implement TLS for arm64

Use the EL0 Read-Only Software Thread ID Register aka TPIDRRO_EL0
to store TLS pointer.

The EL0 Read-Only Software Thread ID Register is read-only in User mode
and read/write in privileged modes.

Change-Id: Idea7e3d66cd391dbbe3f9395cb37716089a49e13
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5673
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Fredrik Holmqvist <fredrik.holmqvist@gmail.com>
Reviewed-by: David Karoly <karolyd577@gmail.com>

src/system/kernel/arch/arm64/arch_thread.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019 Haiku, Inc. All Rights Reserved.
+ * Copyright 2019-2022 Haiku, Inc. All Rights Reserved.
  * Distributed under the terms of the MIT License.
  */
 #include <thread.h>
@@ -62,16 +62,34 @@ arch_thread_init_kthread_stack(Thread* thread, void* _stack, void* _stackTop,
 status_t
 arch_thread_init_tls(Thread *thread)
 {
-	return 0;
+	uint32 tls[TLS_FIRST_FREE_SLOT];
+
+	thread->user_local_storage = thread->user_stack_base
+		+ thread->user_stack_size;
+
+	// initialize default TLS fields
+	memset(tls, 0, sizeof(tls));
+	tls[TLS_BASE_ADDRESS_SLOT] = thread->user_local_storage;
+	tls[TLS_THREAD_ID_SLOT] = thread->id;
+	tls[TLS_USER_THREAD_SLOT] = (addr_t)thread->user_thread;
+
+	return user_memcpy((void *)thread->user_local_storage, tls, sizeof(tls));
 }
 
 
+static void
+arm64_set_tls_context(Thread *thread)
+{
+	WRITE_SPECIALREG(tpidrro_el0, thread->user_local_storage);
+}
+
 extern "C" void _arch_context_swap(arch_thread *from, arch_thread *to);
 
 
 void
 arch_thread_context_switch(Thread *from, Thread *to)
 {
+	arm64_set_tls_context(to);
 	_arch_context_swap(&from->arch_info, &to->arch_info);
 }
 
@@ -89,6 +107,8 @@ status_t
 arch_thread_enter_userspace(Thread *thread, addr_t entry,
 	void *arg1, void *arg2)
 {
+	arm64_set_tls_context(thread);
+
 	addr_t threadExitAddr;
 	{
 		addr_t commpageAdr = (addr_t)thread->team->commpage_address;

src/system/libroot/os/arch/arm64/thread.c

@@ -1,15 +1,19 @@
 /*
- * Copyright 2019 Haiku, Inc. All Rights Reserved.
+ * Copyright 2019-2022 Haiku, Inc. All Rights Reserved.
  * Distributed under the terms of the MIT License.
  */
 
 
 #include <OS.h>
 #include "syscalls.h"
+#include <tls.h>
 
 
 thread_id
 find_thread(const char *name)
 {
+	if (name == NULL)
+		return (thread_id)(addr_t)tls_get(TLS_THREAD_ID_SLOT);
+
 	return _kern_find_thread(name);
 }

src/system/libroot/os/arch/arm64/tls.c

@@ -1,22 +1,33 @@
 /*
- * Copyright 2019 Haiku, Inc. All Rights Reserved.
+ * Copyright 2019-2022, Haiku, Inc. All Rights Reserved.
  * Distributed under the terms of the MIT License.
  */
 
 #include <runtime_loader/runtime_loader.h>
 
-#include "support/TLS.h"
-#include "tls.h"
+#include <support/TLS.h>
+#include <tls.h>
+
 
 struct tls_index {
 	unsigned long ti_module;
 	unsigned long ti_offset;
 };
 
-void* __tls_get_addr(struct tls_index* ti);
 
 static int32 gNextSlot = TLS_FIRST_FREE_SLOT;
 
+void* __tls_get_addr(struct tls_index* ti);
+
+
+static inline void**
+get_tls()
+{
+	void **tls;
+	asm volatile("MRS %0, tpidrro_el0" : "=r" (tls));
+	return tls;
+}
+
 
 int32
 tls_allocate(void)
@@ -32,21 +43,21 @@ tls_allocate(void)
 void *
 tls_get(int32 index)
 {
-	return NULL;
+	return get_tls()[index];
 }
 
 
 void **
 tls_address(int32 index)
 {
-	return NULL;
+	return get_tls() + index;
 }
 
 
 void
 tls_set(int32 index, void *value)
 {
-
+	get_tls()[index] = value;
 }