SYSCALL cleanup and ivt rewrite

[cortex-from-scratch] / ivt.c

diff --git a/ivt.c b/ivt.c
index 0e2d1f2..0d3b8ff 100644 (file)
--- a/ivt.c
+++ b/ivt.c
@@ -34,9 +34,8 @@
 
 /* 
  * These values are pushed on the stack just before
- * entering the ISR. Normally, this would require
- * assembly or inline assembly code. I use a so-called
- * 'naked function' __attribute__ ((interrupt)) which
+ * entering the ISR. I use a so-called
+ * 'naked function' __attribute__ ((naked)) which
  * gives me a little bit more control over the caller
  *
  * The following register are pushed to the stack
@@ -53,7 +52,7 @@ struct interrupt_frame {
        uint32_t lr;
        uint32_t pc;
        uint32_t psr; // N-4
-};
+} frame;
 
 /* 
  * Vector table, each entry contains an interrupt
@@ -64,7 +63,7 @@ struct interrupt_frame {
  * */
 uint32_t __attribute__((aligned(0x100))) ivt[92];
 
-/* Each message corresponds to each and every exception. */
+/* Each message corresponds to an exception in the vector table. */
 char * exception_message(uint8_t intnr) {
 
 char * messages[] = {
@@ -98,70 +97,47 @@ if (intnr < 20) // TODO: strlen
        return messages[intnr];
 
 return "UNKNOWN";
+
 }
 
+/* Function to set entries of the interrupt vector table 
+ * */
 void ivt_set_gate(unsigned char num, void * isr(), short pri) {
 
        ivt[num] = (uint32_t) isr;
-//     if (num <= 32)
-//             *NVIC_ISER0 = (1 << ((uint32_t)(num) & 0x1F));
+       //if (num <= 32)
+       //*NVIC_ISER0 = (1 << ((uint32_t)(num) & 0x1F));
        /* TODO: Priorities */
 }
 
 
-/* Dummy interrupt: comment out the comment to use a naked
- * function */
+/* Dummy interrupt: shows the saved stack registers and then
+ * halts */
+__attribute__ ((naked)) void * dummy_isr(void) {
 
-struct interrupt_frame * frame;
+       uint32_t * current_sp;
 
-//__attribute__ ((interrupt)) 
-void * dummy_isr( struct interrupt_frame * f ) {
+       /* Test whether system call was invoked from supervisor (use MSP) or
+        * user (use PSP) mode */
+       asm volatile (
+       "tst lr, #4" "\n\t"
+       "ite eq" "\n\t"
+       "mrseq %0, msp" "\n\t"
+       "mrsne %0, psp" : "=r" (current_sp));
 
-       //uint32_t link_register = 0;
-       //asm ("mov %0, #33" : "=r" (lp));
-       
-       /* Check Link Register:
-        * If you ever need to debug these: here are the most common
-        * values
-        * 0xFFFFFFF1: return to handler mode (nested interrupts
-        * 0xFFFFFFF9: return to thread mode using main stack
-        * 0xFFFFFFFD: return to thread mode using process stack */
-       // asm ("mov %0, lr" : "=r" (link_register));
-       // printf("%x\n", link_register);
-       // for(;;);
-
-//     asm volatile ("push {r0-r12}"); 
-//     int * stack;
-//     asm volatile ("tst lr, #4" "\n\t" 
-//     "ite eq" "\n\t"
-//     "mrseq %0, msp" "\n\t" 
-//     "mrsne r0, psp" : "=r" (stack));
-//     
-//     printf("STACK:  %x, %x,  %x, %x, %x", stack[32], stack[28], stack[24], stack[20], stack[16]);
-
-//     asm volatile ("CPSID f");
-
-//     uint32_t tmp = args[0];
-//     uint32_t tmp2 = args[1];
-//     printf("%x, %x\n", tmp, tmp2); 
-//     uint32_t tmp3 = args[2];
-//     uint32_t tmp4 = args[3];
-//     printf("%x, %x\n", tmp3, tmp4); 
-
-       struct interrupt_frame * frame = (struct interrupt_frame * )kalloc(get_kheap());
-       memcpy(frame, f, sizeof(struct interrupt_frame));
+       memcpy(&frame, current_sp, sizeof(struct interrupt_frame));
 
        uint8_t nr = *SCB_VTOR_ST & 0xFF;
        printf("EXCEPTION: %s\n", exception_message(nr));
-       printf("STACK TRACE:\n");
-       printf("R0:%p\n",frame->r0);
-       printf("R1:%p\n",frame->r1);
-       printf("R2:%p\n",frame->r2);
-       printf("R3:%p\n",frame->r3);
-       printf("R12:%p\n",frame->r12);
-       printf("LR:%p\n",frame->lr);
-       printf("PC:%p\n",frame->pc);
-       printf("PSR:%p\n",frame->psr);
+       printf("STACKFRAME:\n");
+       printf("R0:%p\n",frame.r0);
+       printf("R1:%p\n",frame.r1);
+       printf("R2:%p\n",frame.r2);
+       printf("R3:%p\n",frame.r3);
+       printf("R12:%p\n",frame.r12);
+       printf("LR:%p\n",frame.lr);
+       printf("PC:%p\n",frame.pc);
+       printf("PSR:%p\n",frame.psr);
        
        for(;;); 
 }