summaryrefslogtreecommitdiffstats
path: root/arch/mips/include/asm/fpu.h
blob: 08f9dd6903b712d6302019860363ea7b021026d8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Copyright (C) 2002 MontaVista Software Inc.
 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
 */
#ifndef _ASM_FPU_H
#define _ASM_FPU_H

#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/ptrace.h>
#include <linux/thread_info.h>
#include <linux/bitops.h>

#include <asm/mipsregs.h>
#include <asm/cpu.h>
#include <asm/cpu-features.h>
#include <asm/fpu_emulator.h>
#include <asm/hazards.h>
#include <asm/ptrace.h>
#include <asm/processor.h>
#include <asm/current.h>
#include <asm/msa.h>

#ifdef CONFIG_MIPS_MT_FPAFF
#include <asm/mips_mt.h>
#endif

/*
 * This enum specifies a mode in which we want the FPU to operate, for cores
 * which implement the Status.FR bit. Note that the bottom bit of the value
 * purposefully matches the desired value of the Status.FR bit.
 */
enum fpu_mode {
	FPU_32BIT = 0,		/* FR = 0 */
	FPU_64BIT,		/* FR = 1, FRE = 0 */
	FPU_AS_IS,
	FPU_HYBRID,		/* FR = 1, FRE = 1 */

#define FPU_FR_MASK		0x1
};

#ifdef CONFIG_MIPS_FP_SUPPORT

extern void _save_fp(struct task_struct *);
extern void _restore_fp(struct task_struct *);

#define __disable_fpu()							\
do {									\
	clear_c0_status(ST0_CU1);					\
	disable_fpu_hazard();						\
} while (0)

static inline int __enable_fpu(enum fpu_mode mode)
{
	int fr;

	switch (mode) {
	case FPU_AS_IS:
		/* just enable the FPU in its current mode */
		set_c0_status(ST0_CU1);
		enable_fpu_hazard();
		return 0;

	case FPU_HYBRID:
		if (!cpu_has_fre)
			return SIGFPE;

		/* set FRE */
		set_c0_config5(MIPS_CONF5_FRE);
		goto fr_common;

	case FPU_64BIT:
#if !(defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR5) || \
      defined(CONFIG_CPU_MIPSR6) || defined(CONFIG_64BIT))
		/* we only have a 32-bit FPU */
		return SIGFPE;
#endif
		fallthrough;
	case FPU_32BIT:
		if (cpu_has_fre) {
			/* clear FRE */
			clear_c0_config5(MIPS_CONF5_FRE);
		}
fr_common:
		/* set CU1 & change FR appropriately */
		fr = (int)mode & FPU_FR_MASK;
		change_c0_status(ST0_CU1 | ST0_FR, ST0_CU1 | (fr ? ST0_FR : 0));
		enable_fpu_hazard();

		/* check FR has the desired value */
		if (!!(read_c0_status() & ST0_FR) == !!fr)
			return 0;

		/* unsupported FR value */
		__disable_fpu();
		return SIGFPE;

	default:
		BUG();
	}

	return SIGFPE;
}

#define clear_fpu_owner()	clear_thread_flag(TIF_USEDFPU)

static inline int __is_fpu_owner(void)
{
	return test_thread_flag(TIF_USEDFPU);
}

static inline int is_fpu_owner(void)
{
	return cpu_has_fpu && __is_fpu_owner();
}

static inline int __own_fpu(void)
{
	enum fpu_mode mode;
	int ret;

	if (test_thread_flag(TIF_HYBRID_FPREGS))
		mode = FPU_HYBRID;
	else
		mode = !test_thread_flag(TIF_32BIT_FPREGS);

	ret = __enable_fpu(mode);
	if (ret)
		return ret;

