STM32H7: Don't use DTCM memory for heap (#396)

* STM32H7: Don't use DTCM memory for heap

* Update CM4 linker script assertion

Author: Jamie Smith

cmsis/device/rtos/TOOLCHAIN_GCC_ARM/mbed_boot_gcc_arm.c

@@ -29,10 +29,20 @@ static osMutexId_t               env_mutex_id;
 static mbed_rtos_storage_mutex_t env_mutex_obj;
 static osMutexAttr_t             env_mutex_attr;
 
+// Stack symbols from linker script
 extern uint32_t             __StackLimit;
 extern uint32_t             __StackTop;
+
+// Heap symbols from linker script
+#if defined(MBED_SPLIT_HEAP)
+extern uint32_t __mbed_sbrk_start;
+extern uint32_t __mbed_krbs_start;
+extern uint32_t __mbed_sbrk_start_0;
+extern uint32_t __mbed_krbs_start_0;
+#else
 extern uint32_t             __end__;
 extern uint32_t             __HeapLimit;
+#endif
 
 extern void __libc_init_array(void);
 
@@ -45,8 +55,15 @@ void software_init_hook(void)
 {
     mbed_stack_isr_start = (unsigned char *) &__StackLimit;
     mbed_stack_isr_size = (uint32_t) &__StackTop - (uint32_t) &__StackLimit;
+#if defined(MBED_SPLIT_HEAP)
+    mbed_heap_start = (unsigned char *) &__mbed_sbrk_start;
+    mbed_heap_size = (uint32_t) &__mbed_krbs_start - (uint32_t) &__mbed_sbrk_start;
+    mbed_heap_start_0 = (unsigned char *) &__mbed_sbrk_start_0;
+    mbed_heap_size_0 = (uint32_t) &__mbed_krbs_start_0 - (uint32_t) &__mbed_sbrk_start_0;
+#else
     mbed_heap_start = (unsigned char *) &__end__;
     mbed_heap_size = (uint32_t) &__HeapLimit - (uint32_t) &__end__;
+#endif
 
     mbed_init();
     mbed_rtos_start();

cmsis/device/rtos/include/mbed_boot.h

@@ -58,6 +58,11 @@ extern "C" {
 extern unsigned char *mbed_heap_start;
 extern uint32_t mbed_heap_size;
 
+#if defined(MBED_SPLIT_HEAP)
+extern unsigned char *mbed_heap_start_0;
+extern uint32_t mbed_heap_size_0;
+#endif
+
 /* Stack limits */
 extern unsigned char *mbed_stack_isr_start;
 extern uint32_t mbed_stack_isr_size;

cmsis/device/rtos/source/mbed_boot.c

@@ -46,7 +46,7 @@
  * - Value INITIAL_SP is ignored
  *
  * GCC Memory layout :
- * - Heap explicitly placed in linker script (*.ld file) and heap start (__end___) and heap end (__HeapLimit) should be defined in linker script
+ * - Heap explicitly placed in linker script (*.ld file) and heap start (__end___) and heap end (__HeapLimit) should be defined in linker script (or __mbed_sbrk_start/__mbed_sbrk_start_0 and __mbed_krbs_start/__mbed_krbs_start_0 for split heap targets)
  * - Interrupt stack placed in linker script **.ld file) and stack start (__StackTop) and stack end (__StackLimit) should be defined in linker script
  *
  * ARM Memory layout :

platform/source/mbed_retarget.cpp

@@ -120,6 +120,11 @@ extern const char __stderr_name[] = "/stderr";
 unsigned char *mbed_heap_start = 0;
 uint32_t mbed_heap_size = 0;
 
+#if defined(MBED_SPLIT_HEAP)
+unsigned char *mbed_heap_start_0 = 0;
+uint32_t mbed_heap_size_0 = 0;
+#endif
+
 #if !MBED_CONF_PLATFORM_STDIO_MINIMAL_CONSOLE_ONLY
 
