parisc: Implement copy_thread_tls

This is required for clone3 which passes the TLS value through a
struct rather than a register.
Signed-off-by: Amanieu d'Antras <amanieu@gmail.com>
Cc: linux-parisc@vger.kernel.org
Cc: <stable@vger.kernel.org> # 5.3.x
Link: https://lore.kernel.org/r/20200102172413.654385-5-amanieu@gmail.comSigned-off-by: Christian Brauner <christian.brauner@ubuntu.com>

arch/parisc/Kconfig

@@ -62,6 +62,7 @@ config PARISC
 	select HAVE_FTRACE_MCOUNT_RECORD if HAVE_DYNAMIC_FTRACE
 	select HAVE_KPROBES_ON_FTRACE
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS
+	select HAVE_COPY_THREAD_TLS
 
 	help
 	  The PA-RISC microprocessor is designed by Hewlett-Packard and used

arch/parisc/kernel/process.c

@@ -208,8 +208,8 @@ arch_initcall(parisc_idle_init);
  * Copy architecture-specific thread state
  */
 int
-copy_thread(unsigned long clone_flags, unsigned long usp,
-	    unsigned long kthread_arg, struct task_struct *p)
+copy_thread_tls(unsigned long clone_flags, unsigned long usp,
+	    unsigned long kthread_arg, struct task_struct *p, unsigned long tls)
 {
 	struct pt_regs *cregs = &(p->thread.regs);
 	void *stack = task_stack_page(p);
@@ -254,9 +254,9 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
 		cregs->ksp = (unsigned long)stack + THREAD_SZ_ALGN + FRAME_SIZE;
 		cregs->kpc = (unsigned long) &child_return;
 
-		/* Setup thread TLS area from the 4th parameter in clone */
+		/* Setup thread TLS area */
 		if (clone_flags & CLONE_SETTLS)
-			cregs->cr27 = cregs->gr[23];
+			cregs->cr27 = tls;
 	}
 
 	return 0;