nios2: System calls handling

This patch adds support for system calls from userspaces. It uses the
asm-generic/unistd.h definitions with architecture spcific syscall.
The sys_call_table is just an array defined in a C file and it contains
pointers to the syscall functions.

Signed-off-by: Ley Foon Tan <lftan@altera.com>

3 files changed, 188 insertions, 0 deletions

diff --git a/arch/nios2/include/asm/syscall.h b/arch/nios2/include/asm/syscall.h
new file mode 100644
index 000000000000..9de220854c4a
--- /dev/null
+++ b/arch/nios2/include/asm/syscall.h
@@ -0,0 +1,138 @@
+/*
+ * Copyright Altera Corporation (C) <2014>. All rights reserved
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __ASM_NIOS2_SYSCALL_H__
+#define __ASM_NIOS2_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->r2;
+}
+
+static inline void syscall_rollback(struct task_struct *task,
+                                struct pt_regs *regs)
+{
+        regs->r2 = regs->orig_r2;
+        regs->r7 = regs->orig_r7;
+}
+
+static inline long syscall_get_error(struct task_struct *task,
+                                struct pt_regs *regs)
+{
+        return regs->r7 ? regs->r2 : 0;
+}
+
+static inline long syscall_get_return_value(struct task_struct *task,
+        struct pt_regs *regs)
+{
+        return regs->r2;
+}
+
+static inline void syscall_set_return_value(struct task_struct *task,
+        struct pt_regs *regs, int error, long val)
+{
+        if (error) {
+                /* error < 0, but nios2 uses > 0 return value */
+                regs->r2 = -error;
+                regs->r7 = 1;
+        } else {
+                regs->r2 = val;
+                regs->r7 = 0;
+        }
+}
+
+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);
+
+        switch (i) {
+        case 0:
+                if (!n--)
+                        break;
+                *args++ = regs->r4;
+        case 1:
+                if (!n--)
+                        break;
+                *args++ = regs->r5;
+        case 2:
+                if (!n--)
+                        break;
+                *args++ = regs->r6;
+        case 3:
+                if (!n--)
+                        break;
+                *args++ = regs->r7;
+        case 4:
+                if (!n--)
+                        break;
+                *args++ = regs->r8;
+        case 5:
+                if (!n--)
+                        break;
+                *args++ = regs->r9;
+        case 6:
+                if (!n--)
+                        break;
+        default:
+                BUG();
+        }
+}
+
+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);
+
+        switch (i) {
+        case 0:
+                if (!n--)
+                        break;
+                regs->r4 = *args++;
+        case 1:
+                if (!n--)
+                        break;
+                regs->r5 = *args++;
+        case 2:
+                if (!n--)
+                        break;
+                regs->r6 = *args++;
+        case 3:
+                if (!n--)
+                        break;
+                regs->r7 = *args++;
+        case 4:
+                if (!n--)
+                        break;
+                regs->r8 = *args++;
+        case 5:
+                if (!n--)
+                        break;
+                regs->r9 = *args++;
+        case 6:
+                if (!n)
+                        break;
+        default:
+                BUG();
+        }
+}
+
+#endif
diff --git a/arch/nios2/include/asm/syscalls.h b/arch/nios2/include/asm/syscalls.h
new file mode 100644
index 000000000000..0245d780351b
--- /dev/null
+++ b/arch/nios2/include/asm/syscalls.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright Altera Corporation (C) 2013. All rights reserved
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#ifndef __ASM_NIOS2_SYSCALLS_H
+#define __ASM_NIOS2_SYSCALLS_H
+
+int sys_cacheflush(unsigned long addr, unsigned long len,
+                                unsigned int op);
+
+#include <asm-generic/syscalls.h>
+
+#endif /* __ASM_NIOS2_SYSCALLS_H */
diff --git a/arch/nios2/include/uapi/asm/unistd.h b/arch/nios2/include/uapi/asm/unistd.h
new file mode 100644
index 000000000000..c4bf79510461
--- /dev/null
+++ b/arch/nios2/include/uapi/asm/unistd.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2013 Altera Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+ #define sys_mmap2 sys_mmap_pgoff
+
+/* Use the standard ABI for syscalls */
+#include <asm-generic/unistd.h>
+
+/* Additional Nios II specific syscalls. */
+#define __NR_cacheflush (__NR_arch_specific_syscall)
+__SYSCALL(__NR_cacheflush, sys_cacheflush)