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1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * Copyright (C) 2002 MontaVista Software Inc.
4 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
5 */
6#ifndef _ASM_FPU_H
7#define _ASM_FPU_H
8
9#include <linux/sched.h>
10#include <linux/sched/task_stack.h>
11#include <linux/ptrace.h>
12#include <linux/thread_info.h>
13#include <linux/bitops.h>
14
15#include <asm/mipsregs.h>
16#include <asm/cpu.h>
17#include <asm/cpu-features.h>
18#include <asm/fpu_emulator.h>
19#include <asm/hazards.h>
20#include <asm/ptrace.h>
21#include <asm/processor.h>
22#include <asm/current.h>
23#include <asm/msa.h>
24
25#ifdef CONFIG_MIPS_MT_FPAFF
26#include <asm/mips_mt.h>
27#endif
28
29/*
30 * This enum specifies a mode in which we want the FPU to operate, for cores
31 * which implement the Status.FR bit. Note that the bottom bit of the value
32 * purposefully matches the desired value of the Status.FR bit.
33 */
34enum fpu_mode {
35 FPU_32BIT = 0, /* FR = 0 */
36 FPU_64BIT, /* FR = 1, FRE = 0 */
37 FPU_AS_IS,
38 FPU_HYBRID, /* FR = 1, FRE = 1 */
39
40#define FPU_FR_MASK 0x1
41};
42
43#ifdef CONFIG_MIPS_FP_SUPPORT
44
45extern void _save_fp(struct task_struct *);
46extern void _restore_fp(struct task_struct *);
47
48#define __disable_fpu() \
49do { \
50 clear_c0_status(ST0_CU1); \
51 disable_fpu_hazard(); \
52} while (0)
53
54static inline int __enable_fpu(enum fpu_mode mode)
55{
56 int fr;
57
58 switch (mode) {
59 case FPU_AS_IS:
60 /* just enable the FPU in its current mode */
61 set_c0_status(ST0_CU1);
62 enable_fpu_hazard();
63 return 0;
64
65 case FPU_HYBRID:
66 if (!cpu_has_fre)
67 return SIGFPE;
68
69 /* set FRE */
70 set_c0_config5(MIPS_CONF5_FRE);
71 goto fr_common;
72
73 case FPU_64BIT:
74#if !(defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6) \
75 || defined(CONFIG_64BIT))
76 /* we only have a 32-bit FPU */
77 return SIGFPE;
78#endif
79 /* fall through */
80 case FPU_32BIT:
81 if (cpu_has_fre) {
82 /* clear FRE */
83 clear_c0_config5(MIPS_CONF5_FRE);
84 }
85fr_common:
86 /* set CU1 & change FR appropriately */
87 fr = (int)mode & FPU_FR_MASK;
88 change_c0_status(ST0_CU1 | ST0_FR, ST0_CU1 | (fr ? ST0_FR : 0));
89 enable_fpu_hazard();
90
91 /* check FR has the desired value */
92 if (!!(read_c0_status() & ST0_FR) == !!fr)
93 return 0;
94
95 /* unsupported FR value */
96 __disable_fpu();
97 return SIGFPE;
98
99 default:
100 BUG();
101 }
102
103 return SIGFPE;
104}
105
106#define clear_fpu_owner() clear_thread_flag(TIF_USEDFPU)
107
108static inline int __is_fpu_owner(void)
109{
110 return test_thread_flag(TIF_USEDFPU);
111}
112
113static inline int is_fpu_owner(void)
114{
115 return cpu_has_fpu && __is_fpu_owner();
116}
117
118static inline int __own_fpu(void)
119{
120 enum fpu_mode mode;
121 int ret;
122
123 if (test_thread_flag(TIF_HYBRID_FPREGS))
124 mode = FPU_HYBRID;
125 else
126 mode = !test_thread_flag(TIF_32BIT_FPREGS);
127
128 ret = __enable_fpu(mode);
129 if (ret)
130 return ret;
131
132 KSTK_STATUS(current) |= ST0_CU1;
133 if (mode == FPU_64BIT || mode == FPU_HYBRID)
134 KSTK_STATUS(current) |= ST0_FR;
135 else /* mode == FPU_32BIT */
136 KSTK_STATUS(current) &= ~ST0_FR;
137
138 set_thread_flag(TIF_USEDFPU);
139 return 0;
140}
141
142static inline int own_fpu_inatomic(int restore)
143{
144 int ret = 0;
145
146 if (cpu_has_fpu && !__is_fpu_owner()) {
147 ret = __own_fpu();
148 if (restore && !ret)
149 _restore_fp(current);
150 }
151 return ret;
152}
153
154static inline int own_fpu(int restore)
155{
156 int ret;
157
158 preempt_disable();
159 ret = own_fpu_inatomic(restore);
160 preempt_enable();
161 return ret;
162}
163
164static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)
165{
166 if (is_msa_enabled()) {
167 if (save) {
168 save_msa(tsk);
169 tsk->thread.fpu.fcr31 =
170 read_32bit_cp1_register(CP1_STATUS);
171 }
172 disable_msa();
173 clear_tsk_thread_flag(tsk, TIF_USEDMSA);
174 __disable_fpu();
175 } else if (is_fpu_owner()) {
176 if (save)
177 _save_fp(tsk);
178 __disable_fpu();
179 } else {
180 /* FPU should not have been left enabled with no owner */
181 WARN(read_c0_status() & ST0_CU1,
182 "Orphaned FPU left enabled");
183 }
184 KSTK_STATUS(tsk) &= ~ST0_CU1;
185 clear_tsk_thread_flag(tsk, TIF_USEDFPU);
186}
187
188static inline void lose_fpu(int save)
189{
190 preempt_disable();
191 lose_fpu_inatomic(save, current);
192 preempt_enable();
193}
194
195/**
196 * init_fp_ctx() - Initialize task FP context
197 * @target: The task whose FP context should be initialized.
