xref: /openbmc/linux/arch/powerpc/include/asm/syscall.h (revision 4a075bd4)
1 /*
2  * Access to user system call parameters and results
3  *
4  * Copyright (C) 2008 Red Hat, Inc.  All rights reserved.
5  *
6  * This copyrighted material is made available to anyone wishing to use,
7  * modify, copy, or redistribute it subject to the terms and conditions
8  * of the GNU General Public License v.2.
9  *
10  * See asm-generic/syscall.h for descriptions of what we must do here.
11  */
12 
13 #ifndef _ASM_SYSCALL_H
14 #define _ASM_SYSCALL_H	1
15 
16 #include <uapi/linux/audit.h>
17 #include <linux/sched.h>
18 #include <linux/thread_info.h>
19 
20 /* ftrace syscalls requires exporting the sys_call_table */
21 extern const unsigned long sys_call_table[];
22 extern const unsigned long compat_sys_call_table[];
23 
24 static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
25 {
26 	/*
27 	 * Note that we are returning an int here. That means 0xffffffff, ie.
28 	 * 32-bit negative 1, will be interpreted as -1 on a 64-bit kernel.
29 	 * This is important for seccomp so that compat tasks can set r0 = -1
30 	 * to reject the syscall.
31 	 */
32 	return TRAP(regs) == 0xc00 ? regs->gpr[0] : -1;
33 }
34 
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 
41 static inline long syscall_get_return_value(struct task_struct *task,
42 					    struct pt_regs *regs)
43 {
44 	return regs->gpr[3];
45 }
46 
47 static inline void syscall_set_return_value(struct task_struct *task,
48 					    struct pt_regs *regs,
49 					    int error, long val)
50 {
51 	/*
52 	 * In the general case it's not obvious that we must deal with CCR
53 	 * here, as the syscall exit path will also do that for us. However
54 	 * there are some places, eg. the signal code, which check ccr to
55 	 * decide if the value in r3 is actually an error.
56 	 */
57 	if (error) {
58 		regs->ccr |= 0x10000000L;
59 		regs->gpr[3] = error;
60 	} else {
61 		regs->ccr &= ~0x10000000L;
62 		regs->gpr[3] = val;
63 	}
64 }
65 
66 static inline void syscall_get_arguments(struct task_struct *task,
67 					 struct pt_regs *regs,
68 					 unsigned long *args)
69 {
70 	unsigned long val, mask = -1UL;
71 	unsigned int n = 6;
72 
73 #ifdef CONFIG_COMPAT
74 	if (test_tsk_thread_flag(task, TIF_32BIT))
75 		mask = 0xffffffff;
76 #endif
77 	while (n--) {
78 		if (n == 0)
79 			val = regs->orig_gpr3;
80 		else
81 			val = regs->gpr[3 + n];
82 
83 		args[n] = val & mask;
84 	}
85 }
86 
87 static inline void syscall_set_arguments(struct task_struct *task,
88 					 struct pt_regs *regs,
89 					 const unsigned long *args)
90 {
91 	memcpy(&regs->gpr[3], args, 6 * sizeof(args[0]));
92 
93 	/* Also copy the first argument into orig_gpr3 */
94 	regs->orig_gpr3 = args[0];
95 }
96 
97 static inline int syscall_get_arch(struct task_struct *task)
98 {
99 	int arch;
100 
101 	if (IS_ENABLED(CONFIG_PPC64) && !test_tsk_thread_flag(task, TIF_32BIT))
102 		arch = AUDIT_ARCH_PPC64;
103 	else
104 		arch = AUDIT_ARCH_PPC;
105 
106 #ifdef __LITTLE_ENDIAN__
107 	arch |= __AUDIT_ARCH_LE;
108 #endif
109 	return arch;
110 }
111 #endif	/* _ASM_SYSCALL_H */
112