From: Ian Pratt <Ian.Pratt@cl.cam.ac.uk>
This patch adds 'ptep_establish_new', in keeping with the existing
'ptep_establish', but for use where a mapping is being established where there
was previously none present. This function is useful (rather than just using
set_pte) because having the virtual address available enables a very important
optimisation for arch-xen.
We introduce HAVE_ARCH_PTEP_ESTABLISH_NEW and define a generic implementation
in asm-generic/pgtable.h, following the pattern of the existing
ptep_establish.
Signed-off-by: Ian Pratt <Ian.Pratt@cl.cam.ac.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/include/asm-generic/pgtable.h | 10 ++++++++++
25-akpm/mm/memory.c | 4 ++--
2 files changed, 12 insertions(+), 2 deletions(-)
diff -puN include/asm-generic/pgtable.h~xen-vmm-4-add-ptep_establish_new-to-make-va-available include/asm-generic/pgtable.h
--- 25/include/asm-generic/pgtable.h~xen-vmm-4-add-ptep_establish_new-to-make-va-available 2005-02-24 23:13:47.000000000 -0800
+++ 25-akpm/include/asm-generic/pgtable.h 2005-02-24 23:13:47.000000000 -0800
@@ -42,6 +42,16 @@ do { \
} while (0)
#endif
+#ifndef __HAVE_ARCH_PTEP_ESTABLISH_NEW
+/*
+ * Establish a mapping where none previously existed
+ */
+#define ptep_establish_new(__vma, __address, __ptep, __entry) \
+do { \
+ set_pte(__ptep, __entry); \
+} while (0)
+#endif
+
#ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
static inline int ptep_test_and_clear_young(pte_t *ptep)
{
diff -puN mm/memory.c~xen-vmm-4-add-ptep_establish_new-to-make-va-available mm/memory.c
--- 25/mm/memory.c~xen-vmm-4-add-ptep_establish_new-to-make-va-available 2005-02-24 23:13:47.000000000 -0800
+++ 25-akpm/mm/memory.c 2005-02-24 23:13:47.000000000 -0800
@@ -1827,7 +1827,7 @@ do_anonymous_page(struct mm_struct *mm,
page_add_anon_rmap(page, vma, addr);
}
- set_pte(page_table, entry);
+ ptep_establish_new(vma, addr, page_table, entry);
pte_unmap(page_table);
/* No need to invalidate - it was non-present before */
@@ -1940,7 +1940,7 @@ retry:
entry = mk_pte(new_page, vma->vm_page_prot);
if (write_access)
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
- set_pte(page_table, entry);
+ ptep_establish_new(vma, address, page_table, entry);
if (anon) {
lru_cache_add_active(new_page);
page_add_anon_rmap(new_page, vma, address);
_