xref: /linux/arch/s390/include/asm/fpu.h (revision 79790b6818e96c58fe2bffee1b418c16e64e7b80)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * In-kernel FPU support functions
4  *
5  *
6  * Consider these guidelines before using in-kernel FPU functions:
7  *
8  *  1. Use kernel_fpu_begin() and kernel_fpu_end() to enclose all in-kernel
9  *     use of floating-point or vector registers and instructions.
10  *
11  *  2. For kernel_fpu_begin(), specify the vector register range you want to
12  *     use with the KERNEL_VXR_* constants. Consider these usage guidelines:
13  *
14  *     a) If your function typically runs in process-context, use the lower
15  *	  half of the vector registers, for example, specify KERNEL_VXR_LOW.
16  *     b) If your function typically runs in soft-irq or hard-irq context,
17  *	  prefer using the upper half of the vector registers, for example,
18  *	  specify KERNEL_VXR_HIGH.
19  *
20  *     If you adhere to these guidelines, an interrupted process context
21  *     does not require to save and restore vector registers because of
22  *     disjoint register ranges.
23  *
24  *     Also note that the __kernel_fpu_begin()/__kernel_fpu_end() functions
25  *     includes logic to save and restore up to 16 vector registers at once.
26  *
27  *  3. You can nest kernel_fpu_begin()/kernel_fpu_end() by using different
28  *     struct kernel_fpu states.  Vector registers that are in use by outer
29  *     levels are saved and restored.  You can minimize the save and restore
30  *     effort by choosing disjoint vector register ranges.
31  *
32  *  5. To use vector floating-point instructions, specify the KERNEL_FPC
33  *     flag to save and restore floating-point controls in addition to any
34  *     vector register range.
35  *
36  *  6. To use floating-point registers and instructions only, specify the
37  *     KERNEL_FPR flag.  This flag triggers a save and restore of vector
38  *     registers V0 to V15 and floating-point controls.
39  *
40  * Copyright IBM Corp. 2015
41  * Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
42  */
43 
44 #ifndef _ASM_S390_FPU_H
45 #define _ASM_S390_FPU_H
46 
47 #include <linux/processor.h>
48 #include <linux/preempt.h>
49 #include <linux/string.h>
50 #include <linux/sched.h>
51 #include <asm/sigcontext.h>
52 #include <asm/fpu-types.h>
53 #include <asm/fpu-insn.h>
54 #include <asm/facility.h>
55 
cpu_has_vx(void)56 static inline bool cpu_has_vx(void)
57 {
58 	return likely(test_facility(129));
59 }
60 
61 enum {
62 	KERNEL_FPC_BIT = 0,
63 	KERNEL_VXR_V0V7_BIT,
64 	KERNEL_VXR_V8V15_BIT,
65 	KERNEL_VXR_V16V23_BIT,
66 	KERNEL_VXR_V24V31_BIT,
67 };
68 
69 #define KERNEL_FPC		BIT(KERNEL_FPC_BIT)
70 #define KERNEL_VXR_V0V7		BIT(KERNEL_VXR_V0V7_BIT)
71 #define KERNEL_VXR_V8V15	BIT(KERNEL_VXR_V8V15_BIT)
72 #define KERNEL_VXR_V16V23	BIT(KERNEL_VXR_V16V23_BIT)
73 #define KERNEL_VXR_V24V31	BIT(KERNEL_VXR_V24V31_BIT)
74 
75 #define KERNEL_VXR_LOW		(KERNEL_VXR_V0V7   | KERNEL_VXR_V8V15)
76 #define KERNEL_VXR_MID		(KERNEL_VXR_V8V15  | KERNEL_VXR_V16V23)
77 #define KERNEL_VXR_HIGH		(KERNEL_VXR_V16V23 | KERNEL_VXR_V24V31)
78 
79 #define KERNEL_VXR		(KERNEL_VXR_LOW	   | KERNEL_VXR_HIGH)
80 #define KERNEL_FPR		(KERNEL_FPC	   | KERNEL_VXR_LOW)
81 
82 void load_fpu_state(struct fpu *state, int flags);
83 void save_fpu_state(struct fpu *state, int flags);
84 void __kernel_fpu_begin(struct kernel_fpu *state, int flags);
85 void __kernel_fpu_end(struct kernel_fpu *state, int flags);
86 
save_vx_regs(__vector128 * vxrs)87 static __always_inline void save_vx_regs(__vector128 *vxrs)
88 {
89 	fpu_vstm(0, 15, &vxrs[0]);
90 	fpu_vstm(16, 31, &vxrs[16]);
91 }
92 
load_vx_regs(__vector128 * vxrs)93 static __always_inline void load_vx_regs(__vector128 *vxrs)
94 {
95 	fpu_vlm(0, 15, &vxrs[0]);
96 	fpu_vlm(16, 31, &vxrs[16]);
97 }
98 
__save_fp_regs(freg_t * fprs,unsigned int offset)99 static __always_inline void __save_fp_regs(freg_t *fprs, unsigned int offset)
100 {
101 	fpu_std(0, &fprs[0 * offset]);
102 	fpu_std(1, &fprs[1 * offset]);
103 	fpu_std(2, &fprs[2 * offset]);
104 	fpu_std(3, &fprs[3 * offset]);
105 	fpu_std(4, &fprs[4 * offset]);
106 	fpu_std(5, &fprs[5 * offset]);
107 	fpu_std(6, &fprs[6 * offset]);
108 	fpu_std(7, &fprs[7 * offset]);
109 	fpu_std(8, &fprs[8 * offset]);
110 	fpu_std(9, &fprs[9 * offset]);
111 	fpu_std(10, &fprs[10 * offset]);
112 	fpu_std(11, &fprs[11 * offset]);
113 	fpu_std(12, &fprs[12 * offset]);
114 	fpu_std(13, &fprs[13 * offset]);
115 	fpu_std(14, &fprs[14 * offset]);
116 	fpu_std(15, &fprs[15 * offset]);
117 }
118 
__load_fp_regs(freg_t * fprs,unsigned int offset)119 static __always_inline void __load_fp_regs(freg_t *fprs, unsigned int offset)
120 {
121 	fpu_ld(0, &fprs[0 * offset]);
122 	fpu_ld(1, &fprs[1 * offset]);
123 	fpu_ld(2, &fprs[2 * offset]);
124 	fpu_ld(3, &fprs[3 * offset]);
125 	fpu_ld(4, &fprs[4 * offset]);
126 	fpu_ld(5, &fprs[5 * offset]);
127 	fpu_ld(6, &fprs[6 * offset]);
128 	fpu_ld(7, &fprs[7 * offset]);
129 	fpu_ld(8, &fprs[8 * offset]);
130 	fpu_ld(9, &fprs[9 * offset]);
131 	fpu_ld(10, &fprs[10 * offset]);
132 	fpu_ld(11, &fprs[11 * offset]);
133 	fpu_ld(12, &fprs[12 * offset]);
134 	fpu_ld(13, &fprs[13 * offset]);
135 	fpu_ld(14, &fprs[14 * offset]);
136 	fpu_ld(15, &fprs[15 * offset]);
137 }
138 
save_fp_regs(freg_t * fprs)139 static __always_inline void save_fp_regs(freg_t *fprs)
140 {
141 	__save_fp_regs(fprs, sizeof(freg_t) / sizeof(freg_t));
142 }
143 
load_fp_regs(freg_t * fprs)144 static __always_inline void load_fp_regs(freg_t *fprs)
145 {
146 	__load_fp_regs(fprs, sizeof(freg_t) / sizeof(freg_t));
147 }
148 
save_fp_regs_vx(__vector128 * vxrs)149 static __always_inline void save_fp_regs_vx(__vector128 *vxrs)
150 {
151 	freg_t *fprs = (freg_t *)&vxrs[0].high;
152 
153 	__save_fp_regs(fprs, sizeof(__vector128) / sizeof(freg_t));
154 }
155 
load_fp_regs_vx(__vector128 * vxrs)156 static __always_inline void load_fp_regs_vx(__vector128 *vxrs)
157 {
158 	freg_t *fprs = (freg_t *)&vxrs[0].high;
159 
160 	__load_fp_regs(fprs, sizeof(__vector128) / sizeof(freg_t));
161 }
162 
load_user_fpu_regs(void)163 static inline void load_user_fpu_regs(void)
164 {
165 	struct thread_struct *thread = &current->thread;
166 
167 	if (!thread->ufpu_flags)
168 		return;
169 	load_fpu_state(&thread->ufpu, thread->ufpu_flags);
170 	thread->ufpu_flags = 0;
171 }
172 
__save_user_fpu_regs(struct thread_struct * thread,int flags)173 static __always_inline void __save_user_fpu_regs(struct thread_struct *thread, int flags)
174 {
175 	save_fpu_state(&thread->ufpu, flags);
176 	__atomic_or(flags, &thread->ufpu_flags);
177 }
178 
save_user_fpu_regs(void)179 static inline void save_user_fpu_regs(void)
180 {
181 	struct thread_struct *thread = &current->thread;
182 	int mask, flags;
183 
184 	mask = __atomic_or(KERNEL_FPC | KERNEL_VXR, &thread->kfpu_flags);
185 	flags = ~READ_ONCE(thread->ufpu_flags) & (KERNEL_FPC | KERNEL_VXR);
186 	if (flags)
187 		__save_user_fpu_regs(thread, flags);
188 	barrier();
189 	WRITE_ONCE(thread->kfpu_flags, mask);
190 }
191 
_kernel_fpu_begin(struct kernel_fpu * state,int flags)192 static __always_inline void _kernel_fpu_begin(struct kernel_fpu *state, int flags)
193 {
194 	struct thread_struct *thread = &current->thread;
195 	int mask, uflags;
196 
197 	mask = __atomic_or(flags, &thread->kfpu_flags);
198 	state->hdr.mask = mask;
199 	uflags = READ_ONCE(thread->ufpu_flags);
200 	if ((uflags & flags) != flags)
201 		__save_user_fpu_regs(thread, ~uflags & flags);
202 	if (mask & flags)
203 		__kernel_fpu_begin(state, flags);
204 }
205 
_kernel_fpu_end(struct kernel_fpu * state,int flags)206 static __always_inline void _kernel_fpu_end(struct kernel_fpu *state, int flags)
207 {
208 	int mask = state->hdr.mask;
209 
210 	if (mask & flags)
211 		__kernel_fpu_end(state, flags);
212 	barrier();
213 	WRITE_ONCE(current->thread.kfpu_flags, mask);
214 }
215 
216 void __kernel_fpu_invalid_size(void);
217 
kernel_fpu_check_size(int flags,unsigned int size)218 static __always_inline void kernel_fpu_check_size(int flags, unsigned int size)
219 {
220 	unsigned int cnt = 0;
221 
222 	if (flags & KERNEL_VXR_V0V7)
223 		cnt += 8;
224 	if (flags & KERNEL_VXR_V8V15)
225 		cnt += 8;
226 	if (flags & KERNEL_VXR_V16V23)
227 		cnt += 8;
228 	if (flags & KERNEL_VXR_V24V31)
229 		cnt += 8;
230 	if (cnt != size)
231 		__kernel_fpu_invalid_size();
232 }
233 
234 #define kernel_fpu_begin(state, flags)					\
235 {									\
236 	typeof(state) s = (state);					\
237 	int _flags = (flags);						\
238 									\
239 	kernel_fpu_check_size(_flags, ARRAY_SIZE(s->vxrs));		\
240 	_kernel_fpu_begin((struct kernel_fpu *)s, _flags);		\
241 }
242 
243 #define kernel_fpu_end(state, flags)					\
244 {									\
245 	typeof(state) s = (state);					\
246 	int _flags = (flags);						\
247 									\
248 	kernel_fpu_check_size(_flags, ARRAY_SIZE(s->vxrs));		\
249 	_kernel_fpu_end((struct kernel_fpu *)s, _flags);		\
250 }
251 
save_kernel_fpu_regs(struct thread_struct * thread)252 static inline void save_kernel_fpu_regs(struct thread_struct *thread)
253 {
254 	if (!thread->kfpu_flags)
255 		return;
256 	save_fpu_state(&thread->kfpu, thread->kfpu_flags);
257 }
258 
restore_kernel_fpu_regs(struct thread_struct * thread)259 static inline void restore_kernel_fpu_regs(struct thread_struct *thread)
260 {
261 	if (!thread->kfpu_flags)
262 		return;
263 	load_fpu_state(&thread->kfpu, thread->kfpu_flags);
264 }
265 
convert_vx_to_fp(freg_t * fprs,__vector128 * vxrs)266 static inline void convert_vx_to_fp(freg_t *fprs, __vector128 *vxrs)
267 {
268 	int i;
269 
270 	for (i = 0; i < __NUM_FPRS; i++)
271 		fprs[i].ui = vxrs[i].high;
272 }
273 
convert_fp_to_vx(__vector128 * vxrs,freg_t * fprs)274 static inline void convert_fp_to_vx(__vector128 *vxrs, freg_t *fprs)
275 {
276 	int i;
277 
278 	for (i = 0; i < __NUM_FPRS; i++)
279 		vxrs[i].high = fprs[i].ui;
280 }
281 
fpregs_store(_s390_fp_regs * fpregs,struct fpu * fpu)282 static inline void fpregs_store(_s390_fp_regs *fpregs, struct fpu *fpu)
283 {
284 	fpregs->pad = 0;
285 	fpregs->fpc = fpu->fpc;
286 	convert_vx_to_fp((freg_t *)&fpregs->fprs, fpu->vxrs);
287 }
288 
fpregs_load(_s390_fp_regs * fpregs,struct fpu * fpu)289 static inline void fpregs_load(_s390_fp_regs *fpregs, struct fpu *fpu)
290 {
291 	fpu->fpc = fpregs->fpc;
292 	convert_fp_to_vx(fpu->vxrs, (freg_t *)&fpregs->fprs);
293 }
294 
295 #endif /* _ASM_S390_FPU_H */
296