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1/*
2 * xsave/xrstor support.
3 *
4 * Author: Suresh Siddha <suresh.b.siddha@intel.com>
5 */
6#include <linux/bootmem.h>
7#include <linux/compat.h>
8#include <asm/i387.h>
9#ifdef CONFIG_IA32_EMULATION
10#include <asm/sigcontext32.h>
11#endif
12#include <asm/xcr.h>
13
14/*
15 * Supported feature mask by the CPU and the kernel.
16 */
17u64 pcntxt_mask;
18
19/*
20 * Represents init state for the supported extended state.
21 */
22static struct xsave_struct *init_xstate_buf;
23
24struct _fpx_sw_bytes fx_sw_reserved;
25#ifdef CONFIG_IA32_EMULATION
26struct _fpx_sw_bytes fx_sw_reserved_ia32;
27#endif
28
29static unsigned int *xstate_offsets, *xstate_sizes, xstate_features;
30
31/*
32 * If a processor implementation discern that a processor state component is
33 * in its initialized state it may modify the corresponding bit in the
34 * xsave_hdr.xstate_bv as '0', with out modifying the corresponding memory
35 * layout in the case of xsaveopt. While presenting the xstate information to
36 * the user, we always ensure that the memory layout of a feature will be in
37 * the init state if the corresponding header bit is zero. This is to ensure
38 * that the user doesn't see some stale state in the memory layout during
39 * signal handling, debugging etc.
40 */
41void __sanitize_i387_state(struct task_struct *tsk)
42{
43 u64 xstate_bv;
44 int feature_bit = 0x2;
45 struct i387_fxsave_struct *fx = &tsk->thread.fpu.state->fxsave;
46
47 if (!fx)
48 return;
49
50 BUG_ON(task_thread_info(tsk)->status & TS_USEDFPU);
51
52 xstate_bv = tsk->thread.fpu.state->xsave.xsave_hdr.xstate_bv;
53
54 /*
55 * None of the feature bits are in init state. So nothing else
56 * to do for us, as the memory layout is up to date.
57 */
58 if ((xstate_bv & pcntxt_mask) == pcntxt_mask)
59 return;
60
61 /*
62 * FP is in init state
63 */
64 if (!(xstate_bv & XSTATE_FP)) {
65 fx->cwd = 0x37f;
66 fx->swd = 0;
67 fx->twd = 0;
68 fx->fop = 0;
69 fx->rip = 0;
70 fx->rdp = 0;
71 memset(&fx->st_space[0], 0, 128);
72 }
73
74 /*
75 * SSE is in init state
76 */
77 if (!(xstate_bv & XSTATE_SSE))
78 memset(&fx->xmm_space[0], 0, 256);
79
80 xstate_bv = (pcntxt_mask & ~xstate_bv) >> 2;
81
82 /*
83 * Update all the other memory layouts for which the corresponding
84 * header bit is in the init state.
85 */
86 while (xstate_bv) {
87 if (xstate_bv & 0x1) {
88 int offset = xstate_offsets[feature_bit];
89 int size = xstate_sizes[feature_bit];
90
91 memcpy(((void *) fx) + offset,
92 ((void *) init_xstate_buf) + offset,
93 size);
94 }
95
96 xstate_bv >>= 1;
97 feature_bit++;
98 }
99}
100
101/*
102 * Check for the presence of extended state information in the
103 * user fpstate pointer in the sigcontext.
104 */
105int check_for_xstate(struct i387_fxsave_struct __user *buf,
106 void __user *fpstate,
107 struct _fpx_sw_bytes *fx_sw_user)
108{
109 int min_xstate_size = sizeof(struct i387_fxsave_struct) +
110 sizeof(struct xsave_hdr_struct);
111 unsigned int magic2;
112 int err;
113
114 err = __copy_from_user(fx_sw_user, &buf->sw_reserved[0],
115 sizeof(struct _fpx_sw_bytes));
116 if (err)
117 return -EFAULT;
118
119 /*
120 * First Magic check failed.
