alloc on write paging, -O3 compile works, 'volatile' is the story of my life

1 files changed, 16 insertions, 8 deletions

diff --git a/src/arch/amd64/cpu/idt.c b/src/arch/amd64/cpu/idt.c
index c286199..3e98b55 100644
--- a/src/arch/amd64/cpu/idt.c
+++ b/src/arch/amd64/cpu/idt.c
@@ -5,6 +5,7 @@
 #include "idt.h"
 #include "backtrace.h"
 #include "debugger.h"
+#include "../paging.h"
 #include "../bindings.h"
 #include "../drivers/pic.h"
 
@@ -72,6 +73,10 @@ void idt_init(void) {
 	__asm__ volatile ("lidt %0" : : "m"(idtr));
 }
 
+#define EX_DEBUG        0x01
+#define EX_BREAKPOINT   0x03
+#define EX_PAGE_FAULT   0x0e
+
 // Intel manual vol 3 ch 6.3.1
 char *EXCEPTIONS[] = {
 	"Division Error",
@@ -109,27 +114,30 @@ char *EXCEPTIONS[] = {
 };
 
 void idt_exception_handler(uint64_t exception, uint64_t code, struct isr_regs *state) {
+	uint64_t cr2;
+
 	switch (exception) {
-	case 0x01: // debug
+	case EX_DEBUG: // debug
 		debugger(state, DEBUG_DBG);
 		return;
-	case 0x03: // breakpoint
+	case EX_BREAKPOINT: // breakpoint
 		debugger(state, DEBUG_INT3);
 		return;
+	case EX_PAGE_FAULT:
+		// page faults store the offending address in cr2
+		__asm__ volatile ("mov %%cr2, %0" : "=r"(cr2));
+		if (!kload_page((void *)cr2))
+			return;
 	}
 
 	kputs("\n\n!!! EXCEPTION !!!\n");
 	kprintf("0x%02lX %s\n", exception, EXCEPTIONS[exception]);
 	kprintf("Error code 0x%lX\n", code);
 
-
-	// page faults store the offending address in cr2
-	if (exception == 0x0E) {
-		uint64_t cr2;
-		__asm__ volatile ("mov %%cr2, %0" : "=r"(cr2));
+	if (exception == EX_PAGE_FAULT) {
 		kprintf("Page fault address: 0x%lX\n", cr2);
 	}
-	
+
 	kputs("\n");
 
 	log_backtrace_ex((void *)state->rip, (void *)state->rbp);