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 if (trap_is_scv(regs)) { 45 unsigned long error = regs->gpr[3]; 46 47 return IS_ERR_VALUE(error) ? error : 0; 48 } else { 49 /* 50 * If the system call failed, 51 * regs->gpr[3] contains a positive ERRORCODE. 52 */ 53 return (regs->ccr & 0x10000000UL) ? -regs->gpr[3] : 0; 54 } 55 } 56 57 static inline long syscall_get_return_value(struct task_struct *task, 58 struct pt_regs *regs) 59 { 60 return regs->gpr[3]; 61 } 62 63 static inline void syscall_set_return_value(struct task_struct *task, 64 struct pt_regs *regs, 65 int error, long val) 66 { 67 if (trap_is_scv(regs)) { 68 regs->gpr[3] = (long) error ?: val; 69 } else { 70 /* 71 * In the general case it's not obvious that we must deal with 72 * CCR here, as the syscall exit path will also do that for us. 73 * However there are some places, eg. the signal code, which 74 * check ccr to decide if the value in r3 is actually an error. 75 */ 76 if (error) { 77 regs->ccr |= 0x10000000L; 78 regs->gpr[3] = error; 79 } else { 80 regs->ccr &= ~0x10000000L; 81 regs->gpr[3] = val; 82 } 83 } 84 } 85 86 static inline void syscall_get_arguments(struct task_struct *task, 87 struct pt_regs *regs, 88 unsigned long *args) 89 { 90 unsigned long val, mask = -1UL; 91 unsigned int n = 6; 92 93 if (is_tsk_32bit_task(task)) 94 mask = 0xffffffff; 95 96 while (n--) { 97 if (n == 0) 98 val = regs->orig_gpr3; 99 else 100 val = regs->gpr[3 + n]; 101 102 args[n] = val & mask; 103 } 104 } 105 106 static inline int syscall_get_arch(struct task_struct *task) 107 { 108 if (is_tsk_32bit_task(task)) 109 return AUDIT_ARCH_PPC; 110 else if (IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN)) 111 return AUDIT_ARCH_PPC64LE; 112 else 113 return AUDIT_ARCH_PPC64; 114 } 115 #endif /* _ASM_SYSCALL_H */ 116