release/src-rt-6.x.4708/linux/linux-2.6.36/arch/sh/kernel/cpu/fpu.c

   1 #include <linux/sched.h>
   2 #include <linux/slab.h>
   3 #include <asm/processor.h>
   4 #include <asm/fpu.h>
   5
   6 int init_fpu(struct task_struct *tsk)
   7 {
   8         if (tsk_used_math(tsk)) {
   9                 if ((boot_cpu_data.flags & CPU_HAS_FPU) && tsk == current)
  10                         unlazy_fpu(tsk, task_pt_regs(tsk));
  11                 return 0;
  12         }
  13
  14         /*
  15          * Memory allocation at the first usage of the FPU and other state.
  16          */
  17         if (!tsk->thread.xstate) {
  18                 tsk->thread.xstate = kmem_cache_alloc(task_xstate_cachep,
  19                                                       GFP_KERNEL);
  20                 if (!tsk->thread.xstate)
  21                         return -ENOMEM;
  22         }
  23
  24         if (boot_cpu_data.flags & CPU_HAS_FPU) {
  25                 struct sh_fpu_hard_struct *fp = &tsk->thread.xstate->hardfpu;
  26                 memset(fp, 0, xstate_size);
  27                 fp->fpscr = FPSCR_INIT;
  28         } else {
  29                 struct sh_fpu_soft_struct *fp = &tsk->thread.xstate->softfpu;
  30                 memset(fp, 0, xstate_size);
  31                 fp->fpscr = FPSCR_INIT;
  32         }
  33
  34         set_stopped_child_used_math(tsk);
  35         return 0;
  36 }
  37
  38 #ifdef CONFIG_SH_FPU
  39 void __fpu_state_restore(void)
  40 {
  41         struct task_struct *tsk = current;
  42
  43         restore_fpu(tsk);
  44
  45         task_thread_info(tsk)->status |= TS_USEDFPU;
  46         tsk->fpu_counter++;
  47 }
  48
  49 void fpu_state_restore(struct pt_regs *regs)
  50 {
  51         struct task_struct *tsk = current;
  52
  53         if (unlikely(!user_mode(regs))) {
  54                 printk(KERN_ERR "BUG: FPU is used in kernel mode.\n");
  55                 BUG();
  56                 return;
  57         }
  58
  59         if (!tsk_used_math(tsk)) {
  60                 local_irq_enable();
  61                 /*
  62                  * does a slab alloc which can sleep
  63                  */
  64                 if (init_fpu(tsk)) {
  65                         /*
  66                          * ran out of memory!
  67                          */
  68                         do_group_exit(SIGKILL);
  69                         return;
  70                 }
  71                 local_irq_disable();
  72         }
  73
  74         grab_fpu(regs);
  75
  76         __fpu_state_restore();
  77 }
  78
  79 BUILD_TRAP_HANDLER(fpu_state_restore)
  80 {
  81         TRAP_HANDLER_DECL;
  82
  83         fpu_state_restore(regs);
  84 }
  85 #endif /* CONFIG_SH_FPU */