Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 36 insertions, 3 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 77e64e3eac80..8ba434287387 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1300,6 +1300,27 @@ static inline bool page_maybe_dma_pinned(struct page *page)
 		GUP_PIN_COUNTING_BIAS;
 }
 
+static inline bool is_cow_mapping(vm_flags_t flags)
+{
+	return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
+}
+
+/*
+ * This should most likely only be called during fork() to see whether we
+ * should break the cow immediately for a page on the src mm.
+ */
+static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma,
+					  struct page *page)
+{
+	if (!is_cow_mapping(vma->vm_flags))
+		return false;
+
+	if (!atomic_read(&vma->vm_mm->has_pinned))
+		return false;
+
+	return page_maybe_dma_pinned(page);
+}
+
 #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
 #define SECTION_IN_PAGE_FLAGS
 #endif
@@ -1440,16 +1461,28 @@ static inline bool cpupid_match_pid(struct task_struct *task, int cpupid)
 
 #if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
 
+/*
+ * KASAN per-page tags are stored xor'ed with 0xff. This allows to avoid
+ * setting tags for all pages to native kernel tag value 0xff, as the default
+ * value 0x00 maps to 0xff.
+ */
+
 static inline u8 page_kasan_tag(const struct page *page)
 {
-	if (kasan_enabled())
-		return (page->flags >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK;
-	return 0xff;
+	u8 tag = 0xff;
+
+	if (kasan_enabled()) {
+		tag = (page->flags >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK;
+		tag ^= 0xff;
+	}
+
+	return tag;
 }
 
 static inline void page_kasan_tag_set(struct page *page, u8 tag)
 {
 	if (kasan_enabled()) {
+		tag ^= 0xff;
 		page->flags &= ~(KASAN_TAG_MASK << KASAN_TAG_PGSHIFT);
 		page->flags |= (tag & KASAN_TAG_MASK) << KASAN_TAG_PGSHIFT;
 	}