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1/*
2 * FPU register's regset abstraction, for ptrace, core dumps, etc.
3 */
4#include <asm/fpu/internal.h>
5#include <asm/fpu/signal.h>
6#include <asm/fpu/regset.h>
7#include <asm/fpu/xstate.h>
8
9/*
10 * The xstateregs_active() routine is the same as the regset_fpregs_active() routine,
11 * as the "regset->n" for the xstate regset will be updated based on the feature
12 * capabilities supported by the xsave.
13 */
14int regset_fpregs_active(struct task_struct *target, const struct user_regset *regset)
15{
16 struct fpu *target_fpu = &target->thread.fpu;
17
18 return target_fpu->fpstate_active ? regset->n : 0;
19}
20
21int regset_xregset_fpregs_active(struct task_struct *target, const struct user_regset *regset)
22{
23 struct fpu *target_fpu = &target->thread.fpu;
24
25 if (boot_cpu_has(X86_FEATURE_FXSR) && target_fpu->fpstate_active)
26 return regset->n;
27 else
28 return 0;
29}
30
31int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
32 unsigned int pos, unsigned int count,
33 void *kbuf, void __user *ubuf)
34{
35 struct fpu *fpu = &target->thread.fpu;
36
37 if (!boot_cpu_has(X86_FEATURE_FXSR))
38 return -ENODEV;
39
40 fpu__activate_fpstate_read(fpu);
41 fpstate_sanitize_xstate(fpu);
42
43 return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
44 &fpu->state.fxsave, 0, -1);
45}
46
47int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
48 unsigned int pos, unsigned int count,
49 const void *kbuf, const void __user *ubuf)
50{
51 struct fpu *fpu = &target->thread.fpu;
52 int ret;
53
54 if (!boot_cpu_has(X86_FEATURE_FXSR))
55 return -ENODEV;
56
57 fpu__activate_fpstate_write(fpu);
58 fpstate_sanitize_xstate(fpu);
59
60 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
61 &fpu->state.fxsave, 0, -1);
62
63 /*
64 * mxcsr reserved bits must be masked to zero for security reasons.
65 */
66 fpu->state.fxsave.mxcsr &= mxcsr_feature_mask;
67
68 /*
69 * update the header bits in the xsave header, indicating the
70 * presence of FP and SSE state.
71 */
72 if (boot_cpu_has(X86_FEATURE_XSAVE))
73 fpu->state.xsave.header.xfeatures |= XFEATURE_MASK_FPSSE;
74
75 return ret;
76}
77
78int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
79 unsigned int pos, unsigned int count,
80 void *kbuf, void __user *ubuf)
81{
82 struct fpu *fpu = &target->thread.fpu;
83 struct xregs_state *xsave;
84 int ret;
85
86 if (!boot_cpu_has(X86_FEATURE_XSAVE))
87 return -ENODEV;
88
89 xsave = &fpu->state.xsave;
90
91 fpu__activate_fpstate_read(fpu);
92
93 if (using_compacted_format()) {
94 ret = copyout_from_xsaves(pos, count, kbuf, ubuf, xsave);
95 } else {
96 fpstate_sanitize_xstate(fpu);
97 /*
98 * Copy the 48 bytes defined by the software into the xsave
99 * area in the thread struct, so that we can copy the whole
100 * area to user using one user_regset_copyout().
101 */
102 memcpy(&xsave->i387.sw_reserved, xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes));
103
104 /*
105 * Copy the xstate memory layout.
106 */
107 ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
108 }
109 return ret;
110}
111
112int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
113 unsigned int pos, unsigned int count,
114 const void *kbuf, const void __user *ubuf)
115{
116 struct fpu *fpu = &target->thread.fpu;
117 struct xregs_state *xsave;
118 int ret;
119
120 if (!boot_cpu_has(X86_FEATURE_XSAVE))
121 return -ENODEV;
122
123 /*
124 * A whole standard-format XSAVE buffer is needed:
125 */
126 if ((pos != 0) || (count < fpu_user_xstate_size))
127 return -EFAULT;
128
129 xsave = &fpu->state.xsave;
130
131 fpu__activate_fpstate_write(fpu);
132
133 if (boot_cpu_has(X86_FEATURE_XSAVES))
134 ret = copyin_to_xsaves(kbuf, ubuf, xsave);
135 else
136 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
137
138 /*
139 * In case of failure, mark all states as init:
140 */
141 if (ret)
142 fpstate_init(&fpu->state);
143
144 /*
145 * mxcsr reserved bits must be masked to zero for security reasons.
