syscall.h

  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
 18typedef long (*syscall_fn)(const struct pt_regs *);
 19#else
 20typedef 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 */
 25extern const syscall_fn sys_call_table[];
 26extern const syscall_fn compat_sys_call_table[];
 27
 28static 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
 42static 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
 52static inline void syscall_rollback(struct task_struct *task,
 53				    struct pt_regs *regs)
 54{
 55	regs->gpr[3] = regs->orig_gpr3;
 56}
 57
 58static 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
 74static inline long syscall_get_return_value(struct task_struct *task,
 75					    struct pt_regs *regs)
 76{
 77	return regs->gpr[3];
 78}
 79
 80static 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
103static 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
123static inline void syscall_set_arguments(struct task_struct *task,
124					 struct pt_regs *regs,
125					 const unsigned long *args)
126{
127	memcpy(&regs->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
133static 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 */