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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * FPU signal frame handling routines.
4 */
5
6#include <linux/compat.h>
7#include <linux/cpu.h>
8
9#include <asm/fpu/internal.h>
10#include <asm/fpu/signal.h>
11#include <asm/fpu/regset.h>
12#include <asm/fpu/xstate.h>
13
14#include <asm/sigframe.h>
15#include <asm/trace/fpu.h>
16
17static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;
18
19/*
20 * Check for the presence of extended state information in the
21 * user fpstate pointer in the sigcontext.
22 */
23static inline int check_for_xstate(struct fxregs_state __user *buf,
24 void __user *fpstate,
25 struct _fpx_sw_bytes *fx_sw)
26{
27 int min_xstate_size = sizeof(struct fxregs_state) +
28 sizeof(struct xstate_header);
29 unsigned int magic2;
30
31 if (__copy_from_user(fx_sw, &buf->sw_reserved[0], sizeof(*fx_sw)))
32 return -1;
33
34 /* Check for the first magic field and other error scenarios. */
35 if (fx_sw->magic1 != FP_XSTATE_MAGIC1 ||
36 fx_sw->xstate_size < min_xstate_size ||
37 fx_sw->xstate_size > fpu_user_xstate_size ||
38 fx_sw->xstate_size > fx_sw->extended_size)
39 return -1;
40
41 /*
42 * Check for the presence of second magic word at the end of memory
43 * layout. This detects the case where the user just copied the legacy
44 * fpstate layout with out copying the extended state information
45 * in the memory layout.
46 */
47 if (__get_user(magic2, (__u32 __user *)(fpstate + fx_sw->xstate_size))
48 || magic2 != FP_XSTATE_MAGIC2)
49 return -1;
50
51 return 0;
52}
53
54/*
55 * Signal frame handlers.
56 */
57static inline int save_fsave_header(struct task_struct *tsk, void __user *buf)
58{
59 if (use_fxsr()) {
60 struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
61 struct user_i387_ia32_struct env;
62 struct _fpstate_32 __user *fp = buf;
63
64 convert_from_fxsr(&env, tsk);
65
66 if (__copy_to_user(buf, &env, sizeof(env)) ||
67 __put_user(xsave->i387.swd, &fp->status) ||
68 __put_user(X86_FXSR_MAGIC, &fp->magic))
69 return -1;
70 } else {
71 struct fregs_state __user *fp = buf;
72 u32 swd;
73 if (__get_user(swd, &fp->swd) || __put_user(swd, &fp->status))
74 return -1;
75 }
76
77 return 0;
78}
79
80static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
81{
82 struct xregs_state __user *x = buf;
83 struct _fpx_sw_bytes *sw_bytes;
84 u32 xfeatures;
85 int err;
86
87 /* Setup the bytes not touched by the [f]xsave and reserved for SW. */
88 sw_bytes = ia32_frame ? &fx_sw_reserved_ia32 : &fx_sw_reserved;
89 err = __copy_to_user(&x->i387.sw_reserved, sw_bytes, sizeof(*sw_bytes));
90
91 if (!use_xsave())
92 return err;
93
94 err |= __put_user(FP_XSTATE_MAGIC2,
95 (__u32 *)(buf + fpu_user_xstate_size));
96
97 /*
98 * Read the xfeatures which we copied (directly from the cpu or
99 * from the state in task struct) to the user buffers.
100 */
101 err |= __get_user(xfeatures, (__u32 *)&x->header.xfeatures);
102
103 /*
104 * For legacy compatible, we always set FP/SSE bits in the bit
105 * vector while saving the state to the user context. This will
106 * enable us capturing any changes(during sigreturn) to
107 * the FP/SSE bits by the legacy applications which don't touch
108 * xfeatures in the xsave header.
109 *
110 * xsave aware apps can change the xfeatures in the xsave
111 * header as well as change any contents in the memory layout.
112 * xrestore as part of sigreturn will capture all the changes.
