glibc/sysdeps/unix/sysv/linux/s390/s390-32/vfork.S
Stefan Liebler e57d8fc97b S390: Always use svc 0
On s390x syscalls are triggered by svc instruction. One can
pass the syscall number encoded in the instruction "svc 123"
or by storing it in r1:
lghi r1,123
svc 0

If the syscall number is encoded in the instruction, this can
cause broken syscall restarts.  Therefore this patch is now just
passing the syscall number in r1.

See also kernel-commit:
"s390/signal: switch to using vdso for sigreturn and syscall restart"
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/arch/s390/[%e2%80%a6]call.c?h=v6.0-rc1&id=df29a7440c4b5c65765c8f60396b3b13063e24e9

As information, the "svc 0" feature was introduced in kernel 2.5.62:
commit b5aad611393ef2e132e3648fa4c6e56a9cfa8708
2022-08-30 10:54:46 +02:00

47 lines
1.5 KiB
ArmAsm

/* Copyright (C) 2004-2022 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
<https://www.gnu.org/licenses/>. */
#include <sysdep.h>
#define _ERRNO_H 1
#include <bits/errno.h>
#include <bits/wordsize.h>
#include <tcb-offsets.h>
/* Clone the calling process, but without copying the whole address space.
The calling process is suspended until the new process exits or is
replaced by a call to `execve'. Return -1 for errors, 0 to the new process,
and the process ID of the new process to the old process. */
ENTRY (__libc_vfork)
/* Do vfork system call. */
lhi %r1,SYS_ify (vfork)
svc 0
/* Check for error. */
lhi %r4,-4095
clr %r2,%r4
jnl SYSCALL_ERROR_LABEL
/* Normal return. */
br %r14
PSEUDO_END (__libc_vfork)
#if IS_IN (libc)
weak_alias (__libc_vfork, vfork)
strong_alias (__libc_vfork, __vfork)
libc_hidden_def (__vfork)
#endif