146 */
147 xsave->i387.mxcsr &= mxcsr_feature_mask;
148 xsave->header.xfeatures &= xfeatures_mask;
149 /*
150 * These bits must be zero.
151 */
152 memset(&xsave->header.reserved, 0, 48);
153
154 return ret;
155}
156
157#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
158
159/*
160 * FPU tag word conversions.
161 */
162
163static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
164{
165 unsigned int tmp; /* to avoid 16 bit prefixes in the code */
166
167 /* Transform each pair of bits into 01 (valid) or 00 (empty) */
168 tmp = ~twd;
169 tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
170 /* and move the valid bits to the lower byte. */
171 tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
172 tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
173 tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
174
175 return tmp;
176}
177
178#define FPREG_ADDR(f, n) ((void *)&(f)->st_space + (n) * 16)
179#define FP_EXP_TAG_VALID 0
180#define FP_EXP_TAG_ZERO 1
181#define FP_EXP_TAG_SPECIAL 2
182#define FP_EXP_TAG_EMPTY 3
183
184static inline u32 twd_fxsr_to_i387(struct fxregs_state *fxsave)
185{
186 struct _fpxreg *st;
187 u32 tos = (fxsave->swd >> 11) & 7;
188 u32 twd = (unsigned long) fxsave->twd;
189 u32 tag;
190 u32 ret = 0xffff0000u;
191 int i;
192
193 for (i = 0; i < 8; i++, twd >>= 1) {
194 if (twd & 0x1) {
195 st = FPREG_ADDR(fxsave, (i - tos) & 7);
196
197 switch (st->exponent & 0x7fff) {
198 case 0x7fff:
199 tag = FP_EXP_TAG_SPECIAL;
200 break;
201 case 0x0000:
202 if (!st->significand[0] &&
203 !st->significand[1] &&
204 !st->significand[2] &&
205 !st->significand[3])
206 tag = FP_EXP_TAG_ZERO;
207 else
208 tag = FP_EXP_TAG_SPECIAL;
209 break;
210 default:
211 if (st->significand[3] & 0x8000)
212 tag = FP_EXP_TAG_VALID;
213 else
214 tag = FP_EXP_TAG_SPECIAL;
215 break;
216 }
217 } else {
218 tag = FP_EXP_TAG_EMPTY;
219 }
220 ret |= tag << (2 * i);
221 }
222 return ret;
223}
224
225/*
226 * FXSR floating point environment conversions.
227 */
228
229void
230convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk)
231{
232 struct fxregs_state *fxsave = &tsk->thread.fpu.state.fxsave;
233 struct _fpreg *to = (struct _fpreg *) &env->st_space[0];
234 struct _fpxreg *from = (struct _fpxreg *) &fxsave->st_space[0];
235 int i;
236
237 env->cwd = fxsave->cwd | 0xffff0000u;
238 env->swd = fxsave->swd | 0xffff0000u;
239 env->twd = twd_fxsr_to_i387(fxsave);
240
241#ifdef CONFIG_X86_64
242 env->fip = fxsave->rip;
243 env->foo = fxsave->rdp;
244 /*
245 * should be actually ds/cs at fpu exception time, but
246 * that information is not available in 64bit mode.
