nrf: port: move the heap after .uninitialized

xobs · xobs · commit 192bb155fafb · 2020-05-18T11:52:20.000+08:00
Previously, it was placed following .bss.  However, now that there is a
new section after .bss, the heap must be moved forward.

Signed-off-by: Sean Cross &lt;sean@xobs.io&gt;
diff --git a/ports/nrf/supervisor/port.c b/ports/nrf/supervisor/port.c
@@ -177,23 +177,27 @@ void reset_cpu(void) {
     NVIC_SystemReset();
 }
 
+// The uninitialized data section is placed directly after BSS, under the theory
+// that Circuit Python has a lot more .data and .bss than the bootloader.  As a
+// result, this section is less likely to be tampered with by the bootloader.
+extern uint32_t _euninitialized;
+
 uint32_t *port_heap_get_bottom(void) {
-    return port_stack_get_limit();
+    return &_euninitialized;
 }
 
 uint32_t *port_heap_get_top(void) {
     return port_stack_get_top();
 }
 
 uint32_t *port_stack_get_limit(void) {
-    return &_ebss;
+    return &_euninitialized;
 }
 
 uint32_t *port_stack_get_top(void) {
     return &_estack;
 }
 
-extern uint32_t _ebss;
 // Place the word to save just after our BSS section that gets blanked.
 void port_set_saved_word(uint32_t value) {
     _ebss = value;

Original file line number	Diff line number	Diff line change
`@@ -177,23 +177,27 @@ void reset_cpu(void) {`
`177`	`177`	`NVIC_SystemReset();`
`178`	`178`	`}`
`179`	`179`
	`180`	`+// The uninitialized data section is placed directly after BSS, under the theory`
	`181`	`+// that Circuit Python has a lot more .data and .bss than the bootloader. As a`
	`182`	`+// result, this section is less likely to be tampered with by the bootloader.`
	`183`	`+extern uint32_t _euninitialized;`
	`184`	`+`
`180`	`185`	`uint32_t *port_heap_get_bottom(void) {`
`181`		`- return port_stack_get_limit();`
	`186`	`+ return &_euninitialized;`
`182`	`187`	`}`
`183`	`188`
`184`	`189`	`uint32_t *port_heap_get_top(void) {`
`185`	`190`	`return port_stack_get_top();`
`186`	`191`	`}`
`187`	`192`
`188`	`193`	`uint32_t *port_stack_get_limit(void) {`
`189`		`- return &_ebss;`
	`194`	`+ return &_euninitialized;`
`190`	`195`	`}`
`191`	`196`
`192`	`197`	`uint32_t *port_stack_get_top(void) {`
`193`	`198`	`return &_estack;`
`194`	`199`	`}`
`195`	`200`
`196`		`-extern uint32_t _ebss;`
`197`	`201`	`// Place the word to save just after our BSS section that gets blanked.`
`198`	`202`	`void port_set_saved_word(uint32_t value) {`
`199`	`203`	`_ebss = value;`