/* * 'math_state_restore()' saves the current math information in the * old math state array, and gets the new ones from the current task * * Careful.. There are problems with IBM-designed IRQ13 behaviour. * Don't touch unless you *really* know how it works. * * Must be called with kernel preemption disabled (in this case, * local interrupts are disabled at the call-site in entry.S). */ asmlinkage void math_state_restore(void) { struct thread_info *thread = current_thread_info(); struct task_struct *tsk = thread->task; if (!tsk_used_math(tsk)) { local_irq_enable(); /* * does a slab alloc which can sleep */ if (init_fpu(tsk)) { /* * ran out of memory! */ do_group_exit(SIGKILL); return; } local_irq_disable(); } clts(); /* Allow maths ops (or we recurse) */ /* * Paranoid restore. send a SIGSEGV if we fail to restore the state. */ if (unlikely(restore_fpu_checking(tsk))) { stts(); force_sig(SIGSEGV, tsk); return; } thread->status |= TS_USEDFPU; /* So we fnsave on switch_to() */ tsk->fpu_counter++; }
/* * This restores directly out of user space. Exceptions are handled. */ static inline int restore_i387(struct _fpstate __user *buf) { struct task_struct *tsk = current; int err; if (!used_math()) { err = init_fpu(tsk); if (err) return err; } if (!(task_thread_info(current)->status & TS_USEDFPU)) { clts(); task_thread_info(current)->status |= TS_USEDFPU; } err = restore_fpu_checking((__force struct i387_fxsave_struct *)buf); if (unlikely(err)) { /* * Encountered an error while doing the restore from the * user buffer, clear the fpu state. */ clear_fpu(tsk); clear_used_math(); } return err; }
/* * 'math_state_restore()' saves the current math information in the * old math state array, and gets the new ones from the current task * * Careful.. There are problems with IBM-designed IRQ13 behaviour. * Don't touch unless you *really* know how it works. */ asmlinkage void math_state_restore(void) { struct task_struct *me = current; clts(); /* Allow maths ops (or we recurse) */ if (!used_math()) init_fpu(me); restore_fpu_checking(&me->thread.i387.fxsave); me->thread_info->status |= TS_USEDFPU; }
/* * __math_state_restore assumes that cr0.TS is already clear and the * fpu state is all ready for use. Used during context switch. */ void __math_state_restore(void) { struct thread_info *thread = current_thread_info(); struct task_struct *tsk = thread->task; /* * Paranoid restore. send a SIGSEGV if we fail to restore the state. */ if (unlikely(restore_fpu_checking(tsk))) { stts(); force_sig(SIGSEGV, tsk); return; } thread->status |= TS_USEDFPU; /* So we fnsave on switch_to() */ tsk->fpu_counter++; }