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>

5 files changed, 11 insertions, 10 deletions

diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
index b99f81c4906..43e20efb251 100644
--- a/arch/sparc/mm/fault_32.c
+++ b/arch/sparc/mm/fault_32.c
@@ -370,7 +370,7 @@ asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
 			       unsigned long address)
 {
 	extern void sun4c_update_mmu_cache(struct vm_area_struct *,
-					   unsigned long,pte_t);
+					   unsigned long,pte_t *);
 	extern pte_t *sun4c_pte_offset_kernel(pmd_t *,unsigned long);
 	struct task_struct *tsk = current;
 	struct mm_struct *mm = tsk->mm;
@@ -447,7 +447,7 @@ asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
 		 *       on the CPU and doing a shrink_mmap() on this vma.
 		 */
 		sun4c_update_mmu_cache (find_vma(current->mm, address), address,
-					*ptep);
+					ptep);
 	else
 		do_sparc_fault(regs, text_fault, write, address);
 }
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index 1886d37d411..9245a822a2f 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -289,12 +289,13 @@ static void flush_dcache(unsigned long pfn)
 	}
 }
 
-void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t pte)
+void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *ptep)
 {
 	struct mm_struct *mm;
 	struct tsb *tsb;
 	unsigned long tag, flags;
 	unsigned long tsb_index, tsb_hash_shift;
+	pte_t pte = *ptep;
 
 	if (tlb_type != hypervisor) {
 		unsigned long pfn = pte_pfn(pte);
diff --git a/arch/sparc/mm/nosun4c.c b/arch/sparc/mm/nosun4c.c
index 196263f895b..4e62c27147c 100644
--- a/arch/sparc/mm/nosun4c.c
+++ b/arch/sparc/mm/nosun4c.c
@@ -62,7 +62,7 @@ pte_t *sun4c_pte_offset_kernel(pmd_t *dir, unsigned long address)
 	return NULL;
 }
 
-void sun4c_update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t pte)
+void sun4c_update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *ptep)
 {
 }
 
diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c
index 367321a030d..df49b200ca4 100644
--- a/arch/sparc/mm/srmmu.c
+++ b/arch/sparc/mm/srmmu.c
@@ -694,7 +694,7 @@ extern void tsunami_setup_blockops(void);
  * The following code is a deadwood that may be necessary when
  * we start to make precise page flushes again. --zaitcev
  */
-static void swift_update_mmu_cache(struct vm_area_struct * vma, unsigned long address, pte_t pte)
+static void swift_update_mmu_cache(struct vm_area_struct * vma, unsigned long address, pte_t *ptep)
 {
 #if 0
 	static unsigned long last;
@@ -703,10 +703,10 @@ static void swift_update_mmu_cache(struct vm_area_struct * vma, unsigned long ad
 
 	if (address == last) {
 		val = srmmu_hwprobe(address);
-		if (val != 0 && pte_val(pte) != val) {
+		if (val != 0 && pte_val(*ptep) != val) {
 			printk("swift_update_mmu_cache: "
 			    "addr %lx put %08x probed %08x from %p\n",
-			    address, pte_val(pte), val,
+			    address, pte_val(*ptep), val,
 			    __builtin_return_address(0));
 			srmmu_flush_whole_tlb();
 		}
diff --git a/arch/sparc/mm/sun4c.c b/arch/sparc/mm/sun4c.c
index a89baf0d875..18652534b91 100644
--- a/arch/sparc/mm/sun4c.c
+++ b/arch/sparc/mm/sun4c.c
@@ -1887,7 +1887,7 @@ static void sun4c_check_pgt_cache(int low, int high)
 /* An experiment, turn off by default for now... -DaveM */
 #define SUN4C_PRELOAD_PSEG
 
-void sun4c_update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t pte)
+void sun4c_update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *ptep)
 {
 	unsigned long flags;
 	int pseg;
@@ -1929,7 +1929,7 @@ void sun4c_update_mmu_cache(struct vm_area_struct *vma, unsigned long address, p
 			start += PAGE_SIZE;
 		}
 #ifndef SUN4C_PRELOAD_PSEG
-		sun4c_put_pte(address, pte_val(pte));
+		sun4c_put_pte(address, pte_val(*ptep));
 #endif
 		local_irq_restore(flags);
 		return;
@@ -1940,7 +1940,7 @@ void sun4c_update_mmu_cache(struct vm_area_struct *vma, unsigned long address, p
 		add_lru(entry);
 	}
 
-	sun4c_put_pte(address, pte_val(pte));
+	sun4c_put_pte(address, pte_val(*ptep));
 	local_irq_restore(flags);
 }