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 if (trap_is_syscall(regs)) 30 return regs->gpr[0]; 31 else 32 return -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_error(struct task_struct *task, 42 struct pt_regs *regs) 43 { 44 /* 45 * If the system call failed, 46 * regs->gpr[3] contains a positive ERRORCODE. 47 */ 48 return (regs->ccr & 0x10000000UL) ? -regs->gpr[3] : 0; 49 } 50 51 static inline long syscall_get_return_value(struct task_struct *task, 52 struct pt_regs *regs) 53 { 54 return regs->gpr[3]; 55 } 56 57 static inline void syscall_set_return_value(struct task_struct *task, 58 struct pt_regs *regs, 59 int error, long val) 60 { 61 /* 62 * In the general case it's not obvious that we must deal with CCR 63 * here, as the syscall exit path will also do that for us. However 64 * there are some places, eg. the signal code, which check ccr to 65 * decide if the value in r3 is actually an error. 66 */ 67 if (error) { 68 regs->ccr |= 0x10000000L; 69 regs->gpr[3] = error; 70 } else { 71 regs->ccr &= ~0x10000000L; 72 regs->gpr[3] = val; 73 } 74 } 75 76 static inline void syscall_get_arguments(struct task_struct *task, 77 struct pt_regs *regs, 78 unsigned long *args) 79 { 80 unsigned long val, mask = -1UL; 81 unsigned int n = 6; 82 83 #ifdef CONFIG_COMPAT 84 if (test_tsk_thread_flag(task, TIF_32BIT)) 85 mask = 0xffffffff; 86 #endif 87 while (n--) { 88 if (n == 0) 89 val = regs->orig_gpr3; 90 else 91 val = regs->gpr[3 + n]; 92 93 args[n] = val & mask; 94 } 95 } 96 97 static inline void syscall_set_arguments(struct task_struct *task, 98 struct pt_regs *regs, 99 const unsigned long *args) 100 { 101 memcpy(®s->gpr[3], args, 6 * sizeof(args[0])); 102 103 /* Also copy the first argument into orig_gpr3 */ 104 regs->orig_gpr3 = args[0]; 105 } 106 107 static inline int syscall_get_arch(struct task_struct *task) 108 { 109 int arch; 110 111 if (IS_ENABLED(CONFIG_PPC64) && !test_tsk_thread_flag(task, TIF_32BIT)) 112 arch = AUDIT_ARCH_PPC64; 113 else 114 arch = AUDIT_ARCH_PPC; 115 116 #ifdef __LITTLE_ENDIAN__ 117 arch |= __AUDIT_ARCH_LE; 118 #endif 119 return arch; 120 } 121 #endif /* _ASM_SYSCALL_H */ 122