1 files changed, 130 insertions, 8 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 92a3ebd8d795..9cf3f341a28a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -467,7 +467,7 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 	 */
 	if (is_cow_mapping(vm_flags)) {
 		ptep_set_wrprotect(src_mm, addr, src_pte);
-		pte = *src_pte;
+		pte = pte_wrprotect(pte);
 	}
 
 	/*
@@ -506,6 +506,7 @@ again:
 	src_pte = pte_offset_map_nested(src_pmd, addr);
 	src_ptl = pte_lockptr(src_mm, src_pmd);
 	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
+	arch_enter_lazy_mmu_mode();
 
 	do {
 		/*
@@ -527,6 +528,7 @@ again:
 		progress += 8;
 	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
 
+	arch_leave_lazy_mmu_mode();
 	spin_unlock(src_ptl);
 	pte_unmap_nested(src_pte - 1);
 	add_mm_rss(dst_mm, rss[0], rss[1]);
@@ -628,6 +630,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 	int anon_rss = 0;
 
 	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+	arch_enter_lazy_mmu_mode();
 	do {
 		pte_t ptent = *pte;
 		if (pte_none(ptent)) {
@@ -690,10 +693,11 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 			continue;
 		if (!pte_file(ptent))
 			free_swap_and_cache(pte_to_swp_entry(ptent));
-		pte_clear_full(mm, addr, pte, tlb->fullmm);
+		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
 	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
 
 	add_mm_rss(mm, file_rss, anon_rss);
+	arch_leave_lazy_mmu_mode();
 	pte_unmap_unlock(pte - 1, ptl);
 
 	return addr;
@@ -1109,6 +1113,7 @@ static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
 	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
 	if (!pte)
 		return -ENOMEM;
+	arch_enter_lazy_mmu_mode();
 	do {
 		struct page *page = ZERO_PAGE(addr);
 		pte_t zero_pte = pte_wrprotect(mk_pte(page, prot));
@@ -1118,6 +1123,7 @@ static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
 		BUG_ON(!pte_none(*pte));
 		set_pte_at(mm, addr, pte, zero_pte);
 	} while (pte++, addr += PAGE_SIZE, addr != end);
+	arch_leave_lazy_mmu_mode();
 	pte_unmap_unlock(pte - 1, ptl);
 	return 0;
 }
@@ -1275,11 +1281,13 @@ static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
 	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
 	if (!pte)
 		return -ENOMEM;
+	arch_enter_lazy_mmu_mode();
 	do {
 		BUG_ON(!pte_none(*pte));
 		set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
 		pfn++;
 	} while (pte++, addr += PAGE_SIZE, addr != end);
+	arch_leave_lazy_mmu_mode();
 	pte_unmap_unlock(pte - 1, ptl);
 	return 0;
 }
@@ -1577,7 +1585,14 @@ gotten:
 		entry = mk_pte(new_page, vma->vm_page_prot);
 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
 		lazy_mmu_prot_update(entry);
-		ptep_establish(vma, address, page_table, entry);
+		/*
+		 * Clear the pte entry and flush it first, before updating the
+		 * pte with the new entry. This will avoid a race condition
+		 * seen in the presence of one thread doing SMC and another
+		 * thread doing COW.
+		 */
+		ptep_clear_flush(vma, address, page_table);
+		set_pte_at(mm, address, page_table, entry);
 		update_mmu_cache(vma, address, entry);
 		lru_cache_add_active(new_page);
 		page_add_new_anon_rmap(new_page, vma, address);
@@ -2256,6 +2271,54 @@ oom:
 }
 
