[PATCH 5.4 62/78] xtensa: Implement copy_thread_tls

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

From: Amanieu d'Antras <amanieu@xxxxxxxxx>

commit c346b94f8c5d1b7d637522c908209de93305a8eb upstream.

This is required for clone3 which passes the TLS value through a
struct rather than a register.

Signed-off-by: Amanieu d'Antras <amanieu@xxxxxxxxx>
Cc: linux-xtensa@xxxxxxxxxxxxxxxx
Cc: <stable@xxxxxxxxxxxxxxx> # 5.3.x
Link: https://lore.kernel.org/r/20200102172413.654385-7-amanieu@xxxxxxxxx
Signed-off-by: Christian Brauner <christian.brauner@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/xtensa/Kconfig          |    1 +
 arch/xtensa/kernel/process.c |    8 ++++----
 2 files changed, 5 insertions(+), 4 deletions(-)

--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -22,6 +22,7 @@ config XTENSA
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_ARCH_KASAN if MMU
 	select HAVE_ARCH_TRACEHOOK
+	select HAVE_COPY_THREAD_TLS
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_EXIT_THREAD
--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -202,8 +202,9 @@ int arch_dup_task_struct(struct task_str
  * involved.  Much simpler to just not copy those live frames across.
  */
 
-int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
-		unsigned long thread_fn_arg, struct task_struct *p)
+int copy_thread_tls(unsigned long clone_flags, unsigned long usp_thread_fn,
+		unsigned long thread_fn_arg, struct task_struct *p,
+		unsigned long tls)
 {
 	struct pt_regs *childregs = task_pt_regs(p);
 
@@ -264,9 +265,8 @@ int copy_thread(unsigned long clone_flag
 			       &regs->areg[XCHAL_NUM_AREGS - len/4], len);
 		}
 
-		/* The thread pointer is passed in the '4th argument' (= a5) */
 		if (clone_flags & CLONE_SETTLS)
-			childregs->threadptr = childregs->areg[5];
+			childregs->threadptr = tls;
 	} else {
 		p->thread.ra = MAKE_RA_FOR_CALL(
 				(unsigned long)ret_from_kernel_thread, 1);