1 /* 2 * This program is free software; you can redistribute it and/or modify 3 * it under the terms of the GNU General Public License as published by 4 * the Free Software Foundation; either version 2 of the License, or 5 * (at your option) any later version. 6 * 7 * This program is distributed in the hope that it will be useful, 8 * but WITHOUT ANY WARRANTY; without even the implied warranty of 9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 10 * GNU General Public License for more details. 11 * 12 * You should have received a copy of the GNU General Public License 13 * along with this program; if not, write to the Free Software 14 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 15 * 16 * Copyright (C) IBM Corporation, 2011 17 * 18 * Authors: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> 19 * Anton Blanchard <anton@au.ibm.com> 20 */ 21 #include <linux/uaccess.h> 22 #include <linux/hardirq.h> 23 #include <asm/switch_to.h> 24 25 int enter_vmx_usercopy(void) 26 { 27 if (in_interrupt()) 28 return 0; 29 30 preempt_disable(); 31 /* 32 * We need to disable page faults as they can call schedule and 33 * thus make us lose the VMX context. So on page faults, we just 34 * fail which will cause a fallback to the normal non-vmx copy. 35 */ 36 pagefault_disable(); 37 38 enable_kernel_altivec(); 39 40 return 1; 41 } 42 43 /* 44 * This function must return 0 because we tail call optimise when calling 45 * from __copy_tofrom_user_power7 which returns 0 on success. 46 */ 47 int exit_vmx_usercopy(void) 48 { 49 pagefault_enable(); 50 preempt_enable(); 51 return 0; 52 } 53 54 int enter_vmx_copy(void) 55 { 56 if (in_interrupt()) 57 return 0; 58 59 preempt_disable(); 60 61 enable_kernel_altivec(); 62 63 return 1; 64 } 65 66 /* 67 * All calls to this function will be optimised into tail calls. We are 68 * passed a pointer to the destination which we return as required by a 69 * memcpy implementation. 70 */ 71 void *exit_vmx_copy(void *dest) 72 { 73 preempt_enable(); 74 return dest; 75 } 76