From: Nick Piggin <nickpiggin@yahoo.com.au>
Move the ZERO_PAGE remapping complexity to the move_pte macro in
asm-generic, have it conditionally depend on
__HAVE_ARCH_MULTIPLE_ZERO_PAGE, which gets defined for MIPS.
For architectures without __HAVE_ARCH_MULTIPLE_ZERO_PAGE, move_pte becomes
a noop.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
include/asm-generic/pgtable.h | 12 ++++++++++++
include/asm-mips/pgtable.h | 2 ++
mm/mremap.c | 6 +++---
3 files changed, 17 insertions(+), 3 deletions(-)
diff -puN include/asm-generic/pgtable.h~mm-move_pte-to-remap-zero_page include/asm-generic/pgtable.h
--- 25/include/asm-generic/pgtable.h~mm-move_pte-to-remap-zero_page Fri Sep 9 17:19:52 2005
+++ 25-akpm/include/asm-generic/pgtable.h Fri Sep 9 17:19:52 2005
@@ -158,6 +158,18 @@ static inline void ptep_set_wrprotect(st
#define lazy_mmu_prot_update(pte) do { } while (0)
#endif
+#ifndef __HAVE_ARCH_MULTIPLE_ZERO_PAGE
+#define move_pte(pte, prot, old_addr, new_addr) (pte)
+#else
+#define move_pte(pte, prot, old_addr, new_addr) \
+({ \
+ pte_t newpte = (pte); \
+ if (pfn_valid(pte_pfn(pte)) && pte_page(pte) == ZERO_PAGE(old_addr)) \
+ newpte = mk_pte(ZERO_PAGE(new_addr), (prot))); \
+ newpte; \
+})
+#endif
+
/*
* When walking page tables, get the address of the next boundary,
* or the end address of the range if that comes earlier. Although no
diff -puN include/asm-mips/pgtable.h~mm-move_pte-to-remap-zero_page include/asm-mips/pgtable.h
--- 25/include/asm-mips/pgtable.h~mm-move_pte-to-remap-zero_page Fri Sep 9 17:19:52 2005
+++ 25-akpm/include/asm-mips/pgtable.h Fri Sep 9 17:19:52 2005
@@ -68,6 +68,8 @@ extern unsigned long zero_page_mask;
#define ZERO_PAGE(vaddr) \
(virt_to_page(empty_zero_page + (((unsigned long)(vaddr)) & zero_page_mask)))
+#define __HAVE_ARCH_MULTIPLE_ZERO_PAGE
+
extern void paging_init(void);
/*
diff -puN mm/mremap.c~mm-move_pte-to-remap-zero_page mm/mremap.c
--- 25/mm/mremap.c~mm-move_pte-to-remap-zero_page Fri Sep 9 17:19:52 2005
+++ 25-akpm/mm/mremap.c Fri Sep 9 17:19:52 2005
@@ -141,10 +141,10 @@ move_one_page(struct vm_area_struct *vma
if (dst) {
pte_t pte;
pte = ptep_clear_flush(vma, old_addr, src);
+
/* ZERO_PAGE can be dependant on virtual addr */
- if (pfn_valid(pte_pfn(pte)) &&
- pte_page(pte) == ZERO_PAGE(old_addr))
- pte = pte_wrprotect(mk_pte(ZERO_PAGE(new_addr), new_vma->vm_page_prot));
+ pte = move_pte(pte, new_vma->vm_page_prot,
+ old_addr, new_addr);
set_pte_at(mm, new_addr, dst, pte);
} else
error = -ENOMEM;
_