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 /* ftrace syscalls requires exporting the sys_call_table */
18 extern const unsigned long sys_call_table[];
19 extern const unsigned long compat_sys_call_table[];
20 
syscall_get_nr(struct task_struct * task,struct pt_regs * regs)21 static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
22 {
23 	/*
24 	 * Note that we are returning an int here. That means 0xffffffff, ie.
25 	 * 32-bit negative 1, will be interpreted as -1 on a 64-bit kernel.
26 	 * This is important for seccomp so that compat tasks can set r0 = -1
27 	 * to reject the syscall.
28 	 */
29 	if (trap_is_syscall(regs))
30 		return regs->gpr[0];
31 	else
32 		return -1;
33 }
34 
syscall_rollback(struct task_struct * task,struct pt_regs * regs)35 static inline void syscall_rollback(struct task_struct *task,
36 				    struct pt_regs *regs)
37 {
38 	regs->gpr[3] = regs->orig_gpr3;
39 }
40 
syscall_get_error(struct task_struct * task,struct pt_regs * regs)41 static inline long syscall_get_error(struct task_struct *task,
42 				     struct pt_regs *regs)
43 {
44 	if (trap_is_scv(regs)) {
45 		unsigned long error = regs->gpr[3];
46 
47 		return IS_ERR_VALUE(error) ? error : 0;
48 	} else {
49 		/*
50 		 * If the system call failed,
51 		 * regs->gpr[3] contains a positive ERRORCODE.
52 		 */
53 		return (regs->ccr & 0x10000000UL) ? -regs->gpr[3] : 0;
54 	}
55 }
56 
syscall_get_return_value(struct task_struct * task,struct pt_regs * regs)57 static inline long syscall_get_return_value(struct task_struct *task,
58 					    struct pt_regs *regs)
59 {
60 	return regs->gpr[3];
61 }
62 
syscall_set_return_value(struct task_struct * task,struct pt_regs * regs,int error,long val)63 static inline void syscall_set_return_value(struct task_struct *task,
64 					    struct pt_regs *regs,
65 					    int error, long val)
66 {
67 	if (trap_is_scv(regs)) {
68 		regs->gpr[3] = (long) error ?: val;
69 	} else {
70 		/*
71 		 * In the general case it's not obvious that we must deal with
72 		 * CCR here, as the syscall exit path will also do that for us.
73 		 * However there are some places, eg. the signal code, which
74 		 * check ccr to decide if the value in r3 is actually an error.
75 		 */
76 		if (error) {
77 			regs->ccr |= 0x10000000L;
78 			regs->gpr[3] = error;
79 		} else {
80 			regs->ccr &= ~0x10000000L;
81 			regs->gpr[3] = val;
82 		}
83 	}
84 }
85 
syscall_get_arguments(struct task_struct * task,struct pt_regs * regs,unsigned long * args)86 static inline void syscall_get_arguments(struct task_struct *task,
87 					 struct pt_regs *regs,
88 					 unsigned long *args)
89 {
90 	unsigned long val, mask = -1UL;
91 	unsigned int n = 6;
92 
93 	if (is_32bit_task())
94 		mask = 0xffffffff;
95 
96 	while (n--) {
97 		if (n == 0)
98 			val = regs->orig_gpr3;
99 		else
100 			val = regs->gpr[3 + n];
101 
102 		args[n] = val & mask;
103 	}
104 }
105 
syscall_get_arch(struct task_struct * task)106 static inline int syscall_get_arch(struct task_struct *task)
107 {
108 	if (is_32bit_task())
109 		return AUDIT_ARCH_PPC;
110 	else if (IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN))
111 		return AUDIT_ARCH_PPC64LE;
112 	else
113 		return AUDIT_ARCH_PPC64;
114 }
115 #endif	/* _ASM_SYSCALL_H */
116