From 241857a79e1a42e23ec29389862f39c92a5dc93e Mon Sep 17 00:00:00 2001
From: Lizzy Fleckenstein <lizzy@vlhl.dev>
Date: Wed, 27 Dec 2023 00:28:56 +0100
Subject: move debugger to separate file

---
 stage3/debug.c | 193 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 193 insertions(+)
 create mode 100644 stage3/debug.c

(limited to 'stage3/debug.c')

diff --git a/stage3/debug.c b/stage3/debug.c
new file mode 100644
index 0000000..0621dbd
--- /dev/null
+++ b/stage3/debug.c
@@ -0,0 +1,193 @@
+#include "fs.h"
+#include "font.h"
+#include "string.h"
+#include "halt.h"
+#include "debug.h"
+
+static str dbg_map = NILS;
+static str dbg_disas = NILS;
+
+static str exception[32] = {
+	S("Division Error"),
+	S("Debug"),
+	S("Non-maskable Interrupt"),
+	S("Breakpoint"),
+	S("Overflow"),
+	S("Bound Range Exceeded"),
+	S("Invalid Opcode"),
+	S("Device Not Available"),
+	S("Double Fault"),
+	S("Coprocessor Segment Overrun"),
+	S("Invalid TSS"),
+	S("Segment Not Present"),
+	S("Stack-Segment Fault"),
+	S("General Protection Fault"),
+	S("Page Fault"),
+	NILS,
+	S("x87 Floating-Point Exception"),
+	S("Alignment Check"),
+	S("Machine Check"),
+	S("SIMD Floating-Point Exception"),
+	S("Virtualization Exception"),
+	S("Control Protection Exception"),
+	NILS, NILS, NILS, NILS, NILS, NILS,
+	S("Hypervisor Injection Exception"),
+	S("VMM Communication Exception"),
+	S("Security Exception"),
+	NILS,
+};
+
+static void dump_frame(interrupt_frame *frame)
+{
+	print(S("rip = "));
+	print_hex(frame->rip);
+
+	if (dbg_map.data != nil) {
+		str entry = NILS;
+		str iter = dbg_map;
+		while (iter.len > 0) {
+			str line = str_walk(&iter, S("\n"));
+			line = str_eat(line, S(" "));
+			if (!str_start(line, S("0x")))
+				continue;
+			line = str_advance(line, 2);
+
+			u64 addr;
+			usize adv = str_parse_num(line, 16, &addr);
+			if (adv == 0)
+				continue;
+			line = str_advance(line, adv);
+
+			if (addr > frame->rip)
+				break;
+
+			line = str_eat(line, S(" "));
+			if (line.len > 0)
+				entry = line;
+		}
+
+		if (entry.len > 0) {
+			print(S(" in "));
+			print(entry);
+		}
+	}
+
+	if (dbg_disas.data != nil) {
+		str iter = dbg_disas;
+		while (iter.len > 0) {
+			str line = str_walk(&iter, S("\n"));
+			u64 addr;
+			if (!str_parse_num(str_eat(line, S(" ")), 16, &addr))
+				continue;
+			if (addr == frame->rip) {
+				print(S("\n"));
+				print(line);
+				break;
+			}
+		}
+	}
+
+	print(S("\n"));
+
+	struct {
+		u8 bit;
+		str name;
+	} flags[] = {
+		{  0, S("CF")  },
+		{  2, S("PF")  },
+		{  4, S("AF")  },
+		{  6, S("ZF")  },
+		{  7, S("SF")  },
+		{  8, S("TF")  },
+		{  9, S("IF")  },
+		{ 10, S("DF")  },
+		{ 11, S("OF")  },
+		{ 16, S("RF")  },
+		{ 17, S("VM")  },
+		{ 18, S("AC")  },
+		{ 19, S("VIF") },
+		{ 20, S("ID")  },
+	};
+
+	print(S("rflags = "));
+
+	usize f = 0;
+	for (usize i = 0; i < 63; i++) {
+		bool has_name = f < LEN(flags) && flags[f].bit == i;
+
+		if (frame->rflags & ((u64) 1 << i)) {
+			if (has_name)
+				print(flags[f].name);
+			else
+				print_dec(i);
+			print(S(" "));
+		}
+
+		if (has_name)
+			f++;
+	}
+
+	print(S("\n"));
+
+#define REG(X) print(S(#X)); if (S(#X).len == 2) print(S(" ")); print(S(" = ")); print_num_pad(frame->X, 16, 16, ' ');
+#define REGS(A, B) REG(A) print(S("    ")); REG(B) print(S("\n"));
+
+	REGS(rax, rbx)
+	REGS(rcx, rdx)
+	REGS(rsp, rbp)
+	REGS(rdi, rsi)
+	REGS(r8,  r9)
+	REGS(r10, r11)
+	REGS(r12, r13)
+	REGS(r14, r15)
+	REGS(ss, cs)
+
+#undef REG
+#undef REGS
+}
+
+void debug_exception(interrupt_frame *frame)
+{
+	// TODO: possible race condition due to printing here
+	// when exception happens in printing code itself
+
+	if (exception[frame->which].data == nil) {
+		print(S("Unknown Exception "));
+		print_dec(frame->which);
+	} else {
+		print(exception[frame->which]);
+	}
+	print_char('\n');
+
+	if (frame->which == 14) {
+		str bits[8] = {
+			S("present"),
+			S("write"),
+			S("user"),
+			S("reserved_write"),
+			S("instruction_fetch"),
+			S("protection_key"),
+			S("shadow_stack"),
+			S("software_guard_extensions"),
+		};
+
+		u8 err = frame->error_code;
+
+		for (int i = 0; i < 8; i++) {
+			print(bits[i]); print(S(" = ")); print((err & 1) ? S("true\n") : S("false\n"));
+			err >>= 1;
+		}
+	} else {
+		print(S("error_code = ")); print_dec(frame->error_code); print_char('\n');
+	}
+
+	dump_frame(frame);
+	freeze();
+}
+
+void debug_init()
+{
+	print(S("loading kernel debug info...\n"));
+	dbg_map = fs_read(S("dbg/kernel.map"));
+	dbg_disas = fs_read(S("dbg/kernel.dis.asm"));
+}
-- 
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