// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 */

#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/seccomp.h>
#include <kern_util.h>
#include <sysdep/ptrace.h>
#include <sysdep/ptrace_user.h>
#include <linux/time-internal.h>
#include <asm/syscall.h>
#include <asm/unistd.h>
#include <asm/delay.h>

void handle_syscall(struct uml_pt_regs *r)
{
        struct pt_regs *regs = container_of(r, struct pt_regs, regs);
        int syscall;

        /* Initialize the syscall number and default return value. */
        UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
        PT_REGS_SET_SYSCALL_RETURN(regs, -ENOSYS);

        if (syscall_trace_enter(regs))
                goto out;

        /* Do the seccomp check after ptrace; failures should be fast. */
        if (secure_computing() == -1)
                goto out;

        syscall = UPT_SYSCALL_NR(r);

        /*
         * If no time passes, then sched_yield may not actually yield, causing
         * broken spinlock implementations in userspace (ASAN) to hang for long
         * periods of time.
         */
        if ((time_travel_mode == TT_MODE_INFCPU ||
             time_travel_mode == TT_MODE_EXTERNAL) &&
            syscall == __NR_sched_yield)
                tt_extra_sched_jiffies += 1;

        if (syscall >= 0 && syscall < __NR_syscalls) {
                unsigned long ret;

                ret = (*sys_call_table[syscall])(UPT_SYSCALL_ARG1(&regs->regs),
                                                 UPT_SYSCALL_ARG2(&regs->regs),
                                                 UPT_SYSCALL_ARG3(&regs->regs),
                                                 UPT_SYSCALL_ARG4(&regs->regs),
                                                 UPT_SYSCALL_ARG5(&regs->regs),
                                                 UPT_SYSCALL_ARG6(&regs->regs));

                PT_REGS_SET_SYSCALL_RETURN(regs, ret);

                /*
                 * An error value here can be some form of -ERESTARTSYS
                 * and then we'd just loop. Make any error syscalls take
                 * some time, so that it won't just loop if something is
                 * not ready, and hopefully other things will make some
                 * progress.
                 */
                if (IS_ERR_VALUE(ret) &&
                    (time_travel_mode == TT_MODE_INFCPU ||
                     time_travel_mode == TT_MODE_EXTERNAL)) {
                        um_udelay(1);
                        schedule();
                }
        }

out:
        syscall_trace_leave(regs);
}