[PATCH v6 05/23] aarch64: Add GCS support to vfork

[Yury Khrustalev]

From: Szabolcs Nagy <szabolcs.nagy@arm.com>

Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
---
 sysdeps/unix/sysv/linux/aarch64/vfork.S | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/sysdeps/unix/sysv/linux/aarch64/vfork.S b/sysdeps/unix/sysv/linux/aarch64/vfork.S
index e71e492da3..beae94bef1 100644
--- a/sysdeps/unix/sysv/linux/aarch64/vfork.S
+++ b/sysdeps/unix/sysv/linux/aarch64/vfork.S
@@ -33,8 +33,13 @@ ENTRY (__vfork)
 
 	cmn	x0, #4095
 	b.cs    .Lsyscall_error
+	cbz	x0, L(child)
 	RET
-
+L(child):
+	/* Return with indirect branch in the child to support GCS.
+	   Compilers insert BTI instruction after vfork() to make
+	   sure return via BR works on systems with BTI.  */
+	br	x30
 PSEUDO_END (__vfork)
 libc_hidden_def (__vfork)
 
-- 
2.39.5