CFI: Move function_nocfi() into compiler.h

[linux-2.6-microblaze.git] / include / linux / mm.h

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 322ec61..b8c28b1 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -124,16 +124,6 @@ extern int mmap_rnd_compat_bits __read_mostly;
 #define lm_alias(x)    __va(__pa_symbol(x))
 #endif
 
-/*
- * With CONFIG_CFI_CLANG, the compiler replaces function addresses in
- * instrumented C code with jump table addresses. Architectures that
- * support CFI can define this macro to return the actual function address
- * when needed.
- */
-#ifndef function_nocfi
-#define function_nocfi(x) (x)
-#endif
-
 /*
  * To prevent common memory management code establishing
  * a zero page mapping on a read fault.
@@ -3216,5 +3206,37 @@ void mem_dump_obj(void *object);
 static inline void mem_dump_obj(void *object) {}
 #endif
 
+/**
+ * seal_check_future_write - Check for F_SEAL_FUTURE_WRITE flag and handle it
+ * @seals: the seals to check
+ * @vma: the vma to operate on
+ *
+ * Check whether F_SEAL_FUTURE_WRITE is set; if so, do proper check/handling on
+ * the vma flags.  Return 0 if check pass, or <0 for errors.
+ */
+static inline int seal_check_future_write(int seals, struct vm_area_struct *vma)
+{
+       if (seals & F_SEAL_FUTURE_WRITE) {
+               /*
+                * New PROT_WRITE and MAP_SHARED mmaps are not allowed when
+                * "future write" seal active.
+                */
+               if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE))
+                       return -EPERM;
+
+               /*
+                * Since an F_SEAL_FUTURE_WRITE sealed memfd can be mapped as
+                * MAP_SHARED and read-only, take care to not allow mprotect to
+                * revert protections on such mappings. Do this only for shared
+                * mappings. For private mappings, don't need to mask
+                * VM_MAYWRITE as we still want them to be COW-writable.
+                */
+               if (vma->vm_flags & VM_SHARED)
+                       vma->vm_flags &= ~(VM_MAYWRITE);
+       }
+
+       return 0;
+}
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_MM_H */