Commit | Line | Data |
---|---|---|
dc1e35c6 SS |
1 | /* |
2 | * xsave/xrstor support. | |
3 | * | |
4 | * Author: Suresh Siddha <suresh.b.siddha@intel.com> | |
5 | */ | |
c767a54b JP |
6 | |
7 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
8 | ||
dc1e35c6 SS |
9 | #include <linux/bootmem.h> |
10 | #include <linux/compat.h> | |
11 | #include <asm/i387.h> | |
1361b83a | 12 | #include <asm/fpu-internal.h> |
c37b5efe SS |
13 | #ifdef CONFIG_IA32_EMULATION |
14 | #include <asm/sigcontext32.h> | |
15 | #endif | |
6152e4b1 | 16 | #include <asm/xcr.h> |
dc1e35c6 SS |
17 | |
18 | /* | |
19 | * Supported feature mask by the CPU and the kernel. | |
20 | */ | |
6152e4b1 | 21 | u64 pcntxt_mask; |
dc1e35c6 | 22 | |
45c2d7f4 RR |
23 | /* |
24 | * Represents init state for the supported extended state. | |
25 | */ | |
26 | static struct xsave_struct *init_xstate_buf; | |
27 | ||
c37b5efe SS |
28 | struct _fpx_sw_bytes fx_sw_reserved; |
29 | #ifdef CONFIG_IA32_EMULATION | |
30 | struct _fpx_sw_bytes fx_sw_reserved_ia32; | |
31 | #endif | |
32 | ||
a1488f8b SS |
33 | static unsigned int *xstate_offsets, *xstate_sizes, xstate_features; |
34 | ||
29104e10 SS |
35 | /* |
36 | * If a processor implementation discern that a processor state component is | |
37 | * in its initialized state it may modify the corresponding bit in the | |
38 | * xsave_hdr.xstate_bv as '0', with out modifying the corresponding memory | |
39 | * layout in the case of xsaveopt. While presenting the xstate information to | |
40 | * the user, we always ensure that the memory layout of a feature will be in | |
41 | * the init state if the corresponding header bit is zero. This is to ensure | |
42 | * that the user doesn't see some stale state in the memory layout during | |
43 | * signal handling, debugging etc. | |
44 | */ | |
45 | void __sanitize_i387_state(struct task_struct *tsk) | |
46 | { | |
47 | u64 xstate_bv; | |
48 | int feature_bit = 0x2; | |
49 | struct i387_fxsave_struct *fx = &tsk->thread.fpu.state->fxsave; | |
50 | ||
51 | if (!fx) | |
52 | return; | |
53 | ||
29104e10 SS |
54 | xstate_bv = tsk->thread.fpu.state->xsave.xsave_hdr.xstate_bv; |
55 | ||
56 | /* | |
57 | * None of the feature bits are in init state. So nothing else | |
0d2eb44f | 58 | * to do for us, as the memory layout is up to date. |
29104e10 SS |
59 | */ |
60 | if ((xstate_bv & pcntxt_mask) == pcntxt_mask) | |
61 | return; | |
62 | ||
63 | /* | |
64 | * FP is in init state | |
65 | */ | |
66 | if (!(xstate_bv & XSTATE_FP)) { | |
67 | fx->cwd = 0x37f; | |
68 | fx->swd = 0; | |
69 | fx->twd = 0; | |
70 | fx->fop = 0; | |
71 | fx->rip = 0; | |
72 | fx->rdp = 0; | |
73 | memset(&fx->st_space[0], 0, 128); | |
74 | } | |
75 | ||
76 | /* | |
77 | * SSE is in init state | |
78 | */ | |
79 | if (!(xstate_bv & XSTATE_SSE)) | |
80 | memset(&fx->xmm_space[0], 0, 256); | |
81 | ||
82 | xstate_bv = (pcntxt_mask & ~xstate_bv) >> 2; | |
83 | ||
84 | /* | |
85 | * Update all the other memory layouts for which the corresponding | |
86 | * header bit is in the init state. | |
87 | */ | |
88 | while (xstate_bv) { | |
89 | if (xstate_bv & 0x1) { | |
90 | int offset = xstate_offsets[feature_bit]; | |
91 | int size = xstate_sizes[feature_bit]; | |
92 | ||
93 | memcpy(((void *) fx) + offset, | |
94 | ((void *) init_xstate_buf) + offset, | |
