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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/cpufeature.h>
48#include <linux/processor.h>
49#include <linux/preempt.h>
50#include <linux/string.h>
51#include <linux/sched.h>
52#include <asm/sigcontext.h>
53#include <asm/fpu-types.h>
54#include <asm/fpu-insn.h>
55
56enum {
57 KERNEL_FPC_BIT = 0,
58 KERNEL_VXR_V0V7_BIT,
59 KERNEL_VXR_V8V15_BIT,
60 KERNEL_VXR_V16V23_BIT,
61 KERNEL_VXR_V24V31_BIT,
62};
63
64#define KERNEL_FPC BIT(KERNEL_FPC_BIT)
65#define KERNEL_VXR_V0V7 BIT(KERNEL_VXR_V0V7_BIT)
66#define KERNEL_VXR_V8V15 BIT(KERNEL_VXR_V8V15_BIT)
67#define KERNEL_VXR_V16V23 BIT(KERNEL_VXR_V16V23_BIT)
68#define KERNEL_VXR_V24V31 BIT(KERNEL_VXR_V24V31_BIT)
69
70#define KERNEL_VXR_LOW (KERNEL_VXR_V0V7 | KERNEL_VXR_V8V15)
71#define KERNEL_VXR_MID (KERNEL_VXR_V8V15 | KERNEL_VXR_V16V23)
72#define KERNEL_VXR_HIGH (KERNEL_VXR_V16V23 | KERNEL_VXR_V24V31)
73
74#define KERNEL_VXR (KERNEL_VXR_LOW | KERNEL_VXR_HIGH)
75#define KERNEL_FPR (KERNEL_FPC | KERNEL_VXR_LOW)
76
77void load_fpu_state(struct fpu *state, int flags);
78void save_fpu_state(struct fpu *state, int flags);
79void __kernel_fpu_begin(struct kernel_fpu *state, int flags);
80void __kernel_fpu_end(struct kernel_fpu *state, int flags);
81
82static __always_inline void save_vx_regs(__vector128 *vxrs)
83{
84 fpu_vstm(0, 15, &vxrs[0]);
85 fpu_vstm(16, 31, &vxrs[16]);
86}
87
88static __always_inline void load_vx_regs(__vector128 *vxrs)
89{
90 fpu_vlm(0, 15, &vxrs[0]);
91 fpu_vlm(16, 31, &vxrs[16]);
92}
93
94static __always_inline void __save_fp_regs(freg_t *fprs, unsigned int offset)
95{
96 fpu_std(0, &fprs[0 * offset]);
97 fpu_std(1, &fprs[1 * offset]);
98 fpu_std(2, &fprs[2 * offset]);
99 fpu_std(3, &fprs[3 * offset]);
100 fpu_std(4, &fprs[4 * offset]);
101 fpu_std(5, &fprs[5 * offset]);
102 fpu_std(6, &fprs[6 * offset]);
103 fpu_std(7, &fprs[7 * offset]);
104 fpu_std(8, &fprs[8 * offset]);
105 fpu_std(9, &fprs[9 * offset]);
106 fpu_std(10, &fprs[10 * offset]);
107 fpu_std(11, &fprs[11 * offset]);
108 fpu_std(12, &fprs[12 * offset]);
109 fpu_std(13, &fprs[13 * offset]);
110 fpu_std(14, &fprs[14 * offset]);
111 fpu_std(15, &fprs[15 * offset]);
112}
113
114static __always_inline void __load_fp_regs(freg_t *fprs, unsigned int offset)
115{
116 fpu_ld(0, &fprs[0 * offset]);
117 fpu_ld(1, &fprs[1 * offset]);
118 fpu_ld(2, &fprs[2 * offset]);
119 fpu_ld(3, &fprs[3 * offset]);
120 fpu_ld(4, &fprs[4 * offset]);
121 fpu_ld(5, &fprs[5 * offset]);
122 fpu_ld(6, &fprs[6 * offset]);
123 fpu_ld(7, &fprs[7 * offset]);
124 fpu_ld(8, &fprs[8 * offset]);
125 fpu_ld(9, &fprs[9 * offset]);
126 fpu_ld(10, &fprs[10 * offset]);
127 fpu_ld(11, &fprs[11 * offset]);
128 fpu_ld(12, &fprs[12 * offset]);
129 fpu_ld(13, &fprs[13 * offset]);
130 fpu_ld(14, &fprs[14 * offset]);
131 fpu_ld(15, &fprs[15 * offset]);
132}
133
134static __always_inline void save_fp_regs(freg_t *fprs)
135{
136 __save_fp_regs(fprs, sizeof(freg_t) / sizeof(freg_t));
137}
138
139static __always_inline void load_fp_regs(freg_t *fprs)
140{
141 __load_fp_regs(fprs, sizeof(freg_t) / sizeof(freg_t));
142}
143
144static __always_inline void save_fp_regs_vx(__vector128 *vxrs)
145{
146 freg_t *fprs = (freg_t *)&vxrs[0].high;
147
148 __save_fp_regs(fprs, sizeof(__vector128) / sizeof(freg_t));
149}
150
151static __always_inline void load_fp_regs_vx(__vector128 *vxrs)
152{
153 freg_t *fprs = (freg_t *)&vxrs[0].high;
154
155 __load_fp_regs(fprs, sizeof(__vector128) / sizeof(freg_t));
156}
157
