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>

5 files changed, 46 insertions, 45 deletions

diff --git a/include/common/bl_common.h b/include/common/bl_common.h
index 4ef916f53..09a394dd1 100644
--- a/include/common/bl_common.h
+++ b/include/common/bl_common.h
@@ -64,33 +64,41 @@
 #include <types.h>
 #include <utils_def.h> /* To retain compatibility */
 
+
 /*
  * Declarations of linker defined symbols to help determine memory layout of
  * BL images
  */
 #if SEPARATE_CODE_AND_RODATA
-extern uintptr_t __TEXT_START__;
-extern uintptr_t __TEXT_END__;
-extern uintptr_t __RODATA_START__;
-extern uintptr_t __RODATA_END__;
+IMPORT_SYM(unsigned long, __TEXT_START__,	BL_CODE_BASE);
+IMPORT_SYM(unsigned long, __TEXT_END__,		BL_CODE_END);
+IMPORT_SYM(unsigned long, __RODATA_START__,	BL_RO_DATA_BASE);
+IMPORT_SYM(unsigned long, __RODATA_END__,	BL_RO_DATA_END);
 #else
-extern uintptr_t __RO_START__;
-extern uintptr_t __RO_END__;
+IMPORT_SYM(unsigned long, __RO_START__,		BL_CODE_BASE);
+IMPORT_SYM(unsigned long, __RO_END__,		BL_CODE_END);
 #endif
 
 #if defined(IMAGE_BL2)
-extern uintptr_t __BL2_END__;
+IMPORT_SYM(unsigned long, __BL2_END__,		BL2_END);
 #elif defined(IMAGE_BL2U)
-extern uintptr_t __BL2U_END__;
+IMPORT_SYM(unsigned long, __BL2U_END__,		BL2U_END);
 #elif defined(IMAGE_BL31)
-extern uintptr_t __BL31_END__;
+IMPORT_SYM(unsigned long, __BL31_END__,		BL31_END);
 #elif defined(IMAGE_BL32)
-extern uintptr_t __BL32_END__;
+IMPORT_SYM(unsigned long, __BL32_END__,		BL32_END);
 #endif /* IMAGE_BLX */
 
+/*
+ * The next 2 constants identify the extents of the coherent memory region.
+ * These addresses are used by the MMU setup code and therefore they must be
+ * page-aligned.  It is the responsibility of the linker script to ensure that
+ * __COHERENT_RAM_START__ and __COHERENT_RAM_END__ linker symbols refer to
+ * page-aligned addresses.
+ */
 #if USE_COHERENT_MEM
-extern uintptr_t __COHERENT_RAM_START__;
-extern uintptr_t __COHERENT_RAM_END__;
+IMPORT_SYM(unsigned long, __COHERENT_RAM_START__,	BL_COHERENT_RAM_BASE);
+IMPORT_SYM(unsigned long, __COHERENT_RAM_END__,		BL_COHERENT_RAM_END);
 #endif
 
 /*******************************************************************************
diff --git a/include/common/runtime_svc.h b/include/common/runtime_svc.h
index d12af227e..5d9fa3908 100644
--- a/include/common/runtime_svc.h
+++ b/include/common/runtime_svc.h
@@ -122,8 +122,8 @@ CASSERT(RT_SVC_DESC_HANDLE == __builtin_offsetof(rt_svc_desc_t, handle), \
 void runtime_svc_init(void);
 uintptr_t handle_runtime_svc(uint32_t smc_fid, void *cookie, void *handle,
 						unsigned int flags);
-extern uintptr_t __RT_SVC_DESCS_START__;
-extern uintptr_t __RT_SVC_DESCS_END__;
+IMPORT_SYM(uintptr_t, __RT_SVC_DESCS_START__,		RT_SVC_DESCS_START);
+IMPORT_SYM(uintptr_t, __RT_SVC_DESCS_END__,		RT_SVC_DESCS_END);
 void init_crash_reporting(void);
 
 extern uint8_t rt_svc_descs_indices[MAX_RT_SVCS];
diff --git a/include/lib/utils_def.h b/include/lib/utils_def.h
index 4a5c3e0bc..8abc73c09 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__ */
diff --git a/include/plat/common/common_def.h b/include/plat/common/common_def.h
index a841c3dbf..84923b9a7 100644
--- a/include/plat/common/common_def.h
+++ b/include/plat/common/common_def.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -74,33 +74,13 @@
  * page of it with the right memory attributes.
  */
 #if SEPARATE_CODE_AND_RODATA
-#define BL_CODE_BASE		(unsigned long)(&__TEXT_START__)
-#define BL_CODE_END		(unsigned long)(&__TEXT_END__)
-#define BL_RO_DATA_BASE		(unsigned long)(&__RODATA_START__)
-#define BL_RO_DATA_END		(unsigned long)(&__RODATA_END__)
 
 #define BL1_CODE_END		BL_CODE_END
-#define BL1_RO_DATA_BASE	(unsigned long)(&__RODATA_START__)
+#define BL1_RO_DATA_BASE	BL_RO_DATA_BASE
 #define BL1_RO_DATA_END		round_up(BL1_ROM_END, PAGE_SIZE)
 #else
-#define BL_CODE_BASE		(unsigned long)(&__RO_START__)
-#define BL_CODE_END		(unsigned long)(&__RO_END__)
 #define BL_RO_DATA_BASE		0
 #define BL_RO_DATA_END		0
-
 #define BL1_CODE_END		round_up(BL1_ROM_END, PAGE_SIZE)
-#define BL1_RO_DATA_BASE	0
-#define BL1_RO_DATA_END		0
 #endif /* SEPARATE_CODE_AND_RODATA */
-
-/*
- * The next 2 constants identify the extents of the coherent memory region.
- * These addresses are used by the MMU setup code and therefore they must be
- * page-aligned.  It is the responsibility of the linker script to ensure that
- * __COHERENT_RAM_START__ and __COHERENT_RAM_END__ linker symbols refer to
- * page-aligned addresses.
- */
-#define BL_COHERENT_RAM_BASE	(unsigned long)(&__COHERENT_RAM_START__)
-#define BL_COHERENT_RAM_END	(unsigned long)(&__COHERENT_RAM_END__)
-
 #endif /* __COMMON_DEF_H__ */
diff --git a/include/services/secure_partition.h b/include/services/secure_partition.h
index 93df2a137..f68f711be 100644
--- a/include/services/secure_partition.h
+++ b/include/services/secure_partition.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -11,15 +11,11 @@
 #include <types.h>
 #include <utils_def.h>
 
-/* Linker symbols */
-extern uintptr_t __SP_IMAGE_XLAT_TABLES_START__;
-extern uintptr_t __SP_IMAGE_XLAT_TABLES_END__;
+/* Import linker symbols */
+IMPORT_SYM(uintptr_t, __SP_IMAGE_XLAT_TABLES_START__,	SP_IMAGE_XLAT_TABLES_START);
+IMPORT_SYM(uintptr_t, __SP_IMAGE_XLAT_TABLES_END__,	SP_IMAGE_XLAT_TABLES_END);
 
 /* Definitions */
-#define SP_IMAGE_XLAT_TABLES_START	\
-	(uintptr_t)(&__SP_IMAGE_XLAT_TABLES_START__)
-#define SP_IMAGE_XLAT_TABLES_END	\
-	(uintptr_t)(&__SP_IMAGE_XLAT_TABLES_END__)
 #define SP_IMAGE_XLAT_TABLES_SIZE	\
 	(SP_IMAGE_XLAT_TABLES_END - SP_IMAGE_XLAT_TABLES_START)