make stack section NOBITS

Signed-off-by: smallkirby <[email protected]>

ymir/arch/x86/interrupt.zig

@@ -78,6 +78,8 @@ pub fn init() void {
     }
 
     // Detailed handling for page faults.
+    // TODO: For page fault, we have to allocate an interrupt stack,
+    //  register it to the TSS, and switch to it because it can be stack overflow.
     registerHandler(page_fault, unhandledFaultHandler);
 
     idt.init();

ymir/linker.ld

@@ -1,24 +1,50 @@
 KERNEL_VADDR_BASE = 0xFFFFFFFF80000000;
 KERNEL_VADDR_TEXT = 0xFFFFFFFF80100000;
 
+STACK_SIZE = 0x5000;
+
+PHDRS {
+    text PT_LOAD;
+    rodata PT_LOAD;
+    data PT_LOAD;
+    bss PT_LOAD;
+
+    __stackguard_upper PT_LOAD FLAGS(4);
+    __stack PT_LOAD FLAGS(6);
+    __stackguard_lower PT_LOAD FLAGS(4);
+}
+
 SECTIONS {
     . = KERNEL_VADDR_TEXT;
 
     .text ALIGN(4K) : AT (ADDR(.text) - KERNEL_VADDR_BASE) {
         *(.text)
         *(.ltext)
-    }
+    } :text
 
     .rodata ALIGN(4K) : AT (ADDR(.rodata) - KERNEL_VADDR_BASE) {
         *(.rodata)
-    }
+    } :rodata
 
     .data ALIGN(4K) : AT (ADDR(.data) - KERNEL_VADDR_BASE) {
         *(.data)
-    }
+    } :data
 
     .bss ALIGN(4K) : AT (ADDR(.bss) - KERNEL_VADDR_BASE) {
         *(COMMON)
         *(.bss)
-    }
+    } :bss
+
+    __stackguard_upper ALIGN(4K) (NOLOAD) : AT (. - KERNEL_VADDR_BASE) {
+        . += 4K;
+    } :__stackguard_upper
+
+    __stack ALIGN(4K) (NOLOAD) : AT (. - KERNEL_VADDR_BASE) {
+        . += STACK_SIZE;
+    } :__stack
+
+    __stackguard_lower ALIGN(4K) (NOLOAD) : AT (. - KERNEL_VADDR_BASE) {
+        __stackguard_lower = .;
+        . += 4K;
+    } :__stackguard_lower
 }

ymir/main.zig

@@ -19,12 +19,8 @@ const page_size = mem.page_size;
 pub const panic = ymir.panic.panic_fn;
 pub const std_options = klog.default_log_options;
 
-/// Size in bytes pages of the kernel stack excluding the guard page.
-const kstack_size = page_size * 5;
-/// Kernel stack.
-/// The first page is used as a guard page.
-/// TODO: make the guard page read-only.
-var kstack: [kstack_size + page_size]u8 align(page_size) = [_]u8{0} ** (kstack_size + page_size);
+/// Guard page placed below the kernel stack.
+extern const __stackguard_lower: [*]const u8;
 
 /// Kernel entry point called by surtr.
 /// The function switches stack from the surtr stack to the kernel stack.
@@ -33,7 +29,7 @@ export fn kernelEntry() callconv(.Naked) noreturn {
         \\movq %[new_stack], %%rsp
         \\call kernelTrampoline
         :
-        : [new_stack] "r" (@intFromPtr(&kstack) + kstack_size + page_size),
+        : [new_stack] "r" (@intFromPtr(&__stackguard_lower) - 0x10),
     );
 }