2 * Copyright (C) 2002 MontaVista Software Inc.
3 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
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.
13 #include <linux/sched.h>
14 #include <linux/sched/task_stack.h>
15 #include <linux/ptrace.h>
16 #include <linux/thread_info.h>
17 #include <linux/bitops.h>
19 #include <asm/mipsregs.h>
21 #include <asm/cpu-features.h>
22 #include <asm/fpu_emulator.h>
23 #include <asm/hazards.h>
24 #include <asm/ptrace.h>
25 #include <asm/processor.h>
26 #include <asm/current.h>
29 #ifdef CONFIG_MIPS_MT_FPAFF
30 #include <asm/mips_mt.h>
33 extern void _save_fp(struct task_struct *);
34 extern void _restore_fp(struct task_struct *);
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 the bottom bit of the value
39 * purposefully matches the desired value of the Status.FR bit.
42 FPU_32BIT = 0, /* FR = 0 */
43 FPU_64BIT, /* FR = 1, FRE = 0 */
45 FPU_HYBRID, /* FR = 1, FRE = 1 */
47 #define FPU_FR_MASK 0x1
50 #define __disable_fpu() \
52 clear_c0_status(ST0_CU1); \
53 disable_fpu_hazard(); \
56 static inline int __enable_fpu(enum fpu_mode mode)
62 /* just enable the FPU in its current mode */
63 set_c0_status(ST0_CU1);
72 set_c0_config5(MIPS_CONF5_FRE);
76 #if !(defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6) \
77 || defined(CONFIG_64BIT))
78 /* we only have a 32-bit FPU */
85 clear_c0_config5(MIPS_CONF5_FRE);
88 /* set CU1 & change FR appropriately */
89 fr = (int)mode & FPU_FR_MASK;
90 change_c0_status(ST0_CU1 | ST0_FR, ST0_CU1 | (fr ? ST0_FR : 0));
93 /* check FR has the desired value */
94 if (!!(read_c0_status() & ST0_FR) == !!fr)
97 /* unsupported FR value */
108 #define clear_fpu_owner() clear_thread_flag(TIF_USEDFPU)
110 static inline int __is_fpu_owner(void)
112 return test_thread_flag(TIF_USEDFPU);
115 static inline int is_fpu_owner(void)
117 return cpu_has_fpu && __is_fpu_owner();
120 static inline int __own_fpu(void)
125 if (test_thread_flag(TIF_HYBRID_FPREGS))
128 mode = !test_thread_flag(TIF_32BIT_FPREGS);
130 ret = __enable_fpu(mode);
134 KSTK_STATUS(current) |= ST0_CU1;
135 if (mode == FPU_64BIT || mode == FPU_HYBRID)
136 KSTK_STATUS(current) |= ST0_FR;
137 else /* mode == FPU_32BIT */
138 KSTK_STATUS(current) &= ~ST0_FR;
140 set_thread_flag(TIF_USEDFPU);
144 static inline int own_fpu_inatomic(int restore)
148 if (cpu_has_fpu && !__is_fpu_owner()) {
151 _restore_fp(current);
156 static inline int own_fpu(int restore)
161 ret = own_fpu_inatomic(restore);
166 static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)
168 if (is_msa_enabled()) {
171 tsk->thread.fpu.fcr31 =
172 read_32bit_cp1_register(CP1_STATUS);
175 clear_tsk_thread_flag(tsk, TIF_USEDMSA);
177 } else if (is_fpu_owner()) {
182 /* FPU should not have been left enabled with no owner */
183 WARN(read_c0_status() & ST0_CU1,
184 "Orphaned FPU left enabled");
186 KSTK_STATUS(tsk) &= ~ST0_CU1;
187 clear_tsk_thread_flag(tsk, TIF_USEDFPU);
190 static inline void lose_fpu(int save)
193 lose_fpu_inatomic(save, current);
198 * init_fp_ctx() - Initialize task FP context
199 * @target: The task whose FP context should be initialized.
201 * Initializes the FP context of the target task to sane default values if that
202 * target task does not already have valid FP context. Once the context has
203 * been initialized, the task will be marked as having used FP & thus having
206 * Returns: true if context is initialized, else false.
208 static inline bool init_fp_ctx(struct task_struct *target)
210 /* If FP has been used then the target already has context */
211 if (tsk_used_math(target))
214 /* Begin with data registers set to all 1s... */
215 memset(&target->thread.fpu.fpr, ~0, sizeof(target->thread.fpu.fpr));
217 /* FCSR has been preset by `mips_set_personality_nan'. */
220 * Record that the target has "used" math, such that the context
221 * just initialised, and any modifications made by the caller,
224 set_stopped_child_used_math(target);
229 static inline void save_fp(struct task_struct *tsk)
235 static inline void restore_fp(struct task_struct *tsk)
241 static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
243 if (tsk == current) {
250 return tsk->thread.fpu.fpr;
253 #endif /* _ASM_FPU_H */