247 */
248 env->fcs = task_pt_regs(tsk)->cs;
249 if (tsk == current) {
250 savesegment(ds, env->fos);
251 } else {
252 env->fos = tsk->thread.ds;
253 }
254 env->fos |= 0xffff0000;
255#else
256 env->fip = fxsave->fip;
257 env->fcs = (u16) fxsave->fcs | ((u32) fxsave->fop << 16);
258 env->foo = fxsave->foo;
259 env->fos = fxsave->fos;
260#endif
261
262 for (i = 0; i < 8; ++i)
263 memcpy(&to[i], &from[i], sizeof(to[0]));
264}
265
266void convert_to_fxsr(struct task_struct *tsk,
267 const struct user_i387_ia32_struct *env)
268
269{
270 struct fxregs_state *fxsave = &tsk->thread.fpu.state.fxsave;
271 struct _fpreg *from = (struct _fpreg *) &env->st_space[0];
272 struct _fpxreg *to = (struct _fpxreg *) &fxsave->st_space[0];
273 int i;
274
275 fxsave->cwd = env->cwd;
276 fxsave->swd = env->swd;
277 fxsave->twd = twd_i387_to_fxsr(env->twd);
278 fxsave->fop = (u16) ((u32) env->fcs >> 16);
279#ifdef CONFIG_X86_64
280 fxsave->rip = env->fip;
281 fxsave->rdp = env->foo;
282 /* cs and ds ignored */
283#else
284 fxsave->fip = env->fip;
285 fxsave->fcs = (env->fcs & 0xffff);
286 fxsave->foo = env->foo;
287 fxsave->fos = env->fos;
288#endif
289
290 for (i = 0; i < 8; ++i)
291 memcpy(&to[i], &from[i], sizeof(from[0]));
292}
293
294int fpregs_get(struct task_struct *target, const struct user_regset *regset,
295 unsigned int pos, unsigned int count,
296 void *kbuf, void __user *ubuf)
297{
298 struct fpu *fpu = &target->thread.fpu;
299 struct user_i387_ia32_struct env;
300
301 fpu__activate_fpstate_read(fpu);
302
303 if (!boot_cpu_has(X86_FEATURE_FPU))
304 return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
305
306 if (!boot_cpu_has(X86_FEATURE_FXSR))
307 return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
308 &fpu->state.fsave, 0,
309 -1);
310
311 fpstate_sanitize_xstate(fpu);
312
313 if (kbuf && pos == 0 && count == sizeof(env)) {
314 convert_from_fxsr(kbuf, target);
315 return 0;
316 }
317
318 convert_from_fxsr(&env, target);
319
320 return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &env, 0, -1);
321}
322
323int fpregs_set(struct task_struct *target, const struct user_regset *regset,
324 unsigned int pos, unsigned int count,
325 const void *kbuf, const void __user *ubuf)
326{
327 struct fpu *fpu = &target->thread.fpu;
328 struct user_i387_ia32_struct env;
329 int ret;
330
331 fpu__activate_fpstate_write(fpu);
332 fpstate_sanitize_xstate(fpu);
333
334 if (!boot_cpu_has(X86_FEATURE_FPU))
335 return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
336
337 if (!boot_cpu_has(X86_FEATURE_FXSR))
338 return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
339 &fpu->state.fsave, 0,
340 -1);
341
342 if (pos > 0 || count < sizeof(env))
343 convert_from_fxsr(&env, target);
344
345 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &env, 0, -1);
346 if (!ret)
347 convert_to_fxsr(target, &env);
348
349 /*
350 * update the header bit in the xsave header, indicating the
351 * presence of FP.
352 */
353 if (boot_cpu_has(X86_FEATURE_XSAVE))
354 fpu->state.xsave.header.xfeatures |= XFEATURE_MASK_FP;
355 return ret;
356}
357
358/*
359 * FPU state for core dumps.
360 * This is only used for a.out dumps now.
361 * It is declared generically using elf_fpregset_t (which is
362 * struct user_i387_struct) but is in fact only used for 32-bit
363 * dumps, so on 64-bit it is really struct user_i387_ia32_struct.
364 */
365int dump_fpu(struct pt_regs *regs, struct user_i387_struct *ufpu)
366{
367 struct task_struct *tsk = current;
368 struct fpu *fpu = &tsk->thread.fpu;
369 int fpvalid;
370
371 fpvalid = fpu->fpstate_active;
372 if (fpvalid)
373 fpvalid = !fpregs_get(tsk, NULL,
374 0, sizeof(struct user_i387_ia32_struct),
375 ufpu, NULL);
376
377 return fpvalid;
378}
379EXPORT_SYMBOL(dump_fpu);
380
381#endif /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * FPU register's regset abstraction, for ptrace, core dumps, etc.
