Mbed TLS: Remove weak heap implementation

The implementation of the heap function plat_get_mbedtls_heap() becomes
mandatory for platforms supporting TRUSTED_BOARD_BOOT.

The shared Mbed TLS heap default weak function implementation is
converted to a helper function get_mbedtls_heap_helper() which can be
used by the platforms for their own function implementation.

Change-Id: Ic8f2994e25e3d9fcd371a21ac459fdcafe07433e
Signed-off-by: Ambroise Vincent <ambroise.vincent@arm.com>

docs/porting-guide.rst

@@ -841,6 +841,33 @@ utilize the C runtime environment. For further details about how TF-A
 represents the power domain topology and how this relates to the linear CPU
 index, please refer `Power Domain Topology Design`_.
 
+Function : plat_get_mbedtls_heap() [when TRUSTED_BOARD_BOOT == 1]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+    Arguments : void **heap_addr, size_t *heap_size
+    Return    : int
+
+This function is invoked during Mbed TLS library initialisation to get a heap,
+by means of a starting address and a size. This heap will then be used
+internally by the Mbed TLS library. Hence, each BL stage that utilises Mbed TLS
+must be able to provide a heap to it.
+
+A helper function can be found in `drivers/auth/mbedtls/mbedtls_common.c` in
+which a heap is statically reserved during compile time inside every image
+(i.e. every BL stage) that utilises Mbed TLS. In this default implementation,
+the function simply returns the address and size of this "pre-allocated" heap.
+For a platform to use this default implementation, only a call to the helper
+from inside plat_get_mbedtls_heap() body is enough and nothing else is needed.
+
+However, by writting their own implementation, platforms have the potential to
+optimise memory usage. For example, on some Arm platforms, the Mbed TLS heap is
+shared between BL1 and BL2 stages and, thus, the necessary space is not reserved
+twice.
+
+On success the function should return 0 and a negative error code otherwise.
+
 Common optional modifications
 -----------------------------
 
@@ -1054,29 +1081,6 @@ can override the common implementation to define a different prefix string for
 the log output. The implementation should be robust to future changes that
 increase the number of log levels.
 
-Function : plat_get_mbedtls_heap()
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-::
-
-    Arguments : void **heap_addr, size_t *heap_size
-    Return    : int
-
-This function is invoked during Mbed TLS library initialisation to get
-a heap, by means of a starting address and a size. This heap will then be used
-internally by the Mbed TLS library. The heap is requested from the current BL
-stage, i.e. the current BL image inside which Mbed TLS is used.
-
-In the default implementation a heap is statically allocated inside every image
-(i.e. every BL stage) that utilises Mbed TLS. So, in this case, the function
-simply returns the address and size of this "pre-allocated" heap. However, by
-overriding the default implementation, platforms have the potential to optimise
-memory usage. For example, on some Arm platforms, the Mbed TLS heap is shared
-between BL1 and BL2 stages and, thus, the necessary space is not reserved
-twice.
-
-On success the function should return 0 and a negative error code otherwise.
-
 Modifications specific to a Boot Loader stage
 ---------------------------------------------
 

drivers/auth/mbedtls/mbedtls_common.c

@@ -16,8 +16,6 @@
 #include <drivers/auth/mbedtls/mbedtls_config.h>
 #include <plat/common/platform.h>
 
-#pragma weak plat_get_mbedtls_heap
-
 static void cleanup(void)
 {
 	ERROR("EXIT from BL2\n");
@@ -58,10 +56,10 @@ void mbedtls_init(void)
 }
 
 /*
- * The following default implementation of the function simply returns the
+ * The following helper function simply returns the default allocated heap.
- * by default allocated heap.
+ * It can be used by platforms for their plat_get_mbedtls_heap() implementation.
  */
-int plat_get_mbedtls_heap(void **heap_addr, size_t *heap_size)
+int get_mbedtls_heap_helper(void **heap_addr, size_t *heap_size)
 {
 	static unsigned char heap[TF_MBEDTLS_HEAP_SIZE];
 

include/plat/common/platform.h

@@ -47,6 +47,7 @@ int plat_get_image_source(unsigned int image_id,
 uintptr_t plat_get_ns_image_entrypoint(void);
 unsigned int plat_my_core_pos(void);
 int plat_core_pos_by_mpidr(u_register_t mpidr);
+int plat_get_mbedtls_heap(void **heap_addr, size_t *heap_size);
 
