arch/x86/kernel/i387_64.c

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