95 | size); | |
96 | } | |
97 | ||
98 | xstate_bv >>= 1; | |
99 | feature_bit++; | |
100 | } | |
101 | } | |
102 | ||
c37b5efe SS |
103 | /* |
104 | * Check for the presence of extended state information in the | |
105 | * user fpstate pointer in the sigcontext. | |
106 | */ | |
107 | int check_for_xstate(struct i387_fxsave_struct __user *buf, | |
108 | void __user *fpstate, | |
109 | struct _fpx_sw_bytes *fx_sw_user) | |
110 | { | |
111 | int min_xstate_size = sizeof(struct i387_fxsave_struct) + | |
112 | sizeof(struct xsave_hdr_struct); | |
113 | unsigned int magic2; | |
114 | int err; | |
115 | ||
116 | err = __copy_from_user(fx_sw_user, &buf->sw_reserved[0], | |
117 | sizeof(struct _fpx_sw_bytes)); | |
c37b5efe | 118 | if (err) |
d6d4d420 | 119 | return -EFAULT; |
c37b5efe SS |
120 | |
121 | /* | |
122 | * First Magic check failed. | |
123 | */ | |
124 | if (fx_sw_user->magic1 != FP_XSTATE_MAGIC1) | |
d6d4d420 | 125 | return -EINVAL; |
c37b5efe SS |
126 | |
127 | /* | |
128 | * Check for error scenarios. | |
129 | */ | |
130 | if (fx_sw_user->xstate_size < min_xstate_size || | |
131 | fx_sw_user->xstate_size > xstate_size || | |
132 | fx_sw_user->xstate_size > fx_sw_user->extended_size) | |
d6d4d420 | 133 | return -EINVAL; |
c37b5efe SS |
134 | |
135 | err = __get_user(magic2, (__u32 *) (((void *)fpstate) + | |
136 | fx_sw_user->extended_size - | |
137 | FP_XSTATE_MAGIC2_SIZE)); | |
d6d4d420 DC |
138 | if (err) |
139 | return err; | |
c37b5efe SS |
140 | /* |
141 | * Check for the presence of second magic word at the end of memory | |
142 | * layout. This detects the case where the user just copied the legacy | |
143 | * fpstate layout with out copying the extended state information | |
144 | * in the memory layout. | |
145 | */ | |
d6d4d420 DC |
146 | if (magic2 != FP_XSTATE_MAGIC2) |
147 | return -EFAULT; | |
c37b5efe SS |
148 | |
149 | return 0; | |
150 | } | |
151 | ||
ab513701 SS |
152 | #ifdef CONFIG_X86_64 |
153 | /* | |
154 | * Signal frame handlers. | |
155 | */ | |
156 | ||
157 | int save_i387_xstate(void __user *buf) | |
158 | { | |
159 | struct task_struct *tsk = current; | |
160 | int err = 0; | |
161 | ||
162 | if (!access_ok(VERIFY_WRITE, buf, sig_xstate_size)) | |
163 | return -EACCES; | |
164 | ||
f65bc214 | 165 | BUG_ON(sig_xstate_size < xstate_size); |
ab513701 | 166 | |
c37b5efe | 167 | if ((unsigned long)buf % 64) |
c767a54b | 168 | pr_err("%s: bad fpstate %p\n", __func__, buf); |
ab513701 SS |
169 | |
170 | if (!used_math()) | |
171 | return 0; | |
06c38d5e | 172 | |
15d8791c | 173 | if (user_has_fpu()) { |
c9ad4882 | 174 | if (use_xsave()) |
c37b5efe SS |
175 | err = xsave_user(buf); |
176 | else | |
177 | err = fxsave_user(buf); | |
178 | ||
ab513701 SS |
179 | if (err) |
180 | return err; | |
15d8791c | 181 | user_fpu_end(); |
ab513701 | 182 | } else { |
29104e10 | 183 | sanitize_i387_state(tsk); |
86603283 | 184 | if (__copy_to_user(buf, &tsk->thread.fpu.state->fxsave, |
ab513701 SS |
185 | xstate_size)) |
186 | return -1; | |
187 | } | |
c37b5efe | 188 | |
06c38d5e SS |
189 | clear_used_math(); /* trigger finit */ |
190 | ||
c9ad4882 | 191 | if (use_xsave()) { |
c37b5efe | 192 | struct _fpstate __user *fx = buf; |
04944b79 SS |
193 | struct _xstate __user *x = buf; |
194 | u64 xstate_bv; | |
c37b5efe SS |
195 | |
