1/*
  2 * Access to user system call parameters and results
  3 *
  4 * This file is subject to the terms and conditions of the GNU General Public
  5 * License.  See the file "COPYING" in the main directory of this archive
  6 * for more details.
  7 *
  8 * See asm-generic/syscall.h for descriptions of what we must do here.
  9 *
 10 * Copyright (C) 2012 Ralf Baechle <ralf@linux-mips.org>
 11 */
 12
 13#ifndef __ASM_MIPS_SYSCALL_H
 14#define __ASM_MIPS_SYSCALL_H
 15
 16#include <linux/compiler.h>
 17#include <uapi/linux/audit.h>
 18#include <linux/elf-em.h>
 19#include <linux/kernel.h>
 20#include <linux/sched.h>
 21#include <linux/uaccess.h>
 22#include <asm/ptrace.h>
 23#include <asm/unistd.h>
 24
 25#ifndef __NR_syscall /* Only defined if _MIPS_SIM == _MIPS_SIM_ABI32 */
 26#define __NR_syscall 4000
 27#endif
 28
 29static inline bool mips_syscall_is_indirect(struct task_struct *task,
 30					    struct pt_regs *regs)
 31{
 32	/* O32 ABI syscall() - Either 64-bit with O32 or 32-bit */
 33	return (IS_ENABLED(CONFIG_32BIT) ||
 34		test_tsk_thread_flag(task, TIF_32BIT_REGS)) &&
 35		(regs->regs[2] == __NR_syscall);
 36}
 37
 38static inline long syscall_get_nr(struct task_struct *task,
 39				  struct pt_regs *regs)
 40{
 41	return current_thread_info()->syscall;
 42}
 43
 44static inline void mips_syscall_update_nr(struct task_struct *task,
 45					  struct pt_regs *regs)
 46{
 47	/*
 48	 * v0 is the system call number, except for O32 ABI syscall(), where it
 49	 * ends up in a0.
 50	 */
 51	if (mips_syscall_is_indirect(task, regs))
 52		task_thread_info(task)->syscall = regs->regs[4];
 53	else
 54		task_thread_info(task)->syscall = regs->regs[2];
 55}
 56
 57static inline unsigned long mips_get_syscall_arg(unsigned long *arg,
 58	struct task_struct *task, struct pt_regs *regs, unsigned int n)
 59{
 60	unsigned long usp __maybe_unused = regs->regs[29];
 61
 62	switch (n) {
 63	case 0: case 1: case 2: case 3:
 64		*arg = regs->regs[4 + n];
 65
 66		return 0;
 67
 68#ifdef CONFIG_32BIT
 69	case 4: case 5: case 6: case 7:
 70		return get_user(*arg, (int *)usp + n);
 71#endif
 72
 73#ifdef CONFIG_64BIT
 74	case 4: case 5: case 6: case 7:
 75#ifdef CONFIG_MIPS32_O32
 76		if (test_thread_flag(TIF_32BIT_REGS))
 77			return get_user(*arg, (int *)usp + n);
 78		else
 79#endif
 80			*arg = regs->regs[4 + n];
 81
 82		return 0;
 83#endif
 84
 85	default:
 86		BUG();
 87	}
 88
 89	unreachable();
 90}
 91
 92static inline long syscall_get_return_value(struct task_struct *task,
 93					    struct pt_regs *regs)
 94{
 95	return regs->regs[2];
 96}
 97
 98static inline void syscall_rollback(struct task_struct *task,
 99				    struct pt_regs *regs)
100{
101	/* Do nothing */
102}
103
104static inline void syscall_set_return_value(struct task_struct *task,
105					    struct pt_regs *regs,
106					    int error, long val)
107{
108	if (error) {
109		regs->regs[2] = -error;
110		regs->regs[7] = 1;
111	} else {
112		regs->regs[2] = val;
113		regs->regs[7] = 0;
114	}
115}
116
117static inline void syscall_get_arguments(struct task_struct *task,
118					 struct pt_regs *regs,
119					 unsigned int i, unsigned int n,
120					 unsigned long *args)
121{
122	int ret;
123
124	/* O32 ABI syscall() */
125	if (mips_syscall_is_indirect(task, regs))
126		i++;
127
128	while (n--)
129		ret |= mips_get_syscall_arg(args++, task, regs, i++);
130
131	/*
132	 * No way to communicate an error because this is a void function.
133	 */
134#if 0
135	return ret;
136#endif
137}
138
139extern const unsigned long sys_call_table[];
140extern const unsigned long sys32_call_table[];
141extern const unsigned long sysn32_call_table[];
142
143static inline int syscall_get_arch(void)
144{
145	int arch = AUDIT_ARCH_MIPS;
146#ifdef CONFIG_64BIT
147	if (!test_thread_flag(TIF_32BIT_REGS)) {
148		arch |= __AUDIT_ARCH_64BIT;
149		/* N32 sets only TIF_32BIT_ADDR */
150		if (test_thread_flag(TIF_32BIT_ADDR))
151			arch |= __AUDIT_ARCH_CONVENTION_MIPS64_N32;
152	}
153#endif
154#if defined(__LITTLE_ENDIAN)
155	arch |=  __AUDIT_ARCH_LE;
156#endif
157	return arch;
158}
159
160#endif	/* __ASM_MIPS_SYSCALL_H */