S390: Call direct system calls for socket operations.

Hi,

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. See 
recv.c, send.c, accept.c in sysdeps/unix/sysv/linux/s390 folder.

The socketcalls in syscalls.list for s390-64 are removed. They were 
never used on s390x.

Bye Stefan

---
2015-10-13  Stefan Liebler  <stli@linux.vnet.ibm.com>

	* sysdeps/unix/sysv/linux/s390/kernel-features.h:
	(__ASSUME_*_SYSCALL) Define new macros.
	* sysdeps/unix/sysv/linux/s390/s390-64/syscalls.list:
	Remove socketcall syscalls.
	* sysdeps/unix/sysv/linux/s390/accept.c: New File.
	* sysdeps/unix/sysv/linux/s390/recv.c: Likewise.
	* sysdeps/unix/sysv/linux/s390/send.c: Likewise.

Hi Stefan,

Some comments below.

On 13-10-2015 07:48, Stefan Liebler wrote:
> Hi,
> 
> 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. See recv.c, send.c, accept.c in sysdeps/unix/sysv/linux/s390 folder.
> 
> The socketcalls in syscalls.list for s390-64 are removed. They were never used on s390x.
> 
> Bye Stefan
> 
> ---
> 2015-10-13  Stefan Liebler  <stli@linux.vnet.ibm.com>
> 
>     * sysdeps/unix/sysv/linux/s390/kernel-features.h:
>     (__ASSUME_*_SYSCALL) Define new macros.
>     * sysdeps/unix/sysv/linux/s390/s390-64/syscalls.list:
>     Remove socketcall syscalls.
>     * sysdeps/unix/sysv/linux/s390/accept.c: New File.
>     * sysdeps/unix/sysv/linux/s390/recv.c: Likewise.
>     * sysdeps/unix/sysv/linux/s390/send.c: Likewise.
> 
> 20151013_direct_socketcalls
> 
> 
> diff --git a/sysdeps/unix/sysv/linux/s390/accept.c b/sysdeps/unix/sysv/linux/s390/accept.c
> new file mode 100644
> index 0000000..c491690
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/s390/accept.c
> @@ -0,0 +1,40 @@
> +/* Copyright (C) 2015 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <errno.h>
> +#include <signal.h>
> +#include <sys/socket.h>
> +
> +#include <sysdep-cancel.h>
> +#include <socketcall.h>
> +#include <sys/syscall.h>
> +#include <kernel-features.h>
> +
> +int
> +__libc_accept (int fd, __SOCKADDR_ARG addr, socklen_t *len)
> +{
> +#ifdef __ASSUME_ACCEPT4_SYSCALL
> +  /* There does not exist a direct accept syscall on s390, thus accept4 is used.
> +     The kernel also wraps this syscall with additional 0 parameters if called
> +     via socketcall.  */
> +  return SYSCALL_CANCEL (accept4, fd, addr.__sockaddr__, len, 0);

I would prefer to not add another arch-specific implementation, but instead
use something like __ASSUME_ACCEPT4_FOR_ACCEPT_SYSCALL and use accept4
directly in sysdeps/unix/sysv/linux/accept.c. Same for recv and send.