196 | err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved, | |
197 | sizeof(struct _fpx_sw_bytes)); | |
198 | ||
199 | err |= __put_user(FP_XSTATE_MAGIC2, | |
200 | (__u32 __user *) (buf + sig_xstate_size | |
201 | - FP_XSTATE_MAGIC2_SIZE)); | |
04944b79 SS |
202 | |
203 | /* | |
204 | * Read the xstate_bv which we copied (directly from the cpu or | |
205 | * from the state in task struct) to the user buffers and | |
206 | * set the FP/SSE bits. | |
207 | */ | |
208 | err |= __get_user(xstate_bv, &x->xstate_hdr.xstate_bv); | |
209 | ||
210 | /* | |
211 | * For legacy compatible, we always set FP/SSE bits in the bit | |
212 | * vector while saving the state to the user context. This will | |
213 | * enable us capturing any changes(during sigreturn) to | |
214 | * the FP/SSE bits by the legacy applications which don't touch | |
215 | * xstate_bv in the xsave header. | |
216 | * | |
217 | * xsave aware apps can change the xstate_bv in the xsave | |
218 | * header as well as change any contents in the memory layout. | |
219 | * xrestore as part of sigreturn will capture all the changes. | |
220 | */ | |
221 | xstate_bv |= XSTATE_FPSSE; | |
222 | ||
223 | err |= __put_user(xstate_bv, &x->xstate_hdr.xstate_bv); | |
224 | ||
f364eada SS |
225 | if (err) |
226 | return err; | |
c37b5efe SS |
227 | } |
228 | ||
ab513701 SS |
229 | return 1; |
230 | } | |
231 | ||
c37b5efe SS |
232 | /* |
233 | * Restore the extended state if present. Otherwise, restore the FP/SSE | |
234 | * state. | |
235 | */ | |
7820b756 | 236 | static int restore_user_xstate(void __user *buf) |
c37b5efe SS |
237 | { |
238 | struct _fpx_sw_bytes fx_sw_user; | |
6152e4b1 | 239 | u64 mask; |
c37b5efe SS |
240 | int err; |
241 | ||
242 | if (((unsigned long)buf % 64) || | |
243 | check_for_xstate(buf, buf, &fx_sw_user)) | |
244 | goto fx_only; | |
245 | ||
6152e4b1 | 246 | mask = fx_sw_user.xstate_bv; |
c37b5efe SS |
247 | |
248 | /* | |
249 | * restore the state passed by the user. | |
250 | */ | |
6152e4b1 | 251 | err = xrestore_user(buf, mask); |
c37b5efe SS |
252 | if (err) |
253 | return err; | |
254 | ||
255 | /* | |
256 | * init the state skipped by the user. | |
257 | */ | |
6152e4b1 | 258 | mask = pcntxt_mask & ~mask; |
8e221b6d SS |
259 | if (unlikely(mask)) |
260 | xrstor_state(init_xstate_buf, mask); | |
c37b5efe SS |
261 | |
262 | return 0; | |
263 | ||
264 | fx_only: | |
265 | /* | |
266 | * couldn't find the extended state information in the | |
267 | * memory layout. Restore just the FP/SSE and init all | |
268 | * the other extended state. | |
269 | */ | |
6152e4b1 | 270 | xrstor_state(init_xstate_buf, pcntxt_mask & ~XSTATE_FPSSE); |
c37b5efe SS |
271 | return fxrstor_checking((__force struct i387_fxsave_struct *)buf); |
272 | } | |
273 | ||
ab513701 SS |
274 | /* |
275 | * This restores directly out of user space. Exceptions are handled. | |
276 | */ | |
277 | int restore_i387_xstate(void __user *buf) | |
278 | { | |
279 | struct task_struct *tsk = current; | |
c37b5efe | 280 | int err = 0; |
ab513701 SS |
281 | |
282 | if (!buf) { | |
c37b5efe SS |
283 | if (used_math()) |
284 | goto clear; | |
ab513701 SS |
285 | return 0; |
286 | } else | |
287 | if (!access_ok(VERIFY_READ, buf, sig_xstate_size)) | |
288 | return -EACCES; | |
289 | ||
290 | if (!used_math()) { | |
