plat/arm: Save BL2 descriptors to reserved memory.

On ARM platforms, the BL2 memory can be overlaid by BL31/BL32. The memory
descriptors describing the list of executable images are created in BL2
R/W memory, which could be possibly corrupted later on by BL31/BL32 due
to overlay. This patch creates a reserved location in SRAM for these
descriptors and are copied over by BL2 before handing over to next BL
image.

Also this patch increases the PLAT_ARM_MAX_BL2_SIZE for juno when TBBR
is enabled.

Fixes ARM-Software/tf-issues#626

Change-Id: I755735706fa702024b4032f51ed4895b3687377f
Signed-off-by: Sathees Balya <sathees.balya@arm.com>

common/desc_image_load.c

@@ -20,11 +20,28 @@ static bl_params_t next_bl_params;
  ******************************************************************************/
 void flush_bl_params_desc(void)
 {
-	flush_dcache_range((uintptr_t)bl_mem_params_desc_ptr,
-			sizeof(*bl_mem_params_desc_ptr) * bl_mem_params_desc_num);
+	flush_bl_params_desc_args(bl_mem_params_desc_ptr,
+		bl_mem_params_desc_num,
+		&next_bl_params);
+}
+
+/*******************************************************************************
+ * This function flushes the data structures specified as arguments so that they
+ * are visible in memory for the next BL image.
+ ******************************************************************************/
+void flush_bl_params_desc_args(bl_mem_params_node_t *mem_params_desc_ptr,
+	unsigned int mem_params_desc_num,
+	bl_params_t *next_bl_params_ptr)
+{
+	assert(mem_params_desc_ptr != NULL);
+	assert(mem_params_desc_num != 0U);
+	assert(next_bl_params_ptr != NULL);
+
+	flush_dcache_range((uintptr_t)mem_params_desc_ptr,
+		sizeof(*mem_params_desc_ptr) * mem_params_desc_num);
 
-	flush_dcache_range((uintptr_t)&next_bl_params,
-			sizeof(next_bl_params));
+	flush_dcache_range((uintptr_t)next_bl_params_ptr,
+			sizeof(*next_bl_params_ptr));
 }
 
 /*******************************************************************************

docs/firmware-design.rst

@@ -1684,6 +1684,21 @@ an example.
 Note: Loading the BL32 image in TZC secured DRAM doesn't change the memory
 layout of the other images in Trusted SRAM.
 
+CONFIG section in memory layouts shown below contains:
+
+::
+
+    +--------------------+
+    |bl2_mem_params_descs|
+    |--------------------|
+    |     fw_configs     |
+    +--------------------+
+
+``bl2_mem_params_descs`` contains parameters passed from BL2 to next the
+BL image during boot.
+
+``fw_configs`` includes soc_fw_config, tos_fw_config and tb_fw_config.
+
 **FVP with TSP in Trusted SRAM with firmware configs :**
 (These diagrams only cover the AArch64 case)
 
@@ -1708,7 +1723,7 @@ layout of the other images in Trusted SRAM.
                |          |  <<<<<<<<<<<<<  |----------------|
                |          |  <<<<<<<<<<<<<  |     BL32       |
     0x04002000 +----------+                 +----------------+
-               |fw_configs|
+               |  CONFIG  |
     0x04001000 +----------+
                |  Shared  |
     0x04000000 +----------+
@@ -1745,7 +1760,7 @@ layout of the other images in Trusted SRAM.
                |              |  <<<<<<<<<<<<<  | BL31 PROGBITS  |
                |              |                 +----------------+
                +--------------+
-               |  fw_configs  |
+               |    CONFIG    |
     0x04001000 +--------------+
                |    Shared    |
     0x04000000 +--------------+
@@ -1779,7 +1794,7 @@ layout of the other images in Trusted SRAM.
                |          |  <<<<<<<<<<<<<  | BL31 PROGBITS  |
                |          |                 +----------------+
     0x04002000 +----------+
-               |fw_configs|
+               |  CONFIG  |
     0x04001000 +----------+
                |  Shared  |
     0x04000000 +----------+

include/common/desc_image_load.h

@@ -31,6 +31,9 @@ extern unsigned int bl_mem_params_desc_num;
 
