syscall.h

  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 task_thread_info(task)->syscall;
 42}
 43
 44static inline void syscall_set_nr(struct task_struct *task,
 45				  struct pt_regs *regs,
 46				  int nr)
 47{
 48	/*
 49	 * New syscall number has to be assigned to regs[2] because
 50	 * it is loaded from there unconditionally after return from
 51	 * syscall_trace_enter() invocation.
 52	 *
 53	 * Consequently, if the syscall was indirect and nr != __NR_syscall,
 54	 * then after this assignment the syscall will cease to be indirect.
 55	 */
 56	task_thread_info(task)->syscall = regs->regs[2] = nr;
 57}
 58
 59static inline void mips_syscall_update_nr(struct task_struct *task,
 60					  struct pt_regs *regs)
 61{
 62	/*
 63	 * v0 is the system call number, except for O32 ABI syscall(), where it
 64	 * ends up in a0.
 65	 */
 66	if (mips_syscall_is_indirect(task, regs))
 67		task_thread_info(task)->syscall = regs->regs[4];
 68	else
 69		task_thread_info(task)->syscall = regs->regs[2];
 70}
 71
 72static inline void mips_get_syscall_arg(unsigned long *arg,
 73	struct task_struct *task, struct pt_regs *regs, unsigned int n)
 74{
 75#ifdef CONFIG_32BIT
 76	switch (n) {
 77	case 0: case 1: case 2: case 3:
 78		*arg = regs->regs[4 + n];
 79		return;
 80	case 4: case 5: case 6: case 7:
 81		*arg = regs->args[n];
 82		return;
 83	}
 84#else
 85	*arg = regs->regs[4 + n];
 86	if ((IS_ENABLED(CONFIG_MIPS32_O32) &&
 87	     test_tsk_thread_flag(task, TIF_32BIT_REGS)))
 88		*arg = (unsigned int)*arg;
 89#endif
 90}
 91
 92static inline void mips_set_syscall_arg(unsigned long *arg,
 93	struct task_struct *task, struct pt_regs *regs, unsigned int n)
 94{
 95#ifdef CONFIG_32BIT
 96	switch (n) {
 97	case 0: case 1: case 2: case 3:
 98		regs->regs[4 + n] = *arg;
 99		return;
100	case 4: case 5: case 6: case 7:
101		*arg = regs->args[n] = *arg;
102		return;
103	}
104#else
105	regs->regs[4 + n] = *arg;
106#endif
107}
108
109static inline long syscall_get_error(struct task_struct *task,
110				     struct pt_regs *regs)
111{
112	return regs->regs[7] ? -regs->regs[2] : 0;
113}
114
115static inline long syscall_get_return_value(struct task_struct *task,
116					    struct pt_regs *regs)
117{
118	return regs->regs[2];
119}
120
121static inline void syscall_rollback(struct task_struct *task,
122				    struct pt_regs *regs)
123{
124	/* Do nothing */
125}
126
127static inline void syscall_set_return_value(struct task_struct *task,
128					    struct pt_regs *regs,
129					    int error, long val)
130{
131	if (error) {
132		regs->regs[2] = -error;
133		regs->regs[7] = 1;
134	} else {
135		regs->regs[2] = val;
136		regs->regs[7] = 0;
137	}
138}
139
140static inline void syscall_get_arguments(struct task_struct *task,
141					 struct pt_regs *regs,
142					 unsigned long *args)
143{
144	unsigned int i = 0;
145	unsigned int n = 6;
146
147	/* O32 ABI syscall() */
148	if (mips_syscall_is_indirect(task, regs))
149		i++;
150
151	while (n--)
152		mips_get_syscall_arg(args++, task, regs, i++);
153}
154
155static inline void syscall_set_arguments(struct task_struct *task,
156					 struct pt_regs *regs,
157					 unsigned long *args)
158{
159	unsigned int i = 0;
160	unsigned int n = 6;
161
162	while (n--)
163		mips_set_syscall_arg(args++, task, regs, i++);
164}
165
166extern const unsigned long sys_call_table[];
167extern const unsigned long sys32_call_table[];
168extern const unsigned long sysn32_call_table[];
169
170static inline int syscall_get_arch(struct task_struct *task)
171{
172	int arch = AUDIT_ARCH_MIPS;
173#ifdef CONFIG_64BIT
174	if (!test_tsk_thread_flag(task, TIF_32BIT_REGS)) {
175		arch |= __AUDIT_ARCH_64BIT;
176		/* N32 sets only TIF_32BIT_ADDR */
177		if (test_tsk_thread_flag(task, TIF_32BIT_ADDR))
178			arch |= __AUDIT_ARCH_CONVENTION_MIPS64_N32;
179	}
180#endif
181#if defined(__LITTLE_ENDIAN)
182	arch |=  __AUDIT_ARCH_LE;
183#endif
184	return arch;
185}
186
187#endif	/* __ASM_MIPS_SYSCALL_H */