Initial commit.

1 files changed, 92 insertions, 0 deletions

diff --git a/kernel/entry.c b/kernel/entry.c
new file mode 100644
index 0000000..d040cfb
--- /dev/null
+++ b/kernel/entry.c
@@ -0,0 +1,92 @@
+#include "types.h"
+
+extern void addr_phys;
+extern void addr_virt;
+extern void addr_virt_end;
+extern void addr_load_virt;
+extern void addr_load_virt_end;
+
+extern void entry_stack;
+
+extern uint32_t entry_pagedir[];
+extern uint32_t entry_pagetable_low[];
+extern uint32_t entry_pagetable_high[];
+
+extern void main();
+
+asm(
+	".globl entry\n"
+	"entry:\n"
+	"mov $entry_stack_top,%esp\n"
+	"push %eax\n"
+	"call entry_main\n"
+);
+
+void entry_serial_out(char* str);
+
+void entry_main(uint32_t mb_magic, void* mb_info) {
+	entry_serial_out("entry_main()\n");
+	if(mb_magic != 0x2badb002) {
+		entry_serial_out("Multiboot magic word is wrong!\n");
+		goto stop;
+	}
+	entry_serial_out("Multiboot ok\n");
+	
+	// TODO: Copy multiboot information.
+	
+	// Create initial page tables.
+	for(unsigned int i = 0; i < 1024; i++) {
+		// Clear page directory.
+		entry_pagedir[i] = 0;
+		
+		// Identity mapping of the current code.
+		entry_pagetable_low[i] = ((uint32_t)&addr_phys & 0xffc00000) | (i << 12) | 0x003;
+		
+		// Map kernelspace.
+		if((i << 12) < ((uint32_t)&addr_virt_end & 0x003ff000 )) {
+			entry_pagetable_high[i] = ((uint32_t)&addr_load_virt + (i << 12)) | 0x003;
+		} else {
+			entry_pagetable_high[i] = 0;
+		}
+	}
+	
+	entry_pagedir[(uint32_t)&addr_phys >> 22] = (uint32_t)&entry_pagetable_low | 0x003;
+	entry_pagedir[(uint32_t)&addr_virt >> 22] = (uint32_t)&entry_pagetable_high | 0x003;
+	
+	// Mapping stack to top without creating another page directory.
+	entry_pagetable_high[1023] = (uint32_t)&entry_stack | 0x003;
+	entry_pagedir[1023] = (uint32_t)&entry_pagetable_high | 0x003;
+	
+	// Enable paging.
+	asm volatile(
+		"mov %0, %%cr3\n"
+		"mov %%cr0, %0\n"
+		"or $0x80000000, %0\n"
+		"mov %0, %%cr0\n"
+		: : "r" (&entry_pagedir) : "%0"
+	);
+	
+	// TODO: Check that segments are loaded and mapped right.
+	
+	// Call main() in virtual memory.
+	main();
+	
+	stop:
+	entry_serial_out("Halting.\n");
+	asm volatile(
+		"cli\n"
+		"hlt\n"
+	);
+	while(1);
+}
+
+#define outb(port, value) asm volatile("out %b0,%w1" : : "a" (value), "d" (port));
+
+void entry_serial_out(char* str) {
+	while(*str) {
+		if(*str == '\n') {
+			outb(0x3f8, '\r');
+		}
+		outb(0x3f8, *str++);
+	}
+}