	KSTK_STATUS(current) |= ST0_CU1;
	if (mode == FPU_64BIT || mode == FPU_HYBRID)
		KSTK_STATUS(current) |= ST0_FR;
	else /* mode == FPU_32BIT */
		KSTK_STATUS(current) &= ~ST0_FR;

	set_thread_flag(TIF_USEDFPU);
	return 0;
}

static inline int own_fpu_inatomic(int restore)
{
	int ret = 0;

	if (cpu_has_fpu && !__is_fpu_owner()) {
		ret = __own_fpu();
		if (restore && !ret)
			_restore_fp(current);
	}
	return ret;
}

static inline int own_fpu(int restore)
{
	int ret;

	preempt_disable();
	ret = own_fpu_inatomic(restore);
	preempt_enable();
	return ret;
}

static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)
{
	if (is_msa_enabled()) {
		if (save) {
			save_msa(tsk);
			tsk->thread.fpu.fcr31 =
					read_32bit_cp1_register(CP1_STATUS);
		}
		disable_msa();
		clear_tsk_thread_flag(tsk, TIF_USEDMSA);
		__disable_fpu();
	} else if (is_fpu_owner()) {
		if (save)
			_save_fp(tsk);
		__disable_fpu();
	} else {
		/* FPU should not have been left enabled with no owner */
		WARN(read_c0_status() & ST0_CU1,
		     "Orphaned FPU left enabled");
	}
	KSTK_STATUS(tsk) &= ~ST0_CU1;
	clear_tsk_thread_flag(tsk, TIF_USEDFPU);
}

static inline void lose_fpu(int save)
{
	preempt_disable();
	lose_fpu_inatomic(save, current);
	preempt_enable();
}

/**
 * init_fp_ctx() - Initialize task FP context
 * @target: The task whose FP context should be initialized.
 *
 * Initializes the FP context of the target task to sane default values if that
 * target task does not already have valid FP context. Once the context has
 * been initialized, the task will be marked as having used FP & thus having
 * valid FP context.
 *
 * Returns: true if context is initialized, else false.
 */
static inline bool init_fp_ctx(struct task_struct *target)
{
	/* If FP has been used then the target already has context */
	if (tsk_used_math(target))
		return false;

	/* Begin with data registers set to all 1s... */
	memset(&target->thread.fpu.fpr, ~0, sizeof(target->thread.fpu.fpr));

	/* FCSR has been preset by `mips_set_personality_nan'.  */

	/*
	 * Record that the target has "used" math, such that the context
	 * just initialised, and any modifications made by the caller,
	 * aren't discarded.
	 */
	set_stopped_child_used_math(target);

	return true;
}

static inline void save_fp(struct task_struct *tsk)
{
	if (cpu_has_fpu)
		_save_fp(tsk);
}

static inline void restore_fp(struct task_struct *tsk)
{
	if (cpu_has_fpu)
		_restore_fp(tsk);
}

static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
{
	if (tsk == current) {
		preempt_disable();
		if (is_fpu_owner())
			_save_fp(current);
		preempt_enable();
	}

	return tsk->thread.fpu.fpr;
}

#else /* !CONFIG_MIPS_FP_SUPPORT */

/*
 * When FP support is disabled we provide only a minimal set of stub functions
 * to avoid callers needing to care too much about CONFIG_MIPS_FP_SUPPORT.
 */

static inline int __enable_fpu(enum fpu_mode mode)
{
	return SIGILL;
}

static inline void __disable_fpu(void)
{
	/* no-op */
}


static inline int is_fpu_owner(void)
{
	return 0;
}

static inline void clear_fpu_owner(void)
{
	/* no-op */
}

static inline int own_fpu_inatomic(int restore)
{
	return SIGILL;
}

static inline int own_fpu(int restore)
{
	return SIGILL;
}

static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)
{
	/* no-op */
}

static inline void lose_fpu(int save)
{
	/* no-op */
}

static inline bool init_fp_ctx(struct task_struct *target)
{
	return false;
}

/*
 * The following functions should only be called in paths where we know that FP
 * support is enabled, typically a path where own_fpu() or __enable_fpu() have
 * returned successfully. When CONFIG_MIPS_FP_SUPPORT=n it is known at compile
 * time that this should never happen, so calls to these functions should be
 * optimized away & never actually be emitted.
 */

extern void save_fp(struct task_struct *tsk)
	__compiletime_error("save_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");

extern void _save_fp(struct task_struct *)
	__compiletime_error("_save_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");

extern void restore_fp(struct task_struct *tsk)
	__compiletime_error("restore_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");

extern void _restore_fp(struct task_struct *)
	__compiletime_error("_restore_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");

extern union fpureg *get_fpu_regs(struct task_struct *tsk)
	__compiletime_error("get_fpu_regs() should not be called when CONFIG_MIPS_FP_SUPPORT=n");

#endif /* !CONFIG_MIPS_FP_SUPPORT */
#endif /* _ASM_FPU_H */