4 */
5#include <linux/sched/task_stack.h>
6#include <linux/vmalloc.h>
7
8#include <asm/fpu/api.h>
9#include <asm/fpu/signal.h>
10#include <asm/fpu/regset.h>
11#include <asm/prctl.h>
12
13#include "context.h"
14#include "internal.h"
15#include "legacy.h"
16#include "xstate.h"
17
18/*
19 * The xstateregs_active() routine is the same as the regset_fpregs_active() routine,
20 * as the "regset->n" for the xstate regset will be updated based on the feature
21 * capabilities supported by the xsave.
22 */
23int regset_fpregs_active(struct task_struct *target, const struct user_regset *regset)
24{
25 return regset->n;
26}
27
28int regset_xregset_fpregs_active(struct task_struct *target, const struct user_regset *regset)
29{
30 if (boot_cpu_has(X86_FEATURE_FXSR))
31 return regset->n;
32 else
33 return 0;
34}
35
36/*
37 * The regset get() functions are invoked from:
38 *
39 * - coredump to dump the current task's fpstate. If the current task
40 * owns the FPU then the memory state has to be synchronized and the
41 * FPU register state preserved. Otherwise fpstate is already in sync.
42 *
43 * - ptrace to dump fpstate of a stopped task, in which case the registers
44 * have already been saved to fpstate on context switch.
45 */
46static void sync_fpstate(struct fpu *fpu)
47{
48 if (fpu == ¤t->thread.fpu)
49 fpu_sync_fpstate(fpu);
50}
51
52/*
53 * Invalidate cached FPU registers before modifying the stopped target
54 * task's fpstate.
55 *
56 * This forces the target task on resume to restore the FPU registers from
57 * modified fpstate. Otherwise the task might skip the restore and operate
58 * with the cached FPU registers which discards the modifications.
59 */
60static void fpu_force_restore(struct fpu *fpu)
61{
62 /*
63 * Only stopped child tasks can be used to modify the FPU
64 * state in the fpstate buffer:
65 */
66 WARN_ON_FPU(fpu == ¤t->thread.fpu);
67
68 __fpu_invalidate_fpregs_state(fpu);
69}
70
71int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
72 struct membuf to)
73{
74 struct fpu *fpu = &target->thread.fpu;
75
76 if (!cpu_feature_enabled(X86_FEATURE_FXSR))
77 return -ENODEV;
78
79 sync_fpstate(fpu);
80
81 if (!use_xsave()) {
82 return membuf_write(&to, &fpu->fpstate->regs.fxsave,
83 sizeof(fpu->fpstate->regs.fxsave));
84 }
85
86 copy_xstate_to_uabi_buf(to, target, XSTATE_COPY_FX);
87 return 0;
88}
89
90int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
91 unsigned int pos, unsigned int count,
92 const void *kbuf, const void __user *ubuf)
93{
94 struct fpu *fpu = &target->thread.fpu;
95 struct fxregs_state newstate;
96 int ret;
97
98 if (!cpu_feature_enabled(X86_FEATURE_FXSR))
99 return -ENODEV;
100
101 /* No funny business with partial or oversized writes is permitted. */
102 if (pos != 0 || count != sizeof(newstate))
103 return -EINVAL;
104
105 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &newstate, 0, -1);
106 if (ret)
107 return ret;
108
109 /* Do not allow an invalid MXCSR value. */
110 if (newstate.mxcsr & ~mxcsr_feature_mask)
111 return -EINVAL;
112
113 fpu_force_restore(fpu);
114
115 /* Copy the state */
116 memcpy(&fpu->fpstate->regs.fxsave, &newstate, sizeof(newstate));
117
118 /* Clear xmm8..15 for 32-bit callers */
