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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// 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#include <linux/pagemap.h>
9
10#include <asm/fpu/internal.h>
11#include <asm/fpu/signal.h>
12#include <asm/fpu/regset.h>
13#include <asm/fpu/xstate.h>
14
15#include <asm/sigframe.h>
16#include <asm/trace/fpu.h>
17
18static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;
19
20/*
21 * Check for the presence of extended state information in the
22 * user fpstate pointer in the sigcontext.
23 */
24static inline int check_for_xstate(struct fxregs_state __user *buf,
25 void __user *fpstate,
26 struct _fpx_sw_bytes *fx_sw)
27{
28 int min_xstate_size = sizeof(struct fxregs_state) +
29 sizeof(struct xstate_header);
30 unsigned int magic2;
31
32 if (__copy_from_user(fx_sw, &buf->sw_reserved[0], sizeof(*fx_sw)))
33 return -1;
34
35 /* Check for the first magic field and other error scenarios. */
36 if (fx_sw->magic1 != FP_XSTATE_MAGIC1 ||
37 fx_sw->xstate_size < min_xstate_size ||
38 fx_sw->xstate_size > fpu_user_xstate_size ||
39 fx_sw->xstate_size > fx_sw->extended_size)
40 return -1;
41
42 /*
43 * Check for the presence of second magic word at the end of memory
44 * layout. This detects the case where the user just copied the legacy
45 * fpstate layout with out copying the extended state information
46 * in the memory layout.
47 */
48 if (__get_user(magic2, (__u32 __user *)(fpstate + fx_sw->xstate_size))
49 || magic2 != FP_XSTATE_MAGIC2)
50 return -1;
51
52 return 0;
53}
54
55/*
56 * Signal frame handlers.
57 */
58static inline int save_fsave_header(struct task_struct *tsk, void __user *buf)
59{
60 if (use_fxsr()) {
61 struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
62 struct user_i387_ia32_struct env;
63 struct _fpstate_32 __user *fp = buf;
64
65 fpregs_lock();
66 if (!test_thread_flag(TIF_NEED_FPU_LOAD))
67 copy_fxregs_to_kernel(&tsk->thread.fpu);
68 fpregs_unlock();
69
70 convert_from_fxsr(&env, tsk);
71
72 if (__copy_to_user(buf, &env, sizeof(env)) ||
73 __put_user(xsave->i387.swd, &fp->status) ||
74 __put_user(X86_FXSR_MAGIC, &fp->magic))
75 return -1;
76 } else {
77 struct fregs_state __user *fp = buf;
78 u32 swd;
79 if (__get_user(swd, &fp->swd) || __put_user(swd, &fp->status))
80 return -1;
81 }
82
83 return 0;
84}
85
86static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
87{
88 struct xregs_state __user *x = buf;
89 struct _fpx_sw_bytes *sw_bytes;
90 u32 xfeatures;
91 int err;
92
93 /* Setup the bytes not touched by the [f]xsave and reserved for SW. */
94 sw_bytes = ia32_frame ? &fx_sw_reserved_ia32 : &fx_sw_reserved;
95 err = __copy_to_user(&x->i387.sw_reserved, sw_bytes, sizeof(*sw_bytes));
96
97 if (!use_xsave())
98 return err;
99
100 err |= __put_user(FP_XSTATE_MAGIC2,
101 (__u32 __user *)(buf + fpu_user_xstate_size));
102
103 /*
104 * Read the xfeatures which we copied (directly from the cpu or
105 * from the state in task struct) to the user buffers.
106 */
107 err |= __get_user(xfeatures, (__u32 __user *)&x->header.xfeatures);
108
109 /*
110 * For legacy compatible, we always set FP/SSE bits in the bit
111 * vector while saving the state to the user context. This will
112 * enable us capturing any changes(during sigreturn) to
113 * the FP/SSE bits by the legacy applications which don't touch
114 * xfeatures in the xsave header.
115 *
116 * xsave aware apps can change the xfeatures in the xsave
117 * header as well as change any contents in the memory layout.
118 * xrestore as part of sigreturn will capture all the changes.
119 */
120 xfeatures |= XFEATURE_MASK_FPSSE;
121
122 err |= __put_user(xfeatures, (__u32 __user *)&x->header.xfeatures);
123
124 return err;
125}
126
127static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf)
128{
129 int err;
130
131 if (use_xsave())
132 err = copy_xregs_to_user(buf);
133 else if (use_fxsr())
134 err = copy_fxregs_to_user((struct fxregs_state __user *) buf);
135 else
136 err = copy_fregs_to_user((struct fregs_state __user *) buf);
137
138 if (unlikely(err) && __clear_user(buf, fpu_user_xstate_size))
139 err = -EFAULT;
140 return err;
141}
142
143/*
144 * Save the fpu, extended register state to the user signal frame.
