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 #include <asm/asm-prototypes.h> 25 26 int enter_vmx_usercopy(void) 27 { 28 if (in_interrupt()) 29 return 0; 30 31 preempt_disable(); 32 /* 33 * We need to disable page faults as they can call schedule and 34 * thus make us lose the VMX context. So on page faults, we just 35 * fail which will cause a fallback to the normal non-vmx copy. 36 */ 37 pagefault_disable(); 38 39 enable_kernel_altivec(); 40 41 return 1; 42 } 43 44 /* 45 * This function must return 0 because we tail call optimise when calling 46 * from __copy_tofrom_user_power7 which returns 0 on success. 47 */ 48 int exit_vmx_usercopy(void) 49 { 50 disable_kernel_altivec(); 51 pagefault_enable(); 52 preempt_enable(); 53 return 0; 54 } 55 56 int enter_vmx_copy(void) 57 { 58 if (in_interrupt()) 59 return 0; 60 61 preempt_disable(); 62 63 enable_kernel_altivec(); 64 65 return 1; 66 } 67 68 /* 69 * All calls to this function will be optimised into tail calls. We are 70 * passed a pointer to the destination which we return as required by a 71 * memcpy implementation. 72 */ 73 void *exit_vmx_copy(void *dest) 74 { 75 disable_kernel_altivec(); 76 preempt_enable(); 77 return dest; 78 } 79