> +#else
> +  return SOCKETCALL_CANCEL (accept, fd, addr.__sockaddr__, len);
> +#endif
> +}
> +weak_alias (__libc_accept, accept)
> +libc_hidden_def (accept)
> diff --git a/sysdeps/unix/sysv/linux/s390/kernel-features.h b/sysdeps/unix/sysv/linux/s390/kernel-features.h
> index 96f73ef..899421f 100644
> --- a/sysdeps/unix/sysv/linux/s390/kernel-features.h
> +++ b/sysdeps/unix/sysv/linux/s390/kernel-features.h
> @@ -20,4 +20,29 @@
>  /* S/390 uses socketcall.  */
>  #define __ASSUME_SOCKETCALL		1
>  
> +/* Direct socketcalls available with kernel 4.3.  */
> +#if __LINUX_KERNEL_VERSION >= 0x040300
> +# define __ASSUME_RECVMMSG_SYSCALL     1
> +# define __ASSUME_SENDMMSG_SYSCALL     1
> +# define __ASSUME_SOCKET_SYSCALL       1
> +# define __ASSUME_SOCKETPAIR_SYSCALL   1
> +# define __ASSUME_BIND_SYSCALL         1
> +# define __ASSUME_CONNECT_SYSCALL      1
> +# define __ASSUME_LISTEN_SYSCALL       1
> +# define __ASSUME_ACCEPT4_SYSCALL      1
> +# define __ASSUME_GETSOCKOPT_SYSCALL   1
> +# define __ASSUME_SETSOCKOPT_SYSCALL   1
> +# define __ASSUME_GETSOCKNAME_SYSCALL  1
> +# define __ASSUME_GETPEERNAME_SYSCALL  1
> +# define __ASSUME_SENDTO_SYSCALL       1
> +# define __ASSUME_SENDMSG_SYSCALL      1
> +# define __ASSUME_RECVFROM_SYSCALL     1
> +# define __ASSUME_RECVMSG_SYSCALL      1
> +# define __ASSUME_SHUTDOWN_SYSCALL     1
> +
> +/* There are no direct recv, send, accept syscalls available on s390. Thus
> +   recvfrom, sendto, accept4 are called if available instead of the socketcall.
> +   See recv.c, send.c, accept.c in sysdeps/unix/sysv/linux/s390 folder.  */
> +#endif
> +
>  #include_next <kernel-features.h>
> diff --git a/sysdeps/unix/sysv/linux/s390/recv.c b/sysdeps/unix/sysv/linux/s390/recv.c
> new file mode 100644
> index 0000000..9c841fb
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/s390/recv.c
> @@ -0,0 +1,41 @@
> +/* Copyright (C) 2015 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <errno.h>
> +#include <signal.h>
> +#include <sys/socket.h>
> +
> +#include <sysdep-cancel.h>
> +#include <socketcall.h>
> +#include <kernel-features.h>
> +#include <sys/syscall.h>
> +
> +ssize_t
> +__libc_recv (int fd, void *buf, size_t len, int flags)
> +{
> +#ifdef __ASSUME_RECVFROM_SYSCALL
> +  /* There does not exist a direct recv syscall on s390, thus recvfrom is used.
> +     The kernel also wraps this syscall with additional 0 parameters if called
> +     via socketcall.  */
> +  return SYSCALL_CANCEL (recvfrom, fd, buf, len, flags, NULL, NULL);
> +#else
> +  return SOCKETCALL_CANCEL (recv, fd, buf, len, flags);
> +#endif
> +}
> +weak_alias (__libc_recv, recv)
> +weak_alias (__libc_recv, __recv)
> +libc_hidden_weak (__recv)
> 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
> diff --git a/sysdeps/unix/sysv/linux/s390/send.c b/sysdeps/unix/sysv/linux/s390/send.c
> new file mode 100644
> index 0000000..e4a695b
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/s390/send.c
> @@ -0,0 +1,41 @@
> +/* Copyright (C) 2015 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <errno.h>
> +#include <signal.h>
> +#include <sys/socket.h>
> +
> +#include <sysdep-cancel.h>
> +#include <socketcall.h>
> +#include <kernel-features.h>
> +#include <sys/syscall.h>
> +
> +ssize_t
> +__libc_send (int fd, const void *buf, size_t len, int flags)
> +{
> +#ifdef __ASSUME_SENDTO_SYSCALL
> +  /* There does not exist a direct send syscall on s390, thus sendto is used.
> +     The kernel also wraps this syscall with additional 0 parameters if called
> +     via socketcall.  */
> +  return SYSCALL_CANCEL (sendto, fd, buf, len, flags, NULL, 0);
> +#else
> +  return SOCKETCALL_CANCEL (send, fd, buf, len, flags);
> +#endif
> +}
> +weak_alias (__libc_send, send)
> +weak_alias (__libc_send, __send)
> +libc_hidden_def (__send)

On Tue, 13 Oct 2015, Adhemerval Zanella wrote:

> I would prefer to not add another arch-specific implementation, but instead
> use something like __ASSUME_ACCEPT4_FOR_ACCEPT_SYSCALL and use accept4
> directly in sysdeps/unix/sysv/linux/accept.c. Same for recv and send.

Also note that using recvfrom for recv and sendto for send is what the 
linux/generic implementations do (but not accept4 for accept - I haven't 
checked if that's simply because of the asm-generic syscall interface 
being introduced before accept4).  Maybe there's futher opportunity for 
sharing with those implementations to reduce duplication?

On 10/13/2015 02:07 PM, Joseph Myers wrote:
> On Tue, 13 Oct 2015, Adhemerval Zanella wrote:
>
>> I would prefer to not add another arch-specific implementation, but instead
>> use something like __ASSUME_ACCEPT4_FOR_ACCEPT_SYSCALL and use accept4
>> directly in sysdeps/unix/sysv/linux/accept.c. Same for recv and send.
>
> Also note that using recvfrom for recv and sendto for send is what the
> linux/generic implementations do (but not accept4 for accept - I haven't
> checked if that's simply because of the asm-generic syscall interface
> being introduced before accept4).  Maybe there's futher opportunity for
> sharing with those implementations to reduce duplication?
>
accept also calls accept4. See <kernel-src>/net/socket.c:
SYSCALL_DEFINE3(accept, int, fd, struct sockaddr __user *, upeer_sockaddr,
		int __user *, upeer_addrlen)
{
	return sys_accept4(fd, upeer_sockaddr, upeer_addrlen, 0);
}

or:
SYSCALL_DEFINE2(socketcall, int, call, unsigned long __user *, args)
{
...
	switch (call) {
...
	case SYS_ACCEPT:
		err = sys_accept4(a0, (struct sockaddr __user *)a1,
				  (int __user *)a[2], 0);


On s390, there are no direct calls for these three syscalls. Thus I have 
to duplicate this behaviour to avoid the socketcall-syscall.