1/* 2 * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 3 * Copyright 2003 PathScale, Inc. 4 * 5 * Licensed under the GPL 6 */ 7 8#include "linux/linkage.h" 9#include "linux/personality.h" 10#include "linux/utsname.h" 11#include "asm/prctl.h" 12#include "asm/uaccess.h" 13#include "os.h" 14 15long arch_prctl(struct task_struct *task, int code, unsigned long __user *addr) 16{ 17 unsigned long *ptr = addr, tmp; 18 long ret; 19 int pid = task->mm->context.id.u.pid; 20 21 /* 22 * With ARCH_SET_FS (and ARCH_SET_GS is treated similarly to 23 * be safe), we need to call arch_prctl on the host because 24 * setting %fs may result in something else happening (like a 25 * GDT or thread.fs being set instead). So, we let the host 26 * fiddle the registers and thread struct and restore the 27 * registers afterwards. 28 * 29 * So, the saved registers are stored to the process (this 30 * needed because a stub may have been the last thing to run), 31 * arch_prctl is run on the host, then the registers are read 32 * back. 33 */ 34 switch (code) { 35 case ARCH_SET_FS: 36 case ARCH_SET_GS: 37 ret = restore_registers(pid, ¤t->thread.regs.regs); 38 if (ret) 39 return ret; 40 break; 41 case ARCH_GET_FS: 42 case ARCH_GET_GS: 43 /* 44 * With these two, we read to a local pointer and 45 * put_user it to the userspace pointer that we were 46 * given. If addr isn't valid (because it hasn't been 47 * faulted in or is just bogus), we want put_user to 48 * fault it in (or return -EFAULT) instead of having 49 * the host return -EFAULT. 50 */ 51 ptr = &tmp; 52 } 53 54 ret = os_arch_prctl(pid, code, ptr); 55 if (ret) 56 return ret; 57 58 switch (code) { 59 case ARCH_SET_FS: 60 current->thread.arch.fs = (unsigned long) ptr; 61 ret = save_registers(pid, ¤t->thread.regs.regs); 62 break; 63 case ARCH_SET_GS: 64 ret = save_registers(pid, ¤t->thread.regs.regs); 65 break; 66 case ARCH_GET_FS: 67 ret = put_user(tmp, addr); 68 break; 69 case ARCH_GET_GS: 70 ret = put_user(tmp, addr); 71 break; 72 } 73 74 return ret; 75} 76 77long sys_arch_prctl(int code, unsigned long addr) 78{ 79 return arch_prctl(current, code, (unsigned long __user *) addr); 80} 81 82long sys_clone(unsigned long clone_flags, unsigned long newsp, 83 void __user *parent_tid, void __user *child_tid) 84{ 85 long ret; 86 87 if (!newsp) 88 newsp = UPT_SP(¤t->thread.regs.regs); 89 current->thread.forking = 1; 90 ret = do_fork(clone_flags, newsp, ¤t->thread.regs, 0, parent_tid, 91 child_tid); 92 current->thread.forking = 0; 93 return ret; 94} 95 96void arch_switch_to(struct task_struct *to) 97{ 98 if ((to->thread.arch.fs == 0) || (to->mm == NULL)) 99 return; 100 101 arch_prctl(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs); 102} 103