158static inline void load_user_fpu_regs(void)
159{
160 struct thread_struct *thread = ¤t->thread;
161
162 if (!thread->ufpu_flags)
163 return;
164 load_fpu_state(&thread->ufpu, thread->ufpu_flags);
165 thread->ufpu_flags = 0;
166}
167
168static __always_inline void __save_user_fpu_regs(struct thread_struct *thread, int flags)
169{
170 save_fpu_state(&thread->ufpu, flags);
171 __atomic_or(flags, &thread->ufpu_flags);
172}
173
174static inline void save_user_fpu_regs(void)
175{
176 struct thread_struct *thread = ¤t->thread;
177 int mask, flags;
178
179 mask = __atomic_or(KERNEL_FPC | KERNEL_VXR, &thread->kfpu_flags);
180 flags = ~READ_ONCE(thread->ufpu_flags) & (KERNEL_FPC | KERNEL_VXR);
181 if (flags)
182 __save_user_fpu_regs(thread, flags);
183 barrier();
184 WRITE_ONCE(thread->kfpu_flags, mask);
185}
186
187static __always_inline void _kernel_fpu_begin(struct kernel_fpu *state, int flags)
188{
189 struct thread_struct *thread = ¤t->thread;
190 int mask, uflags;
191
192 mask = __atomic_or(flags, &thread->kfpu_flags);
193 state->hdr.mask = mask;
194 uflags = READ_ONCE(thread->ufpu_flags);
195 if ((uflags & flags) != flags)
196 __save_user_fpu_regs(thread, ~uflags & flags);
197 if (mask & flags)
198 __kernel_fpu_begin(state, flags);
199}
200
201static __always_inline void _kernel_fpu_end(struct kernel_fpu *state, int flags)
202{
203 int mask = state->hdr.mask;
204
205 if (mask & flags)
206 __kernel_fpu_end(state, flags);
207 barrier();
208 WRITE_ONCE(current->thread.kfpu_flags, mask);
209}
210
211void __kernel_fpu_invalid_size(void);
212
213static __always_inline void kernel_fpu_check_size(int flags, unsigned int size)
214{
215 unsigned int cnt = 0;
216
217 if (flags & KERNEL_VXR_V0V7)
218 cnt += 8;
219 if (flags & KERNEL_VXR_V8V15)
220 cnt += 8;
221 if (flags & KERNEL_VXR_V16V23)
222 cnt += 8;
223 if (flags & KERNEL_VXR_V24V31)
224 cnt += 8;
225 if (cnt != size)
226 __kernel_fpu_invalid_size();
227}
228
229#define kernel_fpu_begin(state, flags) \
230{ \
231 typeof(state) s = (state); \
232 int _flags = (flags); \
233 \
234 kernel_fpu_check_size(_flags, ARRAY_SIZE(s->vxrs)); \
235 _kernel_fpu_begin((struct kernel_fpu *)s, _flags); \
236}
237
238#define kernel_fpu_end(state, flags) \
239{ \
240 typeof(state) s = (state); \
241 int _flags = (flags); \
242 \
243 kernel_fpu_check_size(_flags, ARRAY_SIZE(s->vxrs)); \
244 _kernel_fpu_end((struct kernel_fpu *)s, _flags); \
245}
246
247static inline void save_kernel_fpu_regs(struct thread_struct *thread)
248{
249 if (!thread->kfpu_flags)
250 return;
251 save_fpu_state(&thread->kfpu, thread->kfpu_flags);
252}
253
254static inline void restore_kernel_fpu_regs(struct thread_struct *thread)
255{
256 if (!thread->kfpu_flags)
257 return;
258 load_fpu_state(&thread->kfpu, thread->kfpu_flags);
259}
260
261static inline void convert_vx_to_fp(freg_t *fprs, __vector128 *vxrs)
262{
263 int i;
264
265 for (i = 0; i < __NUM_FPRS; i++)
266 fprs[i].ui = vxrs[i].high;
267}
268
269static inline void convert_fp_to_vx(__vector128 *vxrs, freg_t *fprs)
270{
271 int i;
272
273 for (i = 0; i < __NUM_FPRS; i++)
274 vxrs[i].high = fprs[i].ui;
275}
276
277static inline void fpregs_store(_s390_fp_regs *fpregs, struct fpu *fpu)
278{
279 fpregs->pad = 0;
280 fpregs->fpc = fpu->fpc;
281 convert_vx_to_fp((freg_t *)&fpregs->fprs, fpu->vxrs);
282}
283
284static inline void fpregs_load(_s390_fp_regs *fpregs, struct fpu *fpu)
285{
286 fpu->fpc = fpregs->fpc;
287 convert_fp_to_vx(fpu->vxrs, (freg_t *)&fpregs->fprs);
288}
289
290#endif /* _ASM_S390_FPU_H */