[ion] Ion::Device::reset::jump() jumps to the initialisation vector

ion/src/device/n0100/flash.ld

@@ -30,7 +30,7 @@ SECTIONS {
      * We're generating the ISR vector table in code because it's very
      * convenient: using function pointers, we can easily point to the service
      * routine for each interrupt. */
-
+   _isr_start = .;
     KEEP(*(.isr_vector_table))
   } >FLASH
 

ion/src/device/n0101/flash.ld

@@ -38,7 +38,7 @@ SECTIONS {
      * We're generating the ISR vector table in code because it's very
      * convenient: using function pointers, we can easily point to the service
      * routine for each interrupt. */
-
+   _isr_start = .;
     KEEP(*(.isr_vector_table))
   } >INTERNAL_FLASH
 

ion/src/device/shared/drivers/reset.cpp

@@ -2,6 +2,8 @@
 #include <regs/regs.h>
 #include <drivers/cache.h>
 
+extern void * _isr_start;
+
 namespace Ion {
 namespace Device {
 namespace Reset {
@@ -19,8 +21,8 @@ void jump() {
   Ion::Device::Cache::disableDCache();
   Ion::Device::Cache::disableICache();
 
-  uint32_t * stackPointerAddress = reinterpret_cast<uint32_t *>(0x08000000);
-  uint32_t * resetHandlerAddress = reinterpret_cast<uint32_t *>(0x08000004);
+  uint32_t * stackPointerAddress = reinterpret_cast<uint32_t *>(&_isr_start);
+  uint32_t * resetHandlerAddress = stackPointerAddress + 1;
 
   /* Jump to the reset service routine after having reset the stack pointer.
    * Both addresses are fetched from the base of the Flash memory, just like a

ion/src/device/shared/ram.ld

@@ -23,6 +23,7 @@ STACK_SIZE = 32K;
 
 SECTIONS {
   .isr_vector_table ORIGIN(RAM_BUFFER) : {
+    _isr_start = .;
     KEEP(*(.isr_vector_table))
   } >RAM_BUFFER
 

ion/src/device/shared/usb/dfu.ld

@@ -25,6 +25,10 @@ MEMORY {
   RAM_BUFFER (rw) : ORIGIN = EPSILON_STACK_END, LENGTH = 8K
 }
 
+/* The DFU needs to know to which address it should jump to after a leave
+ * command. This address is used in Ion::Device::Reset::jump(). */
+_isr_start = 0x08000000;
+
 SECTIONS {
   .text : {
     . = ALIGN(4);