Support for exception handling in linker scripts.

This is needed even in plain C when 64 bit variable (e.g. long long int)
arithmetic is used. For example it is required when newlib is compiled with
--enable-newlib-io-long-long.

Conflicts:

	lib/stm32/f1/libopencm3_stm32f1.ld
	lib/stm32/f2/libopencm3_stm32f2.ld

lib/stm32/f2/libopencm3_stm32f2.ld

@@ -40,17 +40,22 @@ SECTIONS
 		. = ALIGN(4);
 	} >rom
 
-	/* exception index - required due to libgcc.a issuing /0 exceptions */
-	__exidx_start = .;
+	/*
+	* Another section used by C++ stuff, appears when using newlib with
+	* 64bit (long long) printf support
+	*/
+	.ARM.extab : {
+		*(.ARM.extab*)
+	} >rom
 	.ARM.exidx : {
-		   *(.ARM.exidx*)
-	} > rom
-	__exidx_end = .;
+		__exidx_start = .;
+		*(.ARM.exidx*)
+		__exidx_end = .;
+	} >rom
 
+	. = ORIGIN(ram);
 
-	_etext = .;
-
-	.data : {
+	.data : AT (__exidx_end) {
 		_data = .;
 		*(.data*)	/* Read-write initialized data */
 		. = ALIGN(4);
@@ -64,11 +69,6 @@ SECTIONS
 		_ebss = .;
 	} >ram
 
-	/* exception unwind data - required due to libgcc.a issuing /0 exceptions */
-	.ARM.extab : {
-		*(.ARM.extab*)
-	} >ram
-
 	. = ALIGN(4);
 	end = .;
 }

lib/stm32/f2/vector.c

@@ -21,7 +21,7 @@
 #define WEAK __attribute__ ((weak))
 
 /* Symbols exported by the linker script(s): */
-extern unsigned _etext, _data, _edata, _ebss, _stack;
+extern unsigned __exidx_end, _data, _edata, _ebss, _stack;
 
 void main(void);
 void reset_handler(void);
@@ -224,7 +224,7 @@ void reset_handler(void)
 
 	__asm__("MSR msp, %0" : : "r"(&_stack));
 
-	for (src = &_etext, dest = &_data; dest < &_edata; src++, dest++)
+	for (src = &__exidx_end, dest = &_data; dest < &_edata; src++, dest++)
 		*dest = *src;
 
 	while (dest < &_ebss)