implement TLS for arm

Use the User Read-only Thread ID Register aka TPIDRURO to store
TLS pointer.

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

see: ARMv7 Architecture Reference Manual,
section B3.12.46 CP15 c13 Software Thread ID registers

Change-Id: I7bff2fd66f41d7bf1a8a247151bcd02b32733c1b
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4994
Tested-by: Commit checker robot <[email protected]>
Reviewed-by: Fredrik Holmqvist <[email protected]>

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

@@ -118,7 +118,7 @@ arch_thread_init_kthread_stack(Thread* thread, void* _stack, void* _stackTop,
 status_t
 arch_thread_init_tls(Thread *thread)
 {
-	uint32 tls[TLS_USER_THREAD_SLOT + 1];
+	uint32 tls[TLS_FIRST_FREE_SLOT];
 
 	thread->user_local_storage = thread->user_stack_base
 		+ thread->user_stack_size;
@@ -149,9 +149,20 @@ arm_swap_pgdir(uint32_t pageDirectoryAddress)
 }
 
 
+void
+arm_set_tls_context(Thread *thread)
+{
+	// Set TPIDRURO to point to TLS base
+	asm volatile("MCR p15, 0, %0, c13, c0, 3"
+		: : "r" (thread->user_local_storage));
+}
+
+
 void
 arch_thread_context_switch(Thread *from, Thread *to)
 {
+	arm_set_tls_context(to);
+
 	VMAddressSpace *oldAddressSpace = from->team->address_space;
 	VMTranslationMap *oldTranslationMap = oldAddressSpace->TranslationMap();
 	phys_addr_t oldPageDirectoryAddress =

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

@@ -1,23 +1,37 @@
-/* 
+/*
-** Copyright 2003, Axel Dörfler, [email protected]. All rights reserved.
+ * Copyright 2019-2022, Haiku, Inc. All Rights Reserved.
-** Distributed under the terms of the MIT License.
+ * Distributed under the terms of the MIT License.
-*/
+ *
+ * Copyright 2003, Axel Dörfler, [email protected]. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
 
-// ToDo: this is a dummy implementation - I've not yet gained enough knowledge
-//	to decide how this should be done, so it's just broken now (okay for single
-//	threaded apps, though).
-
-// we don't want to have the inline assembly included here
 #ifndef _NO_INLINE_ASM
 #	define _NO_INLINE_ASM 1
 #endif
 
-#include "support/TLS.h"
+#include <runtime_loader/runtime_loader.h>
-#include "tls.h"
+
+#include <support/TLS.h>
+#include <tls.h>
+
+
+struct tls_index {
+	unsigned long ti_module;
+	unsigned long ti_offset;
+};
 
 
 static int32 gNextSlot = TLS_FIRST_FREE_SLOT;
-static void *gSlots[TLS_MAX_KEYS];
+
+
+static inline void**
+get_tls()
+{
+	void **tls;
+	asm volatile("MRC p15, 0, %0, c13, c0, 3" : "=r" (tls));
+	return tls;
+}
 
 
 int32
@@ -34,20 +48,27 @@ tls_allocate(void)
 void *
 tls_get(int32 index)
 {
-	return gSlots[index];
+	return get_tls()[index];
 }
 
 
 void **
 tls_address(int32 index)
 {
-	return &gSlots[index];
+	return get_tls() + index;
 }
 
 
 void
 tls_set(int32 index, void *value)
 {
-	gSlots[index] = value;
+	get_tls()[index] = value;
+}
+
+
+void *
+__tls_get_addr(struct tls_index *ti)
+{
+	return __gRuntimeLoader->get_tls_address(ti->ti_module, ti->ti_offset);
 }