 /* newlib has the filehandle field in the FILE struct as a short, so

platform/source/mbed_sdk_boot.c

@@ -17,6 +17,7 @@
 
 #include "mbed_error.h"
 #include "mbed_toolchain.h"
+#include "mbed_boot.h"
 #include <stdlib.h>
 #include <stdint.h>
 #include "cmsis.h"
@@ -28,10 +29,6 @@
  */
 #if !defined(MBED_CONF_RTOS_PRESENT)
 
-/* Heap limits - only used if set */
-extern unsigned char *mbed_heap_start;
-extern uint32_t mbed_heap_size;
-
 /* Stack limits */
 unsigned char *mbed_stack_isr_start = 0;
 uint32_t mbed_stack_isr_size = 0;
@@ -154,17 +151,33 @@ const uint32_t os_cb_sections[] __attribute__((section(".rodata"))) = {};
 
 extern uint32_t             __StackLimit;
 extern uint32_t             __StackTop;
+
+#if defined(MBED_SPLIT_HEAP)
+extern uint32_t __mbed_sbrk_start;
+extern uint32_t __mbed_krbs_start;
+extern uint32_t __mbed_sbrk_start_0;
+extern uint32_t __mbed_krbs_start_0;
+#else
 extern uint32_t             __end__;
 extern uint32_t             __HeapLimit;
+#endif
 
 extern int __real_main(void);
 
 void software_init_hook(void)
 {
     mbed_stack_isr_start = (unsigned char *) &__StackLimit;
     mbed_stack_isr_size = (uint32_t) &__StackTop - (uint32_t) &__StackLimit;
+
+#if defined(MBED_SPLIT_HEAP)
+    mbed_heap_start = (unsigned char *) &__mbed_sbrk_start;
+    mbed_heap_size = (uint32_t) &__mbed_krbs_start - (uint32_t) &__mbed_sbrk_start;
+    mbed_heap_start_0 = (unsigned char *) &__mbed_sbrk_start_0;
+    mbed_heap_size_0 = (uint32_t) &__mbed_krbs_start_0 - (uint32_t) &__mbed_sbrk_start_0;
+#else
     mbed_heap_start = (unsigned char *) &__end__;
     mbed_heap_size = (uint32_t) &__HeapLimit - (uint32_t) &__end__;
+#endif
 
     mbed_init();
     software_init_hook_rtos();

rtos/tests/TESTS/mbed_rtos/heap_and_stack/main.cpp

@@ -28,6 +28,7 @@
 #include "greentea-client/test_env.h"
 #include "utest/utest.h"
 #include "unity/unity.h"
+#include "mbed_boot.h"
 
 using utest::v1::Case;
 
@@ -39,18 +40,9 @@ static const int test_timeout = 30;
 // Malloc fill pattern
 #define MALLOC_FILL                 0x55
 
-extern unsigned char *mbed_heap_start;
-extern uint32_t mbed_heap_size;
 extern unsigned char *mbed_stack_isr_start;
 extern uint32_t mbed_stack_isr_size;
 
-#if defined(TOOLCHAIN_GCC_ARM) && defined(MBED_SPLIT_HEAP)
-extern uint32_t __mbed_sbrk_start_0;
-extern uint32_t __mbed_krbs_start_0;
-unsigned char *mbed_heap_start_0 = (unsigned char *) &__mbed_sbrk_start_0;;
-uint32_t mbed_heap_size_0 = (uint32_t) &__mbed_krbs_start_0 - (uint32_t) &__mbed_sbrk_start_0;
-#endif
-
 struct linked_list {
     linked_list *next;
     uint8_t data[MALLOC_TEST_SIZE];

targets/TARGET_STM/TARGET_STM32H7/linker_scripts/STM32H743_STM32H72x_FAMILIES/STM32H743_H72x.ld

