OpenRISC: System calls

The OpenRISC Linux kernel conforms to the "generic" syscall interface which
contains only the reduced set of syscalls deemed necessary for new
architectures.  Unfortunately, the uClibc port for OpenRISC does not fully
support this reduced set; as such, an additional patch available out-of-tree
needs to be applied to the kernel in order to use the current uClibc.  This
is just a temporary measure until the libc port can be straightened out; it
is likely that OpenRISC will make the transition to glibc shortly where the
generic syscall interface is better supported.
Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

arch/openrisc/include/asm/syscall.h

+/*
+ * OpenRISC Linux
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others.  All original copyrights apply as per the original source
+ * declaration.
+ *
+ * OpenRISC implementation:
+ * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
+ * et al.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __ASM_OPENRISC_SYSCALL_H__
+#define __ASM_OPENRISC_SYSCALL_H__
+
+#include <linux/err.h>
+#include <linux/sched.h>
+
+static inline int
+syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
+{
+	return regs->syscallno ? regs->syscallno : -1;
+}
+
+static inline void
+syscall_rollback(struct task_struct *task, struct pt_regs *regs)
+{
+	regs->gpr[11] = regs->orig_gpr11;
+}
+
+static inline long
+syscall_get_error(struct task_struct *task, struct pt_regs *regs)
+{
+	return IS_ERR_VALUE(regs->gpr[11]) ? regs->gpr[11] : 0;
+}
+
+static inline long
+syscall_get_return_value(struct task_struct *task, struct pt_regs *regs)
+{
+	return regs->gpr[11];
+}
+
+static inline void
+syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
+			 int error, long val)
+{
+	if (error)
+		regs->gpr[11] = -error;
+	else
+		regs->gpr[11] = val;
+}
+
+static inline void
+syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
+		      unsigned int i, unsigned int n, unsigned long *args)
+{
+	BUG_ON(i + n > 6);
+
+	memcpy(args, &regs->gpr[3 + i], n * sizeof(args[0]));
+}
+
+static inline void
+syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
+		      unsigned int i, unsigned int n, const unsigned long *args)
+{
+	BUG_ON(i + n > 6);
+
+	memcpy(&regs->gpr[3 + i], args, n * sizeof(args[0]));
+}
+
+#endif

arch/openrisc/include/asm/syscalls.h

+/*
+ * OpenRISC Linux
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others.  All original copyrights apply as per the original source
+ * declaration.
+ *
+ * OpenRISC implementation:
+ * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
+ * et al.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __ASM_OPENRISC_SYSCALLS_H
+#define __ASM_OPENRISC_SYSCALLS_H
+
+asmlinkage long sys_or1k_atomic(unsigned long type, unsigned long *v1,
+				unsigned long *v2);
+
+#include <asm-generic/syscalls.h>
+
+#endif /* __ASM_OPENRISC_SYSCALLS_H */

arch/openrisc/include/asm/unistd.h

+/*
+ * OpenRISC Linux
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others.  All original copyrights apply as per the original source
+ * declaration.
+ *
+ * OpenRISC implementation:
+ * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
+ * et al.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#if !defined(__ASM_OPENRISC_UNISTD_H) || defined(__SYSCALL)
+#define __ASM_OPENRISC_UNISTD_H
+
+#define __ARCH_HAVE_MMU
+
+#define sys_mmap2 sys_mmap_pgoff
+
+#include <asm-generic/unistd.h>
+
+#define __NR_or1k_atomic __NR_arch_specific_syscall
+__SYSCALL(__NR_or1k_atomic, sys_or1k_atomic)
+
+#endif /* __ASM_OPENRISC_UNISTD_H */

arch/openrisc/kernel/sys_call_table.c

+/*
+ * OpenRISC sys_call_table.c
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others.  All original copyrights apply as per the original source
+ * declaration.
+ *
+ * Modifications for the OpenRISC architecture:
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/syscalls.h>
+#include <linux/signal.h>
+#include <linux/unistd.h>
+
+#include <asm/syscalls.h>
+
+#undef __SYSCALL
+#define __SYSCALL(nr, call) [nr] = (call),
+
+void *sys_call_table[__NR_syscalls] = {
+#include <asm/unistd.h>
+};

arch/openrisc/kernel/sys_or32.c

+/*
+ * OpenRISC sys_or32.c
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others.  All original copyrights apply as per the original source
+ * declaration.
+ *
+ * Modifications for the OpenRISC architecture:
+ * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ *
+ * This file contains various random system calls that
+ * have a non-standard calling sequence on some platforms.
+ * Since we don't have to do any backwards compatibility, our
+ * versions are done in the most "normal" way possible.
+ */
+
+#include <linux/errno.h>
+#include <linux/syscalls.h>
+#include <linux/mm.h>
+
+#include <asm/syscalls.h>
+
+/* These are secondary entry points as the primary entry points are defined in
+ * entry.S where we add the 'regs' parameter value
+ */
+
+asmlinkage long _sys_clone(unsigned long clone_flags, unsigned long newsp,
+			   int __user *parent_tid, int __user *child_tid,
+			   struct pt_regs *regs)
+{
+	long ret;
+
+	/* FIXME: Is alignment necessary? */
+	/* newsp = ALIGN(newsp, 4); */
+
+	if (!newsp)
+		newsp = regs->sp;
+
+	ret = do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
+
+	return ret;
+}
+
+asmlinkage int _sys_fork(struct pt_regs *regs)
+{
+#ifdef CONFIG_MMU
+	return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
+#else
+	return -EINVAL;
+#endif
+}