um: 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 <[email protected]>
Cc: [email protected]
Cc: <[email protected]> # 5.3.x
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Christian Brauner <[email protected]>

1 files changed, 3 insertions, 4 deletions

diff --git a/arch/x86/um/tls_64.c b/arch/x86/um/tls_64.c
index 3a621e0d3925..ebd3855d9b13 100644
--- a/arch/x86/um/tls_64.c
+++ b/arch/x86/um/tls_64.c
@@ -6,14 +6,13 @@ void clear_flushed_tls(struct task_struct *task)
 {
 }
 
-int arch_copy_tls(struct task_struct *t)
+int arch_set_tls(struct task_struct *t, unsigned long tls)
 {
 	/*
 	 * If CLONE_SETTLS is set, we need to save the thread id
-	 * (which is argument 5, child_tid, of clone) so it can be set
-	 * during context switches.
+	 * so it can be set during context switches.
 	 */
-	t->thread.arch.fs = t->thread.regs.regs.gp[R8 / sizeof(long)];
+	t->thread.arch.fs = tls;
 
 	return 0;
 }