 #if STACK_PROTECTOR_ENABLED
 /*
@@ -103,7 +104,6 @@ void plat_panic_handler(void) __dead2;
 const char *plat_log_get_prefix(unsigned int log_level);
 void bl2_plat_preload_setup(void);
 int plat_try_next_boot_source(void);
-int plat_get_mbedtls_heap(void **heap_addr, size_t *heap_size);
 uint64_t *plat_init_apiakey(void);
 
 /*******************************************************************************
@@ -262,6 +262,7 @@ int plat_get_nv_ctr(void *cookie, unsigned int *nv_ctr);
 int plat_set_nv_ctr(void *cookie, unsigned int nv_ctr);
 int plat_set_nv_ctr2(void *cookie, const struct auth_img_desc_s *img_desc,
 		unsigned int nv_ctr);
+int get_mbedtls_heap_helper(void **heap_addr, size_t *heap_size);
 
 /*******************************************************************************
  * Secure Partitions functions

plat/arm/board/juno/juno_security.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2014-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -10,6 +10,7 @@
 #include <platform_def.h>
 #include <plat/arm/common/plat_arm.h>
 #include <plat/arm/soc/common/soc_css.h>
+#include <plat/common/platform.h>
 
 #include "juno_tzmp1_def.h"
 
@@ -144,3 +145,10 @@ void plat_arm_security_setup(void)
 	init_v550();
 #endif
 }
+
+#if TRUSTED_BOARD_BOOT
+int plat_get_mbedtls_heap(void **heap_addr, size_t *heap_size)
+{
+	return get_mbedtls_heap_helper(heap_addr, heap_size);
+}
+#endif

plat/hisilicon/hikey/hikey_tbbr.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -29,3 +29,8 @@ int plat_set_nv_ctr(void *cookie, unsigned int nv_ctr)
 {
 	return 1;
 }
+
+int plat_get_mbedtls_heap(void **heap_addr, size_t *heap_size)
+{
+	return get_mbedtls_heap_helper(heap_addr, heap_size);
+}

plat/hisilicon/hikey960/hikey960_tbbr.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -29,3 +29,8 @@ int plat_set_nv_ctr(void *cookie, unsigned int nv_ctr)
 {
 	return 1;
 }
+
+int plat_get_mbedtls_heap(void **heap_addr, size_t *heap_size)
+{
+	return get_mbedtls_heap_helper(heap_addr, heap_size);
+}

plat/imx/imx7/warp7/warp7_trusted_boot.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -29,3 +29,8 @@ int plat_set_nv_ctr(void *cookie, unsigned int nv_ctr)
 {
 	return 1;
 }
+
+int plat_get_mbedtls_heap(void **heap_addr, size_t *heap_size)
+{
+	return get_mbedtls_heap_helper(heap_addr, heap_size);
+}

plat/qemu/qemu_trusted_boot.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -29,3 +29,8 @@ int plat_set_nv_ctr(void *cookie, unsigned int nv_ctr)
 {
 	return 1;
 }
+
+int plat_get_mbedtls_heap(void **heap_addr, size_t *heap_size)
+{
+	return get_mbedtls_heap_helper(heap_addr, heap_size);
+}

plat/rpi3/rpi3_trusted_boot.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -29,3 +29,8 @@ int plat_set_nv_ctr(void *cookie, unsigned int nv_ctr)
 {
 	return 1;
 }
+
+int plat_get_mbedtls_heap(void **heap_addr, size_t *heap_size)
+{
+	return get_mbedtls_heap_helper(heap_addr, heap_size);
+}

plat/socionext/uniphier/uniphier_tbbr.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -33,3 +33,8 @@ int plat_set_nv_ctr(void *cookie, unsigned int nv_ctr)
 {
 	return 0;
 }
+
+int plat_get_mbedtls_heap(void **heap_addr, size_t *heap_size)
+{
+	return get_mbedtls_heap_helper(heap_addr, heap_size);
+}