113 */
114 xfeatures |= XFEATURE_MASK_FPSSE;
115
116 err |= __put_user(xfeatures, (__u32 *)&x->header.xfeatures);
117
118 return err;
119}
120
121static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf)
122{
123 int err;
124
125 if (use_xsave())
126 err = copy_xregs_to_user(buf);
127 else if (use_fxsr())
128 err = copy_fxregs_to_user((struct fxregs_state __user *) buf);
129 else
130 err = copy_fregs_to_user((struct fregs_state __user *) buf);
131
132 if (unlikely(err) && __clear_user(buf, fpu_user_xstate_size))
133 err = -EFAULT;
134 return err;
135}
136
137/*
138 * Save the fpu, extended register state to the user signal frame.
139 *
140 * 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
141 * state is copied.
142 * 'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
143 *
144 * buf == buf_fx for 64-bit frames and 32-bit fsave frame.
145 * buf != buf_fx for 32-bit frames with fxstate.
146 *
147 * If the fpu, extended register state is live, save the state directly
148 * to the user frame pointed by the aligned pointer 'buf_fx'. Otherwise,
149 * copy the thread's fpu state to the user frame starting at 'buf_fx'.
150 *
151 * If this is a 32-bit frame with fxstate, put a fsave header before
152 * the aligned state at 'buf_fx'.
153 *
154 * For [f]xsave state, update the SW reserved fields in the [f]xsave frame
155 * indicating the absence/presence of the extended state to the user.
156 */
157int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
158{
159 struct fpu *fpu = ¤t->thread.fpu;
160 struct xregs_state *xsave = &fpu->state.xsave;
161 struct task_struct *tsk = current;
162 int ia32_fxstate = (buf != buf_fx);
163
164 ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
165 IS_ENABLED(CONFIG_IA32_EMULATION));
166
167 if (!access_ok(VERIFY_WRITE, buf, size))
168 return -EACCES;
169
170 if (!static_cpu_has(X86_FEATURE_FPU))
171 return fpregs_soft_get(current, NULL, 0,
172 sizeof(struct user_i387_ia32_struct), NULL,
173 (struct _fpstate_32 __user *) buf) ? -1 : 1;
174
175 if (fpu->initialized || using_compacted_format()) {
176 /* Save the live register state to the user directly. */
177 if (copy_fpregs_to_sigframe(buf_fx))
178 return -1;
179 /* Update the thread's fxstate to save the fsave header. */
180 if (ia32_fxstate)
181 copy_fxregs_to_kernel(fpu);
182 } else {
183 /*
184 * It is a *bug* if kernel uses compacted-format for xsave
185 * area and we copy it out directly to a signal frame. It
186 * should have been handled above by saving the registers
187 * directly.
188 */
189 if (boot_cpu_has(X86_FEATURE_XSAVES)) {
190 WARN_ONCE(1, "x86/fpu: saving compacted-format xsave area to a signal frame!\n");
191 return -1;
192 }
193
194 fpstate_sanitize_xstate(fpu);
195 if (__copy_to_user(buf_fx, xsave, fpu_user_xstate_size))
196 return -1;
197 }
198
199 /* Save the fsave header for the 32-bit frames. */
200 if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
201 return -1;
202
203 if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
204 return -1;
205
206 return 0;
207}
208
209static inline void
210sanitize_restored_xstate(struct task_struct *tsk,
211 struct user_i387_ia32_struct *ia32_env,
212 u64 xfeatures, int fx_only)
213{
214 struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
215 struct xstate_header *header = &xsave->header;
216
217 if (use_xsave()) {
218 /*
219 * Note: we don't need to zero the reserved bits in the
220 * xstate_header here because we either didn't copy them at all,
221 * or we checked earlier that they aren't set.
222 */
223
224 /*
225 * Init the state that is not present in the memory
226 * layout and not enabled by the OS.
227 */
228 if (fx_only)
229 header->xfeatures = XFEATURE_MASK_FPSSE;
230 else
231 header->xfeatures &= xfeatures;
232 }
233
234 if (use_fxsr()) {
235 /*
236 * mscsr reserved bits must be masked to zero for security
237 * reasons.
238 */
239 xsave->i387.mxcsr &= mxcsr_feature_mask;
240
241 convert_to_fxsr(tsk, ia32_env);
242 }
243}
244
245/*
246 * Restore the extended state if present. Otherwise, restore the FP/SSE state.