121 */
122 if (fx_sw_user->magic1 != FP_XSTATE_MAGIC1)
123 return -EINVAL;
124
125 /*
126 * Check for error scenarios.
127 */
128 if (fx_sw_user->xstate_size < min_xstate_size ||
129 fx_sw_user->xstate_size > xstate_size ||
130 fx_sw_user->xstate_size > fx_sw_user->extended_size)
131 return -EINVAL;
132
133 err = __get_user(magic2, (__u32 *) (((void *)fpstate) +
134 fx_sw_user->extended_size -
135 FP_XSTATE_MAGIC2_SIZE));
136 if (err)
137 return err;
138 /*
139 * Check for the presence of second magic word at the end of memory
140 * layout. This detects the case where the user just copied the legacy
141 * fpstate layout with out copying the extended state information
142 * in the memory layout.
143 */
144 if (magic2 != FP_XSTATE_MAGIC2)
145 return -EFAULT;
146
147 return 0;
148}
149
150#ifdef CONFIG_X86_64
151/*
152 * Signal frame handlers.
153 */
154
155int save_i387_xstate(void __user *buf)
156{
157 struct task_struct *tsk = current;
158 int err = 0;
159
160 if (!access_ok(VERIFY_WRITE, buf, sig_xstate_size))
161 return -EACCES;
162
163 BUG_ON(sig_xstate_size < xstate_size);
164
165 if ((unsigned long)buf % 64)
166 printk("save_i387_xstate: bad fpstate %p\n", buf);
167
168 if (!used_math())
169 return 0;
170
171 if (task_thread_info(tsk)->status & TS_USEDFPU) {
172 if (use_xsave())
173 err = xsave_user(buf);
174 else
175 err = fxsave_user(buf);
176
177 if (err)
178 return err;
179 task_thread_info(tsk)->status &= ~TS_USEDFPU;
180 stts();
181 } else {
182 sanitize_i387_state(tsk);
183 if (__copy_to_user(buf, &tsk->thread.fpu.state->fxsave,
184 xstate_size))
185 return -1;
186 }
187
188 clear_used_math(); /* trigger finit */
189
190 if (use_xsave()) {
191 struct _fpstate __user *fx = buf;
192 struct _xstate __user *x = buf;
193 u64 xstate_bv;
194
195 err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved,
196 sizeof(struct _fpx_sw_bytes));
197
198 err |= __put_user(FP_XSTATE_MAGIC2,
199 (__u32 __user *) (buf + sig_xstate_size
200 - FP_XSTATE_MAGIC2_SIZE));
201
202 /*
203 * Read the xstate_bv which we copied (directly from the cpu or
204 * from the state in task struct) to the user buffers and
205 * set the FP/SSE bits.
206 */
207 err |= __get_user(xstate_bv, &x->xstate_hdr.xstate_bv);
208
209 /*
210 * For legacy compatible, we always set FP/SSE bits in the bit
211 * vector while saving the state to the user context. This will
212 * enable us capturing any changes(during sigreturn) to
213 * the FP/SSE bits by the legacy applications which don't touch
214 * xstate_bv in the xsave header.
215 *
216 * xsave aware apps can change the xstate_bv in the xsave
217 * header as well as change any contents in the memory layout.
218 * xrestore as part of sigreturn will capture all the changes.
219 */
220 xstate_bv |= XSTATE_FPSSE;
221
222 err |= __put_user(xstate_bv, &x->xstate_hdr.xstate_bv);
223
224 if (err)
225 return err;
226 }
227
228 return 1;
229}
230
231/*
232 * Restore the extended state if present. Otherwise, restore the FP/SSE
233 * state.
234 */
235static int restore_user_xstate(void __user *buf)
236{
237 struct _fpx_sw_bytes fx_sw_user;
238 u64 mask;
239 int err;
240
241 if (((unsigned long)buf % 64) ||
242 check_for_xstate(buf, buf, &fx_sw_user))
243 goto fx_only;
244
245 mask = fx_sw_user.xstate_bv;
246
247 /*
248 * restore the state passed by the user.