119 BUILD_BUG_ON(sizeof(fpu->__fpstate.regs.fxsave.xmm_space) != 16 * 16);
120 if (in_ia32_syscall())
121 memset(&fpu->fpstate->regs.fxsave.xmm_space[8*4], 0, 8 * 16);
122
123 /* Mark FP and SSE as in use when XSAVE is enabled */
124 if (use_xsave())
125 fpu->fpstate->regs.xsave.header.xfeatures |= XFEATURE_MASK_FPSSE;
126
127 return 0;
128}
129
130int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
131 struct membuf to)
132{
133 if (!cpu_feature_enabled(X86_FEATURE_XSAVE))
134 return -ENODEV;
135
136 sync_fpstate(&target->thread.fpu);
137
138 copy_xstate_to_uabi_buf(to, target, XSTATE_COPY_XSAVE);
139 return 0;
140}
141
142int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
143 unsigned int pos, unsigned int count,
144 const void *kbuf, const void __user *ubuf)
145{
146 struct fpu *fpu = &target->thread.fpu;
147 struct xregs_state *tmpbuf = NULL;
148 int ret;
149
150 if (!cpu_feature_enabled(X86_FEATURE_XSAVE))
151 return -ENODEV;
152
153 /*
154 * A whole standard-format XSAVE buffer is needed:
155 */
156 if (pos != 0 || count != fpu_user_cfg.max_size)
157 return -EFAULT;
158
159 if (!kbuf) {
160 tmpbuf = vmalloc(count);
161 if (!tmpbuf)
162 return -ENOMEM;
163
164 if (copy_from_user(tmpbuf, ubuf, count)) {
165 ret = -EFAULT;
166 goto out;
167 }
168 }
169
170 fpu_force_restore(fpu);
171 ret = copy_uabi_from_kernel_to_xstate(fpu->fpstate, kbuf ?: tmpbuf, &target->thread.pkru);
172
173out:
174 vfree(tmpbuf);
175 return ret;
176}
177
178#ifdef CONFIG_X86_USER_SHADOW_STACK
179int ssp_active(struct task_struct *target, const struct user_regset *regset)
180{
181 if (target->thread.features & ARCH_SHSTK_SHSTK)
182 return regset->n;
183
184 return 0;
185}
186
187int ssp_get(struct task_struct *target, const struct user_regset *regset,
188 struct membuf to)
189{
190 struct fpu *fpu = &target->thread.fpu;
191 struct cet_user_state *cetregs;
192
193 if (!cpu_feature_enabled(X86_FEATURE_USER_SHSTK) ||
194 !ssp_active(target, regset))
195 return -ENODEV;
196
197 sync_fpstate(fpu);
198 cetregs = get_xsave_addr(&fpu->fpstate->regs.xsave, XFEATURE_CET_USER);
199 if (WARN_ON(!cetregs)) {
200 /*
201 * This shouldn't ever be NULL because shadow stack was
202 * verified to be enabled above. This means
203 * MSR_IA32_U_CET.CET_SHSTK_EN should be 1 and so
204 * XFEATURE_CET_USER should not be in the init state.
205 */
206 return -ENODEV;
207 }
208
209 return membuf_write(&to, (unsigned long *)&cetregs->user_ssp,
210 sizeof(cetregs->user_ssp));
211}
212
213int ssp_set(struct task_struct *target, const struct user_regset *regset,
214 unsigned int pos, unsigned int count,
215 const void *kbuf, const void __user *ubuf)
216{
217 struct fpu *fpu = &target->thread.fpu;
218 struct xregs_state *xsave = &fpu->fpstate->regs.xsave;
219 struct cet_user_state *cetregs;
220 unsigned long user_ssp;
221 int r;
222
223 if (!cpu_feature_enabled(X86_FEATURE_USER_SHSTK) ||
224 !ssp_active(target, regset))
225 return -ENODEV;
226
227 if (pos != 0 || count != sizeof(user_ssp))
228 return -EINVAL;
229
230 r = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &user_ssp, 0, -1);
231 if (r)
232 return r;
233
234 /*
235 * Some kernel instructions (IRET, etc) can cause exceptions in the case
236 * of disallowed CET register values. Just prevent invalid values.