247 */
248static inline int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only)
249{
250 if (use_xsave()) {
251 if ((unsigned long)buf % 64 || fx_only) {
252 u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE;
253 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
254 return copy_user_to_fxregs(buf);
255 } else {
256 u64 init_bv = xfeatures_mask & ~xbv;
257 if (unlikely(init_bv))
258 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
259 return copy_user_to_xregs(buf, xbv);
260 }
261 } else if (use_fxsr()) {
262 return copy_user_to_fxregs(buf);
263 } else
264 return copy_user_to_fregs(buf);
265}
266
267static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
268{
269 int ia32_fxstate = (buf != buf_fx);
270 struct task_struct *tsk = current;
271 struct fpu *fpu = &tsk->thread.fpu;
272 int state_size = fpu_kernel_xstate_size;
273 u64 xfeatures = 0;
274 int fx_only = 0;
275
276 ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
277 IS_ENABLED(CONFIG_IA32_EMULATION));
278
279 if (!buf) {
280 fpu__clear(fpu);
281 return 0;
282 }
283
284 if (!access_ok(VERIFY_READ, buf, size))
285 return -EACCES;
286
287 fpu__initialize(fpu);
288
289 if (!static_cpu_has(X86_FEATURE_FPU))
290 return fpregs_soft_set(current, NULL,
291 0, sizeof(struct user_i387_ia32_struct),
292 NULL, buf) != 0;
293
294 if (use_xsave()) {
295 struct _fpx_sw_bytes fx_sw_user;
296 if (unlikely(check_for_xstate(buf_fx, buf_fx, &fx_sw_user))) {
297 /*
298 * Couldn't find the extended state information in the
299 * memory layout. Restore just the FP/SSE and init all
300 * the other extended state.
301 */
302 state_size = sizeof(struct fxregs_state);
303 fx_only = 1;
304 trace_x86_fpu_xstate_check_failed(fpu);
305 } else {
306 state_size = fx_sw_user.xstate_size;
307 xfeatures = fx_sw_user.xfeatures;
308 }
309 }
310
311 if (ia32_fxstate) {
312 /*
313 * For 32-bit frames with fxstate, copy the user state to the
314 * thread's fpu state, reconstruct fxstate from the fsave
315 * header. Validate and sanitize the copied state.
316 */
317 struct fpu *fpu = &tsk->thread.fpu;
318 struct user_i387_ia32_struct env;
319 int err = 0;
320
321 /*
322 * Drop the current fpu which clears fpu->initialized. This ensures
323 * that any context-switch during the copy of the new state,
324 * avoids the intermediate state from getting restored/saved.
325 * Thus avoiding the new restored state from getting corrupted.
326 * We will be ready to restore/save the state only after
327 * fpu->initialized is again set.
328 */
329 fpu__drop(fpu);
330
331 if (using_compacted_format()) {
332 err = copy_user_to_xstate(&fpu->state.xsave, buf_fx);
333 } else {
334 err = __copy_from_user(&fpu->state.xsave, buf_fx, state_size);
335
336 if (!err && state_size > offsetof(struct xregs_state, header))
337 err = validate_xstate_header(&fpu->state.xsave.header);
338 }
339
340 if (err || __copy_from_user(&env, buf, sizeof(env))) {
341 fpstate_init(&fpu->state);
342 trace_x86_fpu_init_state(fpu);
343 err = -1;
344 } else {
345 sanitize_restored_xstate(tsk, &env, xfeatures, fx_only);
346 }
347
348 fpu->initialized = 1;
349 preempt_disable();
350 fpu__restore(fpu);
351 preempt_enable();
352
353 return err;
354 } else {
355 /*
356 * For 64-bit frames and 32-bit fsave frames, restore the user
357 * state to the registers directly (with exceptions handled).
