/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Access to user system call parameters and results
 *
 * Copyright (C) 2008 Red Hat, Inc.  All rights reserved.
 *
 * See asm-generic/syscall.h for descriptions of what we must do here.
 */

#ifndef _ASM_SYSCALL_H
#define _ASM_SYSCALL_H  1

#include <uapi/linux/audit.h>
#include <linux/sched.h>
#include <linux/thread_info.h>

#ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER
typedef long (*syscall_fn)(const struct pt_regs *);
#else
typedef long (*syscall_fn)(unsigned long, unsigned long, unsigned long,
                           unsigned long, unsigned long, unsigned long);
#endif

/* ftrace syscalls requires exporting the sys_call_table */
extern const syscall_fn sys_call_table[];
extern const syscall_fn compat_sys_call_table[];

static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
{
        /*
         * Note that we are returning an int here. That means 0xffffffff, ie.
         * 32-bit negative 1, will be interpreted as -1 on a 64-bit kernel.
         * This is important for seccomp so that compat tasks can set r0 = -1
         * to reject the syscall.
         */
        if (trap_is_syscall(regs))
                return regs->gpr[0];
        else
                return -1;
}

static inline void syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr)
{
        /*
         * Unlike syscall_get_nr(), syscall_set_nr() can be called only when
         * the target task is stopped for tracing on entering syscall, so
         * there is no need to have the same check syscall_get_nr() has.
         */
        regs->gpr[0] = nr;
}

static inline void syscall_rollback(struct task_struct *task,
                                    struct pt_regs *regs)
{
        regs->gpr[3] = regs->orig_gpr3;
}

static inline long syscall_get_error(struct task_struct *task,
                                     struct pt_regs *regs)
{
        if (trap_is_scv(regs)) {
                unsigned long error = regs->gpr[3];

                return IS_ERR_VALUE(error) ? error : 0;
        } else {
                /*
                 * If the system call failed,
                 * regs->gpr[3] contains a positive ERRORCODE.
                 */
                return (regs->ccr & 0x10000000UL) ? -regs->gpr[3] : 0;
        }
}

static inline long syscall_get_return_value(struct task_struct *task,
                                            struct pt_regs *regs)
{
        return regs->gpr[3];
}

static inline void syscall_set_return_value(struct task_struct *task,
                                            struct pt_regs *regs,
                                            int error, long val)
{
        if (trap_is_scv(regs)) {
                regs->gpr[3] = (long) error ?: val;
        } else {
                /*
                 * In the general case it's not obvious that we must deal with
                 * CCR here, as the syscall exit path will also do that for us.
                 * However there are some places, eg. the signal code, which
                 * check ccr to decide if the value in r3 is actually an error.
                 */
                if (error) {
                        regs->ccr |= 0x10000000L;
                        regs->gpr[3] = error;
                } else {
                        regs->ccr &= ~0x10000000L;
                        regs->gpr[3] = val;
                }
        }
}

static inline void syscall_get_arguments(struct task_struct *task,
                                         struct pt_regs *regs,
                                         unsigned long *args)
{
        unsigned long val, mask = -1UL;
        unsigned int n = 6;

        if (is_tsk_32bit_task(task))
                mask = 0xffffffff;

        while (n--) {
                if (n == 0)
                        val = regs->orig_gpr3;
                else
                        val = regs->gpr[3 + n];

                args[n] = val & mask;
        }
}

static inline void syscall_set_arguments(struct task_struct *task,
                                         struct pt_regs *regs,
                                         const unsigned long *args)
{
        memcpy(&regs->gpr[3], args, 6 * sizeof(args[0]));

        /* Also copy the first argument into orig_gpr3 */
        regs->orig_gpr3 = args[0];
}

static inline int syscall_get_arch(struct task_struct *task)
{
        if (is_tsk_32bit_task(task))
                return AUDIT_ARCH_PPC;
        else if (IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN))
                return AUDIT_ARCH_PPC64LE;
        else
                return AUDIT_ARCH_PPC64;
}
#endif  /* _ASM_SYSCALL_H */