linux/arch/x86/um/syscalls_64.c
Al Viro d2ce4e92fa um: kill thread->forking
we only use that to tell copy_thread() done by syscall from that
done by kernel_thread().  However, it's easier to do simply by
checking PF_KTHREAD in thread flags.

Merge sys_clone() guts for 32bit and 64bit, while we are at it...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-09-27 18:04:55 +02:00

86 lines
2.2 KiB
C

/*
* Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Copyright 2003 PathScale, Inc.
*
* Licensed under the GPL
*/
#include <linux/sched.h>
#include <asm/prctl.h> /* XXX This should get the constants from libc */
#include <os.h>
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.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:
ret = restore_registers(pid, &current->thread.regs.regs);
if (ret)
return ret;
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;
ret = save_registers(pid, &current->thread.regs.regs);
break;
case ARCH_SET_GS:
ret = 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);
}
void arch_switch_to(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);
}