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//! CPU exception handler
const kata_memory = @import("../kata/memory.zig");
const memory = @import("../asm/memory.zig");
const panic = @import("panic.zig");
const sensei = @import("../kata/sensei/sensei.zig");
const serial = @import("../drivers/serial/serial.zig");
const types = @import("types.zig");
const NAMES = [_][]const u8{
"Division By Zero",
"Debug",
"Non-Maskable Interrupt",
"Breakpoint",
"Overflow",
"Bound Range Exceeded",
"Invalid Opcode",
"Device Not Available",
"Double Fault",
"Coprocessor Segment Overrun",
"Invalid TSS",
"Segment Not Present",
"Stack-Segment Fault",
"General Protection Fault",
"Page Fault",
"Reserved",
"x87 Floating-Point Exception",
"Alignment Check",
"Machine Check",
"SIMD Floating-Point Exception",
"Virtualization Exception",
"Control Protection Exception",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Hypervisor Injection Exception",
"VMM Communication Exception",
"Security Exception",
"Reserved",
};
var in_exception: bool = false;
export fn exception_handler(frame_ptr: u64) void {
const frame = @as(*types.ExceptionFrame, @ptrFromInt(frame_ptr));
// Prevent infinite recursion if exception handler itself faults
if (in_exception) {
serial.print("NESTED EXCEPTION - HALTING\n");
while (true) {
asm volatile ("cli; hlt");
}
}
in_exception = true;
// Handle page faults - check for stack growth
if (frame.int_num == 14) {
const cr2 = memory.read_page_fault_address();
const is_not_present = (frame.error_code & 1) == 0;
const is_rsvd = (frame.error_code & 8) != 0;
// Check if fault is in user stack region (demand paging)
if (sensei.get_current_kata()) |kata| {
if (cr2 >= kata.user_stack_bottom and cr2 < kata.user_stack_top and is_not_present and !is_rsvd) {
if (kata_memory.grow_stack(kata, cr2)) {
in_exception = false;
return;
}
}
}
}
serial.print("\n!!! EXCEPTION: ");
if (frame.int_num < NAMES.len) {
serial.print(NAMES[frame.int_num]);
} else {
serial.print("Unknown");
}
serial.print(" !!!\n");
serial.printf("Vector: {x}\n", .{frame.int_num});
serial.printf("Error Code: {x}\n", .{frame.error_code});
serial.printf("RIP: {x}\n", .{frame.rip});
serial.printf("CS: {x}\n", .{frame.cs});
serial.printf("RFLAGS: {x}\n", .{frame.rflags});
serial.printf("RSP: {x}\n", .{frame.rsp});
serial.printf("SS: {x}\n", .{frame.ss});
if (frame.int_num == 14) {
const cr2 = memory.read_page_fault_address();
serial.printf("CR2 (fault addr): {x}\n", .{cr2});
if (sensei.get_current_kata()) |kata| {
serial.printf("Stack: bottom={x} committed={x} top={x}\n", .{ kata.user_stack_bottom, kata.user_stack_committed, kata.user_stack_top });
serial.printf("Kata: id={x} PT={x}\n", .{ kata.id, kata.page_table });
}
serial.print("Fault type: ");
if ((frame.error_code & 1) == 0) {
serial.print("Page not present");
} else {
serial.print("Protection violation");
}
if ((frame.error_code & 2) != 0) {
serial.print(", Write");
} else {
serial.print(", Read");
}
if ((frame.error_code & 4) != 0) {
serial.print(", User mode");
} else {
serial.print(", Kernel mode");
}
if ((frame.error_code & 8) != 0) {
serial.print(", RESERVED BIT SET");
}
serial.print("\n");
serial.printf("CR3 (page table): {x}\n", .{memory.read_page_table_base()});
}
serial.print("\nRegisters:\n");
serial.printf("RAX: {x} RBX: {x}\n", .{ frame.rax, frame.rbx });
serial.printf("RCX: {x} RDX: {x}\n", .{ frame.rcx, frame.rdx });
serial.printf("RSI: {x} RDI: {x}\n", .{ frame.rsi, frame.rdi });
serial.printf("RBP: {x}\n", .{frame.rbp});
serial.printf("R8: {x} R9: {x}\n", .{ frame.r8, frame.r9 });
serial.printf("R10: {x} R11: {x}\n", .{ frame.r10, frame.r11 });
serial.printf("R12: {x} R13: {x}\n", .{ frame.r12, frame.r13 });
serial.printf("R14: {x} R15: {x}\n", .{ frame.r14, frame.r15 });
panic.collapse(if (frame.int_num < NAMES.len) NAMES[frame.int_num] else "Unknown Exception", null);
}
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