237 */
238 if (user_ssp >= TASK_SIZE_MAX || !IS_ALIGNED(user_ssp, 8))
239 return -EINVAL;
240
241 fpu_force_restore(fpu);
242
243 cetregs = get_xsave_addr(xsave, XFEATURE_CET_USER);
244 if (WARN_ON(!cetregs)) {
245 /*
246 * This shouldn't ever be NULL because shadow stack was
247 * verified to be enabled above. This means
248 * MSR_IA32_U_CET.CET_SHSTK_EN should be 1 and so
249 * XFEATURE_CET_USER should not be in the init state.
250 */
251 return -ENODEV;
252 }
253
254 cetregs->user_ssp = user_ssp;
255 return 0;
256}
257#endif /* CONFIG_X86_USER_SHADOW_STACK */
258
259#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
260
261/*
262 * FPU tag word conversions.
263 */
264
265static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
266{
267 unsigned int tmp; /* to avoid 16 bit prefixes in the code */
268
269 /* Transform each pair of bits into 01 (valid) or 00 (empty) */
270 tmp = ~twd;
271 tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
272 /* and move the valid bits to the lower byte. */
273 tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
274 tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
275 tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
276
277 return tmp;
278}
279
280#define FPREG_ADDR(f, n) ((void *)&(f)->st_space + (n) * 16)
281#define FP_EXP_TAG_VALID 0
282#define FP_EXP_TAG_ZERO 1
283#define FP_EXP_TAG_SPECIAL 2
284#define FP_EXP_TAG_EMPTY 3
285
286static inline u32 twd_fxsr_to_i387(struct fxregs_state *fxsave)
287{
288 struct _fpxreg *st;
289 u32 tos = (fxsave->swd >> 11) & 7;
290 u32 twd = (unsigned long) fxsave->twd;
291 u32 tag;
292 u32 ret = 0xffff0000u;
293 int i;
294
295 for (i = 0; i < 8; i++, twd >>= 1) {
296 if (twd & 0x1) {
297 st = FPREG_ADDR(fxsave, (i - tos) & 7);
298
299 switch (st->exponent & 0x7fff) {
300 case 0x7fff:
301 tag = FP_EXP_TAG_SPECIAL;
302 break;
303 case 0x0000:
304 if (!st->significand[0] &&
305 !st->significand[1] &&
306 !st->significand[2] &&
307 !st->significand[3])
308 tag = FP_EXP_TAG_ZERO;
309 else
310 tag = FP_EXP_TAG_SPECIAL;
311 break;
312 default:
313 if (st->significand[3] & 0x8000)
314 tag = FP_EXP_TAG_VALID;
315 else
316 tag = FP_EXP_TAG_SPECIAL;
317 break;
318 }
319 } else {
320 tag = FP_EXP_TAG_EMPTY;
321 }
322 ret |= tag << (2 * i);
323 }
324 return ret;
325}
326
327/*
328 * FXSR floating point environment conversions.
329 */
330
331static void __convert_from_fxsr(struct user_i387_ia32_struct *env,
332 struct task_struct *tsk,
333 struct fxregs_state *fxsave)
334{
335 struct _fpreg *to = (struct _fpreg *) &env->st_space[0];
336 struct _fpxreg *from = (struct _fpxreg *) &fxsave->st_space[0];
337 int i;
338
339 env->cwd = fxsave->cwd | 0xffff0000u;
340 env->swd = fxsave->swd | 0xffff0000u;
341 env->twd = twd_fxsr_to_i387(fxsave);
342
343#ifdef CONFIG_X86_64
344 env->fip = fxsave->rip;
345 env->foo = fxsave->rdp;
346 /*
347 * should be actually ds/cs at fpu exception time, but
348 * that information is not available in 64bit mode.