198 *
199 * Initializes the FP context of the target task to sane default values if that
200 * target task does not already have valid FP context. Once the context has
201 * been initialized, the task will be marked as having used FP & thus having
202 * valid FP context.
203 *
204 * Returns: true if context is initialized, else false.
205 */
206static inline bool init_fp_ctx(struct task_struct *target)
207{
208 /* If FP has been used then the target already has context */
209 if (tsk_used_math(target))
210 return false;
211
212 /* Begin with data registers set to all 1s... */
213 memset(&target->thread.fpu.fpr, ~0, sizeof(target->thread.fpu.fpr));
214
215 /* FCSR has been preset by `mips_set_personality_nan'. */
216
217 /*
218 * Record that the target has "used" math, such that the context
219 * just initialised, and any modifications made by the caller,
220 * aren't discarded.
221 */
222 set_stopped_child_used_math(target);
223
224 return true;
225}
226
227static inline void save_fp(struct task_struct *tsk)
228{
229 if (cpu_has_fpu)
230 _save_fp(tsk);
231}
232
233static inline void restore_fp(struct task_struct *tsk)
234{
235 if (cpu_has_fpu)
236 _restore_fp(tsk);
237}
238
239static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
240{
241 if (tsk == current) {
242 preempt_disable();
243 if (is_fpu_owner())
244 _save_fp(current);
245 preempt_enable();
246 }
247
248 return tsk->thread.fpu.fpr;
249}
250
251#else /* !CONFIG_MIPS_FP_SUPPORT */
252
253/*
254 * When FP support is disabled we provide only a minimal set of stub functions
255 * to avoid callers needing to care too much about CONFIG_MIPS_FP_SUPPORT.
256 */
257
258static inline int __enable_fpu(enum fpu_mode mode)
259{
260 return SIGILL;
261}
262
263static inline void __disable_fpu(void)
264{
265 /* no-op */
266}
267
268
269static inline int is_fpu_owner(void)
270{
271 return 0;
272}
273
274static inline void clear_fpu_owner(void)
275{
276 /* no-op */
277}
278
279static inline int own_fpu_inatomic(int restore)
280{
281 return SIGILL;
282}
283
284static inline int own_fpu(int restore)
285{
286 return SIGILL;
287}
288
289static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)
290{
291 /* no-op */
292}
293
294static inline void lose_fpu(int save)
295{
296 /* no-op */
297}
298
299static inline bool init_fp_ctx(struct task_struct *target)
300{
301 return false;
302}
303
304/*
305 * The following functions should only be called in paths where we know that FP
306 * support is enabled, typically a path where own_fpu() or __enable_fpu() have
307 * returned successfully. When CONFIG_MIPS_FP_SUPPORT=n it is known at compile
308 * time that this should never happen, so calls to these functions should be
309 * optimized away & never actually be emitted.
310 */
311
312extern void save_fp(struct task_struct *tsk)
313 __compiletime_error("save_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");
314
315extern void _save_fp(struct task_struct *)
316 __compiletime_error("_save_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");
317
318extern void restore_fp(struct task_struct *tsk)
319 __compiletime_error("restore_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");
320
321extern void _restore_fp(struct task_struct *)
322 __compiletime_error("_restore_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");
323
324extern union fpureg *get_fpu_regs(struct task_struct *tsk)
325 __compiletime_error("get_fpu_regs() should not be called when CONFIG_MIPS_FP_SUPPORT=n");
326
327#endif /* !CONFIG_MIPS_FP_SUPPORT */
328#endif /* _ASM_FPU_H */
1/*
2 * Copyright (C) 2002 MontaVista Software Inc.
3 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License as published by the
7 * Free Software Foundation; either version 2 of the License, or (at your
8 * option) any later version.
