ARM: Cleanup of port support code.

This also implements the fault handler correctly now, and cleans up the
exception handling. Seems a lot more stable now, no unexpected panics or
faults happening anymore.

headers/private/kernel/arch/arm/arch_cpu.h

@@ -12,6 +12,7 @@
 
 /* raw exception frames */
 struct iframe {
+	uint32 spsr;
 	uint32 r0;
 	uint32 r1;
 	uint32 r2;
@@ -25,10 +26,11 @@ struct iframe {
 	uint32 r10;
 	uint32 r11;
 	uint32 r12;
-	uint32 r13;
-	uint32 lr;
+	uint32 usr_sp;
+	uint32 usr_lr;
+	uint32 svc_sp;
+	uint32 svc_lr;
 	uint32 pc;
-	uint32 cpsr;
 } _PACKED;
 
 typedef struct arch_cpu_info {
@@ -40,6 +42,20 @@ extern int arch_mmu_type;
 extern int arch_platform;
 extern int arch_machine;
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern addr_t arm_get_far(void);
+extern int32 arm_get_fsr(void);
+
+extern int mmu_read_c1(void);
+extern int mmu_write_c1(int val);
+
+#ifdef __cplusplus
+};
+#endif
+
 #endif	// !_ASSEMBLER
 
 #endif	/* _KERNEL_ARCH_ARM_CPU_H */