249 */
250 err = xrestore_user(buf, mask);
251 if (err)
252 return err;
253
254 /*
255 * init the state skipped by the user.
256 */
257 mask = pcntxt_mask & ~mask;
258 if (unlikely(mask))
259 xrstor_state(init_xstate_buf, mask);
260
261 return 0;
262
263fx_only:
264 /*
265 * couldn't find the extended state information in the
266 * memory layout. Restore just the FP/SSE and init all
267 * the other extended state.
268 */
269 xrstor_state(init_xstate_buf, pcntxt_mask & ~XSTATE_FPSSE);
270 return fxrstor_checking((__force struct i387_fxsave_struct *)buf);
271}
272
273/*
274 * This restores directly out of user space. Exceptions are handled.
275 */
276int restore_i387_xstate(void __user *buf)
277{
278 struct task_struct *tsk = current;
279 int err = 0;
280
281 if (!buf) {
282 if (used_math())
283 goto clear;
284 return 0;
285 } else
286 if (!access_ok(VERIFY_READ, buf, sig_xstate_size))
287 return -EACCES;
288
289 if (!used_math()) {
290 err = init_fpu(tsk);
291 if (err)
292 return err;
293 }
294
295 if (!(task_thread_info(current)->status & TS_USEDFPU)) {
296 clts();
297 task_thread_info(current)->status |= TS_USEDFPU;
298 }
299 if (use_xsave())
300 err = restore_user_xstate(buf);
301 else
302 err = fxrstor_checking((__force struct i387_fxsave_struct *)
303 buf);
304 if (unlikely(err)) {
305 /*
306 * Encountered an error while doing the restore from the
307 * user buffer, clear the fpu state.
308 */
309clear:
310 clear_fpu(tsk);
311 clear_used_math();
312 }
313 return err;
314}
315#endif
316
317/*
318 * Prepare the SW reserved portion of the fxsave memory layout, indicating
319 * the presence of the extended state information in the memory layout
320 * pointed by the fpstate pointer in the sigcontext.
321 * This will be saved when ever the FP and extended state context is
322 * saved on the user stack during the signal handler delivery to the user.
323 */
324static void prepare_fx_sw_frame(void)
325{
326 int size_extended = (xstate_size - sizeof(struct i387_fxsave_struct)) +
327 FP_XSTATE_MAGIC2_SIZE;
328
329 sig_xstate_size = sizeof(struct _fpstate) + size_extended;
330
331#ifdef CONFIG_IA32_EMULATION
332 sig_xstate_ia32_size = sizeof(struct _fpstate_ia32) + size_extended;
333#endif
334
335 memset(&fx_sw_reserved, 0, sizeof(fx_sw_reserved));
336
337 fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
338 fx_sw_reserved.extended_size = sig_xstate_size;
339 fx_sw_reserved.xstate_bv = pcntxt_mask;
340 fx_sw_reserved.xstate_size = xstate_size;
341#ifdef CONFIG_IA32_EMULATION
342 memcpy(&fx_sw_reserved_ia32, &fx_sw_reserved,
343 sizeof(struct _fpx_sw_bytes));
344 fx_sw_reserved_ia32.extended_size = sig_xstate_ia32_size;
345#endif
346}
347
348#ifdef CONFIG_X86_64
349unsigned int sig_xstate_size = sizeof(struct _fpstate);
350#endif
351
352/*
353 * Enable the extended processor state save/restore feature
354 */
355static inline void xstate_enable(void)
356{
357 set_in_cr4(X86_CR4_OSXSAVE);
358 xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask);
359}
360
361/*
362 * Record the offsets and sizes of different state managed by the xsave
363 * memory layout.
