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 #ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER 18 typedef long (*syscall_fn)(const struct pt_regs *); 19 #else 20 typedef long (*syscall_fn)(unsigned long, unsigned long, unsigned long, 21 unsigned long, unsigned long, unsigned long); 22 #endif 23 24 /* ftrace syscalls requires exporting the sys_call_table */ 25 extern const syscall_fn sys_call_table[]; 26 extern const syscall_fn compat_sys_call_table[]; 27 28 static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs) 29 { 30 /* 31 * Note that we are returning an int here. That means 0xffffffff, ie. 32 * 32-bit negative 1, will be interpreted as -1 on a 64-bit kernel. 33 * This is important for seccomp so that compat tasks can set r0 = -1 34 * to reject the syscall. 35 */ 36 if (trap_is_syscall(regs)) 37 return regs->gpr[0]; 38 else 39 return -1; 40 } 41 42 static inline void syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr) 43 { 44 /* 45 * Unlike syscall_get_nr(), syscall_set_nr() can be called only when 46 * the target task is stopped for tracing on entering syscall, so 47 * there is no need to have the same check syscall_get_nr() has. 48 */ 49 regs->gpr[0] = nr; 50 } 51 52 static inline void syscall_rollback(struct task_struct *task, 53 struct pt_regs *regs) 54 { 55 regs->gpr[3] = regs->orig_gpr3; 56 } 57 58 static inline long syscall_get_error(struct task_struct *task, 59 struct pt_regs *regs) 60 { 61 if (trap_is_scv(regs)) { 62 unsigned long error = regs->gpr[3]; 63 64 return IS_ERR_VALUE(error) ? error : 0; 65 } else { 66 /* 67 * If the system call failed, 68 * regs->gpr[3] contains a positive ERRORCODE. 69 */ 70 return (regs->ccr & 0x10000000UL) ? -regs->gpr[3] : 0; 71 } 72 } 73 74 static inline long syscall_get_return_value(struct task_struct *task, 75 struct pt_regs *regs) 76 { 77 return regs->gpr[3]; 78 } 79 80 static inline void syscall_set_return_value(struct task_struct *task, 81 struct pt_regs *regs, 82 int error, long val) 83 { 84 if (trap_is_scv(regs)) { 85 regs->gpr[3] = (long) error ?: val; 86 } else { 87 /* 88 * In the general case it's not obvious that we must deal with 89 * CCR here, as the syscall exit path will also do that for us. 90 * However there are some places, eg. the signal code, which 91 * check ccr to decide if the value in r3 is actually an error. 92 */ 93 if (error) { 94 regs->ccr |= 0x10000000L; 95 regs->gpr[3] = error; 96 } else { 97 regs->ccr &= ~0x10000000L; 98 regs->gpr[3] = val; 99 } 100 } 101 } 102 103 static inline void syscall_get_arguments(struct task_struct *task, 104 struct pt_regs *regs, 105 unsigned long *args) 106 { 107 unsigned long val, mask = -1UL; 108 unsigned int n = 6; 109 110 if (is_tsk_32bit_task(task)) 111 mask = 0xffffffff; 112 113 while (n--) { 114 if (n == 0) 115 val = regs->orig_gpr3; 116 else 117 val = regs->gpr[3 + n]; 118 119 args[n] = val & mask; 120 } 121 } 122 123 static inline void syscall_set_arguments(struct task_struct *task, 124 struct pt_regs *regs, 125 const unsigned long *args) 126 { 127 memcpy(®s->gpr[3], args, 6 * sizeof(args[0])); 128 129 /* Also copy the first argument into orig_gpr3 */ 130 regs->orig_gpr3 = args[0]; 131 } 132 133 static inline int syscall_get_arch(struct task_struct *task) 134 { 135 if (is_tsk_32bit_task(task)) 136 return AUDIT_ARCH_PPC; 137 else if (IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN)) 138 return AUDIT_ARCH_PPC64LE; 139 else 140 return AUDIT_ARCH_PPC64; 141 } 142 #endif /* _ASM_SYSCALL_H */ 143