349 */
350 env->fcs = task_pt_regs(tsk)->cs;
351 if (tsk == current) {
352 savesegment(ds, env->fos);
353 } else {
354 env->fos = tsk->thread.ds;
355 }
356 env->fos |= 0xffff0000;
357#else
358 env->fip = fxsave->fip;
359 env->fcs = (u16) fxsave->fcs | ((u32) fxsave->fop << 16);
360 env->foo = fxsave->foo;
361 env->fos = fxsave->fos;
362#endif
363
364 for (i = 0; i < 8; ++i)
365 memcpy(&to[i], &from[i], sizeof(to[0]));
366}
367
368void
369convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk)
370{
371 __convert_from_fxsr(env, tsk, &tsk->thread.fpu.fpstate->regs.fxsave);
372}
373
374void convert_to_fxsr(struct fxregs_state *fxsave,
375 const struct user_i387_ia32_struct *env)
376
377{
378 struct _fpreg *from = (struct _fpreg *) &env->st_space[0];
379 struct _fpxreg *to = (struct _fpxreg *) &fxsave->st_space[0];
380 int i;
381
382 fxsave->cwd = env->cwd;
383 fxsave->swd = env->swd;
384 fxsave->twd = twd_i387_to_fxsr(env->twd);
385 fxsave->fop = (u16) ((u32) env->fcs >> 16);
386#ifdef CONFIG_X86_64
387 fxsave->rip = env->fip;
388 fxsave->rdp = env->foo;
389 /* cs and ds ignored */
390#else
391 fxsave->fip = env->fip;
392 fxsave->fcs = (env->fcs & 0xffff);
393 fxsave->foo = env->foo;
394 fxsave->fos = env->fos;
395#endif
396
397 for (i = 0; i < 8; ++i)
398 memcpy(&to[i], &from[i], sizeof(from[0]));
399}
400
401int fpregs_get(struct task_struct *target, const struct user_regset *regset,
402 struct membuf to)
403{
404 struct fpu *fpu = &target->thread.fpu;
405 struct user_i387_ia32_struct env;
406 struct fxregs_state fxsave, *fx;
407
408 sync_fpstate(fpu);
409
410 if (!cpu_feature_enabled(X86_FEATURE_FPU))
411 return fpregs_soft_get(target, regset, to);
412
413 if (!cpu_feature_enabled(X86_FEATURE_FXSR)) {
414 return membuf_write(&to, &fpu->fpstate->regs.fsave,
415 sizeof(struct fregs_state));
416 }
417
418 if (use_xsave()) {
419 struct membuf mb = { .p = &fxsave, .left = sizeof(fxsave) };
420
421 /* Handle init state optimized xstate correctly */
422 copy_xstate_to_uabi_buf(mb, target, XSTATE_COPY_FP);
423 fx = &fxsave;
424 } else {
425 fx = &fpu->fpstate->regs.fxsave;
426 }
427
428 __convert_from_fxsr(&env, target, fx);
429 return membuf_write(&to, &env, sizeof(env));
430}
431
432int fpregs_set(struct task_struct *target, const struct user_regset *regset,
433 unsigned int pos, unsigned int count,
434 const void *kbuf, const void __user *ubuf)
435{
436 struct fpu *fpu = &target->thread.fpu;
437 struct user_i387_ia32_struct env;
438 int ret;
439
440 /* No funny business with partial or oversized writes is permitted. */
441 if (pos != 0 || count != sizeof(struct user_i387_ia32_struct))
442 return -EINVAL;
443
444 if (!cpu_feature_enabled(X86_FEATURE_FPU))
445 return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
446
447 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &env, 0, -1);
448 if (ret)
449 return ret;
450
451 fpu_force_restore(fpu);
452
453 if (cpu_feature_enabled(X86_FEATURE_FXSR))
454 convert_to_fxsr(&fpu->fpstate->regs.fxsave, &env);
455 else
456 memcpy(&fpu->fpstate->regs.fsave, &env, sizeof(env));
457
458 /*
459 * Update the header bit in the xsave header, indicating the
460 * presence of FP.
461 */
462 if (cpu_feature_enabled(X86_FEATURE_XSAVE))
463 fpu->fpstate->regs.xsave.header.xfeatures |= XFEATURE_MASK_FP;
464
465 return 0;
466}
467
468#endif /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */