sparc: implement thread local storage support

The sparc ABI reserves the g7 register for this.

Change-Id: I93b81ecef72cde859972ef7b7f6b9991d35f9f29
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3583
Reviewed-by: waddlesplash <[email protected]>

headers/private/kernel/arch/sparc/arch_thread.h

@@ -16,17 +16,11 @@
 extern "C" {
 #endif
 
-void ppc_push_iframe(struct iframe_stack *stack, struct iframe *frame);
-void ppc_pop_iframe(struct iframe_stack *stack);
-struct iframe *ppc_get_user_iframe(void);
-
-
 static inline Thread *
 arch_thread_get_current_thread(void)
 {
     Thread *t;
-    //asm volatile("mfsprg2 %0" : "=r"(t));
+    asm volatile("mov %%g7, %0" : "=r"(t));
-	t = NULL;
     return t;
 }
 
@@ -34,7 +28,7 @@ arch_thread_get_current_thread(void)
 static inline void
 arch_thread_set_current_thread(Thread *t)
 {
-    //asm volatile("mtsprg2 %0" : : "r"(t));
+    asm volatile("mov %0,%%g7" : : "r"(t));
 }
 
 

src/system/kernel/arch/sparc/arch_debug.cpp

@@ -44,6 +44,13 @@ arch_debug_call_with_fault_handler(cpu_ent* cpu, jmp_buf jumpBuffer,
 }
 
 
+void
+arch_debug_unset_current_thread(void)
+{
+	asm volatile("mov %g0, %g7");
+}
+
+
 bool
 arch_is_debug_variable_defined(const char* variableName)
 {