Fixed annoying bug with bootup when compiling with new GCC.

The problem was the BSS segment was not aligned with size 4,
thus the routine to clear the BSS segment was infinite looping,
clobbering everything in it's wake until it ran off the memory edge and
caused a hard fault.

This commit does a couple of things.

  1. Fixes the alignment issue in the linker script
  2. Panics if the bss/data segments are not aligned properly
  3. Makes the logging the _first_ thing to initialize. Much easier to
     debug that way!

3 files changed, 61 insertions, 30 deletions

diff --git a/src/kern/init.c b/src/kern/init.c
index 9869749..4c2bfcd 100644
--- a/src/kern/init.c
+++ b/src/kern/init.c
@@ -36,32 +36,55 @@ extern uint32_t INIT_5_END;
 extern uint32_t INIT_6_END;
 extern uint32_t INIT_7_END;
 
-init0()
+init2()
 {
-  /* Enable a higher clock speed. This is the first thing we do
-   * beacuse it will boost the boot up time. */
-  set_system_clock_MHz(80);
-}
+  volatile uint32_t bss_start_ptr = (uint32_t) &BSS_START;
+  volatile uint32_t bss_end_ptr = (uint32_t) &BSS_END;
+  volatile uint32_t init_data_values_ptr = (uint32_t) &INIT_DATA_VALUES;
+  volatile uint32_t data_segment_start_ptr = (uint32_t) &DATA_SEGMENT_START;
+  volatile uint32_t data_segment_stop_ptr = (uint32_t) &DATA_SEGMENT_STOP;
+
+  if ((data_segment_start_ptr | data_segment_start_ptr) & 3) {
+    panic(".data segment not aligned with sizeof(uint32_t)!\n");
+  }
+
+  if (init_data_values_ptr & 3) {
+    panic("init data values pointer not aligned with sizeof(uint32_t)!\n");
+  }
+
+  if ((bss_start_ptr | bss_end_ptr) & 3) {
+    panic(".bss data segment not aligned with sizeof(uint32_t)!\n");
+  }
+  
+  klogf("Copy data segments from flash ... \n");
 
-init1()
-{
   /* Next, we'll copy the data sections from flash to ram. */
   uint32_t* src;
   uint32_t* dest;
 
+  klogf("  .data ...\n");
+  klogf("    set  (%p - %p)\n", &DATA_SEGMENT_START, &DATA_SEGMENT_STOP);
+  klogf("    from (%p)\n", &INIT_DATA_VALUES);
+
   src = &INIT_DATA_VALUES;
   dest = &DATA_SEGMENT_START;
 
   /* Copy the values from flash into the data segment. */
-  while (dest != &DATA_SEGMENT_STOP) {
+  while (dest < &DATA_SEGMENT_STOP) {
     *(dest++) = *(src++);
   }
 
+  klogf("  .bss ...\n");
+  klogf("    clear (%p - %p)\n", &BSS_START, &BSS_END);
+
   /* Everything in the BSS segment is set to zero. */
   dest = &BSS_START;
+
   while (dest != &BSS_END) {
     *(dest++) = 0;
   }
+
+  klogf("Done!\n");
 }
 
 init3()
@@ -84,11 +107,20 @@ void run_init_routines()
       &INIT_7_END,
   };
 
+  initialize_logging();
+
   void (**initfn)();
+
+  /* Enable a higher clock speed. This is the first thing we do
+   * beacuse it will boost the boot up time. */
+  set_system_clock_MHz(80);
+
+  klogf("Init Level 0 ...\n");
   for (initfn = &INIT_ROUTINES_FLASH_START; initfn < &INIT_ROUTINES_FLASH_STOP;
        ++initfn) {
     while (initfn == init_boundaries[initlevel] && initlevel < INIT_LEVEL_7) {
       ++initlevel;
+      klogf("Init Level %d ...\n", initlevel);
     }
 
     (*initfn)();
@@ -105,6 +137,7 @@ void run_init_routines()
  */
 _Noreturn void on_reset()
 {
+
   initlevel = INIT_LEVEL_0;
 
   run_init_routines();
diff --git a/src/kern/log.c b/src/kern/log.c
index e9bd424..e6bbec6 100644
--- a/src/kern/log.c
+++ b/src/kern/log.c
@@ -12,12 +12,14 @@ void setup_usart2(uint32_t baud_rate);
 /** This module requires an initialization routine. This is a level2 routine,
  * so anything running at level3 or lower is guaranteed to have access
  * to the klong. */
-init2()
+void initialize_logging()
 {
   setup_usart2(115200);
   regset(USART2.c_r1, usart_txeie, 1);
   regset(USART2.c_r1, usart_rxneie, 1);
   usart_set_enabled(&USART2, USART_ENABLE_TX | USART_ENABLE_RX);
+
+  klogf("Logging has been initalized!\n");
 }
 
 void klogf(const char* fmt, ...)
diff --git a/src/kern/panic.c b/src/kern/panic.c
index de1d143..e005bcc 100644
--- a/src/kern/panic.c
+++ b/src/kern/panic.c
@@ -15,30 +15,26 @@ _Noreturn void panic(const char* fmt, ...)
   uint32_t base[0];
   disable_all_interrupts();
 
-  if (get_system_init_level() > INIT_LEVEL_2) {
-    va_list l;
-    va_start(l, fmt);
+  va_list l;
+  va_start(l, fmt);
 
-    kerr_logf("** Kernel Panic! **\n");
-    kerr_vlogf(fmt, l);
-    kerr_logf("** Stack:\n");
+  kerr_logf("** Kernel Panic! **\n");
+  kerr_vlogf(fmt, l);
+  kerr_logf("** Stack:\n");
 
-    int i = 0;
-    for (; i < 20 && &base[i] != (void*)STACK_TOP; ++ i) {
-      kerr_logf(" (%p) %p\n", &base[i], base[i]);
-    }
+  int i = 0;
+  for (; i < 20 && &base[i] != (void*)STACK_TOP; ++ i) {
+    kerr_logf(" (%p) %p\n", &base[i], base[i]);
+  }
+
+  set_system_clock_MHz(4); /* reduce power usage while we do nothing. */
+  gpio_reserved_pin_t pin3 = get_sysled();
 
-    set_system_clock_MHz(4); /* reduce power usage while we do nothing. */
-    for(;;);
-  } else {
-    set_system_clock_MHz(4); /* reduce power usage while we do nothing. */
-    gpio_reserved_pin_t pin3 = get_sysled();
-    for (;;) {
-      set_gpio_pin_high(pin3);
-      delay(100000);
-      set_gpio_pin_low(pin3);
-      delay(100000);
-    }
+  for (;;) {
+    set_gpio_pin_high(pin3);
+    delay(100000);
+    set_gpio_pin_low(pin3);
+    delay(100000);
   }
 }
 #endif