1 files changed, 58 insertions, 42 deletions

diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c
index d0d17b6a3703..0d414c28eb2c 100644
--- a/arch/arm/mm/fault-armv.c
+++ b/arch/arm/mm/fault-armv.c
@@ -16,6 +16,7 @@
 #include <linux/vmalloc.h>
 #include <linux/init.h>
 #include <linux/pagemap.h>
+#include <linux/gfp.h>
 
 #include <asm/bugs.h>
 #include <asm/cacheflush.h>
@@ -23,6 +24,8 @@
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 
+#include "mm.h"
+
 static unsigned long shared_pte_mask = L_PTE_MT_BUFFERABLE;
 
 /*
@@ -34,28 +37,12 @@ static unsigned long shared_pte_mask = L_PTE_MT_BUFFERABLE;
  * Therefore those configurations which might call adjust_pte (those
  * without CONFIG_CPU_CACHE_VIPT) cannot support split page_table_lock.
  */
-static int adjust_pte(struct vm_area_struct *vma, unsigned long address)
+static int do_adjust_pte(struct vm_area_struct *vma, unsigned long address,
+        unsigned long pfn, pte_t *ptep)
 {
-        pgd_t *pgd;
-        pmd_t *pmd;
-        pte_t *pte, entry;
+        pte_t entry = *ptep;
         int ret;
 
-        pgd = pgd_offset(vma->vm_mm, address);
-        if (pgd_none(*pgd))
-                goto no_pgd;
-        if (pgd_bad(*pgd))
-                goto bad_pgd;
-
-        pmd = pmd_offset(pgd, address);
-        if (pmd_none(*pmd))
-                goto no_pmd;
-        if (pmd_bad(*pmd))
-                goto bad_pmd;
-
-        pte = pte_offset_map(pmd, address);
-        entry = *pte;
-
         /*
          * If this page is present, it's actually being shared.
          */
@@ -66,33 +53,55 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address)
          * fault (ie, is old), we can safely ignore any issues.
          */
         if (ret && (pte_val(entry) & L_PTE_MT_MASK) != shared_pte_mask) {
-                unsigned long pfn = pte_pfn(entry);
                 flush_cache_page(vma, address, pfn);
                 outer_flush_range((pfn << PAGE_SHIFT),
                                   (pfn << PAGE_SHIFT) + PAGE_SIZE);
                 pte_val(entry) &= ~L_PTE_MT_MASK;
                 pte_val(entry) |= shared_pte_mask;
-                set_pte_at(vma->vm_mm, address, pte, entry);
+                set_pte_at(vma->vm_mm, address, ptep, entry);
                 flush_tlb_page(vma, address);
         }
-        pte_unmap(pte);
+
         return ret;
+}
+
+static int adjust_pte(struct vm_area_struct *vma, unsigned long address,
+        unsigned long pfn)
+{
+        spinlock_t *ptl;
+        pgd_t *pgd;
+        pmd_t *pmd;
+        pte_t *pte;
+        int ret;
 
-bad_pgd:
-        pgd_ERROR(*pgd);
-        pgd_clear(pgd);
-no_pgd:
-        return 0;
-
-bad_pmd:
-        pmd_ERROR(*pmd);
-        pmd_clear(pmd);
-no_pmd:
-        return 0;
+        pgd = pgd_offset(vma->vm_mm, address);
+        if (pgd_none_or_clear_bad(pgd))
+                return 0;
+
+        pmd = pmd_offset(pgd, address);
+        if (pmd_none_or_clear_bad(pmd))
+                return 0;
+
+        /*
+         * This is called while another page table is mapped, so we
+         * must use the nested version.  This also means we need to
+         * open-code the spin-locking.
+         */
+        ptl = pte_lockptr(vma->vm_mm, pmd);
+        pte = pte_offset_map_nested(pmd, address);
+        spin_lock(ptl);
+
+        ret = do_adjust_pte(vma, address, pfn, pte);
+
+        spin_unlock(ptl);
+        pte_unmap_nested(pte);
+
+        return ret;
 }
 
 static void
-make_coherent(struct address_space *mapping, struct vm_area_struct *vma, unsigned long addr, unsigned long pfn)
+make_coherent(struct address_space *mapping, struct vm_area_struct *vma,
+        unsigned long addr, pte_t *ptep, unsigned long pfn)
 {
         struct mm_struct *mm = vma->vm_mm;
         struct vm_area_struct *mpnt;
@@ -120,11 +129,11 @@ make_coherent(struct address_space *mapping, struct vm_area_struct *vma, unsigne
                 if (!(mpnt->vm_flags & VM_MAYSHARE))
                         continue;
                 offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
-                aliases += adjust_pte(mpnt, mpnt->vm_start + offset);
+                aliases += adjust_pte(mpnt, mpnt->vm_start + offset, pfn);
         }
         flush_dcache_mmap_unlock(mapping);
         if (aliases)
-                adjust_pte(vma, addr);
+                do_adjust_pte(vma, addr, pfn, ptep);
         else
                 flush_cache_page(vma, addr, pfn);
 }
@@ -142,16 +151,24 @@ make_coherent(struct address_space *mapping, struct vm_area_struct *vma, unsigne
  *
  * Note that the pte lock will be held.
  */
-void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
+void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr,
+        pte_t *ptep)
 {
-        unsigned long pfn = pte_pfn(pte);
+        unsigned long pfn = pte_pfn(*ptep);
         struct address_space *mapping;
         struct page *page;
 
         if (!pfn_valid(pfn))
                 return;
 
+        /*
+         * The zero page is never written to, so never has any dirty
+         * cache lines, and therefore never needs to be flushed.
+         */
         page = pfn_to_page(pfn);
+        if (page == ZERO_PAGE(0))
+                return;
+
         mapping = page_mapping(page);
 #ifndef CONFIG_SMP
         if (test_and_clear_bit(PG_dcache_dirty, &page->flags))
@@ -159,7 +176,7 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
 #endif
         if (mapping) {
                 if (cache_is_vivt())
-                        make_coherent(mapping, vma, addr, pfn);
+                        make_coherent(mapping, vma, addr, ptep, pfn);
                 else if (vma->vm_flags & VM_EXEC)
                         __flush_icache_all();
         }
@@ -198,9 +215,8 @@ void __init check_writebuffer_bugs(void)
         page = alloc_page(GFP_KERNEL);
         if (page) {
                 unsigned long *p1, *p2;
-                pgprot_t prot = __pgprot(L_PTE_PRESENT|L_PTE_YOUNG|
-                                         L_PTE_DIRTY|L_PTE_WRITE|
-                                         L_PTE_MT_BUFFERABLE);
+                pgprot_t prot = __pgprot_modify(PAGE_KERNEL,
+                                        L_PTE_MT_MASK, L_PTE_MT_BUFFERABLE);
 
                 p1 = vmap(&page, 1, VM_IOREMAP, prot);
                 p2 = vmap(&page, 1, VM_IOREMAP, prot);