291 | err = init_fpu(tsk); | |
292 | if (err) | |
293 | return err; | |
294 | } | |
295 | ||
15d8791c | 296 | user_fpu_begin(); |
c9ad4882 | 297 | if (use_xsave()) |
c37b5efe SS |
298 | err = restore_user_xstate(buf); |
299 | else | |
300 | err = fxrstor_checking((__force struct i387_fxsave_struct *) | |
301 | buf); | |
ab513701 SS |
302 | if (unlikely(err)) { |
303 | /* | |
304 | * Encountered an error while doing the restore from the | |
305 | * user buffer, clear the fpu state. | |
306 | */ | |
c37b5efe | 307 | clear: |
ab513701 SS |
308 | clear_fpu(tsk); |
309 | clear_used_math(); | |
310 | } | |
311 | return err; | |
312 | } | |
313 | #endif | |
314 | ||
c37b5efe SS |
315 | /* |
316 | * Prepare the SW reserved portion of the fxsave memory layout, indicating | |
317 | * the presence of the extended state information in the memory layout | |
318 | * pointed by the fpstate pointer in the sigcontext. | |
319 | * This will be saved when ever the FP and extended state context is | |
320 | * saved on the user stack during the signal handler delivery to the user. | |
321 | */ | |
8bcad30f | 322 | static void prepare_fx_sw_frame(void) |
c37b5efe SS |
323 | { |
324 | int size_extended = (xstate_size - sizeof(struct i387_fxsave_struct)) + | |
325 | FP_XSTATE_MAGIC2_SIZE; | |
326 | ||
327 | sig_xstate_size = sizeof(struct _fpstate) + size_extended; | |
328 | ||
329 | #ifdef CONFIG_IA32_EMULATION | |
330 | sig_xstate_ia32_size = sizeof(struct _fpstate_ia32) + size_extended; | |
331 | #endif | |
332 | ||
333 | memset(&fx_sw_reserved, 0, sizeof(fx_sw_reserved)); | |
334 | ||
335 | fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1; | |
336 | fx_sw_reserved.extended_size = sig_xstate_size; | |
6152e4b1 | 337 | fx_sw_reserved.xstate_bv = pcntxt_mask; |
c37b5efe SS |
338 | fx_sw_reserved.xstate_size = xstate_size; |
339 | #ifdef CONFIG_IA32_EMULATION | |
340 | memcpy(&fx_sw_reserved_ia32, &fx_sw_reserved, | |
341 | sizeof(struct _fpx_sw_bytes)); | |
342 | fx_sw_reserved_ia32.extended_size = sig_xstate_ia32_size; | |
343 | #endif | |
344 | } | |
345 | ||
3c1c7f10 SS |
346 | #ifdef CONFIG_X86_64 |
347 | unsigned int sig_xstate_size = sizeof(struct _fpstate); | |
348 | #endif | |
349 | ||
dc1e35c6 SS |
350 | /* |
351 | * Enable the extended processor state save/restore feature | |
352 | */ | |
1cff92d8 | 353 | static inline void xstate_enable(void) |
dc1e35c6 | 354 | { |
dc1e35c6 | 355 | set_in_cr4(X86_CR4_OSXSAVE); |
6152e4b1 | 356 | xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask); |
dc1e35c6 SS |
357 | } |
358 | ||
a1488f8b SS |
359 | /* |
360 | * Record the offsets and sizes of different state managed by the xsave | |
361 | * memory layout. | |
362 | */ | |
4995b9db | 363 | static void __init setup_xstate_features(void) |
a1488f8b SS |
364 | { |
365 | int eax, ebx, ecx, edx, leaf = 0x2; | |
366 | ||
367 | xstate_features = fls64(pcntxt_mask); | |
368 | xstate_offsets = alloc_bootmem(xstate_features * sizeof(int)); | |
369 | xstate_sizes = alloc_bootmem(xstate_features * sizeof(int)); | |
370 | ||
371 | do { | |
ee813d53 | 372 | cpuid_count(XSTATE_CPUID, leaf, &eax, &ebx, &ecx, &edx); |
a1488f8b SS |
373 | |
374 | if (eax == 0) | |
375 | break; | |
376 | ||
377 | xstate_offsets[leaf] = ebx; | |
378 | xstate_sizes[leaf] = eax; | |
379 | ||
380 | leaf++; | |