@@ -187,15 +187,14 @@ SECTIONS
         _ebss = .;
     } > SRAM
 
-    .heap (COPY):
+    /* Check if data + stack will exceed SRAM limit */
+    ASSERT(_ebss < ORIGIN(SRAM) + LENGTH(SRAM) - MBED_CONF_TARGET_BOOT_STACK_SIZE, "region SRAM does not have enough space for boot stack size")
+
+    .heap_0 (NOLOAD):
     {
-        __end__ = .;
-        PROVIDE(end = .);
-        PROVIDE(__mbed_sbrk_start = .);
-        *(.heap*)
+        PROVIDE(__mbed_sbrk_start_0 = .);
         . = ORIGIN(SRAM) + LENGTH(SRAM) - MBED_CONF_TARGET_BOOT_STACK_SIZE;
-        PROVIDE(__mbed_krbs_start = .);
-        __HeapLimit = .;
+        PROVIDE(__mbed_krbs_start_0 = .);
     } > SRAM
 
     /* .stack_dummy section doesn't contains any symbols. It is only
@@ -213,9 +212,6 @@ SECTIONS
     __StackLimit = __StackTop - MBED_CONF_TARGET_BOOT_STACK_SIZE;
     PROVIDE(__stack = __StackTop);
 
-    /* Check if data + heap + stack exceeds SRAM limit */
-    ASSERT(__StackLimit >= __HeapLimit, "region SRAM overflowed with stack")
-
     /* Ethernet DMA descriptors should be at the start of SRAM_D2 because they need an MPU region 
        and because the CM4 and CM7 have to agree on their location.*/
     .eth_descriptors (NOLOAD) : {
@@ -230,11 +226,11 @@ SECTIONS
         *(.EthBuffers)
     } >SRAM_D2 
 
-    /* Use the rest of DTCM as additional heap */
-    .heap_0 (COPY):
+    /* Use SRAM_D2 as additional heap */
+    .heap (NOLOAD):
     {
-        PROVIDE(__mbed_sbrk_start_0 = .);
-        . += (ORIGIN(SRAM_DTC) + LENGTH(SRAM_DTC) - .);
-        PROVIDE(__mbed_krbs_start_0 = .);
-    } > SRAM_DTC
+        PROVIDE(__mbed_sbrk_start = .);
+        . += (ORIGIN(SRAM_D2) + LENGTH(SRAM_D2) - .);
+        PROVIDE(__mbed_krbs_start = .);
+    } > SRAM_D2
 }

targets/TARGET_STM/TARGET_STM32H7/linker_scripts/STM32H745_47_FAMILY/CM4/STM32H745_H747_CM4.ld

@@ -182,14 +182,15 @@ SECTIONS
         _ebss = .;
     } > SRAM_D2
 
+    /* Check if data + stack will exceed SRAM limit */
+    ASSERT(_ebss < ORIGIN(SRAM_D2) + LENGTH(SRAM_D2) - MBED_CONF_TARGET_BOOT_STACK_SIZE, "region SRAM does not have enough space for boot stack size")
+
     .heap (COPY):
     {
         __end__ = .;
         PROVIDE(end = .);
-        PROVIDE(__mbed_sbrk_start = .);
         *(.heap*)
         . = ORIGIN(SRAM_D2) + LENGTH(SRAM_D2) - MBED_CONF_TARGET_BOOT_STACK_SIZE;
-        PROVIDE(__mbed_krbs_start = .);
         __HeapLimit = .;
     } > SRAM_D2
     /* .stack_dummy section doesn't contains any symbols. It is only
@@ -207,9 +208,6 @@ SECTIONS
     __StackLimit = __StackTop - MBED_CONF_TARGET_BOOT_STACK_SIZE;
     PROVIDE(__stack = __StackTop);
 
-    /* Check if data + heap + stack exceeds SRAM_D2 limit */
-    ASSERT(__StackLimit >= __HeapLimit, "region SRAM_D2 overflowed with stack")
-
     /* Put crash data in the otherwise unused D3 SRAM */
     .crash_data_ram :
     {

targets/TARGET_STM/TARGET_STM32H7/linker_scripts/STM32H745_47_FAMILY/CM7/STM32H745_H747_CM7.ld