145 *
146 * 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
147 * state is copied.
148 * 'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
149 *
150 * buf == buf_fx for 64-bit frames and 32-bit fsave frame.
151 * buf != buf_fx for 32-bit frames with fxstate.
152 *
153 * Try to save it directly to the user frame with disabled page fault handler.
154 * If this fails then do the slow path where the FPU state is first saved to
155 * task's fpu->state and then copy it to the user frame pointed to by the
156 * aligned pointer 'buf_fx'.
157 *
158 * If this is a 32-bit frame with fxstate, put a fsave header before
159 * the aligned state at 'buf_fx'.
160 *
161 * For [f]xsave state, update the SW reserved fields in the [f]xsave frame
162 * indicating the absence/presence of the extended state to the user.
163 */
164int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
165{
166 struct task_struct *tsk = current;
167 int ia32_fxstate = (buf != buf_fx);
168 int ret;
169
170 ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
171 IS_ENABLED(CONFIG_IA32_EMULATION));
172
173 if (!static_cpu_has(X86_FEATURE_FPU)) {
174 struct user_i387_ia32_struct fp;
175 fpregs_soft_get(current, NULL, (struct membuf){.p = &fp,
176 .left = sizeof(fp)});
177 return copy_to_user(buf, &fp, sizeof(fp)) ? -EFAULT : 0;
178 }
179
180 if (!access_ok(buf, size))
181 return -EACCES;
182retry:
183 /*
184 * Load the FPU registers if they are not valid for the current task.
185 * With a valid FPU state we can attempt to save the state directly to
186 * userland's stack frame which will likely succeed. If it does not,
187 * resolve the fault in the user memory and try again.
188 */
189 fpregs_lock();
190 if (test_thread_flag(TIF_NEED_FPU_LOAD))
191 __fpregs_load_activate();
192
193 pagefault_disable();
194 ret = copy_fpregs_to_sigframe(buf_fx);
195 pagefault_enable();
196 fpregs_unlock();
197
198 if (ret) {
199 if (!fault_in_pages_writeable(buf_fx, fpu_user_xstate_size))
200 goto retry;
201 return -EFAULT;
202 }
203
204 /* Save the fsave header for the 32-bit frames. */
205 if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
206 return -1;
207
208 if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
209 return -1;
210
211 return 0;
212}
213
214static inline void
215sanitize_restored_user_xstate(union fpregs_state *state,
216 struct user_i387_ia32_struct *ia32_env,
217 u64 user_xfeatures, int fx_only)
218{
219 struct xregs_state *xsave = &state->xsave;
220 struct xstate_header *header = &xsave->header;
221
222 if (use_xsave()) {
223 /*
224 * Note: we don't need to zero the reserved bits in the
225 * xstate_header here because we either didn't copy them at all,
226 * or we checked earlier that they aren't set.
227 */
228
229 /*
230 * 'user_xfeatures' might have bits clear which are
231 * set in header->xfeatures. This represents features that
232 * were in init state prior to a signal delivery, and need
233 * to be reset back to the init state. Clear any user
234 * feature bits which are set in the kernel buffer to get
235 * them back to the init state.
236 *
237 * Supervisor state is unchanged by input from userspace.
238 * Ensure supervisor state bits stay set and supervisor
239 * state is not modified.
240 */
241 if (fx_only)
242 header->xfeatures = XFEATURE_MASK_FPSSE;
243 else
244 header->xfeatures &= user_xfeatures |
245 xfeatures_mask_supervisor();
246 }
247
248 if (use_fxsr()) {
249 /*
250 * mscsr reserved bits must be masked to zero for security
251 * reasons.
252 */
253 xsave->i387.mxcsr &= mxcsr_feature_mask;
254
255 if (ia32_env)
256 convert_to_fxsr(&state->fxsave, ia32_env);
257 }
258}
259
260/*
261 * Restore the extended state if present. Otherwise, restore the FP/SSE state.