381 | } while (1); | |
382 | } | |
383 | ||
dc1e35c6 SS |
384 | /* |
385 | * setup the xstate image representing the init state | |
386 | */ | |
a19aac85 | 387 | static void __init setup_xstate_init(void) |
dc1e35c6 | 388 | { |
29104e10 SS |
389 | setup_xstate_features(); |
390 | ||
391 | /* | |
392 | * Setup init_xstate_buf to represent the init state of | |
393 | * all the features managed by the xsave | |
394 | */ | |
10340ae1 SS |
395 | init_xstate_buf = alloc_bootmem_align(xstate_size, |
396 | __alignof__(struct xsave_struct)); | |
dc1e35c6 | 397 | init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT; |
a1488f8b | 398 | |
29104e10 SS |
399 | clts(); |
400 | /* | |
401 | * Init all the features state with header_bv being 0x0 | |
402 | */ | |
403 | xrstor_state(init_xstate_buf, -1); | |
404 | /* | |
405 | * Dump the init state again. This is to identify the init state | |
406 | * of any feature which is not represented by all zero's. | |
407 | */ | |
408 | xsave_state(init_xstate_buf, -1); | |
409 | stts(); | |
dc1e35c6 SS |
410 | } |
411 | ||
412 | /* | |
413 | * Enable and initialize the xsave feature. | |
414 | */ | |
1cff92d8 | 415 | static void __init xstate_enable_boot_cpu(void) |
dc1e35c6 SS |
416 | { |
417 | unsigned int eax, ebx, ecx, edx; | |
418 | ||
ee813d53 RR |
419 | if (boot_cpu_data.cpuid_level < XSTATE_CPUID) { |
420 | WARN(1, KERN_ERR "XSTATE_CPUID missing\n"); | |
421 | return; | |
422 | } | |
423 | ||
424 | cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); | |
6152e4b1 | 425 | pcntxt_mask = eax + ((u64)edx << 32); |
dc1e35c6 | 426 | |
6152e4b1 | 427 | if ((pcntxt_mask & XSTATE_FPSSE) != XSTATE_FPSSE) { |
c767a54b | 428 | pr_err("FP/SSE not shown under xsave features 0x%llx\n", |
6152e4b1 | 429 | pcntxt_mask); |
dc1e35c6 SS |
430 | BUG(); |
431 | } | |
432 | ||
433 | /* | |
a30469e7 | 434 | * Support only the state known to OS. |
dc1e35c6 | 435 | */ |
6152e4b1 | 436 | pcntxt_mask = pcntxt_mask & XCNTXT_MASK; |
97e80a70 | 437 | |
1cff92d8 | 438 | xstate_enable(); |
dc1e35c6 SS |
439 | |
440 | /* | |
441 | * Recompute the context size for enabled features | |
442 | */ | |
ee813d53 | 443 | cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); |
dc1e35c6 SS |
444 | xstate_size = ebx; |
445 | ||
5b3efd50 | 446 | update_regset_xstate_info(xstate_size, pcntxt_mask); |
c37b5efe SS |
447 | prepare_fx_sw_frame(); |
448 | ||
dc1e35c6 SS |
449 | setup_xstate_init(); |
450 | ||
c767a54b JP |
451 | pr_info("enabled xstate_bv 0x%llx, cntxt size 0x%x\n", |
452 | pcntxt_mask, xstate_size); | |
dc1e35c6 | 453 | } |
82d4150c | 454 | |
1cff92d8 PA |
455 | /* |
456 | * For the very first instance, this calls xstate_enable_boot_cpu(); | |
457 | * for all subsequent instances, this calls xstate_enable(). | |
458 | * | |
459 | * This is somewhat obfuscated due to the lack of powerful enough | |
460 | * overrides for the section checks. | |
461 | */ | |
82d4150c RR |
462 | void __cpuinit xsave_init(void) |
463 | { | |
1cff92d8 PA |
464 | static __refdata void (*next_func)(void) = xstate_enable_boot_cpu; |
465 | void (*this_func)(void); | |
466 | ||
0e49bf66 RR |
467 | if (!cpu_has_xsave) |
468 | return; | |
469 | ||
1cff92d8 PA |
470 | this_func = next_func; |
471 | next_func = xstate_enable; | |
472 | this_func(); | |
82d4150c | 473 | } |