364 */
365static void __init setup_xstate_features(void)
366{
367 int eax, ebx, ecx, edx, leaf = 0x2;
368
369 xstate_features = fls64(pcntxt_mask);
370 xstate_offsets = alloc_bootmem(xstate_features * sizeof(int));
371 xstate_sizes = alloc_bootmem(xstate_features * sizeof(int));
372
373 do {
374 cpuid_count(XSTATE_CPUID, leaf, &eax, &ebx, &ecx, &edx);
375
376 if (eax == 0)
377 break;
378
379 xstate_offsets[leaf] = ebx;
380 xstate_sizes[leaf] = eax;
381
382 leaf++;
383 } while (1);
384}
385
386/*
387 * setup the xstate image representing the init state
388 */
389static void __init setup_xstate_init(void)
390{
391 setup_xstate_features();
392
393 /*
394 * Setup init_xstate_buf to represent the init state of
395 * all the features managed by the xsave
396 */
397 init_xstate_buf = alloc_bootmem_align(xstate_size,
398 __alignof__(struct xsave_struct));
399 init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT;
400
401 clts();
402 /*
403 * Init all the features state with header_bv being 0x0
404 */
405 xrstor_state(init_xstate_buf, -1);
406 /*
407 * Dump the init state again. This is to identify the init state
408 * of any feature which is not represented by all zero's.
409 */
410 xsave_state(init_xstate_buf, -1);
411 stts();
412}
413
414/*
415 * Enable and initialize the xsave feature.
416 */
417static void __init xstate_enable_boot_cpu(void)
418{
419 unsigned int eax, ebx, ecx, edx;
420
421 if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
422 WARN(1, KERN_ERR "XSTATE_CPUID missing\n");
423 return;
424 }
425
426 cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
427 pcntxt_mask = eax + ((u64)edx << 32);
428
429 if ((pcntxt_mask & XSTATE_FPSSE) != XSTATE_FPSSE) {
430 printk(KERN_ERR "FP/SSE not shown under xsave features 0x%llx\n",
431 pcntxt_mask);
432 BUG();
433 }
434
435 /*
436 * Support only the state known to OS.
437 */
438 pcntxt_mask = pcntxt_mask & XCNTXT_MASK;
439
440 xstate_enable();
441
442 /*
443 * Recompute the context size for enabled features
444 */
445 cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
446 xstate_size = ebx;
447
448 update_regset_xstate_info(xstate_size, pcntxt_mask);
449 prepare_fx_sw_frame();
450
451 setup_xstate_init();
452
453 printk(KERN_INFO "xsave/xrstor: enabled xstate_bv 0x%llx, "
454 "cntxt size 0x%x\n",
455 pcntxt_mask, xstate_size);
456}
457
458/*
459 * For the very first instance, this calls xstate_enable_boot_cpu();
460 * for all subsequent instances, this calls xstate_enable().
461 *
462 * This is somewhat obfuscated due to the lack of powerful enough
463 * overrides for the section checks.
464 */
465void __cpuinit xsave_init(void)
466{
467 static __refdata void (*next_func)(void) = xstate_enable_boot_cpu;
468 void (*this_func)(void);
469
470 if (!cpu_has_xsave)
471 return;
472
473 this_func = next_func;
474 next_func = xstate_enable;
475 this_func();
476}
1/*
2 * xsave/xrstor support.
3 *
4 * Author: Suresh Siddha <suresh.b.siddha@intel.com>
5 */
6
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <linux/bootmem.h>
10#include <linux/compat.h>
11#include <asm/i387.h>
12#include <asm/fpu-internal.h>
13#include <asm/sigframe.h>
14#include <asm/xcr.h>
15
16/*
17 * Supported feature mask by the CPU and the kernel.
18 */
19u64 pcntxt_mask;
20
21/*
22 * Represents init state for the supported extended state.
23 */
24struct xsave_struct *init_xstate_buf;
25
26static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;
27static unsigned int *xstate_offsets, *xstate_sizes, xstate_features;
28
29/*
30 * If a processor implementation discern that a processor state component is
31 * in its initialized state it may modify the corresponding bit in the
32 * xsave_hdr.xstate_bv as '0', with out modifying the corresponding memory
33 * layout in the case of xsaveopt. While presenting the xstate information to
34 * the user, we always ensure that the memory layout of a feature will be in
35 * the init state if the corresponding header bit is zero. This is to ensure
36 * that the user doesn't see some stale state in the memory layout during
37 * signal handling, debugging etc.