 /*
+ * do_no_pfn() tries to create a new page mapping for a page without
+ * a struct_page backing it
+ *
+ * As this is called only for pages that do not currently exist, we
+ * do not need to flush old virtual caches or the TLB.
+ *
+ * We enter with non-exclusive mmap_sem (to exclude vma changes,
+ * but allow concurrent faults), and pte mapped but not yet locked.
+ * We return with mmap_sem still held, but pte unmapped and unlocked.
+ *
+ * It is expected that the ->nopfn handler always returns the same pfn
+ * for a given virtual mapping.
+ *
+ * Mark this `noinline' to prevent it from bloating the main pagefault code.
+ */
+static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
+		     unsigned long address, pte_t *page_table, pmd_t *pmd,
+		     int write_access)
+{
+	spinlock_t *ptl;
+	pte_t entry;
+	unsigned long pfn;
+	int ret = VM_FAULT_MINOR;
+
+	pte_unmap(page_table);
+	BUG_ON(!(vma->vm_flags & VM_PFNMAP));
+	BUG_ON(is_cow_mapping(vma->vm_flags));
+
+	pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK);
+	if (pfn == NOPFN_OOM)
+		return VM_FAULT_OOM;
+	if (pfn == NOPFN_SIGBUS)
+		return VM_FAULT_SIGBUS;
+
+	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
+
+	/* Only go through if we didn't race with anybody else... */
+	if (pte_none(*page_table)) {
+		entry = pfn_pte(pfn, vma->vm_page_prot);
+		if (write_access)
+			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+		set_pte_at(mm, address, page_table, entry);
+	}
+	pte_unmap_unlock(page_table, ptl);
+	return ret;
+}
+
+/*
  * Fault of a previously existing named mapping. Repopulate the pte
  * from the encoded file_pte if possible. This enables swappable
  * nonlinear vmas.
@@ -2317,11 +2380,17 @@ static inline int handle_pte_fault(struct mm_struct *mm,
 	old_entry = entry = *pte;
 	if (!pte_present(entry)) {
 		if (pte_none(entry)) {
-			if (!vma->vm_ops || !vma->vm_ops->nopage)
-				return do_anonymous_page(mm, vma, address,
-					pte, pmd, write_access);
-			return do_no_page(mm, vma, address,
-					pte, pmd, write_access);
+			if (vma->vm_ops) {
+				if (vma->vm_ops->nopage)
+					return do_no_page(mm, vma, address,
+							  pte, pmd,
+							  write_access);
+				if (unlikely(vma->vm_ops->nopfn))
+					return do_no_pfn(mm, vma, address, pte,
+							 pmd, write_access);
+			}
+			return do_anonymous_page(mm, vma, address,
+						 pte, pmd, write_access);
 		}
 		if (pte_file(entry))
 			return do_file_page(mm, vma, address,
@@ -2550,3 +2619,56 @@ int in_gate_area_no_task(unsigned long addr)
 }
 
 #endif	/* __HAVE_ARCH_GATE_AREA */
+
+/*
+ * Access another process' address space.
+ * Source/target buffer must be kernel space,
+ * Do not walk the page table directly, use get_user_pages
+ */
+int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
+{
+	struct mm_struct *mm;
+	struct vm_area_struct *vma;
+	struct page *page;
+	void *old_buf = buf;
+
+	mm = get_task_mm(tsk);
+	if (!mm)
+		return 0;
+
+	down_read(&mm->mmap_sem);
+	/* ignore errors, just check how much was sucessfully transfered */
+	while (len) {
+		int bytes, ret, offset;
+		void *maddr;
+
+		ret = get_user_pages(tsk, mm, addr, 1,
+				write, 1, &page, &vma);
+		if (ret <= 0)
+			break;
+
+		bytes = len;
+		offset = addr & (PAGE_SIZE-1);
+		if (bytes > PAGE_SIZE-offset)
+			bytes = PAGE_SIZE-offset;
+
+		maddr = kmap(page);
+		if (write) {
+			copy_to_user_page(vma, page, addr,
+					  maddr + offset, buf, bytes);
+			set_page_dirty_lock(page);
+		} else {
+			copy_from_user_page(vma, page, addr,
+					    buf, maddr + offset, bytes);
+		}
+		kunmap(page);
+		page_cache_release(page);
+		len -= bytes;
+		buf += bytes;
+		addr += bytes;
+	}
+	up_read(&mm->mmap_sem);
+	mmput(mm);
+
+	return buf - old_buf;
+}