ARC: align child stack in clone

The ARCv2 ABI requires 4 byte stack pointer alignment. Don't allow to
use unaligned child stack in clone. As the stack grows down,
align it down.

This was pointed by misc/tst-misalign-clone-internal and
misc/tst-misalign-clone tests. Stack alignmet fixes these tests
fails.
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

diff --git a/sysdeps/unix/sysv/linux/arc/clone.S b/sysdeps/unix/sysv/linux/arc/clone.S
index e41a594..7666496 100644 (file)
--- a/sysdeps/unix/sysv/linux/arc/clone.S
+++ b/sysdeps/unix/sysv/linux/arc/clone.S
@@ -41,6 +41,7 @@
 
 ENTRY (__clone)
        cmp     r0, 0           /* @fn can't be NULL.  */
+       and     r1,r1,-4        /* @child_stack be 4 bytes aligned per ABI.  */
        cmp.ne  r1, 0           /* @child_stack can't be NULL.  */
        bz      L (__sys_err)