358 */
359 user_fpu_begin();
360 if (copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only)) {
361 fpu__clear(fpu);
362 return -1;
363 }
364 }
365
366 return 0;
367}
368
369static inline int xstate_sigframe_size(void)
370{
371 return use_xsave() ? fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE :
372 fpu_user_xstate_size;
373}
374
375/*
376 * Restore FPU state from a sigframe:
377 */
378int fpu__restore_sig(void __user *buf, int ia32_frame)
379{
380 void __user *buf_fx = buf;
381 int size = xstate_sigframe_size();
382
383 if (ia32_frame && use_fxsr()) {
384 buf_fx = buf + sizeof(struct fregs_state);
385 size += sizeof(struct fregs_state);
386 }
387
388 return __fpu__restore_sig(buf, buf_fx, size);
389}
390
391unsigned long
392fpu__alloc_mathframe(unsigned long sp, int ia32_frame,
393 unsigned long *buf_fx, unsigned long *size)
394{
395 unsigned long frame_size = xstate_sigframe_size();
396
397 *buf_fx = sp = round_down(sp - frame_size, 64);
398 if (ia32_frame && use_fxsr()) {
399 frame_size += sizeof(struct fregs_state);
400 sp -= sizeof(struct fregs_state);
401 }
402
403 *size = frame_size;
404
405 return sp;
406}
407/*
408 * Prepare the SW reserved portion of the fxsave memory layout, indicating
409 * the presence of the extended state information in the memory layout
410 * pointed by the fpstate pointer in the sigcontext.
411 * This will be saved when ever the FP and extended state context is
412 * saved on the user stack during the signal handler delivery to the user.
413 */
414void fpu__init_prepare_fx_sw_frame(void)
415{
416 int size = fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE;
417
418 fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
419 fx_sw_reserved.extended_size = size;
420 fx_sw_reserved.xfeatures = xfeatures_mask;
421 fx_sw_reserved.xstate_size = fpu_user_xstate_size;
422
423 if (IS_ENABLED(CONFIG_IA32_EMULATION) ||
424 IS_ENABLED(CONFIG_X86_32)) {
425 int fsave_header_size = sizeof(struct fregs_state);
426
427 fx_sw_reserved_ia32 = fx_sw_reserved;
428 fx_sw_reserved_ia32.extended_size = size + fsave_header_size;
429 }
430}
431
1/*
2 * FPU signal frame handling routines.
3 */
4
5#include <linux/compat.h>
6#include <linux/cpu.h>
7
8#include <asm/fpu/internal.h>
9#include <asm/fpu/signal.h>
10#include <asm/fpu/regset.h>
11#include <asm/fpu/xstate.h>
12
13#include <asm/sigframe.h>
14#include <asm/trace/fpu.h>
15
16static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;
17
18/*
19 * Check for the presence of extended state information in the
20 * user fpstate pointer in the sigcontext.
21 */
22static inline int check_for_xstate(struct fxregs_state __user *buf,
23 void __user *fpstate,
24 struct _fpx_sw_bytes *fx_sw)
25{
26 int min_xstate_size = sizeof(struct fxregs_state) +
27 sizeof(struct xstate_header);
28 unsigned int magic2;
29
30 if (__copy_from_user(fx_sw, &buf->sw_reserved[0], sizeof(*fx_sw)))
31 return -1;
32
33 /* Check for the first magic field and other error scenarios. */
34 if (fx_sw->magic1 != FP_XSTATE_MAGIC1 ||
35 fx_sw->xstate_size < min_xstate_size ||
36 fx_sw->xstate_size > fpu_user_xstate_size ||
37 fx_sw->xstate_size > fx_sw->extended_size)
38 return -1;
39
40 /*
41 * Check for the presence of second magic word at the end of memory
42 * layout. This detects the case where the user just copied the legacy
43 * fpstate layout with out copying the extended state information
44 * in the memory layout.
45 */
46 if (__get_user(magic2, (__u32 __user *)(fpstate + fx_sw->xstate_size))
47 || magic2 != FP_XSTATE_MAGIC2)
48 return -1;
49
50 return 0;
51}
52
53/*
54 * Signal frame handlers.
