1 files changed, 19 insertions, 3 deletions

diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 88af13c00d3c..70c009741aab 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -34,6 +34,7 @@
 #include <linux/string.h>
 #include <linux/types.h>
 #include <linux/vmalloc.h>
+#include <linux/bug.h>
 
 #include "kasan.h"
 #include "../slab.h"
@@ -62,7 +63,7 @@ void kasan_unpoison_shadow(const void *address, size_t size)
         }
 }
 
-static void __kasan_unpoison_stack(struct task_struct *task, void *sp)
+static void __kasan_unpoison_stack(struct task_struct *task, const void *sp)
 {
         void *base = task_stack_page(task);
         size_t size = sp - base;
@@ -77,9 +78,24 @@ void kasan_unpoison_task_stack(struct task_struct *task)
 }
 
 /* Unpoison the stack for the current task beyond a watermark sp value. */
-asmlinkage void kasan_unpoison_remaining_stack(void *sp)
+asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
 {
-        __kasan_unpoison_stack(current, sp);
+        __kasan_unpoison_stack(current, watermark);
+}
+
+/*
+ * Clear all poison for the region between the current SP and a provided
+ * watermark value, as is sometimes required prior to hand-crafted asm function
+ * returns in the middle of functions.
+ */
+void kasan_unpoison_stack_above_sp_to(const void *watermark)
+{
+        const void *sp = __builtin_frame_address(0);
+        size_t size = watermark - sp;
+
+        if (WARN_ON(sp > watermark))
+                return;
+        kasan_unpoison_shadow(sp, size);
 }
 
 /*