 /* BL image loading utility functions */
 void flush_bl_params_desc(void);
+void flush_bl_params_desc_args(bl_mem_params_node_t *mem_params_desc_ptr,
+	unsigned int mem_params_desc_num,
+	bl_params_t *next_bl_params_ptr);
 int get_bl_params_node_index(unsigned int image_id);
 bl_mem_params_node_t *get_bl_mem_params_node(unsigned int image_id);
 bl_load_info_t *get_bl_load_info_from_mem_params_desc(void);

include/plat/arm/common/arm_def.h

@@ -348,7 +348,20 @@
  * and limit. Leave enough space of BL2 meminfo.
  */
 #define ARM_TB_FW_CONFIG_BASE		(ARM_BL_RAM_BASE + sizeof(meminfo_t))
-#define ARM_TB_FW_CONFIG_LIMIT		(ARM_BL_RAM_BASE + PAGE_SIZE)
+#define ARM_TB_FW_CONFIG_LIMIT		(ARM_BL_RAM_BASE + (PAGE_SIZE / 2U))
+
+/*
+ * Boot parameters passed from BL2 to BL31/BL32 are stored here
+ */
+#define ARM_BL2_MEM_DESC_BASE		ARM_TB_FW_CONFIG_LIMIT
+#define ARM_BL2_MEM_DESC_LIMIT		(ARM_BL2_MEM_DESC_BASE +	\
+							(PAGE_SIZE / 2U))
+
+/*
+ * Define limit of firmware configuration memory:
+ * ARM_TB_FW_CONFIG + ARM_BL2_MEM_DESC memory
+ */
+#define ARM_FW_CONFIG_LIMIT		(ARM_BL_RAM_BASE + PAGE_SIZE)
 
 /*******************************************************************************
  * BL1 specific defines.
@@ -443,7 +456,7 @@
  * SP_MIN is the only BL image in SRAM. Allocate the whole of SRAM (excluding
  * the page reserved for fw_configs) to BL32
  */
-#  define BL32_BASE			ARM_TB_FW_CONFIG_LIMIT
+#  define BL32_BASE			ARM_FW_CONFIG_LIMIT
 #  define BL32_LIMIT			(ARM_BL_RAM_BASE + ARM_BL_RAM_SIZE)
 # else
 /* Put BL32 below BL2 in the Trusted SRAM.*/
@@ -481,7 +494,7 @@
 #  define TSP_SEC_MEM_BASE		ARM_BL_RAM_BASE
 #  define TSP_SEC_MEM_SIZE		ARM_BL_RAM_SIZE
 #  define TSP_PROGBITS_LIMIT		BL31_BASE
-#  define BL32_BASE			ARM_TB_FW_CONFIG_LIMIT
+#  define BL32_BASE			ARM_FW_CONFIG_LIMIT
 #  define BL32_LIMIT			BL31_BASE
 # elif ARM_TSP_RAM_LOCATION_ID == ARM_TRUSTED_DRAM_ID
 #  define TSP_SEC_MEM_BASE		PLAT_ARM_TRUSTED_DRAM_BASE

include/plat/arm/common/plat_arm.h

@@ -188,6 +188,7 @@ void arm_bl2_plat_arch_setup(void);
 uint32_t arm_get_spsr_for_bl32_entry(void);
 uint32_t arm_get_spsr_for_bl33_entry(void);
 int arm_bl2_handle_post_image_load(unsigned int image_id);
+struct bl_params *arm_get_next_bl_params(void);
 
 /* BL2 at EL3 functions */
 void arm_bl2_el3_early_platform_setup(void);

plat/arm/board/juno/include/platform_def.h

@@ -143,7 +143,7 @@
 #elif TF_MBEDTLS_KEY_ALG_ID == TF_MBEDTLS_ECDSA
 # define PLAT_ARM_MAX_BL2_SIZE		UL(0x1D000)
 #else
-# define PLAT_ARM_MAX_BL2_SIZE		UL(0x1C000)
+# define PLAT_ARM_MAX_BL2_SIZE		UL(0x1D000)
 #endif
 #else
 # define PLAT_ARM_MAX_BL2_SIZE		UL(0xF000)

plat/arm/common/arm_image_load.c

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
+#include <assert.h>
 #include <common/bl_common.h>
 #include <common/desc_image_load.h>
 #include <plat/common/platform.h>
@@ -14,6 +15,7 @@
 #pragma weak plat_get_bl_image_load_info
 #pragma weak plat_get_next_bl_params
 