38 */
39void __sanitize_i387_state(struct task_struct *tsk)
40{
41 struct i387_fxsave_struct *fx = &tsk->thread.fpu.state->fxsave;
42 int feature_bit = 0x2;
43 u64 xstate_bv;
44
45 if (!fx)
46 return;
47
48 xstate_bv = tsk->thread.fpu.state->xsave.xsave_hdr.xstate_bv;
49
50 /*
51 * None of the feature bits are in init state. So nothing else
52 * to do for us, as the memory layout is up to date.
53 */
54 if ((xstate_bv & pcntxt_mask) == pcntxt_mask)
55 return;
56
57 /*
58 * FP is in init state
59 */
60 if (!(xstate_bv & XSTATE_FP)) {
61 fx->cwd = 0x37f;
62 fx->swd = 0;
63 fx->twd = 0;
64 fx->fop = 0;
65 fx->rip = 0;
66 fx->rdp = 0;
67 memset(&fx->st_space[0], 0, 128);
68 }
69
70 /*
71 * SSE is in init state
72 */
73 if (!(xstate_bv & XSTATE_SSE))
74 memset(&fx->xmm_space[0], 0, 256);
75
76 xstate_bv = (pcntxt_mask & ~xstate_bv) >> 2;
77
78 /*
79 * Update all the other memory layouts for which the corresponding
80 * header bit is in the init state.
81 */
82 while (xstate_bv) {
83 if (xstate_bv & 0x1) {
84 int offset = xstate_offsets[feature_bit];
85 int size = xstate_sizes[feature_bit];
86
87 memcpy(((void *) fx) + offset,
88 ((void *) init_xstate_buf) + offset,
89 size);
90 }
91
92 xstate_bv >>= 1;
93 feature_bit++;
94 }
95}
96
97/*
98 * Check for the presence of extended state information in the
99 * user fpstate pointer in the sigcontext.
100 */
101static inline int check_for_xstate(struct i387_fxsave_struct __user *buf,
102 void __user *fpstate,
103 struct _fpx_sw_bytes *fx_sw)
104{
105 int min_xstate_size = sizeof(struct i387_fxsave_struct) +
106 sizeof(struct xsave_hdr_struct);
107 unsigned int magic2;
108
109 if (__copy_from_user(fx_sw, &buf->sw_reserved[0], sizeof(*fx_sw)))
110 return -1;
111
112 /* Check for the first magic field and other error scenarios. */
113 if (fx_sw->magic1 != FP_XSTATE_MAGIC1 ||
114 fx_sw->xstate_size < min_xstate_size ||
115 fx_sw->xstate_size > xstate_size ||
116 fx_sw->xstate_size > fx_sw->extended_size)
117 return -1;
118
119 /*
120 * Check for the presence of second magic word at the end of memory
121 * layout. This detects the case where the user just copied the legacy
122 * fpstate layout with out copying the extended state information
123 * in the memory layout.
124 */
125 if (__get_user(magic2, (__u32 __user *)(fpstate + fx_sw->xstate_size))
126 || magic2 != FP_XSTATE_MAGIC2)
127 return -1;
128
129 return 0;
130}
131
132/*
133 * Signal frame handlers.
