From 13946b17585feb6cda0656fcf3b60210fafd78eb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Lov=C3=A9n?= <thomasloven@gmail.com>
Date: Fri, 26 Jan 2018 15:02:13 +0100
Subject: [PATCH] Pass around tcbs instead of thread stacks

---
 src/kernel/include/thread.h | 10 ++++++----
 src/kernel/proc/scheduler.c |  6 +++---
 src/kernel/proc/thread.c    | 15 ++++++++-------
 3 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/src/kernel/include/thread.h b/src/kernel/include/thread.h
index 6b11d24..d22259b 100644
--- a/src/kernel/include/thread.h
+++ b/src/kernel/include/thread.h
@@ -2,7 +2,7 @@
 #include <memory.h>
 
 
-struct tcb
+struct thread
 {
   uintptr_t stack_ptr;
   uint64_t tid;
@@ -10,10 +10,10 @@ struct tcb
   struct thread *next;
 };
 
-#define TCB_OFFSET (PAGE_SIZE - sizeof(struct tcb))
+#define TCB_OFFSET (PAGE_SIZE - sizeof(struct thread))
 #define SWTCH_STACK_SIZE (0x8*8)
 
-struct thread
+struct thread_stack
 {
   uint8_t stack[TCB_OFFSET-SWTCH_STACK_SIZE];
   uint64_t RBP;
@@ -25,9 +25,11 @@ struct thread
   uint64_t RBP2;
   uint64_t ret;
 
-  struct tcb tcb;
+  struct thread tcb;
 }__attribute__((packed));
 
+#define thread_stack(th) (struct thread_stack *)((uintptr_t)th - TCB_OFFSET)
+
 struct thread *new_thread(void (*function)(void));
 void yield();
 int get_tid();
diff --git a/src/kernel/proc/scheduler.c b/src/kernel/proc/scheduler.c
index f27bff9..c94f454 100644
--- a/src/kernel/proc/scheduler.c
+++ b/src/kernel/proc/scheduler.c
@@ -9,10 +9,10 @@ void ready(struct thread *th)
 {
   if(!readyQ.last)
   {
-    th->tcb.next = 0;
+    th->next = 0;
     readyQ.first = readyQ.last = th;
   } else {
-    readyQ.last->tcb.next = th;
+    readyQ.last->next = th;
     readyQ.last = th;
   }
 }
@@ -20,7 +20,7 @@ void ready(struct thread *th)
 struct thread *scheduler_next()
 {
   struct thread *th = readyQ.first;
-  if(!(readyQ.first = th->tcb.next))
+  if(!(readyQ.first = th->next))
     readyQ.last = 0;
   return th;
 }
diff --git a/src/kernel/proc/thread.c b/src/kernel/proc/thread.c
index 4759b08..7b24d64 100644
--- a/src/kernel/proc/thread.c
+++ b/src/kernel/proc/thread.c
@@ -7,12 +7,13 @@ struct thread *_current_thread = 0;
 uint64_t next_tid = 1;
 struct thread *new_thread(void (*function)(void))
 {
-  struct thread *th = P2V(pmm_alloc());
+  struct thread_stack *stk = P2V(pmm_alloc());
+  struct thread *th = &stk->tcb;
 
-  th->tcb.tid = next_tid++;
-  th->RBP = (uint64_t)&th->RBP2;
-  th->ret = (uint64_t)function;
-  th->tcb.stack_ptr = (uint64_t)&th->RBP;
+  th->tid = next_tid++;
+  stk->RBP = (uint64_t)&stk->RBP2;
+  stk->ret = (uint64_t)function;
+  th->stack_ptr = (uint64_t)&stk->RBP;
 
   return th;
 }
@@ -30,7 +31,7 @@ void set_current_thread(struct thread *th)
 void switch_thread(struct thread *old, struct thread *new)
 {
   set_current_thread(new);
-  swtch(&old->tcb.stack_ptr, &new->tcb.stack_ptr);
+  swtch(&old->stack_ptr, &new->stack_ptr);
 }
 
 void yield()
@@ -49,5 +50,5 @@ void yield()
 
 int get_tid()
 {
-  return current_thread()->tcb.tid;
+  return current_thread()->tid;
 }