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
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 return TRAP(regs) == 0xc00 ? regs->gpr[0] : -1;
30 }
31
32 static inline void syscall_rollback(struct task_struct *task,
33 struct pt_regs *regs)
34 {
35 regs->gpr[3] = regs->orig_gpr3;
36 }
37
38 static inline long syscall_get_error(struct task_struct *task,
39 struct pt_regs *regs)
40 {
41 /*
42 * If the system call failed,
43 * regs->gpr[3] contains a positive ERRORCODE.
44 */
45 return (regs->ccr & 0x10000000UL) ? -regs->gpr[3] : 0;
46 }
47
48 static inline long syscall_get_return_value(struct task_struct *task,
49 struct pt_regs *regs)
50 {
51 return regs->gpr[3];
52 }
53
54 static inline void syscall_set_return_value(struct task_struct *task,
55 struct pt_regs *regs,
56 int error, long val)
57 {
58 /*
59 * In the general case it's not obvious that we must deal with CCR
60 * here, as the syscall exit path will also do that for us. However
61 * there are some places, eg. the signal code, which check ccr to
62 * decide if the value in r3 is actually an error.
63 */
64 if (error) {
65 regs->ccr |= 0x10000000L;
66 regs->gpr[3] = error;
67 } else {
68 regs->ccr &= ~0x10000000L;
69 regs->gpr[3] = val;
70 }
71 }
72
73 static inline void syscall_get_arguments(struct task_struct *task,
74 struct pt_regs *regs,
75 unsigned long *args)
76 {
77 unsigned long val, mask = -1UL;
78 unsigned int n = 6;
79
80 #ifdef CONFIG_COMPAT
81 if (test_tsk_thread_flag(task, TIF_32BIT))
82 mask = 0xffffffff;
83 #endif
84 while (n--) {
85 if (n == 0)
86 val = regs->orig_gpr3;
87 else
88 val = regs->gpr[3 + n];
89
90 args[n] = val & mask;
91 }
92 }
93
94 static inline void syscall_set_arguments(struct task_struct *task,
95 struct pt_regs *regs,
96 const unsigned long *args)
97 {
98 memcpy(®s->gpr[3], args, 6 * sizeof(args[0]));
99
100 /* Also copy the first argument into orig_gpr3 */
101 regs->orig_gpr3 = args[0];
102 }
103
104 static inline int syscall_get_arch(struct task_struct *task)
105 {
106 int arch;
107
108 if (IS_ENABLED(CONFIG_PPC64) && !test_tsk_thread_flag(task, TIF_32BIT))
109 arch = AUDIT_ARCH_PPC64;
110 else
111 arch = AUDIT_ARCH_PPC;
112
113 #ifdef __LITTLE_ENDIAN__
114 arch |= __AUDIT_ARCH_LE;
115 #endif
116 return arch;
117 }
118 #endif /* _ASM_SYSCALL_H */
119
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