262 */
263static int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only)
264{
265 u64 init_bv;
266 int r;
267
268 if (use_xsave()) {
269 if (fx_only) {
270 init_bv = xfeatures_mask_user() & ~XFEATURE_MASK_FPSSE;
271
272 r = copy_user_to_fxregs(buf);
273 if (!r)
274 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
275 return r;
276 } else {
277 init_bv = xfeatures_mask_user() & ~xbv;
278
279 r = copy_user_to_xregs(buf, xbv);
280 if (!r && unlikely(init_bv))
281 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
282 return r;
283 }
284 } else if (use_fxsr()) {
285 return copy_user_to_fxregs(buf);
286 } else
287 return copy_user_to_fregs(buf);
288}
289
290static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
291{
292 struct user_i387_ia32_struct *envp = NULL;
293 int state_size = fpu_kernel_xstate_size;
294 int ia32_fxstate = (buf != buf_fx);
295 struct task_struct *tsk = current;
296 struct fpu *fpu = &tsk->thread.fpu;
297 struct user_i387_ia32_struct env;
298 u64 user_xfeatures = 0;
299 int fx_only = 0;
300 int ret = 0;
301
302 ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
303 IS_ENABLED(CONFIG_IA32_EMULATION));
304
305 if (!buf) {
306 fpu__clear_user_states(fpu);
307 return 0;
308 }
309
310 if (!access_ok(buf, size))
311 return -EACCES;
312
313 if (!static_cpu_has(X86_FEATURE_FPU))
314 return fpregs_soft_set(current, NULL,
315 0, sizeof(struct user_i387_ia32_struct),
316 NULL, buf) != 0;
317
318 if (use_xsave()) {
319 struct _fpx_sw_bytes fx_sw_user;
320 if (unlikely(check_for_xstate(buf_fx, buf_fx, &fx_sw_user))) {
321 /*
322 * Couldn't find the extended state information in the
323 * memory layout. Restore just the FP/SSE and init all
324 * the other extended state.
325 */
326 state_size = sizeof(struct fxregs_state);
327 fx_only = 1;
328 trace_x86_fpu_xstate_check_failed(fpu);
329 } else {
330 state_size = fx_sw_user.xstate_size;
331 user_xfeatures = fx_sw_user.xfeatures;
332 }
333 }
334
335 if ((unsigned long)buf_fx % 64)
336 fx_only = 1;
337
338 if (!ia32_fxstate) {
339 /*
340 * Attempt to restore the FPU registers directly from user
341 * memory. For that to succeed, the user access cannot cause
342 * page faults. If it does, fall back to the slow path below,
343 * going through the kernel buffer with the enabled pagefault
344 * handler.
345 */
346 fpregs_lock();
347 pagefault_disable();
348 ret = copy_user_to_fpregs_zeroing(buf_fx, user_xfeatures, fx_only);
349 pagefault_enable();
350 if (!ret) {
351
352 /*
353 * Restore supervisor states: previous context switch
354 * etc has done XSAVES and saved the supervisor states
355 * in the kernel buffer from which they can be restored
356 * now.
357 *
358 * We cannot do a single XRSTORS here - which would
359 * be nice - because the rest of the FPU registers are
360 * being restored from a user buffer directly. The
361 * single XRSTORS happens below, when the user buffer
362 * has been copied to the kernel one.
363 */
364 if (test_thread_flag(TIF_NEED_FPU_LOAD) &&
365 xfeatures_mask_supervisor())
366 copy_kernel_to_xregs(&fpu->state.xsave,
367 xfeatures_mask_supervisor());
368 fpregs_mark_activate();
369 fpregs_unlock();
370 return 0;
371 }
372 fpregs_unlock();
373 } else {
374 /*
375 * For 32-bit frames with fxstate, copy the fxstate so it can
376 * be reconstructed later.
377 */
378 ret = __copy_from_user(&env, buf, sizeof(env));
379 if (ret)
380 goto err_out;
381 envp = &env;
382 }
383
384 /*
385 * By setting TIF_NEED_FPU_LOAD it is ensured that our xstate is
386 * not modified on context switch and that the xstate is considered
387 * to be loaded again on return to userland (overriding last_cpu avoids
388 * the optimisation).
389 */
390 fpregs_lock();
391
392 if (!test_thread_flag(TIF_NEED_FPU_LOAD)) {
393
394 /*
395 * Supervisor states are not modified by user space input. Save
396 * current supervisor states first and invalidate the FPU regs.
