1/* 2 * linux/arch/x86_64/kernel/i387.c 3 * 4 * Copyright (C) 1994 Linus Torvalds 5 * Copyright (C) 2002 Andi Kleen, SuSE Labs 6 * 7 * Pentium III FXSR, SSE support 8 * General FPU state handling cleanups 9 * Gareth Hughes <gareth@valinux.com>, May 2000 10 * 11 * x86-64 rework 2002 Andi Kleen. 12 * Does direct fxsave in and out of user space now for signal handlers. 13 * All the FSAVE<->FXSAVE conversion code has been moved to the 32bit emulation, 14 * the 64bit user space sees a FXSAVE frame directly. 15 */ 16 17#include <linux/sched.h> 18#include <linux/init.h> 19#include <asm/processor.h> 20#include <asm/i387.h> 21#include <asm/sigcontext.h> 22#include <asm/user.h> 23#include <asm/ptrace.h> 24#include <asm/uaccess.h> 25 26unsigned int mxcsr_feature_mask __read_mostly = 0xffffffff; 27 28void mxcsr_feature_mask_init(void) 29{ 30 unsigned int mask; 31 clts(); 32 memset(¤t->thread.i387.fxsave, 0, sizeof(struct i387_fxsave_struct)); 33 asm volatile("fxsave %0" : : "m" (current->thread.i387.fxsave)); 34 mask = current->thread.i387.fxsave.mxcsr_mask; 35 if (mask == 0) mask = 0x0000ffbf; 36 mxcsr_feature_mask &= mask; 37 stts(); 38} 39 40/* 41 * Called at bootup to set up the initial FPU state that is later cloned 42 * into all processes. 43 */ 44void __cpuinit fpu_init(void) 45{ 46 unsigned long oldcr0 = read_cr0(); 47 extern void __bad_fxsave_alignment(void); 48 49 if (offsetof(struct task_struct, thread.i387.fxsave) & 15) 50 __bad_fxsave_alignment(); 51 set_in_cr4(X86_CR4_OSFXSR); 52 set_in_cr4(X86_CR4_OSXMMEXCPT); 53 54 write_cr0(oldcr0 & ~((1UL<<3)|(1UL<<2))); /* clear TS and EM */ 55 56 mxcsr_feature_mask_init(); 57 /* clean state in init */ 58 current_thread_info()->status = 0; 59 clear_used_math(); 60} 61 62void init_fpu(struct task_struct *child) 63{ 64 if (tsk_used_math(child)) { 65 if (child == current) 66 unlazy_fpu(child); 67 return; 68 } 69 memset(&child->thread.i387.fxsave, 0, sizeof(struct i387_fxsave_struct)); 70 child->thread.i387.fxsave.cwd = 0x37f; 71 child->thread.i387.fxsave.mxcsr = 0x1f80; 72 /* only the device not available exception or ptrace can call init_fpu */ 73 set_stopped_child_used_math(child); 74} 75 76/* 77 * Signal frame handlers. 78 */ 79 80int save_i387(struct _fpstate __user *buf) 81{ 82 struct task_struct *tsk = current; 83 int err = 0; 84 85 BUILD_BUG_ON(sizeof(struct user_i387_struct) != 86 sizeof(tsk->thread.i387.fxsave)); 87 88 if ((unsigned long)buf % 16) 89 printk("save_i387: bad fpstate %p\n",buf); 90 91 if (!used_math()) 92 return 0; 93 clear_used_math(); /* trigger finit */ 94 if (task_thread_info(tsk)->status & TS_USEDFPU) { 95 err = save_i387_checking((struct i387_fxsave_struct __user *)buf); 96 if (err) return err; 97 stts(); 98 } else { 99 if (__copy_to_user(buf, &tsk->thread.i387.fxsave, 100 sizeof(struct i387_fxsave_struct))) 101 return -1; 102 } 103 return 1; 104} 105 106/* 107 * ptrace request handlers. 108 */ 109 110int get_fpregs(struct user_i387_struct __user *buf, struct task_struct *tsk) 111{ 112 init_fpu(tsk); 113 return __copy_to_user(buf, &tsk->thread.i387.fxsave, 114 sizeof(struct user_i387_struct)) ? -EFAULT : 0; 115} 116 117int set_fpregs(struct task_struct *tsk, struct user_i387_struct __user *buf) 118{ 119 if (__copy_from_user(&tsk->thread.i387.fxsave, buf, 120 sizeof(struct user_i387_struct))) 121 return -EFAULT; 122 return 0; 123} 124 125/* 126 * FPU state for core dumps. 127 */ 128 129int dump_fpu( struct pt_regs *regs, struct user_i387_struct *fpu ) 130{ 131 struct task_struct *tsk = current; 132 133 if (!used_math()) 134 return 0; 135 136 unlazy_fpu(tsk); 137 memcpy(fpu, &tsk->thread.i387.fxsave, sizeof(struct user_i387_struct)); 138 return 1; 139} 140 141int dump_task_fpu(struct task_struct *tsk, struct user_i387_struct *fpu) 142{ 143 int fpvalid = !!tsk_used_math(tsk); 144 145 if (fpvalid) { 146 if (tsk == current) 147 unlazy_fpu(tsk); 148 memcpy(fpu, &tsk->thread.i387.fxsave, sizeof(struct user_i387_struct)); 149} 150 return fpvalid; 151} 152