134 */
135static inline int save_fsave_header(struct task_struct *tsk, void __user *buf)
136{
137 if (use_fxsr()) {
138 struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;
139 struct user_i387_ia32_struct env;
140 struct _fpstate_ia32 __user *fp = buf;
141
142 convert_from_fxsr(&env, tsk);
143
144 if (__copy_to_user(buf, &env, sizeof(env)) ||
145 __put_user(xsave->i387.swd, &fp->status) ||
146 __put_user(X86_FXSR_MAGIC, &fp->magic))
147 return -1;
148 } else {
149 struct i387_fsave_struct __user *fp = buf;
150 u32 swd;
151 if (__get_user(swd, &fp->swd) || __put_user(swd, &fp->status))
152 return -1;
153 }
154
155 return 0;
156}
157
158static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
159{
160 struct xsave_struct __user *x = buf;
161 struct _fpx_sw_bytes *sw_bytes;
162 u32 xstate_bv;
163 int err;
164
165 /* Setup the bytes not touched by the [f]xsave and reserved for SW. */
166 sw_bytes = ia32_frame ? &fx_sw_reserved_ia32 : &fx_sw_reserved;
167 err = __copy_to_user(&x->i387.sw_reserved, sw_bytes, sizeof(*sw_bytes));
168
169 if (!use_xsave())
170 return err;
171
172 err |= __put_user(FP_XSTATE_MAGIC2, (__u32 *)(buf + xstate_size));
173
174 /*
175 * Read the xstate_bv which we copied (directly from the cpu or
176 * from the state in task struct) to the user buffers.
177 */
178 err |= __get_user(xstate_bv, (__u32 *)&x->xsave_hdr.xstate_bv);
179
180 /*
181 * For legacy compatible, we always set FP/SSE bits in the bit
182 * vector while saving the state to the user context. This will
183 * enable us capturing any changes(during sigreturn) to
184 * the FP/SSE bits by the legacy applications which don't touch
185 * xstate_bv in the xsave header.
186 *
187 * xsave aware apps can change the xstate_bv in the xsave
188 * header as well as change any contents in the memory layout.
189 * xrestore as part of sigreturn will capture all the changes.
190 */
191 xstate_bv |= XSTATE_FPSSE;
192
193 err |= __put_user(xstate_bv, (__u32 *)&x->xsave_hdr.xstate_bv);
194
195 return err;
196}
197
198static inline int save_user_xstate(struct xsave_struct __user *buf)
199{
200 int err;
201
202 if (use_xsave())
203 err = xsave_user(buf);
204 else if (use_fxsr())
205 err = fxsave_user((struct i387_fxsave_struct __user *) buf);
206 else
207 err = fsave_user((struct i387_fsave_struct __user *) buf);
208
209 if (unlikely(err) && __clear_user(buf, xstate_size))
210 err = -EFAULT;
211 return err;
212}
213
214/*
215 * Save the fpu, extended register state to the user signal frame.
216 *
217 * 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
218 * state is copied.
219 * 'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
220 *
221 * buf == buf_fx for 64-bit frames and 32-bit fsave frame.
222 * buf != buf_fx for 32-bit frames with fxstate.
223 *
224 * If the fpu, extended register state is live, save the state directly
225 * to the user frame pointed by the aligned pointer 'buf_fx'. Otherwise,
226 * copy the thread's fpu state to the user frame starting at 'buf_fx'.
227 *
228 * If this is a 32-bit frame with fxstate, put a fsave header before
229 * the aligned state at 'buf_fx'.
230 *
231 * For [f]xsave state, update the SW reserved fields in the [f]xsave frame
232 * indicating the absence/presence of the extended state to the user.
233 */
234int save_xstate_sig(void __user *buf, void __user *buf_fx, int size)
235{
236 struct xsave_struct *xsave = ¤t->thread.fpu.state->xsave;
237 struct task_struct *tsk = current;
238 int ia32_fxstate = (buf != buf_fx);
239
240 ia32_fxstate &= (config_enabled(CONFIG_X86_32) ||
241 config_enabled(CONFIG_IA32_EMULATION));
242
243 if (!access_ok(VERIFY_WRITE, buf, size))
244 return -EACCES;
245
246 if (!static_cpu_has(X86_FEATURE_FPU))
247 return fpregs_soft_get(current, NULL, 0,
248 sizeof(struct user_i387_ia32_struct), NULL,
249 (struct _fpstate_ia32 __user *) buf) ? -1 : 1;
250
251 if (user_has_fpu()) {
252 /* Save the live register state to the user directly. */
253 if (save_user_xstate(buf_fx))
254 return -1;
255 /* Update the thread's fxstate to save the fsave header. */
256 if (ia32_fxstate)
257 fpu_fxsave(&tsk->thread.fpu);
258 } else {
259 sanitize_i387_state(tsk);
260 if (__copy_to_user(buf_fx, xsave, xstate_size))
261 return -1;
262 }
263
264 /* Save the fsave header for the 32-bit frames. */
265 if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
266 return -1;
267
268 if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
269 return -1;
270
271 drop_init_fpu(tsk); /* trigger finit */
272
273 return 0;
274}
275
276static inline void
277sanitize_restored_xstate(struct task_struct *tsk,
278 struct user_i387_ia32_struct *ia32_env,
279 u64 xstate_bv, int fx_only)
280{
281 struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;
282 struct xsave_hdr_struct *xsave_hdr = &xsave->xsave_hdr;
283
284 if (use_xsave()) {
285 /* These bits must be zero. */
286 xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0;
287
288 /*
289 * Init the state that is not present in the memory
290 * layout and not enabled by the OS.
