compiler: Define OPTIMIZER_HIDE_VAR

Part of upstream commit fe8c8a126806 ('crypto: more robust
crypto_memneq'), needed by commit d4c5efdb9777 ('random: add and use
memzero_explicit() for clearing data').

diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 5633053..9ac1a7a 100644 (file)
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -37,6 +37,9 @@
     __asm__ ("" : "=r"(__ptr) : "0"(ptr));             \
     (typeof(ptr)) (__ptr + (off)); })
 
     __asm__ ("" : "=r"(__ptr) : "0"(ptr));             \
     (typeof(ptr)) (__ptr + (off)); })
 

+/* Make the optimizer believe the variable can be manipulated arbitrarily. */
+#define OPTIMIZER_HIDE_VAR(var) __asm__ ("" : "=r" (var) : "0" (var))
+

 #ifdef __CHECKER__
 #define __must_be_array(arr) 0
 #else
 #ifdef __CHECKER__
 #define __must_be_array(arr) 0
 #else

diff --git a/include/linux/compiler-intel.h b/include/linux/compiler-intel.h
index cba9593..1a97cac 100644 (file)
--- a/include/linux/compiler-intel.h
+++ b/include/linux/compiler-intel.h
@@ -15,6 +15,7 @@
  */
 #undef barrier
 #undef RELOC_HIDE
  */
 #undef barrier
 #undef RELOC_HIDE

+#undef OPTIMIZER_HIDE_VAR

 
 #define barrier() __memory_barrier()
 
 
 #define barrier() __memory_barrier()
 


@@ -23,6 +24,12 @@
      __ptr = (unsigned long) (ptr);                            \
     (typeof(ptr)) (__ptr + (off)); })
 
      __ptr = (unsigned long) (ptr);                            \
     (typeof(ptr)) (__ptr + (off)); })
 

+/* This should act as an optimization barrier on var.
+ * Given that this compiler does not have inline assembly, a compiler barrier
+ * is the best we can do.
+ */
+#define OPTIMIZER_HIDE_VAR(var) barrier()
+

 /* Intel ECC compiler doesn't support __builtin_types_compatible_p() */
 #define __must_be_array(a) 0
 
 /* Intel ECC compiler doesn't support __builtin_types_compatible_p() */
 #define __must_be_array(a) 0
 

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 320d6c9..7c7546b 100644 (file)
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -164,6 +164,10 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
     (typeof(ptr)) (__ptr + (off)); })
 #endif
 
     (typeof(ptr)) (__ptr + (off)); })
 #endif
 

+#ifndef OPTIMIZER_HIDE_VAR
+#define OPTIMIZER_HIDE_VAR(var) barrier()
+#endif
+

 #endif /* __KERNEL__ */
 
 #endif /* __ASSEMBLY__ */
 #endif /* __KERNEL__ */
 
 #endif /* __ASSEMBLY__ */