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>
34 * This enum specifies a mode in which we want the FPU to operate, for cores
35 * which implement the Status.FR bit. Note that the bottom bit of the value
36 * purposefully matches the desired value of the Status.FR bit.
39 FPU_32BIT = 0, /* FR = 0 */
40 FPU_64BIT, /* FR = 1, FRE = 0 */
42 FPU_HYBRID, /* FR = 1, FRE = 1 */
44 #define FPU_FR_MASK 0x1
47 #ifdef CONFIG_MIPS_FP_SUPPORT
49 extern void _save_fp(struct task_struct *);
50 extern void _restore_fp(struct task_struct *);
52 #define __disable_fpu() \
54 clear_c0_status(ST0_CU1); \
55 disable_fpu_hazard(); \
58 static inline int __enable_fpu(enum fpu_mode mode)
64 /* just enable the FPU in its current mode */
65 set_c0_status(ST0_CU1);
74 set_c0_config5(MIPS_CONF5_FRE);
78 #if !(defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6) \
79 || defined(CONFIG_64BIT))
80 /* we only have a 32-bit FPU */
87 clear_c0_config5(MIPS_CONF5_FRE);
90 /* set CU1 & change FR appropriately */
91 fr = (int)mode & FPU_FR_MASK;
92 change_c0_status(ST0_CU1 | ST0_FR, ST0_CU1 | (fr ? ST0_FR : 0));
95 /* check FR has the desired value */
96 if (!!(read_c0_status() & ST0_FR) == !!fr)
99 /* unsupported FR value */
110 #define clear_fpu_owner() clear_thread_flag(TIF_USEDFPU)
112 static inline int __is_fpu_owner(void)
114 return test_thread_flag(TIF_USEDFPU);
117 static inline int is_fpu_owner(void)
119 return cpu_has_fpu && __is_fpu_owner();
122 static inline int __own_fpu(void)
127 if (test_thread_flag(TIF_HYBRID_FPREGS))
130 mode = !test_thread_flag(TIF_32BIT_FPREGS);
132 ret = __enable_fpu(mode);
136 KSTK_STATUS(current) |= ST0_CU1;
137 if (mode == FPU_64BIT || mode == FPU_HYBRID)
138 KSTK_STATUS(current) |= ST0_FR;
139 else /* mode == FPU_32BIT */
140 KSTK_STATUS(current) &= ~ST0_FR;
142 set_thread_flag(TIF_USEDFPU);
146 static inline int own_fpu_inatomic(int restore)
150 if (cpu_has_fpu && !__is_fpu_owner()) {
153 _restore_fp(current);
158 static inline int own_fpu(int restore)
163 ret = own_fpu_inatomic(restore);
168 static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)
170 if (is_msa_enabled()) {
173 tsk->thread.fpu.fcr31 =
174 read_32bit_cp1_register(CP1_STATUS);
177 clear_tsk_thread_flag(tsk, TIF_USEDMSA);
179 } else if (is_fpu_owner()) {
184 /* FPU should not have been left enabled with no owner */
185 WARN(read_c0_status() & ST0_CU1,
186 "Orphaned FPU left enabled");
188 KSTK_STATUS(tsk) &= ~ST0_CU1;
189 clear_tsk_thread_flag(tsk, TIF_USEDFPU);
192 static inline void lose_fpu(int save)
195 lose_fpu_inatomic(save, current);
200 * init_fp_ctx() - Initialize task FP context
201 * @target: The task whose FP context should be initialized.
203 * Initializes the FP context of the target task to sane default values if that
204 * target task does not already have valid FP context. Once the context has
205 * been initialized, the task will be marked as having used FP & thus having
208 * Returns: true if context is initialized, else false.
210 static inline bool init_fp_ctx(struct task_struct *target)
212 /* If FP has been used then the target already has context */
213 if (tsk_used_math(target))
216 /* Begin with data registers set to all 1s... */
217 memset(&target->thread.fpu.fpr, ~0, sizeof(target->thread.fpu.fpr));
219 /* FCSR has been preset by `mips_set_personality_nan'. */
222 * Record that the target has "used" math, such that the context
223 * just initialised, and any modifications made by the caller,
226 set_stopped_child_used_math(target);
231 static inline void save_fp(struct task_struct *tsk)
237 static inline void restore_fp(struct task_struct *tsk)
243 static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
245 if (tsk == current) {
252 return tsk->thread.fpu.fpr;
255 #else /* !CONFIG_MIPS_FP_SUPPORT */
258 * When FP support is disabled we provide only a minimal set of stub functions
259 * to avoid callers needing to care too much about CONFIG_MIPS_FP_SUPPORT.
262 static inline int __enable_fpu(enum fpu_mode mode)
267 static inline void __disable_fpu(void)
273 static inline int is_fpu_owner(void)
278 static inline void clear_fpu_owner(void)
283 static inline int own_fpu_inatomic(int restore)
288 static inline int own_fpu(int restore)
293 static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)
298 static inline void lose_fpu(int save)
303 static inline bool init_fp_ctx(struct task_struct *target)
309 * The following functions should only be called in paths where we know that FP
310 * support is enabled, typically a path where own_fpu() or __enable_fpu() have
311 * returned successfully. When CONFIG_MIPS_FP_SUPPORT=n it is known at compile
312 * time that this should never happen, so calls to these functions should be
313 * optimized away & never actually be emitted.
316 extern void save_fp(struct task_struct *tsk)
317 __compiletime_error("save_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");
319 extern void _save_fp(struct task_struct *)
320 __compiletime_error("_save_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");
322 extern void restore_fp(struct task_struct *tsk)
323 __compiletime_error("restore_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");
325 extern void _restore_fp(struct task_struct *)
326 __compiletime_error("_restore_fp() should not be called when CONFIG_MIPS_FP_SUPPORT=n");
328 extern union fpureg *get_fpu_regs(struct task_struct *tsk)
329 __compiletime_error("get_fpu_regs() should not be called when CONFIG_MIPS_FP_SUPPORT=n");
331 #endif /* !CONFIG_MIPS_FP_SUPPORT */
332 #endif /* _ASM_FPU_H */