higher half in x86_64

kernel is now located at -2GB
heap blocks are aligned on block size
paging will allocate new page tables on heap

1 files changed, 25 insertions, 30 deletions

diff --git a/kernel/src/mem/paging.c b/kernel/src/mem/paging.c
index 19a2c3a..f714f66 100644
--- a/kernel/src/mem/paging.c
+++ b/kernel/src/mem/paging.c
@@ -1,17 +1,15 @@
 #include <types.h>
 #include <paging.h>
 
+#include <heap.h>
 #include <libk/stdio.h>
-#include <debug.h>
+#include <kernel_vma.h>
 
 void load_pt_lvl4(uint64_t*);
 
 __attribute__((aligned(4096))) uint64_t page_table_lvl4[512];
 __attribute__((aligned(4096))) uint64_t page_table_lvl3[512];
-__attribute__((aligned(4096))) uint64_t page_table_lvl2_0[512];
-__attribute__((aligned(4096))) uint64_t page_table_lvl2_1[512];
-__attribute__((aligned(4096))) uint64_t page_table_lvl2_2[512];
-__attribute__((aligned(4096))) uint64_t page_table_lvl2_3[512];
+__attribute__((aligned(4096))) uint64_t page_table_lvl2[512];
 
 void map_addr(uint64_t virt, uint64_t phys, uint32_t flags)
 {
@@ -24,38 +22,35 @@ void map_addr(uint64_t virt, uint64_t phys, uint32_t flags)
 	size_t pt_lvl2_i = (virt >> 21) % 0x200; // 2mb entry
 //	size_t pt_lvl1_i = (virt >> 12) % 0x200; // 4kb entry
 
-	// first 4gb
-	if (pt_lvl4_i == 0) {
-		switch(pt_lvl3_i) {
-			case 0:
-				page_table_lvl2_0[pt_lvl2_i] = phys | flags;
-				break;
-			case 1:
-				page_table_lvl2_1[pt_lvl2_i] = phys | flags;
-				break;
-			case 2:
-				page_table_lvl2_2[pt_lvl2_i] = phys | flags;
-				break;
-			case 3:
-				page_table_lvl2_3[pt_lvl2_i] = phys | flags;
-				break;
-		}
+	uint64_t* pt_lvl3 = (uint64_t*)(page_table_lvl4[pt_lvl4_i] + KERNEL_VMA);
+	if (!((uint64_t)pt_lvl3 & FLAG_PRESENT)) {
+		pt_lvl3 = (uint64_t*)kalloc(4096);
+		page_table_lvl4[pt_lvl4_i] = ((uint64_t)pt_lvl3 - KERNEL_VMA) | flags;
+	} else {
+		pt_lvl3 = (uint64_t*)((uint64_t)pt_lvl3 - (uint64_t)pt_lvl3 % 4096);
 	}
+
+	uint64_t* pt_lvl2 = (uint64_t*)(pt_lvl3[pt_lvl3_i] + KERNEL_VMA);
+	if (!((uint64_t)pt_lvl2 & FLAG_PRESENT)) {
+		pt_lvl2 = (uint64_t*)kalloc(4096);
+		pt_lvl3[pt_lvl3_i] = ((uint64_t)pt_lvl2 - KERNEL_VMA) | flags;
+	} else {
+		pt_lvl2 -= (uint64_t)pt_lvl2 % 4096;
+	}
+
+	pt_lvl2[pt_lvl2_i] = virt | flags;
 }
 
 void init_paging(void)
 {
-	page_table_lvl4[0] = (uint64_t)page_table_lvl3   + FLAG_PRESENT + FLAG_WRITABLE + FLAG_USER - KERNEL_VMA;
-	page_table_lvl3[0] = (uint64_t)page_table_lvl2_0 + FLAG_PRESENT + FLAG_WRITABLE + FLAG_USER - KERNEL_VMA;
-	page_table_lvl3[1] = (uint64_t)page_table_lvl2_1 + FLAG_PRESENT + FLAG_WRITABLE + FLAG_USER - KERNEL_VMA;
-	page_table_lvl3[2] = (uint64_t)page_table_lvl2_2 + FLAG_PRESENT + FLAG_WRITABLE + FLAG_USER - KERNEL_VMA;
-	page_table_lvl3[3] = (uint64_t)page_table_lvl2_3 + FLAG_PRESENT + FLAG_WRITABLE + FLAG_USER - KERNEL_VMA;
-
-	// higher half map first 6mb
-	for (size_t i = 0; i < 3; i++) {
-		map_addr(KERNEL_VMA + PAGE_SIZE * i, 0x00000000 + PAGE_SIZE * i, FLAG_PRESENT + FLAG_WRITABLE + FLAG_USER + FLAG_HUGE);
+	page_table_lvl4[511] = (uint64_t)page_table_lvl3 + FLAG_PRESENT + FLAG_WRITABLE + FLAG_USER - KERNEL_VMA;
+	page_table_lvl3[510] = (uint64_t)page_table_lvl2 + FLAG_PRESENT + FLAG_WRITABLE + FLAG_USER - KERNEL_VMA;
+	// 16mb kernel + 32mb heap
+	for (size_t i = 0; i < 24; i++) {
+		page_table_lvl2[i] = (uint64_t)0x0 + PAGE_SIZE * i + FLAG_PRESENT + FLAG_WRITABLE + FLAG_USER + FLAG_HUGE;
 	}
 
+
 	load_pt_lvl4(page_table_lvl4);
 }