9 */
10#ifndef _ASM_FPU_H
11#define _ASM_FPU_H
12
13#include <linux/sched.h>
14#include <linux/thread_info.h>
15#include <linux/bitops.h>
16
17#include <asm/mipsregs.h>
18#include <asm/cpu.h>
19#include <asm/cpu-features.h>
20#include <asm/hazards.h>
21#include <asm/processor.h>
22#include <asm/current.h>
23
24#ifdef CONFIG_MIPS_MT_FPAFF
25#include <asm/mips_mt.h>
26#endif
27
28struct sigcontext;
29struct sigcontext32;
30
31extern void fpu_emulator_init_fpu(void);
32extern void _init_fpu(void);
33extern void _save_fp(struct task_struct *);
34extern void _restore_fp(struct task_struct *);
35
36/*
37 * This enum specifies a mode in which we want the FPU to operate, for cores
38 * which implement the Status.FR bit. Note that FPU_32BIT & FPU_64BIT
39 * purposefully have the values 0 & 1 respectively, so that an integer value
40 * of Status.FR can be trivially casted to the corresponding enum fpu_mode.
41 */
42enum fpu_mode {
43 FPU_32BIT = 0, /* FR = 0 */
44 FPU_64BIT, /* FR = 1 */
45 FPU_AS_IS,
46};
47
48static inline int __enable_fpu(enum fpu_mode mode)
49{
50 int fr;
51
52 switch (mode) {
53 case FPU_AS_IS:
54 /* just enable the FPU in its current mode */
55 set_c0_status(ST0_CU1);
56 enable_fpu_hazard();
57 return 0;
58
59 case FPU_64BIT:
60#if !(defined(CONFIG_CPU_MIPS32_R2) || defined(CONFIG_64BIT))
61 /* we only have a 32-bit FPU */
62 return SIGFPE;
63#endif
64 /* fall through */
65 case FPU_32BIT:
66 /* set CU1 & change FR appropriately */
67 fr = (int)mode;
68 change_c0_status(ST0_CU1 | ST0_FR, ST0_CU1 | (fr ? ST0_FR : 0));
69 enable_fpu_hazard();
70
71 /* check FR has the desired value */
72 return (!!(read_c0_status() & ST0_FR) == !!fr) ? 0 : SIGFPE;
73
74 default:
75 BUG();
76 }
77
78 return SIGFPE;
79}
80
81#define __disable_fpu() \
82do { \
83 clear_c0_status(ST0_CU1); \
84 disable_fpu_hazard(); \
85} while (0)
86
87#define clear_fpu_owner() clear_thread_flag(TIF_USEDFPU)
88
89static inline int __is_fpu_owner(void)
90{
91 return test_thread_flag(TIF_USEDFPU);
92}
93
94static inline int is_fpu_owner(void)
95{
96 return cpu_has_fpu && __is_fpu_owner();
97}
98
99static inline int __own_fpu(void)
100{
101 enum fpu_mode mode;
102 int ret;
103
104 mode = !test_thread_flag(TIF_32BIT_FPREGS);
105 ret = __enable_fpu(mode);
106 if (ret)
107 return ret;
108
109 KSTK_STATUS(current) |= ST0_CU1;
110 if (mode == FPU_64BIT)
111 KSTK_STATUS(current) |= ST0_FR;
112 else /* mode == FPU_32BIT */
113 KSTK_STATUS(current) &= ~ST0_FR;
114
115 set_thread_flag(TIF_USEDFPU);
116 return 0;
117}
118
119static inline int own_fpu_inatomic(int restore)
120{
121 int ret = 0;
122
123 if (cpu_has_fpu && !__is_fpu_owner()) {
124 ret = __own_fpu();
125 if (restore && !ret)
126 _restore_fp(current);
127 }
128 return ret;
129}
130
131static inline int own_fpu(int restore)
132{
133 int ret;
134
135 preempt_disable();
136 ret = own_fpu_inatomic(restore);
137 preempt_enable();
138 return ret;
139}
140
141static inline void lose_fpu(int save)
142{
143 preempt_disable();
144 if (is_fpu_owner()) {
145 if (save)
146 _save_fp(current);
147 KSTK_STATUS(current) &= ~ST0_CU1;
148 clear_thread_flag(TIF_USEDFPU);
149 __disable_fpu();
150 }
151 preempt_enable();
152}
153
154static inline int init_fpu(void)
155{
156 int ret = 0;
157
158 preempt_disable();
159 if (cpu_has_fpu) {
160 ret = __own_fpu();
161 if (!ret)
162 _init_fpu();
163 } else {
164 fpu_emulator_init_fpu();
165 }
166
167 preempt_enable();
168 return ret;
169}
170
171static inline void save_fp(struct task_struct *tsk)
172{
173 if (cpu_has_fpu)
174 _save_fp(tsk);
175}
176
177static inline void restore_fp(struct task_struct *tsk)
178{
179 if (cpu_has_fpu)
180 _restore_fp(tsk);
181}
182
183static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
184{
185 if (tsk == current) {
186 preempt_disable();
187 if (is_fpu_owner())
188 _save_fp(current);
189 preempt_enable();
190 }
191
192 return tsk->thread.fpu.fpr;
193}
194
195#endif /* _ASM_FPU_H */