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 
init_fpu(struct task_struct * tsk)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
__fpu_state_restore(void)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 
fpu_state_restore(struct pt_regs * regs)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 		int ret;
66 		/*
67 		 * does a slab alloc which can sleep
68 		 */
69 		local_irq_enable();
70 		ret = init_fpu(tsk);
71 		local_irq_disable();
72 		if (ret) {
73 			/*
74 			 * ran out of memory!
75 			 */
76 			force_sig(SIGKILL);
77 			return;
78 		}
79 	}
80 
81 	grab_fpu(regs);
82 
83 	__fpu_state_restore();
84 }
85 
BUILD_TRAP_HANDLER(fpu_state_restore)86 BUILD_TRAP_HANDLER(fpu_state_restore)
87 {
88 	TRAP_HANDLER_DECL;
89 
90 	fpu_state_restore(regs);
91 }
92 #endif /* CONFIG_SH_FPU */
93