We have a ring 3 thread! :D

Twometer · Jan 17, 2021 · 7fe39a7 · 7fe39a7
1 parent 6622c92
commit 7fe39a7
Show file tree

Hide file tree

Showing 8 changed files with 29 additions and 43 deletions.
diff --git a/kernel/arch/interrupts.asm b/kernel/arch/interrupts.asm
@@ -17,17 +17,12 @@ irq%1:
   save_all_regs
   save_segments
   
-  ; get the flags from the stack
-  ; they are just for analyzing and stuff, and don't get written back
-  ;mov dword eax, [esp + 8]
-  ;mov dword [s_flags], eax
-
-  ; call interrupt handler
+  ; call the interrupt handler
   call irq%1_handler
 
   ; load reg states back
-  load_segments
   load_all_regs
+  load_segments
   iret
 %endmacro
 

diff --git a/kernel/arch/regutil.asm b/kernel/arch/regutil.asm
@@ -22,16 +22,15 @@ s_ds: dd 0
 %endmacro
 
 %macro save_segments 0
-  mov ax, ds
-  mov [s_ds], ax
+  mov [s_ds], ds
 %endmacro
 
 %macro load_segments 0
   mov ax, [s_ds]
-  mov ds,ax
-  mov es,ax 
-  mov fs,ax 
-  mov gs,ax
+  mov ds, ax
+  mov es, ax 
+  mov fs, ax 
+  mov gs, ax
 %endmacro
 
 %macro save_all_regs 0

diff --git a/kernel/include/tasks/thread.h b/kernel/include/tasks/thread.h
@@ -7,7 +7,6 @@
 #include <memory/pagedirectory.h>
 
 #define THREAD_STACK_SIZE 4096
-#define RING3_MASK 0x00
 
 namespace Kernel
 {

diff --git a/kernel/kernel.cpp b/kernel/kernel.cpp
@@ -29,7 +29,7 @@ void testThreadEP()
 {
 	for (;;)
 	{
-		//printf("Hello from thread #2 %d\n", TimeManager::GetInstance()->GetUptime());
+		printf("Hello from thread #2 %d\n", TimeManager::GetInstance()->GetUptime());
 		Thread::current->Sleep(1000);
 	}
 }
@@ -43,13 +43,10 @@ void testExitingThread()
 
 void ring3Thread()
 {
-	// asm("int $0x80");
-	printf("Hello from ring 3 :3\n"); // if everything works correctly, this should crash with a GPF as it directly accesses the screen buffer
 	for (;;)
 	{
 		;
 	}
-	//
 }
 
 extern "C"
@@ -99,6 +96,7 @@ extern "C"
 		PageDirectory pageDir;
 
 		// Identity map the first megabyte
+		// IMPORTANT FIXME: The first MB is only mapped into userspace here, because the test-ring3 func is in there, and it obviously needs to be able to access itself.
 		for (uint32_t i = 0; i < MBYTE; i += PAGE_SIZE)
 			pageDir.MapPage((paddress_t)i, (vaddress_t)i, PAGE_BIT_READ_WRITE | PAGE_BIT_ALLOW_USER);
 
@@ -146,7 +144,7 @@ extern "C"
 		gdt.Set(SEG_USER_DATA, 0x00, 0xffffffff, GDTEntryType::Data, Ring::Ring3);
 		gdt.SetTssEntry(SEG_TSS);
 		gdt.Load();
-		setTss(SEG_TSS | RING3_MASK);
+		setTss(SEG_TSS);
 
 		printf("Setting up interrupts\n");
 		Interrupts::SetupIdt();

diff --git a/kernel/memory/pagedirectory.cpp b/kernel/memory/pagedirectory.cpp
@@ -100,7 +100,7 @@ namespace Memory
             if (virt_directory_ptr[idx] == 0x00)
             {
                 auto table = (uint32_t)NewPage();
-                virt_directory_ptr[idx] = table | PAGE_BIT_PRESENT | PAGE_BIT_READ_WRITE;
+                virt_directory_ptr[idx] = table | PAGE_BIT_PRESENT | PAGE_BIT_READ_WRITE | PAGE_BIT_ALLOW_USER;
                 FlushPage(table); // Flush TLB for that page, so that we for sure have that
                 // Load();
             }
@@ -113,14 +113,17 @@ namespace Memory
             if (table == 0x00) // Allocate page table if it does not exist
             {
                 table = (uint32_t)NewPage();
-                virt_directory_ptr[idx] = table | PAGE_BIT_PRESENT | PAGE_BIT_READ_WRITE;
+                virt_directory_ptr[idx] = table | PAGE_BIT_PRESENT | PAGE_BIT_READ_WRITE | PAGE_BIT_ALLOW_USER;
             }
             return (uint32_t *)table;
         }
     }
 
