arch/x86_64/kernel/i387.c

   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/config.h>
  18 #include <linux/sched.h>
  19 #include <linux/init.h>
  20 #include <asm/processor.h>
  21 #include <asm/i387.h>
  22 #include <asm/sigcontext.h>
  23 #include <asm/user.h>
  24 #include <asm/ptrace.h>
  25 #include <asm/uaccess.h>
  26
  27 unsigned int mxcsr_feature_mask = 0xffffffff;
  28
  29 void mxcsr_feature_mask_init(void)
  30 {
  31         unsigned int mask;
  32         clts();
  33         memset(&current->thread.i387.fxsave, 0, sizeof(struct i387_fxsave_struct));
  34         asm volatile("fxsave %0" : : "m" (current->thread.i387.fxsave));
  35         mask = current->thread.i387.fxsave.mxcsr_mask;
  36         if (mask == 0) mask = 0x0000ffbf;
  37         mxcsr_feature_mask &= mask;
  38         stts();
  39 }
  40
  41 /*
  42  * Called at bootup to set up the initial FPU state that is later cloned
  43  * into all processes.
  44  */
  45 void __init fpu_init(void)
  46 {
  47         unsigned long oldcr0 = read_cr0();
  48         extern void __bad_fxsave_alignment(void);
  49
  50         if (offsetof(struct task_struct, thread.i387.fxsave) & 15)
  51                 __bad_fxsave_alignment();
  52         set_in_cr4(X86_CR4_OSFXSR);
  53         set_in_cr4(X86_CR4_OSXMMEXCPT);
  54
  55         write_cr0(oldcr0 & ~((1UL<<3)|(1UL<<2))); /* clear TS and EM */
  56
  57         mxcsr_feature_mask_init();
  58         /* clean state in init */
  59         current_thread_info()->status = 0;
  60         clear_used_math();
  61 }
  62
  63 void init_fpu(struct task_struct *child)
  64 {
  65         if (tsk_used_math(child)) {
  66                 if (child == current)
  67                         unlazy_fpu(child);
  68                 return;
  69         }
  70         memset(&child->thread.i387.fxsave, 0, sizeof(struct i387_fxsave_struct));
  71         child->thread.i387.fxsave.cwd = 0x37f;
  72         child->thread.i387.fxsave.mxcsr = 0x1f80;
  73         /* only the device not available exception or ptrace can call init_fpu */
  74         set_stopped_child_used_math(child);
  75 }
  76
  77 /*
  78  * Signal frame handlers.
  79  */
  80
  81 int save_i387(struct _fpstate __user *buf)
  82 {
  83         struct task_struct *tsk = current;
  84         int err = 0;
  85
  86         {
  87                 extern void bad_user_i387_struct(void);
  88                 if (sizeof(struct user_i387_struct) != sizeof(tsk->thread.i387.fxsave))
  89                         bad_user_i387_struct();
  90         }
  91
  92         if ((unsigned long)buf % 16)
  93                 printk("save_i387: bad fpstate %p\n",buf);
  94
  95         if (!used_math())
  96                 return 0;
  97         clear_used_math(); /* trigger finit */
  98         if (tsk->thread_info->status & TS_USEDFPU) {
  99                 err = save_i387_checking((struct i387_fxsave_struct __user *)buf);
 100                 if (err) return err;
 101                 stts();
 102                 } else {
 103                 if (__copy_to_user(buf, &tsk->thread.i387.fxsave,
 104                                    sizeof(struct i387_fxsave_struct)))
 105                         return -1;
 106         }
 107                 return 1;
 108 }
 109
 110 /*
 111  * ptrace request handlers.
 112  */
 113
 114 int get_fpregs(struct user_i387_struct __user *buf, struct task_struct *tsk)
 115 {
 116         init_fpu(tsk);
 117         return __copy_to_user(buf, &tsk->thread.i387.fxsave,
 118                                sizeof(struct user_i387_struct)) ? -EFAULT : 0;
 119 }
 120
 121 int set_fpregs(struct task_struct *tsk, struct user_i387_struct __user *buf)
 122 {
 123         if (__copy_from_user(&tsk->thread.i387.fxsave, buf,
 124                              sizeof(struct user_i387_struct)))
 125                 return -EFAULT;
 126                 return 0;
 127 }
 128
 129 /*
 130  * FPU state for core dumps.
 131  */
 132
 133 int dump_fpu( struct pt_regs *regs, struct user_i387_struct *fpu )
 134 {
 135         struct task_struct *tsk = current;
 136
 137         if (!used_math())
 138                 return 0;
 139
 140         unlazy_fpu(tsk);
 141         memcpy(fpu, &tsk->thread.i387.fxsave, sizeof(struct user_i387_struct));
 142         return 1;
 143 }
 144
 145 int dump_task_fpu(struct task_struct *tsk, struct user_i387_struct *fpu)
 146 {
 147         int fpvalid = !!tsk_used_math(tsk);
 148
 149         if (fpvalid) {
 150                 if (tsk == current)
 151                         unlazy_fpu(tsk);
 152                 memcpy(fpu, &tsk->thread.i387.fxsave, sizeof(struct user_i387_struct));
 153 }
 154         return fpvalid;
 155 }