nios2: fixed broken sys_clone syscall

stable inclusion
from stable-5.10.20
commit 1fe02a86fa92dd22b79dd25b1d0fe5cab7024f14
bugzilla: 50608

--------------------------------

[ Upstream commit 9abcfcb2 ]

The tls pointer must be pushed on the stack prior to calling nios2_clone
as it is the 5th function argument. Prior handling of the tls pointer was
done inside former called function copy_thread_tls using the r8 register
from the current_pt_regs directly. This was a bad design and resulted in
the current bug introduced in 04bd52fb.

Fixes: 04bd52fb ("nios2: enable HAVE_COPY_THREAD_TLS, switch to kernel_clone_args")
Signed-off-by: NAndreas Oetken <andreas.oetken@siemens.com>
Signed-off-by: NLey Foon Tan <ley.foon.tan@intel.com>
Acked-by: NChristian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/nios2/kernel/entry.S

@@ -389,7 +389,10 @@ ENTRY(ret_from_interrupt)
  */
 ENTRY(sys_clone)
 	SAVE_SWITCH_STACK
+	subi    sp, sp, 4 /* make space for tls pointer */
+	stw     r8, 0(sp) /* pass tls pointer (r8) via stack (5th argument) */
 	call	nios2_clone
+	addi    sp, sp, 4
 	RESTORE_SWITCH_STACK
 	ret