MM: Pass a PTE pointer to update_mmu_cache() rather than the PTE itself

On VIVT ARM, when we have multiple shared mappings of the same file
in the same MM, we need to ensure that we have coherency across all
copies.  We do this via make_coherent() by making the pages
uncacheable.

This used to work fine, until we allowed highmem with highpte - we
now have a page table which is mapped as required, and is not available
for modification via update_mmu_cache().

Ralf Beache suggested getting rid of the PTE value passed to
update_mmu_cache():

  On MIPS update_mmu_cache() calls __update_tlb() which walks pagetables
  to construct a pointer to the pte again.  Passing a pte_t * is much
  more elegant.  Maybe we might even replace the pte argument with the
  pte_t?

Ben Herrenschmidt would also like the pte pointer for PowerPC:

  Passing the ptep in there is exactly what I want.  I want that
  -instead- of the PTE value, because I have issue on some ppc cases,
  for I$/D$ coherency, where set_pte_at() may decide to mask out the
  _PAGE_EXEC.

So, pass in the mapped page table pointer into update_mmu_cache(), and
remove the PTE value, updating all implementations and call sites to
suit.

Includes a fix from Stephen Rothwell:

  sparc: fix fallout from update_mmu_cache API change

  Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 10 insertions, 10 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e91b81b..94cd94d 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2088,7 +2088,7 @@ static void set_huge_ptep_writable(struct vm_area_struct *vma,
 
 	entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
 	if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) {
-		update_mmu_cache(vma, address, entry);
+		update_mmu_cache(vma, address, ptep);
 	}
 }
 
@@ -2559,7 +2559,7 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 	entry = pte_mkyoung(entry);
 	if (huge_ptep_set_access_flags(vma, address, ptep, entry,
 						flags & FAULT_FLAG_WRITE))
-		update_mmu_cache(vma, address, entry);
+		update_mmu_cache(vma, address, ptep);
 
 out_page_table_lock:
 	spin_unlock(&mm->page_table_lock);
diff --git a/mm/memory.c b/mm/memory.c
index 09e4b1b..72fb5f3 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1593,7 +1593,7 @@ static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 	/* Ok, finally just insert the thing.. */
 	entry = pte_mkspecial(pfn_pte(pfn, prot));
 	set_pte_at(mm, addr, pte, entry);
-	update_mmu_cache(vma, addr, entry); /* XXX: why not for insert_page? */
+	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
 
 	retval = 0;
 out_unlock:
@@ -2116,7 +2116,7 @@ reuse:
 		entry = pte_mkyoung(orig_pte);
 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
 		if (ptep_set_access_flags(vma, address, page_table, entry,1))
-			update_mmu_cache(vma, address, entry);
+			update_mmu_cache(vma, address, page_table);
 		ret |= VM_FAULT_WRITE;
 		goto unlock;
 	}
@@ -2185,7 +2185,7 @@ gotten:
 		 * new page to be mapped directly into the secondary page table.
 		 */
 		set_pte_at_notify(mm, address, page_table, entry);
-		update_mmu_cache(vma, address, entry);
+		update_mmu_cache(vma, address, page_table);
 		if (old_page) {
 			/*
 			 * Only after switching the pte to the new page may
@@ -2629,7 +2629,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	}
 
 	/* No need to invalidate - it was non-present before */
-	update_mmu_cache(vma, address, pte);
+	update_mmu_cache(vma, address, page_table);
 unlock:
 	pte_unmap_unlock(page_table, ptl);
 out:
@@ -2694,7 +2694,7 @@ setpte:
 	set_pte_at(mm, address, page_table, entry);
 
 	/* No need to invalidate - it was non-present before */
-	update_mmu_cache(vma, address, entry);
+	update_mmu_cache(vma, address, page_table);
 unlock:
 	pte_unmap_unlock(page_table, ptl);
 	return 0;
@@ -2855,7 +2855,7 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 		set_pte_at(mm, address, page_table, entry);
 
 		/* no need to invalidate: a not-present page won't be cached */
-		update_mmu_cache(vma, address, entry);
+		update_mmu_cache(vma, address, page_table);
 	} else {
 		if (charged)
 			mem_cgroup_uncharge_page(page);
@@ -2992,7 +2992,7 @@ static inline int handle_pte_fault(struct mm_struct *mm,
 	}
 	entry = pte_mkyoung(entry);
 	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
-		update_mmu_cache(vma, address, entry);
+		update_mmu_cache(vma, address, pte);
 	} else {
 		/*
 		 * This is needed only for protection faults but the arch code
diff --git a/mm/migrate.c b/mm/migrate.c
index efddbf0..e58e5da 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -134,7 +134,7 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
 		page_add_file_rmap(new);
 
 	/* No need to invalidate - it was non-present before */
-	update_mmu_cache(vma, addr, pte);
+	update_mmu_cache(vma, addr, ptep);
 unlock:
 	pte_unmap_unlock(ptep, ptl);
 out: