From a8661c1fb81a035ebfdf134393eec4c476a7b51b Mon Sep 17 00:00:00 2001
From: Stefan Lankes <slankes@eonerc.rwth-aachen.de>
Date: Wed, 30 Dec 2015 09:51:03 +0100
Subject: [PATCH] add a platform independent function to manage the TLS

---
 hermit/arch/x86/include/asm/processor.h | 18 ++++++++++++++++++
 hermit/kernel/main.c                    |  4 ++--
 hermit/kernel/tasks.c                   |  8 ++++++++
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/hermit/arch/x86/include/asm/processor.h b/hermit/arch/x86/include/asm/processor.h
index 09ef6f1ec..b77e8fca0 100644
--- a/hermit/arch/x86/include/asm/processor.h
+++ b/hermit/arch/x86/include/asm/processor.h
@@ -477,6 +477,24 @@ extern func_read_fsgs readgs;
 extern func_write_fsgs writefs;
 extern func_write_fsgs writegs;
 
+/** @brife Get thread local storage
+ *
+ * Helper function to get the TLS of the current task
+ */
+static inline size_t get_tls(void)
+{
+	return readfs();
+}
+
+/** @brief Set thread local storage
+ *
+ * Helper function to set the TLS of the current task
+ */
+static inline void set_tls(size_t addr)
+{
+	writefs(addr);
+}
+
 /** @brief Flush cache
  *
  * The wbinvd asm instruction which stands for "Write back and invalidate"
diff --git a/hermit/kernel/main.c b/hermit/kernel/main.c
index b6c226b37..f17d3dcef 100644
--- a/hermit/kernel/main.c
+++ b/hermit/kernel/main.c
@@ -290,9 +290,9 @@ static int initd(void* arg)
 		memcpy((void*) tls_addr, (void*) curr_task->tls_addr, curr_task->tls_size);
 
 		// set fs register to the TLS segment
-		writefs((size_t) tls_addr);
+		set_tls((size_t) tls_addr);
 		kprintf("Task %d set fs to 0x%zx\n", curr_task->id, tls_addr);
-	} else writefs(0); // no TLS => clear fs register
+	} else set_tls(0); // no TLS => clear fs register
 
 	//init_rcce();
 
diff --git a/hermit/kernel/tasks.c b/hermit/kernel/tasks.c
index 53cf60717..baa666733 100644
--- a/hermit/kernel/tasks.c
+++ b/hermit/kernel/tasks.c
@@ -222,6 +222,7 @@ void finish_task_switch(void)
 void NORETURN do_exit(int arg)
 {
 	task_t* curr_task = per_core(current_task);
+	void* tls_addr = NULL;
 	const uint32_t core_id = CORE_ID;
 
 	kprintf("Terminate task: %u, return value %d\n", curr_task->id, arg);
@@ -237,6 +238,13 @@ void NORETURN do_exit(int arg)
 	readyqueues[core_id].nr_tasks--;
 	spinlock_irqsave_unlock(&readyqueues[core_id].lock);
 
+	// do we need to release the TLS?
+	tls_addr = (void*)get_tls();
+	if (tls_addr) {
+		kprintf("Release TLS %p\n", tls_addr);
+		kfree(tls_addr);
+	}
+
 	curr_task->status = TASK_FINISHED;
 	reschedule();