55 */
56static inline int save_fsave_header(struct task_struct *tsk, void __user *buf)
57{
58 if (use_fxsr()) {
59 struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
60 struct user_i387_ia32_struct env;
61 struct _fpstate_32 __user *fp = buf;
62
63 convert_from_fxsr(&env, tsk);
64
65 if (__copy_to_user(buf, &env, sizeof(env)) ||
66 __put_user(xsave->i387.swd, &fp->status) ||
67 __put_user(X86_FXSR_MAGIC, &fp->magic))
68 return -1;
69 } else {
70 struct fregs_state __user *fp = buf;
71 u32 swd;
72 if (__get_user(swd, &fp->swd) || __put_user(swd, &fp->status))
73 return -1;
74 }
75
76 return 0;
77}
78
79static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
80{
81 struct xregs_state __user *x = buf;
82 struct _fpx_sw_bytes *sw_bytes;
83 u32 xfeatures;
84 int err;
85
86 /* Setup the bytes not touched by the [f]xsave and reserved for SW. */
87 sw_bytes = ia32_frame ? &fx_sw_reserved_ia32 : &fx_sw_reserved;
88 err = __copy_to_user(&x->i387.sw_reserved, sw_bytes, sizeof(*sw_bytes));
89
90 if (!use_xsave())
91 return err;
92
93 err |= __put_user(FP_XSTATE_MAGIC2,
94 (__u32 *)(buf + fpu_user_xstate_size));
95
96 /*
97 * Read the xfeatures which we copied (directly from the cpu or
98 * from the state in task struct) to the user buffers.
99 */
100 err |= __get_user(xfeatures, (__u32 *)&x->header.xfeatures);
101
102 /*
103 * For legacy compatible, we always set FP/SSE bits in the bit
104 * vector while saving the state to the user context. This will
105 * enable us capturing any changes(during sigreturn) to
106 * the FP/SSE bits by the legacy applications which don't touch
107 * xfeatures in the xsave header.
108 *
109 * xsave aware apps can change the xfeatures in the xsave
110 * header as well as change any contents in the memory layout.
111 * xrestore as part of sigreturn will capture all the changes.
112 */
113 xfeatures |= XFEATURE_MASK_FPSSE;
114
115 err |= __put_user(xfeatures, (__u32 *)&x->header.xfeatures);
116
117 return err;
118}
119
120static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf)
121{
122 int err;
123
124 if (use_xsave())
125 err = copy_xregs_to_user(buf);
126 else if (use_fxsr())
127 err = copy_fxregs_to_user((struct fxregs_state __user *) buf);
128 else
129 err = copy_fregs_to_user((struct fregs_state __user *) buf);
130
131 if (unlikely(err) && __clear_user(buf, fpu_user_xstate_size))
132 err = -EFAULT;
133 return err;
134}
135
136/*
137 * Save the fpu, extended register state to the user signal frame.
138 *
139 * 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
140 * state is copied.
141 * 'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
142 *
143 * buf == buf_fx for 64-bit frames and 32-bit fsave frame.
144 * buf != buf_fx for 32-bit frames with fxstate.
145 *
146 * If the fpu, extended register state is live, save the state directly
147 * to the user frame pointed by the aligned pointer 'buf_fx'. Otherwise,
148 * copy the thread's fpu state to the user frame starting at 'buf_fx'.
149 *
150 * If this is a 32-bit frame with fxstate, put a fsave header before
151 * the aligned state at 'buf_fx'.
152 *
153 * For [f]xsave state, update the SW reserved fields in the [f]xsave frame
154 * indicating the absence/presence of the extended state to the user.
155 */
156int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
157{
158 struct xregs_state *xsave = ¤t->thread.fpu.state.xsave;
159 struct task_struct *tsk = current;
160 int ia32_fxstate = (buf != buf_fx);
161
162 ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
163 IS_ENABLED(CONFIG_IA32_EMULATION));
164
165 if (!access_ok(VERIFY_WRITE, buf, size))
166 return -EACCES;
167
168 if (!static_cpu_has(X86_FEATURE_FPU))
169 return fpregs_soft_get(current, NULL, 0,
170 sizeof(struct user_i387_ia32_struct), NULL,
171 (struct _fpstate_32 __user *) buf) ? -1 : 1;
172
173 if (fpregs_active() || using_compacted_format()) {
174 /* Save the live register state to the user directly. */
175 if (copy_fpregs_to_sigframe(buf_fx))
176 return -1;
177 /* Update the thread's fxstate to save the fsave header. */
178 if (ia32_fxstate)
179 copy_fxregs_to_kernel(&tsk->thread.fpu);
180 } else {
181 /*
182 * It is a *bug* if kernel uses compacted-format for xsave
183 * area and we copy it out directly to a signal frame. It
184 * should have been handled above by saving the registers
185 * directly.
