Backport part of this upstream commit:
commit 016495b818cb61df7d0d10e6db54074271b3e3a5
Author: Stefan Liebler <stli@linux.vnet.ibm.com>
Date: Mon Nov 9 16:14:49 2015 +0100
S390: Call direct system calls for socket operations.
this patch calls direct system calls for socket operations in the same way as power does. The system calls were introduced in kernel commit https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=977108f89c989b1eeb5c8d938e1e71913391eb5f.
There are no direct recv, send, accept syscalls available on s390. Thus
recvfrom, sendto, accept4 are called instead of the socketcall by defining __ASSUME_*_FOR_*_SYSCALL macros. See recv.c, send.c, accept.c in sysdeps/unix/sysv/linux/ folder.
The socketcalls in syscalls.list for s390-64 are removed. They were never used on s390x.
The removal is required due to the kernel change because otherwise,
these system calls will be used unconditionally with new kernel
headers.
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/syscalls.list b/sysdeps/unix/sysv/linux/s390/s390-64/syscalls.list
index 5b8c102..9f03d26 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/syscalls.list
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/syscalls.list
@@ -12,22 +12,3 @@ shmget - shmget i:iii __shmget shmget
semop - semop i:ipi __semop semop
semget - semget i:iii __semget semget
semctl - semctl i:iiii __semctl semctl
-
-# proper socket implementations:
-accept - accept Ci:iBN __libc_accept __accept accept
-bind - bind i:ipi __bind bind
-connect - connect Ci:ipi __libc_connect __connect connect
-getpeername - getpeername i:ipp __getpeername getpeername
-getsockname - getsockname i:ipp __getsockname getsockname
-getsockopt - getsockopt i:iiiBN __getsockopt getsockopt
-listen - listen i:ii __listen listen
-recv - recv Ci:ibni __libc_recv __recv recv
-recvfrom - recvfrom Ci:ibniBN __libc_recvfrom __recvfrom recvfrom
-recvmsg - recvmsg Ci:ipi __libc_recvmsg __recvmsg recvmsg
-send - send Ci:ibni __libc_send __send send
-sendmsg - sendmsg Ci:ipi __libc_sendmsg __sendmsg sendmsg
-sendto - sendto Ci:ibnibn __libc_sendto __sendto sendto
-setsockopt - setsockopt i:iiibn __setsockopt setsockopt
-shutdown - shutdown i:ii __shutdown shutdown
-socket - socket i:iii __socket socket
-socketpair - socketpair i:iiif __socketpair socketpair