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>

2 files changed, 4 insertions, 4 deletions

diff --git a/arch/m32r/mm/fault-nommu.c b/arch/m32r/mm/fault-nommu.c
index 88469178ea6b..888aab1157ed 100644
--- a/arch/m32r/mm/fault-nommu.c
+++ b/arch/m32r/mm/fault-nommu.c
@@ -95,7 +95,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code,
  * update_mmu_cache()
  *======================================================================*/
 void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr,
-        pte_t pte)
+        pte_t *ptep)
 {
         BUG();
 }
diff --git a/arch/m32r/mm/fault.c b/arch/m32r/mm/fault.c
index 7274b47f4c22..28ee389e5f5a 100644
--- a/arch/m32r/mm/fault.c
+++ b/arch/m32r/mm/fault.c
@@ -336,7 +336,7 @@ vmalloc_fault:
 
                 addr = (address & PAGE_MASK);
                 set_thread_fault_code(error_code);
-                update_mmu_cache(NULL, addr, *pte_k);
+                update_mmu_cache(NULL, addr, pte_k);
                 set_thread_fault_code(0);
                 return;
         }
@@ -349,7 +349,7 @@ vmalloc_fault:
 #define ITLB_END        (unsigned long *)(ITLB_BASE + (NR_TLB_ENTRIES * 8))
 #define DTLB_END        (unsigned long *)(DTLB_BASE + (NR_TLB_ENTRIES * 8))
 void update_mmu_cache(struct vm_area_struct *vma, unsigned long vaddr,
-        pte_t pte)
+        pte_t *ptep)
 {
         volatile unsigned long *entry1, *entry2;
         unsigned long pte_data, flags;
@@ -365,7 +365,7 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long vaddr,
 
         vaddr = (vaddr & PAGE_MASK) | get_asid();
 
-        pte_data = pte_val(pte);
+        pte_data = pte_val(*ptep);
 
 #ifdef CONFIG_CHIP_OPSP
         entry1 = (unsigned long *)ITLB_BASE;