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