arch/sh/kernel/cpu/fpu.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/sched/signal.h>
   3 #include <linux/sched/task.h>
   4 #include <linux/sched/task_stack.h>
   5 #include <linux/slab.h>
   6 #include <asm/processor.h>
   7 #include <asm/fpu.h>
   8 #include <asm/traps.h>
   9 #include <asm/ptrace.h>
  10
  11 int init_fpu(struct task_struct *tsk)
  12 {
  13         if (tsk_used_math(tsk)) {
  14                 if ((boot_cpu_data.flags & CPU_HAS_FPU) && tsk == current)
  15                         unlazy_fpu(tsk, task_pt_regs(tsk));
  16                 return 0;
  17         }
  18
  19         /*
  20          * Memory allocation at the first usage of the FPU and other state.
  21          */
  22         if (!tsk->thread.xstate) {
  23                 tsk->thread.xstate = kmem_cache_alloc(task_xstate_cachep,
  24                                                       GFP_KERNEL);
  25                 if (!tsk->thread.xstate)
  26                         return -ENOMEM;
  27         }
  28
  29         if (boot_cpu_data.flags & CPU_HAS_FPU) {
  30                 struct sh_fpu_hard_struct *fp = &tsk->thread.xstate->hardfpu;
  31                 memset(fp, 0, xstate_size);
  32                 fp->fpscr = FPSCR_INIT;
  33         } else {
  34                 struct sh_fpu_soft_struct *fp = &tsk->thread.xstate->softfpu;
  35                 memset(fp, 0, xstate_size);
  36                 fp->fpscr = FPSCR_INIT;
  37         }
  38
  39         set_stopped_child_used_math(tsk);
  40         return 0;
  41 }
  42
  43 #ifdef CONFIG_SH_FPU
  44 void __fpu_state_restore(void)
  45 {
  46         struct task_struct *tsk = current;
  47
  48         restore_fpu(tsk);
  49
  50         task_thread_info(tsk)->status |= TS_USEDFPU;
  51         tsk->thread.fpu_counter++;
  52 }
  53
  54 void fpu_state_restore(struct pt_regs *regs)
  55 {
  56         struct task_struct *tsk = current;
  57
  58         if (unlikely(!user_mode(regs))) {
  59                 printk(KERN_ERR "BUG: FPU is used in kernel mode.\n");
  60                 BUG();
  61                 return;
  62         }
  63
  64         if (!tsk_used_math(tsk)) {
  65                 local_irq_enable();
  66                 /*
  67                  * does a slab alloc which can sleep
  68                  */
  69                 if (init_fpu(tsk)) {
  70                         /*
  71                          * ran out of memory!
  72                          */
  73                         do_group_exit(SIGKILL);
  74                         return;
  75                 }
  76                 local_irq_disable();
  77         }
  78
  79         grab_fpu(regs);
  80
  81         __fpu_state_restore();
  82 }
  83
  84 BUILD_TRAP_HANDLER(fpu_state_restore)
  85 {
  86         TRAP_HANDLER_DECL;
  87
  88         fpu_state_restore(regs);
  89 }
  90 #endif /* CONFIG_SH_FPU */