1 /* SPDX-License-Identifier: GPL-2.0-or-later */
3 * Copyright (C) 2002 MontaVista Software Inc.
4 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
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>
15 #include <asm/mipsregs.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>
25 #ifdef CONFIG_MIPS_MT_FPAFF
26 #include <asm/mips_mt.h>
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.
35 FPU_32BIT = 0, /* FR = 0 */
36 FPU_64BIT, /* FR = 1, FRE = 0 */
38 FPU_HYBRID, /* FR = 1, FRE = 1 */
40 #define FPU_FR_MASK 0x1
43 #ifdef CONFIG_MIPS_FP_SUPPORT
45 extern void _save_fp(struct task_struct *);
46 extern void _restore_fp(struct task_struct *);
48 #define __disable_fpu() \
50 clear_c0_status(ST0_CU1); \
51 disable_fpu_hazard(); \
54 static inline int __enable_fpu(enum fpu_mode mode)
60 /* just enable the FPU in its current mode */
61 set_c0_status(ST0_CU1);
70 set_c0_config5(MIPS_CONF5_FRE);
74 #if !(defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6) \
75 || defined(CONFIG_64BIT))
76 /* we only have a 32-bit FPU */
83 clear_c0_config5(MIPS_CONF5_FRE);
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));
91 /* check FR has the desired value */
92 if (!!(read_c0_status() & ST0_FR) == !!fr)
95 /* unsupported FR value */
106 #define clear_fpu_owner() clear_thread_flag(TIF_USEDFPU)
108 static inline int __is_fpu_owner(void)
110 return test_thread_flag(TIF_USEDFPU);
113 static inline int is_fpu_owner(void)
115 return cpu_has_fpu && __is_fpu_owner();
118 static inline int __own_fpu(void)
123 if (test_thread_flag(TIF_HYBRID_FPREGS))
126 mode = !test_thread_flag(TIF_32BIT_FPREGS);
128 ret = __enable_fpu(mode);
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;
138 set_thread_flag(TIF_USEDFPU);
142 static inline int own_fpu_inatomic(int restore)
146 if (cpu_has_fpu && !__is_fpu_owner()) {
149 _restore_fp(current);
154 static inline int own_fpu(int restore)
159 ret = own_fpu_inatomic(restore);
164 static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)
166 if (is_msa_enabled()) {
169 tsk->thread.fpu.fcr31 =
170 read_32bit_cp1_register(CP1_STATUS);
173 clear_tsk_thread_flag(tsk, TIF_USEDMSA);
175 } else if (is_fpu_owner()) {
180 /* FPU should not have been left enabled with no owner */
181 WARN(read_c0_status() & ST0_CU1,
182 "Orphaned FPU left enabled");
184 KSTK_STATUS(tsk) &= ~ST0_CU1;
185 clear_tsk_thread_flag(tsk, TIF_USEDFPU);
188 static inline void lose_fpu(int save)
191 lose_fpu_inatomic(save, current);
196 * init_fp_ctx() - Initialize task FP context
197 * @target: The task whose FP context should be initialized.
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
204 * Returns: true if context is initialized, else false.
206 static inline bool init_fp_ctx(struct task_struct *target)
208 /* If FP has been used then the target already has context */
209 if (tsk_used_math(target))
212 /* Begin with data registers set to all 1s... */
213 memset(&target->thread.fpu.fpr, ~0, sizeof(target->thread.fpu.fpr));
215 /* FCSR has been preset by `mips_set_personality_nan'. */
218 * Record that the target has "used" math, such that the context
219 * just initialised, and any modifications made by the caller,
222 set_stopped_child_used_math(target);
227 static inline void save_fp(struct task_struct *tsk)
233 static inline void restore_fp(struct task_struct *tsk)
239 static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
241 if (tsk == current) {
248 return tsk->thread.fpu.fpr;
251 #else /* !CONFIG_MIPS_FP_SUPPORT */
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.
258 static inline int __enable_fpu(enum fpu_mode mode)
263 static inline void __disable_fpu(void)
269 static inline int is_fpu_owner(void)
274 static inline void clear_fpu_owner(void)
279 static inline int own_fpu_inatomic(int restore)
284 static inline int own_fpu(int restore)
289 static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)
294 static inline void lose_fpu(int save)
299 static inline bool init_fp_ctx(struct task_struct *target)
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.
312 extern void save_fp(struct task_struct *tsk)
313 __compiletime_error("save_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");
315 extern void _save_fp(struct task_struct *)
316 __compiletime_error("_save_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");
318 extern void restore_fp(struct task_struct *tsk)
319 __compiletime_error("restore_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");
321 extern void _restore_fp(struct task_struct *)
322 __compiletime_error("_restore_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");
324 extern 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");
327 #endif /* !CONFIG_MIPS_FP_SUPPORT */
328 #endif /* _ASM_FPU_H */