186 */
187 if (boot_cpu_has(X86_FEATURE_XSAVES)) {
188 WARN_ONCE(1, "x86/fpu: saving compacted-format xsave area to a signal frame!\n");
189 return -1;
190 }
191
192 fpstate_sanitize_xstate(&tsk->thread.fpu);
193 if (__copy_to_user(buf_fx, xsave, fpu_user_xstate_size))
194 return -1;
195 }
196
197 /* Save the fsave header for the 32-bit frames. */
198 if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
199 return -1;
200
201 if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
202 return -1;
203
204 return 0;
205}
206
207static inline void
208sanitize_restored_xstate(struct task_struct *tsk,
209 struct user_i387_ia32_struct *ia32_env,
210 u64 xfeatures, int fx_only)
211{
212 struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
213 struct xstate_header *header = &xsave->header;
214
215 if (use_xsave()) {
216 /* These bits must be zero. */
217 memset(header->reserved, 0, 48);
218
219 /*
220 * Init the state that is not present in the memory
221 * layout and not enabled by the OS.
222 */
223 if (fx_only)
224 header->xfeatures = XFEATURE_MASK_FPSSE;
225 else
226 header->xfeatures &= (xfeatures_mask & xfeatures);
227 }
228
229 if (use_fxsr()) {
230 /*
231 * mscsr reserved bits must be masked to zero for security
232 * reasons.
233 */
234 xsave->i387.mxcsr &= mxcsr_feature_mask;
235
236 convert_to_fxsr(tsk, ia32_env);
237 }
238}
239
240/*
241 * Restore the extended state if present. Otherwise, restore the FP/SSE state.
242 */
243static inline int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only)
244{
245 if (use_xsave()) {
246 if ((unsigned long)buf % 64 || fx_only) {
247 u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE;
248 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
249 return copy_user_to_fxregs(buf);
250 } else {
251 u64 init_bv = xfeatures_mask & ~xbv;
252 if (unlikely(init_bv))
253 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
254 return copy_user_to_xregs(buf, xbv);
255 }
256 } else if (use_fxsr()) {
257 return copy_user_to_fxregs(buf);
258 } else
259 return copy_user_to_fregs(buf);
260}
261
262static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
263{
264 int ia32_fxstate = (buf != buf_fx);
265 struct task_struct *tsk = current;
266 struct fpu *fpu = &tsk->thread.fpu;
267 int state_size = fpu_kernel_xstate_size;
268 u64 xfeatures = 0;
269 int fx_only = 0;
270
271 ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
272 IS_ENABLED(CONFIG_IA32_EMULATION));
273
274 if (!buf) {
275 fpu__clear(fpu);
276 return 0;
277 }
278
279 if (!access_ok(VERIFY_READ, buf, size))
280 return -EACCES;
281
282 fpu__activate_curr(fpu);
283
284 if (!static_cpu_has(X86_FEATURE_FPU))
285 return fpregs_soft_set(current, NULL,
286 0, sizeof(struct user_i387_ia32_struct),
287 NULL, buf) != 0;
288
289 if (use_xsave()) {
290 struct _fpx_sw_bytes fx_sw_user;
291 if (unlikely(check_for_xstate(buf_fx, buf_fx, &fx_sw_user))) {
292 /*
293 * Couldn't find the extended state information in the
294 * memory layout. Restore just the FP/SSE and init all
295 * the other extended state.
