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
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
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
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
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
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
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
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
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
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
163 static inline void load_user_fpu_regs(void)
164 {
165 struct thread_struct *thread = ¤t->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
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
179 static inline void save_user_fpu_regs(void)
180 {
181 struct thread_struct *thread = ¤t->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
192 static __always_inline void _kernel_fpu_begin(struct kernel_fpu *state, int flags)
193 {
194 struct thread_struct *thread = ¤t->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
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
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
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
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
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
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
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
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
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