Clean usage of void pointers to access symbols
Void pointers have been used to access linker symbols, by declaring an
extern pointer, then taking the address of it. This limits symbols
values to aligned pointer values. To remove this restriction an
IMPORT_SYM macro has been introduced, which declares it as a char
pointer and casts it to the required type.
Change-Id: I89877fc3b13ed311817bb8ba79d4872b89bfd3b0
Signed-off-by: Joel Hutton <Joel.Hutton@Arm.com>
diff --git a/include/lib/utils_def.h b/include/lib/utils_def.h
index 4a5c3e0..8abc73c 100644
--- a/include/lib/utils_def.h
+++ b/include/lib/utils_def.h
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2016-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@@ -99,4 +99,21 @@
((ARM_ARCH_MAJOR > _maj) || \
((ARM_ARCH_MAJOR == _maj) && (ARM_ARCH_MINOR >= _min)))
+/*
+ * Import an assembly or linker symbol as a C expression with the specified
+ * type
+ */
+#define IMPORT_SYM(type, sym, name) \
+ extern char sym[];\
+ static const __attribute__((unused)) type name = (type) sym;
+
+/*
+ * When the symbol is used to hold a pointer, its alignment can be asserted
+ * with this macro. For example, if there is a linker symbol that is going to
+ * be used as a 64-bit pointer, the value of the linker symbol must also be
+ * aligned to 64 bit. This macro makes sure this is the case.
+ */
+#define ASSERT_SYM_PTR_ALIGN(sym) assert(((size_t)(sym) % __alignof__(*(sym))) == 0)
+
+
#endif /* __UTILS_DEF_H__ */