397 */
398 if (xfeatures_mask_supervisor())
399 copy_supervisor_to_kernel(&fpu->state.xsave);
400 set_thread_flag(TIF_NEED_FPU_LOAD);
401 }
402 __fpu_invalidate_fpregs_state(fpu);
403 fpregs_unlock();
404
405 if (use_xsave() && !fx_only) {
406 u64 init_bv = xfeatures_mask_user() & ~user_xfeatures;
407
408 if (using_compacted_format()) {
409 ret = copy_user_to_xstate(&fpu->state.xsave, buf_fx);
410 } else {
411 ret = __copy_from_user(&fpu->state.xsave, buf_fx, state_size);
412
413 if (!ret && state_size > offsetof(struct xregs_state, header))
414 ret = validate_user_xstate_header(&fpu->state.xsave.header);
415 }
416 if (ret)
417 goto err_out;
418
419 sanitize_restored_user_xstate(&fpu->state, envp, user_xfeatures,
420 fx_only);
421
422 fpregs_lock();
423 if (unlikely(init_bv))
424 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
425
426 /*
427 * Restore previously saved supervisor xstates along with
428 * copied-in user xstates.
429 */
430 ret = copy_kernel_to_xregs_err(&fpu->state.xsave,
431 user_xfeatures | xfeatures_mask_supervisor());
432
433 } else if (use_fxsr()) {
434 ret = __copy_from_user(&fpu->state.fxsave, buf_fx, state_size);
435 if (ret) {
436 ret = -EFAULT;
437 goto err_out;
438 }
439
440 sanitize_restored_user_xstate(&fpu->state, envp, user_xfeatures,
441 fx_only);
442
443 fpregs_lock();
444 if (use_xsave()) {
445 u64 init_bv;
446
447 init_bv = xfeatures_mask_user() & ~XFEATURE_MASK_FPSSE;
448 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
449 }
450
451 ret = copy_kernel_to_fxregs_err(&fpu->state.fxsave);
452 } else {
453 ret = __copy_from_user(&fpu->state.fsave, buf_fx, state_size);
454 if (ret)
455 goto err_out;
456
457 fpregs_lock();
458 ret = copy_kernel_to_fregs_err(&fpu->state.fsave);
459 }
460 if (!ret)
461 fpregs_mark_activate();
462 else
463 fpregs_deactivate(fpu);
464 fpregs_unlock();
465
466err_out:
467 if (ret)
468 fpu__clear_user_states(fpu);
469 return ret;
470}
471
472static inline int xstate_sigframe_size(void)
473{
474 return use_xsave() ? fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE :
475 fpu_user_xstate_size;
476}
477
478/*
479 * Restore FPU state from a sigframe:
480 */
481int fpu__restore_sig(void __user *buf, int ia32_frame)
482{
483 void __user *buf_fx = buf;
484 int size = xstate_sigframe_size();
485
486 if (ia32_frame && use_fxsr()) {
487 buf_fx = buf + sizeof(struct fregs_state);
488 size += sizeof(struct fregs_state);
489 }
490
491 return __fpu__restore_sig(buf, buf_fx, size);
492}
493
494unsigned long
495fpu__alloc_mathframe(unsigned long sp, int ia32_frame,
496 unsigned long *buf_fx, unsigned long *size)
497{
498 unsigned long frame_size = xstate_sigframe_size();
499
500 *buf_fx = sp = round_down(sp - frame_size, 64);
501 if (ia32_frame && use_fxsr()) {
502 frame_size += sizeof(struct fregs_state);
503 sp -= sizeof(struct fregs_state);
504 }
505
506 *size = frame_size;
507
508 return sp;
509}
510/*
511 * Prepare the SW reserved portion of the fxsave memory layout, indicating
512 * the presence of the extended state information in the memory layout
513 * pointed by the fpstate pointer in the sigcontext.
514 * This will be saved when ever the FP and extended state context is
515 * saved on the user stack during the signal handler delivery to the user.
516 */
517void fpu__init_prepare_fx_sw_frame(void)
518{
519 int size = fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE;
520
521 fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
522 fx_sw_reserved.extended_size = size;
523 fx_sw_reserved.xfeatures = xfeatures_mask_user();
524 fx_sw_reserved.xstate_size = fpu_user_xstate_size;
525
526 if (IS_ENABLED(CONFIG_IA32_EMULATION) ||
527 IS_ENABLED(CONFIG_X86_32)) {
528 int fsave_header_size = sizeof(struct fregs_state);
529
530 fx_sw_reserved_ia32 = fx_sw_reserved;
531 fx_sw_reserved_ia32.extended_size = size + fsave_header_size;
532 }
533}
534