     void PageDirectory::FlushPage(uint32_t addr)
     {
+        if (!IS_PAGE_ALIGNED(addr))
+            Kernel::Panic("page_directory", "Can't flush non-page-aligned memory.");
+
         asm volatile("invlpg (%0)" ::"r"(addr)
                      : "memory");
     }

diff --git a/kernel/stack.cpp b/kernel/stack.cpp
@@ -4,19 +4,14 @@
 
 namespace Kernel
 {
-
+    
     Stack::Stack(void *stack_bottom, size_t size)
     {
         this->stack_bottom = (uint8_t *)stack_bottom;
         this->stack_top = this->stack_bottom + size;
         this->stack_ptr = this->stack_top;
     }
 
-    Stack::~Stack()
-    {
-        delete[] stack_bottom;
-    }
-
     void Stack::Push(uint32_t data)
     {
         size_t data_size = sizeof(data);

diff --git a/kernel/tasks/scheduler.cpp b/kernel/tasks/scheduler.cpp
@@ -4,7 +4,7 @@
 #include <kernel/timemanager.h>
 #include <tasks/scheduler.h>
 
-#define SCHEDULER_DBG 1
+#define SCHEDULER_DBG 0
 
 namespace Kernel
 {
@@ -89,8 +89,8 @@ namespace Kernel
         {
             auto &newregs = newThread->registers;
             printf("scheduler: %d -> %d after %dms\n", oldThread->id, newThread->id, oldThread->GetRuntime());
-            printf("  old: %x, %x\n", regs->esp, regs->eax);
-            printf("  new: %x, %x\n", newregs.esp, newregs.eax);
+            printf("  old: %x, %x\n", regs->esp, regs->ds);
+            printf("  new: %x, %x\n", newregs.esp, newregs.ds);
         }
 #endif
 

diff --git a/kernel/tasks/thread.cpp b/kernel/tasks/thread.cpp
@@ -42,12 +42,10 @@ namespace Kernel
             // Push the kernel thread return func#
             stack->Push((uint32_t)(thread_exit_func_krnl));
 
-            // put stuff on stack that an iret needs later
-            // note for the flags: I observed this value from the stack in an irq.
-            //                     I know that it keeps interrupts enabled. I don't know what else it does, but it works.
-            stack->Push(0x202);                // Flags, 0x202 for now.
+            stack->Push(0x202);                // Flags, 0x202: interrupt enable = true
             stack->Push(SEG_KRNL_CODE);        // Code Segment
             stack->Push((uint32_t)entryPoint); // IP = entry_point
+            registers.ds = SEG_KRNL_DATA;
             registers.esp = (uint32_t)this->stack->GetStackPtr();
         }
         else
@@ -63,16 +61,15 @@ namespace Kernel
             stack->Push((uint32_t)(thread_exit_func_user));
 
             // put stuff on the stack that iret needs
-            stack->Push(SEG_USER_DATA | RING3_MASK); // stackseg
-            stack->Push((uint32_t)stack_virt);       // stack ptr
-            stack->Push(0x202);                      // flags
-            stack->Push(SEG_USER_CODE | RING3_MASK); // code seg
-            stack->Push((uint32_t)entryPoint);       // ret ptr
-
-            registers.ds = SEG_USER_DATA | RING3_MASK;
-            registers.esp = (uint32_t)stack_virt;
+            stack->Push(SEG_USER_DATA | 0b11);             // stackseg
+            stack->Push((uint32_t)(stack->GetStackPtr())); // stack ptr
+            stack->Push(0x202);                            // flags
+            stack->Push(SEG_USER_CODE | 0b11);             // code seg
+            stack->Push((uint32_t)entryPoint);             // ret ptr
+
+            registers.ds = SEG_USER_DATA | 0b11;
+            registers.esp = (uint32_t)stack->GetStackPtr();
         }
-
 
         // make sure we restore to kernel page directory before continuing
         if (ring == Ring::Ring3)