acrn-kernel/arch/um/sys-x86_64/syscalls.c

/*
 * Copyright 2003 PathScale, Inc.
 *
 * Licensed under the GPL
 */

#include "linux/linkage.h"
#include "linux/slab.h"
#include "linux/shm.h"
#include "linux/utsname.h"
#include "linux/personality.h"
#include "asm/uaccess.h"
#define __FRAME_OFFSETS
#include "asm/ptrace.h"
#include "asm/unistd.h"
#include "asm/prctl.h" /* XXX This should get the constants from libc */
#include "kern.h"
#include "os.h"

asmlinkage long sys_uname64(struct new_utsname __user * name)
{
	int err;
	down_read(&uts_sem);
	err = copy_to_user(name, utsname(), sizeof (*name));
	up_read(&uts_sem);
	if (personality(current->personality) == PER_LINUX32)
		err |= copy_to_user(&name->machine, "i686", 5);
	return err ? -EFAULT : 0;
}

long arch_prctl(struct task_struct *task, int code, unsigned long __user *addr)
{
        unsigned long *ptr = addr, tmp;
	long ret;
	int pid = task->mm->context.skas.id.u.pid;

	/*
	 * With ARCH_SET_FS (and ARCH_SET_GS is treated similarly to
	 * be safe), we need to call arch_prctl on the host because
	 * setting %fs may result in something else happening (like a
	 * GDT or thread.fs being set instead).  So, we let the host
	 * fiddle the registers and thread struct and restore the
	 * registers afterwards.
	 *
	 * So, the saved registers are stored to the process (this
	 * needed because a stub may have been the last thing to run),
	 * arch_prctl is run on the host, then the registers are read
	 * back.
	 */
	switch(code){
	case ARCH_SET_FS:
	case ARCH_SET_GS:
                restore_registers(pid, &current->thread.regs.regs);
                break;
        case ARCH_GET_FS:
        case ARCH_GET_GS:
                /*
                 * With these two, we read to a local pointer and
                 * put_user it to the userspace pointer that we were
                 * given.  If addr isn't valid (because it hasn't been
                 * faulted in or is just bogus), we want put_user to
                 * fault it in (or return -EFAULT) instead of having
                 * the host return -EFAULT.
                 */
                ptr = &tmp;
        }

        ret = os_arch_prctl(pid, code, ptr);
        if(ret)
                return ret;

        switch(code){
	case ARCH_SET_FS:
		current->thread.arch.fs = (unsigned long) ptr;
		save_registers(pid, &current->thread.regs.regs);
		break;
	case ARCH_SET_GS:
                save_registers(pid, &current->thread.regs.regs);
		break;
	case ARCH_GET_FS:
		ret = put_user(tmp, addr);
	        break;
	case ARCH_GET_GS:
		ret = put_user(tmp, addr);
	        break;
	}

	return ret;
}

long sys_arch_prctl(int code, unsigned long addr)
{
	return arch_prctl(current, code, (unsigned long __user *) addr);
}

long sys_clone(unsigned long clone_flags, unsigned long newsp,
	       void __user *parent_tid, void __user *child_tid)
{
	long ret;

	if (!newsp)
		newsp = UPT_SP(&current->thread.regs.regs);
	current->thread.forking = 1;
	ret = do_fork(clone_flags, newsp, &current->thread.regs, 0, parent_tid,
		      child_tid);
	current->thread.forking = 0;
	return ret;
}

void arch_switch_to(struct task_struct *from, struct task_struct *to)
{
        if((to->thread.arch.fs == 0) || (to->mm == NULL))
                return;

        arch_prctl(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs);
}