From 6523b10984df379c6de7fecc4fc3fc2abd9a2b72 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Lov=C3=A9n?= <thomasloven@gmail.com>
Date: Tue, 20 Feb 2018 20:38:32 +0100
Subject: [PATCH] Threads have isolated memory spaces

---
 src/kernel/boot/kmain.c     | 22 +++++++++++++---------
 src/kernel/include/thread.h |  1 +
 src/kernel/proc/thread.c    |  3 +++
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/src/kernel/boot/kmain.c b/src/kernel/boot/kmain.c
index c0c27e5..127be07 100644
--- a/src/kernel/boot/kmain.c
+++ b/src/kernel/boot/kmain.c
@@ -8,14 +8,14 @@
 #include <thread.h>
 #include <scheduler.h>
 
-int thread_id;
+int *thread_id = (int *)0x20000;
 void thread_function()
 {
-  thread_id = thread()->tid;
+  *thread_id = thread()->tid;
 
   while(1)
   {
-    debug("Thread %d\n", thread_id);
+    debug("Thread %d\n", *thread_id);
     yield();
   }
 }
@@ -35,15 +35,19 @@ void kmain(uint64_t multiboot_magic, void *multiboot_data)
 
   cpu_init();
 
-  uintptr_t P4 = new_P4();
-  write_cr3(P4);
+  struct thread *th1 = new_thread(thread_function);
+  vmm_set_page(th1->P4, 0x20000, pmm_alloc(), PAGE_WRITE | PAGE_PRESENT);
+  struct thread *th2 = new_thread(thread_function);
+  vmm_set_page(th2->P4, 0x20000, pmm_alloc(), PAGE_WRITE | PAGE_PRESENT);
+  struct thread *th3 = new_thread(thread_function);
+  vmm_set_page(th3->P4, 0x20000, pmm_alloc(), PAGE_WRITE | PAGE_PRESENT);
+
+  ready(th1);
+  ready(th2);
+  ready(th3);
 
   debug_ok("Boot \"Complete\"\n");
 
-  ready(new_thread(thread_function));
-  ready(new_thread(thread_function));
-  ready(new_thread(thread_function));
-
   start_scheduler();
 
   PANIC("Reached end of kernel main function\n");
diff --git a/src/kernel/include/thread.h b/src/kernel/include/thread.h
index 397019c..ed212dd 100644
--- a/src/kernel/include/thread.h
+++ b/src/kernel/include/thread.h
@@ -8,6 +8,7 @@ struct thread
   uint64_t tid;
   void *stack_ptr;
   uint64_t state;
+  uint64_t P4;
   QUEUE_SPOT(runQ);
   uint8_t stack[];
 };
diff --git a/src/kernel/proc/thread.c b/src/kernel/proc/thread.c
index 1e3bd9b..6b3f993 100644
--- a/src/kernel/proc/thread.c
+++ b/src/kernel/proc/thread.c
@@ -1,6 +1,7 @@
 #include <thread.h>
 #include <scheduler.h>
 #include <memory.h>
+#include <cpu.h>
 
 struct swtch_stack
 {
@@ -23,6 +24,7 @@ struct thread *new_thread(void (*function)(void))
   struct thread *th = P2V(pmm_calloc());
   th->tid = next_tid++;
   th->stack_ptr = incptr(th, PAGE_SIZE - sizeof(struct swtch_stack));
+  th->P4 = new_P4();
 
   struct swtch_stack *stk = th->stack_ptr;
   stk->RBP = (uint64_t)&stk->RBP2;
@@ -49,6 +51,7 @@ void scheduler()
     while(!(new = scheduler_next()));
 
     _thread = new;
+    write_cr3(new->P4);
     switch_stack(&sched_th->stack_ptr, &new->stack_ptr);
 
     ready(_thread);