Handout

kernel/memory/pagefault.cc

@@ -0,0 +1,49 @@
+
+#include "memory/pagefault.h"
+
+#include "arch/core.h"
+#include "arch/core_interrupt.h"
+#include "arch/idt.h"
+#include "debug/output.h"
+#include "memory/config.h"
+
+namespace PageFault {
+
+union ErrorCode {
+	uint32_t value;
+	struct {
+		uint32_t present : 1;	   ///< was the page present?
+		uint32_t write : 1;		   ///< was the access a write?
+		uint32_t usermode : 1;	   ///< was it in user mode?
+		uint32_t reserved : 1;	   ///< reserved bit violation
+		uint32_t instruction : 1;  ///< was it caused by instruction fetch?
+		uint32_t : 0;
+	} __attribute__((packed));
+
+	explicit ErrorCode(uint32_t value) : value(value) {}
+};
+
+assert_size(ErrorCode, 4);
+
+[[gnu::interrupt]] static void pagefault_handler(InterruptContext *context,
+												 uint64_t err) {
+	PageFault::ErrorCode error(err);
+	// Get the faulting address
+	uintptr_t virt;
+	asm volatile("mov %%cr2, %0" : "=r"(virt));
+	DBG << "Page fault at " << hex << virt << dec << endl;
+
+	// show page fault message
+	DBG << "PAGEFAULT: " << hex << virt << ":" << dec << error.present
+		<< error.write << error.usermode << error.reserved << error.instruction
+		<< " @ " << hex << context->ip << endl;
+
+	Core::die();
+}
+
+void init() {
+	IDT::set(Core::Interrupt::Vector::PAGE_FAULT,
+			 IDT::InterruptDescriptor::ReturningWithError(pagefault_handler));
+}
+
+}  // namespace PageFault