LXR linux-old/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 <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
  26extern int exception_trace;
  27
  28void init_fpu(struct task_struct *child)
  29{
  30        if (child->used_math) { 
  31                unlazy_fpu(child);
  32                return;
  33        }
  34        memset(&child->thread.i387.fxsave, 0, sizeof(struct i387_fxsave_struct));
  35        child->thread.i387.fxsave.cwd = 0x37f;
  36        child->thread.i387.fxsave.mxcsr = 0x1f80;
  37        child->used_math = 1;
  38}
  39
  40/*
  41 * Signal frame handlers.
  42 */
  43
  44int save_i387(struct _fpstate *buf)
  45{
  46        struct task_struct *tsk = current;
  47        int err = 0;
  48
  49        { 
  50                extern void bad_user_i387_struct(void); 
  51                if (sizeof(struct user_i387_struct) != sizeof(tsk->thread.i387.fxsave))
  52                        bad_user_i387_struct();
  53        } 
  54
  55        if (!tsk->used_math) 
  56                return 0; 
  57        tsk->used_math = 0; /* trigger finit */ 
  58        if (tsk->flags & PF_USEDFPU) { 
  59                err = save_i387_checking((struct i387_fxsave_struct *)buf);
  60                if (err) { 
  61                        if (exception_trace) 
  62                                printk("%s[%d] unaligned signal floating point context %p\n", 
  63                                        tsk->comm, tsk->pid, buf); 
  64                        return err;
  65                }
  66                stts();
  67        } else { 
  68                if (__copy_to_user(buf, &tsk->thread.i387.fxsave, 
  69                                   sizeof(struct i387_fxsave_struct)))
  70                        return -1;
  71        } 
  72        return 1; 
  73}
  74
  75/*
  76 * ptrace request handlers.
  77 */
  78
  79int get_fpregs(struct user_i387_struct *buf, struct task_struct *tsk)
  80{
  81        init_fpu(tsk);
  82        return __copy_to_user((void *)buf, &tsk->thread.i387.fxsave,
  83                               sizeof(struct user_i387_struct)) ? -EFAULT : 0;
  84}
  85
  86int set_fpregs(struct task_struct *tsk, struct user_i387_struct *buf)
  87{       
  88        if (__copy_from_user(&tsk->thread.i387.fxsave, buf, 
  89                             sizeof(struct user_i387_struct)))
  90                return -EFAULT;
  91        /* mxcsr bit 6 and 31-16 must be zero for security reasons. */
  92        tsk->thread.i387.fxsave.mxcsr &= 0xffbf;
  93        return 0;
  94}
  95
  96/*
  97 * FPU state for core dumps.
  98 */
  99
 100int dump_fpu( struct pt_regs *regs, struct user_i387_struct *fpu )
 101{
 102        struct task_struct *tsk = current;
 103
 104        if (!tsk->used_math) 
 105                return 0;
 106        unlazy_fpu(tsk);
 107
 108        memcpy(fpu, &tsk->thread.i387.fxsave, sizeof(struct user_i387_struct)); 
 109        return 1; 
 110}
 111