@@ -174,14 +174,14 @@ SECTIONS
         _ebss = .;
     } > SRAM
 
+    /* Check if data + stack will exceed SRAM limit */
+    ASSERT(_ebss < ORIGIN(SRAM) + LENGTH(SRAM) - MBED_CONF_TARGET_BOOT_STACK_SIZE, "region SRAM does not have enough space for boot stack size")
+
     .heap (COPY):
     {
         __end__ = .;
         PROVIDE(end = .);
-        PROVIDE(__mbed_sbrk_start = .);
-        *(.heap*)
         . = ORIGIN(SRAM) + LENGTH(SRAM) - MBED_CONF_TARGET_BOOT_STACK_SIZE;
-        PROVIDE(__mbed_krbs_start = .);
         __HeapLimit = .;
     } > SRAM
 
@@ -230,12 +230,4 @@ SECTIONS
         . = ALIGN(8);
         __CRASH_DATA_RAM_END__ = .; /* Define a global symbol at data end */
     } > SRAM_D3
-    
-    /* Use the rest of DTCM as additional heap */
-    .heap_0 (COPY):
-    {
-        PROVIDE(__mbed_sbrk_start_0 = .);
-        . += (ORIGIN(SRAM_DTC) + LENGTH(SRAM_DTC) - .);
-        PROVIDE(__mbed_krbs_start_0 = .);
-    } > SRAM_DTC
 }

targets/TARGET_STM/TARGET_STM32H7/linker_scripts/STM32H7Ax_FAMILY/STM32H7Ax.ld

@@ -174,15 +174,14 @@ SECTIONS
         _ebss = .;
     } > SRAM
 
-    .heap (COPY):
+    /* Check if data + stack will exceed SRAM limit */
+    ASSERT(_ebss < ORIGIN(SRAM) + LENGTH(SRAM) - MBED_CONF_TARGET_BOOT_STACK_SIZE, "region SRAM does not have enough space for boot stack size")
+
+    .heap_0 (NOLOAD):
     {
-        __end__ = .;
-        PROVIDE(end = .);
-        PROVIDE(__mbed_sbrk_start = .);
-        *(.heap*)
+        PROVIDE(__mbed_sbrk_start_0 = .);
         . = ORIGIN(SRAM) + LENGTH(SRAM) - MBED_CONF_TARGET_BOOT_STACK_SIZE;
-        PROVIDE(__mbed_krbs_start = .);
-        __HeapLimit = .;
+        PROVIDE(__mbed_krbs_start_0 = .);
     } > SRAM
 
     /* .stack_dummy section doesn't contains any symbols. It is only
@@ -200,9 +199,6 @@ SECTIONS
     __StackLimit = __StackTop - MBED_CONF_TARGET_BOOT_STACK_SIZE;
     PROVIDE(__stack = __StackTop);
 
-    /* Check if data + heap + stack exceeds SRAM limit */
-    ASSERT(__StackLimit >= __HeapLimit, "region SRAM overflowed with stack")
-
     /* Put crash data in the otherwise unused D3 SRAM */
     .crash_data_ram :
     {
@@ -229,11 +225,11 @@ SECTIONS
         *(.EthBuffers)
     } >SRAM_AXI 
 
-    /* Use the rest of DTCM as additional heap */
-    .heap_0 (COPY):
+    /* Use SRAM_AXI as additional heap */
+    .heap (NOLOAD):
     {
-        PROVIDE(__mbed_sbrk_start_0 = .);
-        . += (ORIGIN(SRAM_DTC) + LENGTH(SRAM_DTC) - .);
-        PROVIDE(__mbed_krbs_start_0 = .);
-    } > SRAM_DTC
+        PROVIDE(__mbed_sbrk_start = .);
+        . += (ORIGIN(SRAM_AXI) + LENGTH(SRAM_AXI) - .);
+        PROVIDE(__mbed_krbs_start = .);
+    } > SRAM_AXI
 }