arch: i386: paging: do the recursive paging trick

Map the page directory to the last page table. This allows the kernel to
access every page table on the system from the address 0xFFC00000 plus
an offset.

Signed-off-by: Danny Holman <dholman@gymli.org>

3 files changed, 30 insertions, 13 deletions

diff --git a/arch/i386/include/kernel/asm.h b/arch/i386/include/kernel/asm.h
index a002a44..d692917 100644
--- a/arch/i386/include/kernel/asm.h
+++ b/arch/i386/include/kernel/asm.h
@@ -4,13 +4,6 @@
 #include <kernel/gdt.h>
 #include <stdint.h>
 
-extern uintptr_t _kernel_start;
-extern uintptr_t _kernel_end;
-#define KSTART          ((uintptr_t)&_kernel_start)
-#define KEND            ((uintptr_t)&_kernel_end - 0xC0000000)
-
-#define PAGE_SIZE       4096
-
 #define PCI_CONFIG_ADDR 0xCF8
 #define PCI_CONFIG_DATA 0xCFC
 
@@ -108,7 +101,6 @@ void aquire_lock(int *lock);
 void release_lock(int *lock);
 
 void enable_paging(uint32_t new_cr3);
-
 void flush_gdt(void);
 
 static inline void outb(uint16_t port, uint8_t value) {
@@ -153,6 +145,10 @@ static inline void flush_tss(void) {
         __asm__ volatile("movw $0x28, %ax; ltr %ax");
 }
 
+static inline void flush_tlb(void) {
+        __asm__ volatile("movl %cr3, %eax; movl %eax, %cr3");
+}
+
 static inline void invlpg(void *addr) {
         __asm__ volatile("invlpg (%0)" : : "b"(addr) : "memory");
 }
diff --git a/arch/i386/include/kernel/paging.h b/arch/i386/include/kernel/paging.h
index 5999986..d8bb8f3 100644
--- a/arch/i386/include/kernel/paging.h
+++ b/arch/i386/include/kernel/paging.h
@@ -5,6 +5,8 @@
 #include <kernel/multiboot.h>
 #include <stdint.h>
 
+#define PAGE_SIZE       4096
+
 #define PD_PRES         0x0001
 #define PD_RW           0x0002
 #define PD_USR          0x0004
@@ -28,14 +30,16 @@
 #define GET_PADDR(x)    (((uint32_t)(x)) - 0xC0000000)
 #define GET_VADDR(x)    (((uint32_t)(x)) + 0xC0000000)
 
-#define GET_PDX(x)      (((uintptr_t)(x) >> 22) & 0x3FF)
-#define GET_PTX(x)      (((uintptr_t)(x) >> 12) & 0x3FF)
+#define GET_PDX(x)      ((uintptr_t)(x) >> 22)
+#define GET_PTX(x)      (((uintptr_t)(x) >> 12) & 0x03FF)
+
+uintptr_t get_physaddr(void *vaddr);
 
-uintptr_t* init_page_table(void);
 void paging_init(void);
 
-void map_page(uint32_t *pd, uintptr_t paddr, uintptr_t vaddr, uint32_t flags);
-void unmap_page(uint32_t *pd, uintptr_t vaddr);
+uintptr_t init_page_directory(void);
+void map_page(uintptr_t paddr, uintptr_t vaddr, uint32_t flags);
+void unmap_page(uintptr_t vaddr);
 
 void page_fault_handler(struct isr_frame *frame);
 
diff --git a/arch/i386/include/kernel/vmem.h b/arch/i386/include/kernel/vmem.h
new file mode 100644
index 0000000..94aa32d
--- /dev/null
+++ b/arch/i386/include/kernel/vmem.h
@@ -0,0 +1,17 @@
+#ifndef I386_VMEM_H
+#define I386_VMEM_H
+
+extern uintptr_t _kernel_start;
+extern uintptr_t _kernel_end;
+
+#define KSTART          ((uintptr_t)&_kernel_start)
+#define KEND            ((uintptr_t)&_kernel_end - 0xC0000000)
+
+#define KHEAP_START     (GET_VADDR(KEND) + 0x2000)
+#define KHEAP_STOP      0xFF7FF000
+
+#define PAGE_DIR_MAP    0xFFFFF000
+#define PAGE_TAB_MAP    0xFFC00000
+#define PAGE_TMP_MAP    0xFFBFF000
+
+#endif