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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Jeff Dikeba180fd2007-10-16 01:27:00 -07002 * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003 * Copyright 2003 PathScale, Inc.
4 *
5 * Licensed under the GPL
6 */
7
Al Virod2ce4e92012-09-20 09:28:25 -04008#include <linux/sched.h>
Richard Weinberger7017f422015-05-12 00:13:05 +02009#include <linux/uaccess.h>
Al Virod2ce4e92012-09-20 09:28:25 -040010#include <asm/prctl.h> /* XXX This should get the constants from libc */
11#include <os.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070012
Jeff Dike77bf4402007-10-16 01:26:58 -070013long arch_prctl(struct task_struct *task, int code, unsigned long __user *addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070014{
Jeff Dikeba180fd2007-10-16 01:27:00 -070015 unsigned long *ptr = addr, tmp;
Jeff Dikef3555592007-02-10 01:44:29 -080016 long ret;
Jeff Dike6c738ff2007-10-16 01:27:06 -070017 int pid = task->mm->context.id.u.pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -070018
Jeff Dikef3555592007-02-10 01:44:29 -080019 /*
20 * With ARCH_SET_FS (and ARCH_SET_GS is treated similarly to
21 * be safe), we need to call arch_prctl on the host because
22 * setting %fs may result in something else happening (like a
Jeff Dike6e6d74c2007-02-10 01:44:30 -080023 * GDT or thread.fs being set instead). So, we let the host
24 * fiddle the registers and thread struct and restore the
25 * registers afterwards.
Jeff Dikef3555592007-02-10 01:44:29 -080026 *
27 * So, the saved registers are stored to the process (this
28 * needed because a stub may have been the last thing to run),
29 * arch_prctl is run on the host, then the registers are read
30 * back.
31 */
Jeff Dikeba180fd2007-10-16 01:27:00 -070032 switch (code) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070033 case ARCH_SET_FS:
Paolo 'Blaisorblade' Giarrussof767b022005-05-28 15:52:03 -070034 case ARCH_SET_GS:
Jeff Dike3e6f2ac2008-02-04 22:30:58 -080035 ret = restore_registers(pid, &current->thread.regs.regs);
36 if (ret)
37 return ret;
Jeff Dikeba180fd2007-10-16 01:27:00 -070038 break;
39 case ARCH_GET_FS:
40 case ARCH_GET_GS:
41 /*
42 * With these two, we read to a local pointer and
43 * put_user it to the userspace pointer that we were
44 * given. If addr isn't valid (because it hasn't been
45 * faulted in or is just bogus), we want put_user to
46 * fault it in (or return -EFAULT) instead of having
47 * the host return -EFAULT.
48 */
49 ptr = &tmp;
50 }
Jeff Dikef3555592007-02-10 01:44:29 -080051
Jeff Dikeba180fd2007-10-16 01:27:00 -070052 ret = os_arch_prctl(pid, code, ptr);
53 if (ret)
54 return ret;
Jeff Dikef3555592007-02-10 01:44:29 -080055
Jeff Dikeba180fd2007-10-16 01:27:00 -070056 switch (code) {
Jeff Dikef3555592007-02-10 01:44:29 -080057 case ARCH_SET_FS:
Jeff Dike44f5c4c2007-03-07 20:41:26 -080058 current->thread.arch.fs = (unsigned long) ptr;
Jeff Dike3e6f2ac2008-02-04 22:30:58 -080059 ret = save_registers(pid, &current->thread.regs.regs);
Jeff Dike44f5c4c2007-03-07 20:41:26 -080060 break;
Jeff Dikef3555592007-02-10 01:44:29 -080061 case ARCH_SET_GS:
Jeff Dike3e6f2ac2008-02-04 22:30:58 -080062 ret = save_registers(pid, &current->thread.regs.regs);
Paolo 'Blaisorblade' Giarrussof767b022005-05-28 15:52:03 -070063 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 case ARCH_GET_FS:
Jeff Dikef3555592007-02-10 01:44:29 -080065 ret = put_user(tmp, addr);
Jeff Dikeba180fd2007-10-16 01:27:00 -070066 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -070067 case ARCH_GET_GS:
Jeff Dikef3555592007-02-10 01:44:29 -080068 ret = put_user(tmp, addr);
Jeff Dikeba180fd2007-10-16 01:27:00 -070069 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -070070 }
71
Jeff Dikef3555592007-02-10 01:44:29 -080072 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -070073}
Linus Torvalds1da177e2005-04-16 15:20:36 -070074
75long sys_arch_prctl(int code, unsigned long addr)
76{
Jeff Dike77bf4402007-10-16 01:26:58 -070077 return arch_prctl(current, code, (unsigned long __user *) addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -070078}
79
Karol Swietlicki291248f2008-02-04 22:30:49 -080080void arch_switch_to(struct task_struct *to)
Jeff Dikef3555592007-02-10 01:44:29 -080081{
Jeff Dikeba180fd2007-10-16 01:27:00 -070082 if ((to->thread.arch.fs == 0) || (to->mm == NULL))
83 return;
Jeff Dikef3555592007-02-10 01:44:29 -080084
Jeff Dikeba180fd2007-10-16 01:27:00 -070085 arch_prctl(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs);
Jeff Dikef3555592007-02-10 01:44:29 -080086}