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