Add simple stack trace to exception handler

src/kernel/boot.s

@@ -19,6 +19,9 @@ _start:
 	cli
 
 	mov rsp, stack_end
+	push 0 ; signal end of stack with 0 return address
+
+	mov rbp, rsp
 	extern kernel_main
 	call kernel_main
 
@@ -40,6 +43,7 @@ interrupts_disable:
 	ret
 
 section .bss
+align 0x100
 stack_begin:
 	resb 0x4000 ; 16KiB stack space
 stack_end:

src/kernel/debug.s

@@ -10,3 +10,20 @@ global _halt
 _halt:
 	hlt
 	jmp _halt
+
+
+global get_frame
+get_frame:
+	mov rcx, rbp
+
+.loop:
+	mov rax, [rcx + 8]
+	mov rcx, [rcx]
+	cmp rdi, 0
+	je .done
+
+	sub rdi, 1
+	jmp .loop
+
+.done:
+	ret

src/kernel/interrupts.cpp

@@ -208,6 +208,8 @@ struct registers
 
 #define print_reg(name, value) cons->printf("         %s: %lx\n", name, (value));
 
+extern "C" uint64_t get_frame(int frame);
+
 void
 isr_handler(registers regs)
 {
@@ -277,6 +279,15 @@ isr_handler(registers regs)
 		print_reg(" ef", regs.eflags);
 		print_reg("esp", regs.user_esp);
 		print_reg(" ss", regs.ss);
+
+		cons->puts("\n");
+
+		int frame = 0;
+		uint64_t bp = get_frame(0);
+		while (bp) {
+			cons->printf("    frame %2d: %lx\n", frame, bp);
+			bp = get_frame(++frame);
+		}
 		while(1) asm("hlt");
 	}
 

src/kernel/main.cpp

@@ -50,6 +50,10 @@ init_console(const popcorn_data *header)
 	log::enable(logs::devices, log::level::debug);
 }
 
+void do_error_3() { int x = 1 / 0; }
+void do_error_2() { do_error_3(); }
+void do_error_1() { do_error_2(); }
+
 void
 kernel_main(popcorn_data *header)
 {
@@ -80,7 +84,7 @@ kernel_main(popcorn_data *header)
 	log::info(logs::boot, "CPU Family %x Model %x Stepping %x",
 			cpu.family(), cpu.model(), cpu.stepping());
 
-	// int x = 1 / 0;
+	// do_error_1();
 	// __asm__ __volatile__("int $15");
 
 	g_console.puts("boogity!");