_offset_kernel(dir,addr)    (pmd_page_vaddr(*(dir)) + __pte_index(addr))
-#define pte_offset_map(dir,addr)       (pmd_page_vaddr(*(dir)) + __pte_index(addr))
-#define pte_offset_map_nested(dir,addr)        (pmd_page_vaddr(*(dir)) + __pte_index(addr))
-#define pte_unmap(pte)         do { } while (0)
-#define pte_unmap_nested(pte)  do { } while (0)
+
+#define pte_offset_map(dir,addr)       (__pte_map(dir, KM_PTE0) + __pte_index(addr))
+#define pte_offset_map_nested(dir,addr)        (__pte_map(dir, KM_PTE1) + __pte_index(addr))
+#define pte_unmap(pte)                 __pte_unmap(pte, KM_PTE0)
+#define pte_unmap_nested(pte)          __pte_unmap(pte, KM_PTE1)
+
+#ifndef CONFIG_HIGHPTE
+#define __pte_map(dir,km)      pmd_page_vaddr(*(dir))
+#define __pte_unmap(pte,km)    do { } while (0)
+#else
+#define __pte_map(dir,km)      ((pte_t *)kmap_atomic(pmd_page(*(dir)), km) + PTRS_PER_PTE)
+#define __pte_unmap(pte,km)    kunmap_atomic((pte - PTRS_PER_PTE), km)
+#endif
 
 #define set_pte_ext(ptep,pte,ext) cpu_set_pte_ext(ptep,pte,ext)
 

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 6fdcbb7..5fa8dea 100644 (file)
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -16,6 +16,7 @@
 #include <linux/kprobes.h>
 #include <linux/uaccess.h>
 #include <linux/page-flags.h>
+#include <linux/highmem.h>
 
 #include <asm/system.h>
 #include <asm/pgtable.h>