refactor(paging): move kernel pd and empty page

CMakeLists.txt

@@ -40,8 +40,8 @@ if (CMAKE_BUILD_TYPE STREQUAL "Debug")
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O0 -g")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O0 -g")
 elseif(CMAKE_BUILD_TYPE STREQUAL "Release")
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O")
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O2")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O2")
 endif()
 
 if (NOT DEFINED FDISK_BIN)

include/kernel/mem.h

@@ -107,7 +107,7 @@ void* ki_malloc(size_t size);
 
 void ki_free(void* ptr);
 
-#define KERNEL_PAGE_DIRECTORY_ADDR ((pd_t)0x00000000)
+#define KERNEL_PAGE_DIRECTORY_ADDR ((pd_t)0x00001000)
 
 void init_mem(void);
 

src/boot.s

@@ -111,37 +111,37 @@ setup_early_kernel_page_table:
 # set up early kernel page table
 
 # the early kernel page directory is located at physical
-# address 0x00000000, size 4k, and the empty page is at
-# 0x5000-0x5fff, so we fill the first 6KiB
+# address 0x00001000, size 4k, and the empty page is at
+# 0x0000-0x0fff, so we fill the first 6KiB
     movl $0x00000000, %eax
     movl $0x6000, %ecx
     call _fill_zero
 
 # map the first 16MiB identically
-# 0x0000-0x0fff: early kernel pd
-# 0x1000-0x4fff: pde 0 - 4
-    movl $0x00000000, %eax
-    movl $0x00001003, %ebx
+# 0x1000-0x1fff: early kernel pd
+# 0x2000-0x5fff: pde 0 - 4
+    movl $0x00001000, %eax
+    movl $0x00002003, %ebx
 _fill_pde_loop:
     movl %ebx, (%eax)
     addl $4, %eax
     addl $0x1000, %ebx
-    cmpl $0x5003, %ebx
+    cmpl $0x6003, %ebx
     jne _fill_pde_loop
 
 # then, create page tables
     movl $0x00000003, %eax
-    movl $0x00001000, %ecx
+    movl $0x00002000, %ecx
 
 _create_page_table_loop1:
     movl %eax, (%ecx)
     addl $4, %ecx
     addl $0x1000, %eax
-    cmpl $0x4ffc, %ecx
+    cmpl $0x5ffc, %ecx
     jle _create_page_table_loop1
 
 load_early_kernel_page_table:
-    movl $0x00000000, %eax
+    movl $0x00001000, %eax
     movl %eax, %cr3
 
     movl %cr0, %eax

src/kernel/hw/ata.cpp

@@ -145,7 +145,7 @@ size_t _ata_read(fs::special_node* sn, char* buf, size_t buf_size, size_t offset
         end = sn->data1 + sn->data2;
     offset %= 512;
     for (size_t i = start; i < end; ++i) {
-        (*ata_bus)->read_sector(b, i, 0);
+        (void)(*ata_bus)->read_sector(b, i, 0);
         size_t to_copy = 0;
         if (offset)
             to_copy = 512 - offset;

src/kernel/mem.cpp

@@ -21,8 +21,8 @@ mm_list* kernel_mms;
 
 // constant values
 
-#define EMPTY_PAGE_ADDR ((pptr_t)0x5000)
-#define EMPTY_PAGE_END ((pptr_t)0x6000)
+#define EMPTY_PAGE_ADDR ((pptr_t)0x0000)
+#define EMPTY_PAGE_END ((pptr_t)0x1000)
 
 #define IDENTICALLY_MAPPED_HEAP_SIZE ((size_t)0x400000)
 
@@ -361,7 +361,7 @@ static inline void init_mem_layout(void)
     mem_size += 64 * 1024 * mem_size_info.n_64k_blks;
 
     // mark kernel page directory
-    mark_addr_range(0x00000000, 0x00005000);
+    mark_addr_range(0x00001000, 0x00006000);
     // mark empty page
     mark_addr_range(EMPTY_PAGE_ADDR, EMPTY_PAGE_END);
     // mark EBDA and upper memory as allocated
@@ -603,6 +603,8 @@ void init_mem(void)
     empty_page.phys_page_id = to_page(EMPTY_PAGE_ADDR);
     empty_page.ref_count = types::kernel_ident_allocator_new<size_t>(1);
     empty_page.pte = to_pte(*KERNEL_PAGE_DIRECTORY_ADDR, empty_page.phys_page_id);
+    empty_page.pte->in.rw = 0;
+    invalidate_tlb(0x00000000);
 
     // TODO: improve the algorithm SO FREAKING SLOW
     // while (kernel_mm_head->len < 256 * 1024 * 1024 / PAGE_SIZE) {