296 */
297 state_size = sizeof(struct fxregs_state);
298 fx_only = 1;
299 trace_x86_fpu_xstate_check_failed(fpu);
300 } else {
301 state_size = fx_sw_user.xstate_size;
302 xfeatures = fx_sw_user.xfeatures;
303 }
304 }
305
306 if (ia32_fxstate) {
307 /*
308 * For 32-bit frames with fxstate, copy the user state to the
309 * thread's fpu state, reconstruct fxstate from the fsave
310 * header. Sanitize the copied state etc.
311 */
312 struct fpu *fpu = &tsk->thread.fpu;
313 struct user_i387_ia32_struct env;
314 int err = 0;
315
316 /*
317 * Drop the current fpu which clears fpu->fpstate_active. This ensures
318 * that any context-switch during the copy of the new state,
319 * avoids the intermediate state from getting restored/saved.
320 * Thus avoiding the new restored state from getting corrupted.
321 * We will be ready to restore/save the state only after
322 * fpu->fpstate_active is again set.
323 */
324 fpu__drop(fpu);
325
326 if (using_compacted_format()) {
327 err = copyin_to_xsaves(NULL, buf_fx,
328 &fpu->state.xsave);
329 } else {
330 err = __copy_from_user(&fpu->state.xsave,
331 buf_fx, state_size);
332 }
333
334 if (err || __copy_from_user(&env, buf, sizeof(env))) {
335 fpstate_init(&fpu->state);
336 trace_x86_fpu_init_state(fpu);
337 err = -1;
338 } else {
339 sanitize_restored_xstate(tsk, &env, xfeatures, fx_only);
340 }
341
342 fpu->fpstate_active = 1;
343 preempt_disable();
344 fpu__restore(fpu);
345 preempt_enable();
346
347 return err;
348 } else {
349 /*
350 * For 64-bit frames and 32-bit fsave frames, restore the user
351 * state to the registers directly (with exceptions handled).
352 */
353 user_fpu_begin();
354 if (copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only)) {
355 fpu__clear(fpu);
356 return -1;
357 }
358 }
359
360 return 0;
361}
362
363static inline int xstate_sigframe_size(void)
364{
365 return use_xsave() ? fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE :
366 fpu_user_xstate_size;
367}
368
369/*
370 * Restore FPU state from a sigframe:
371 */
372int fpu__restore_sig(void __user *buf, int ia32_frame)
373{
374 void __user *buf_fx = buf;
375 int size = xstate_sigframe_size();
376
377 if (ia32_frame && use_fxsr()) {
378 buf_fx = buf + sizeof(struct fregs_state);
379 size += sizeof(struct fregs_state);
380 }
381
382 return __fpu__restore_sig(buf, buf_fx, size);
383}
384
385unsigned long
386fpu__alloc_mathframe(unsigned long sp, int ia32_frame,
387 unsigned long *buf_fx, unsigned long *size)
388{
389 unsigned long frame_size = xstate_sigframe_size();
390
391 *buf_fx = sp = round_down(sp - frame_size, 64);
392 if (ia32_frame && use_fxsr()) {
393 frame_size += sizeof(struct fregs_state);
394 sp -= sizeof(struct fregs_state);
395 }
396
397 *size = frame_size;
398
399 return sp;
400}
401/*
402 * Prepare the SW reserved portion of the fxsave memory layout, indicating
403 * the presence of the extended state information in the memory layout
404 * pointed by the fpstate pointer in the sigcontext.
405 * This will be saved when ever the FP and extended state context is
406 * saved on the user stack during the signal handler delivery to the user.
407 */
408void fpu__init_prepare_fx_sw_frame(void)
409{
410 int size = fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE;
411
412 fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
413 fx_sw_reserved.extended_size = size;
414 fx_sw_reserved.xfeatures = xfeatures_mask;
415 fx_sw_reserved.xstate_size = fpu_user_xstate_size;
416
417 if (IS_ENABLED(CONFIG_IA32_EMULATION) ||
418 IS_ENABLED(CONFIG_X86_32)) {
419 int fsave_header_size = sizeof(struct fregs_state);
420
421 fx_sw_reserved_ia32 = fx_sw_reserved;
422 fx_sw_reserved_ia32.extended_size = size + fsave_header_size;
423 }
424}
425