+static bl_params_t *next_bl_params_cpy_ptr;
 
 /*******************************************************************************
  * This function flushes the data structures so that they are visible
@@ -21,7 +23,11 @@
  ******************************************************************************/
 void plat_flush_next_bl_params(void)
 {
-	flush_bl_params_desc();
+	assert(next_bl_params_cpy_ptr != NULL);
+
+	flush_bl_params_desc_args(bl_mem_params_desc_ptr,
+		bl_mem_params_desc_num,
+		next_bl_params_cpy_ptr);
 }
 
 /*******************************************************************************
@@ -33,12 +39,53 @@ struct bl_load_info *plat_get_bl_image_load_info(void)
 }
 
 /*******************************************************************************
- * This function returns the list of executable images.
+ * ARM helper function to return the list of executable images.Since the default
+ * descriptors are allocated within BL2 RW memory, this prevents BL31/BL32
+ * overlay of BL2 memory. Hence this function also copies the descriptors to a
+ * pre-allocated memory indicated by ARM_BL2_MEM_DESC_BASE.
  ******************************************************************************/
-struct bl_params *plat_get_next_bl_params(void)
+struct bl_params *arm_get_next_bl_params(void)
 {
-	bl_params_t *next_bl_params = get_next_bl_params_from_mem_params_desc();
+	bl_mem_params_node_t *bl2_mem_params_descs_cpy
+			= (bl_mem_params_node_t *)ARM_BL2_MEM_DESC_BASE;
+	const bl_params_t *next_bl_params;
+
+	next_bl_params_cpy_ptr =
+		(bl_params_t *)(ARM_BL2_MEM_DESC_BASE +
+		(bl_mem_params_desc_num * sizeof(bl_mem_params_node_t)));
+
+	/*
+	 * Copy the memory descriptors to ARM_BL2_MEM_DESC_BASE area.
+	 */
+	(void) memcpy(bl2_mem_params_descs_cpy, bl_mem_params_desc_ptr,
+		(bl_mem_params_desc_num * sizeof(bl_mem_params_node_t)));
+
+	/*
+	 * Modify the global 'bl_mem_params_desc_ptr' to point to the
+	 * copied location.
+	 */
+	bl_mem_params_desc_ptr = bl2_mem_params_descs_cpy;
+
+	next_bl_params = get_next_bl_params_from_mem_params_desc();
+	assert(next_bl_params != NULL);
+
+	/*
+	 * Copy 'next_bl_params' to the reserved location after the copied
+	 * memory descriptors.
+	 */
+	(void) memcpy(next_bl_params_cpy_ptr, next_bl_params,
+						(sizeof(bl_params_t)));
+
+	populate_next_bl_params_config(next_bl_params_cpy_ptr);
 
-	populate_next_bl_params_config(next_bl_params);
-	return next_bl_params;
+	return next_bl_params_cpy_ptr;
 }
+
+/*******************************************************************************
+ * This function returns the list of executable images
+ ******************************************************************************/
+struct bl_params *plat_get_next_bl_params(void)
+{
+	return arm_get_next_bl_params();
+}
+

plat/arm/css/sgi/sgi_image_load.c

@@ -11,6 +11,7 @@
 #include <common/desc_image_load.h>
 #include <plat/common/platform.h>
 
+#include <plat_arm.h>
 #include <sgi_variant.h>
 
 /*******************************************************************************
@@ -72,14 +73,11 @@ static int plat_sgi_append_config_node(void)
 bl_params_t *plat_get_next_bl_params(void)
 {
 	int ret;
-	bl_params_t *next_bl_params;
 
 	ret = plat_sgi_append_config_node();
 	if (ret != 0)
 		panic();
 
-	next_bl_params = get_next_bl_params_from_mem_params_desc();
-	populate_next_bl_params_config(next_bl_params);
-
-	return next_bl_params;
+	return arm_get_next_bl_params();
 }
+