1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Access to user system call parameters and results
4 *
5 * Copyright (C) 2008 Red Hat, Inc.  All rights reserved.
6 *
7 * See asm-generic/syscall.h for descriptions of what we must do here.
8 */
9
10#ifndef _ASM_SYSCALL_H
11#define _ASM_SYSCALL_H	1
12
13#include <uapi/linux/audit.h>
14#include <linux/sched.h>
15#include <linux/thread_info.h>
16
17#ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER
18typedef long (*syscall_fn)(const struct pt_regs *);
19#else
20typedef long (*syscall_fn)(unsigned long, unsigned long, unsigned long,
21			   unsigned long, unsigned long, unsigned long);
22#endif
23
24/* ftrace syscalls requires exporting the sys_call_table */
25extern const syscall_fn sys_call_table[];
26extern const syscall_fn compat_sys_call_table[];
27
28static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
29{
30	/*
31	 * Note that we are returning an int here. That means 0xffffffff, ie.
32	 * 32-bit negative 1, will be interpreted as -1 on a 64-bit kernel.
33	 * This is important for seccomp so that compat tasks can set r0 = -1
34	 * to reject the syscall.
35	 */
36	if (trap_is_syscall(regs))
37		return regs->gpr[0];
38	else
39		return -1;
40}
41
42static inline void syscall_rollback(struct task_struct *task,
43				    struct pt_regs *regs)
44{
45	regs->gpr[3] = regs->orig_gpr3;
46}
47
48static inline long syscall_get_error(struct task_struct *task,
49				     struct pt_regs *regs)
50{
51	if (trap_is_scv(regs)) {
52		unsigned long error = regs->gpr[3];
53
54		return IS_ERR_VALUE(error) ? error : 0;
55	} else {
56		/*
57		 * If the system call failed,
58		 * regs->gpr[3] contains a positive ERRORCODE.
59		 */
60		return (regs->ccr & 0x10000000UL) ? -regs->gpr[3] : 0;
61	}
62}
63
64static inline long syscall_get_return_value(struct task_struct *task,
65					    struct pt_regs *regs)
66{
67	return regs->gpr[3];
68}
69
70static inline void syscall_set_return_value(struct task_struct *task,
71					    struct pt_regs *regs,
72					    int error, long val)
73{
74	if (trap_is_scv(regs)) {
75		regs->gpr[3] = (long) error ?: val;
76	} else {
77		/*
78		 * In the general case it's not obvious that we must deal with
79		 * CCR here, as the syscall exit path will also do that for us.
80		 * However there are some places, eg. the signal code, which
81		 * check ccr to decide if the value in r3 is actually an error.
82		 */
83		if (error) {
84			regs->ccr |= 0x10000000L;
85			regs->gpr[3] = error;
86		} else {
87			regs->ccr &= ~0x10000000L;
88			regs->gpr[3] = val;
89		}
90	}
91}
92
93static inline void syscall_get_arguments(struct task_struct *task,
94					 struct pt_regs *regs,
95					 unsigned long *args)
96{
97	unsigned long val, mask = -1UL;
98	unsigned int n = 6;
99
100	if (is_tsk_32bit_task(task))
101		mask = 0xffffffff;
102
103	while (n--) {
104		if (n == 0)
105			val = regs->orig_gpr3;
106		else
107			val = regs->gpr[3 + n];
108
109		args[n] = val & mask;
110	}
111}
112
113static inline int syscall_get_arch(struct task_struct *task)
114{
115	if (is_tsk_32bit_task(task))
116		return AUDIT_ARCH_PPC;
117	else if (IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN))
118		return AUDIT_ARCH_PPC64LE;
119	else
120		return AUDIT_ARCH_PPC64;
121}
122#endif	/* _ASM_SYSCALL_H */
123