291 */
292 if (fx_only)
293 xsave_hdr->xstate_bv = XSTATE_FPSSE;
294 else
295 xsave_hdr->xstate_bv &= (pcntxt_mask & xstate_bv);
296 }
297
298 if (use_fxsr()) {
299 /*
300 * mscsr reserved bits must be masked to zero for security
301 * reasons.
302 */
303 xsave->i387.mxcsr &= mxcsr_feature_mask;
304
305 convert_to_fxsr(tsk, ia32_env);
306 }
307}
308
309/*
310 * Restore the extended state if present. Otherwise, restore the FP/SSE state.
311 */
312static inline int restore_user_xstate(void __user *buf, u64 xbv, int fx_only)
313{
314 if (use_xsave()) {
315 if ((unsigned long)buf % 64 || fx_only) {
316 u64 init_bv = pcntxt_mask & ~XSTATE_FPSSE;
317 xrstor_state(init_xstate_buf, init_bv);
318 return fxrstor_user(buf);
319 } else {
320 u64 init_bv = pcntxt_mask & ~xbv;
321 if (unlikely(init_bv))
322 xrstor_state(init_xstate_buf, init_bv);
323 return xrestore_user(buf, xbv);
324 }
325 } else if (use_fxsr()) {
326 return fxrstor_user(buf);
327 } else
328 return frstor_user(buf);
329}
330
331int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
332{
333 int ia32_fxstate = (buf != buf_fx);
334 struct task_struct *tsk = current;
335 int state_size = xstate_size;
336 u64 xstate_bv = 0;
337 int fx_only = 0;
338
339 ia32_fxstate &= (config_enabled(CONFIG_X86_32) ||
340 config_enabled(CONFIG_IA32_EMULATION));
341
342 if (!buf) {
343 drop_init_fpu(tsk);
344 return 0;
345 }
346
347 if (!access_ok(VERIFY_READ, buf, size))
348 return -EACCES;
349
350 if (!used_math() && init_fpu(tsk))
351 return -1;
352
353 if (!static_cpu_has(X86_FEATURE_FPU))
354 return fpregs_soft_set(current, NULL,
355 0, sizeof(struct user_i387_ia32_struct),
356 NULL, buf) != 0;
357
358 if (use_xsave()) {
359 struct _fpx_sw_bytes fx_sw_user;
360 if (unlikely(check_for_xstate(buf_fx, buf_fx, &fx_sw_user))) {
361 /*
362 * Couldn't find the extended state information in the
363 * memory layout. Restore just the FP/SSE and init all
364 * the other extended state.
365 */
366 state_size = sizeof(struct i387_fxsave_struct);
367 fx_only = 1;
368 } else {
369 state_size = fx_sw_user.xstate_size;
370 xstate_bv = fx_sw_user.xstate_bv;
371 }
372 }
373
374 if (ia32_fxstate) {
375 /*
376 * For 32-bit frames with fxstate, copy the user state to the
377 * thread's fpu state, reconstruct fxstate from the fsave
378 * header. Sanitize the copied state etc.
379 */
380 struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;
381 struct user_i387_ia32_struct env;
382 int err = 0;
383
384 /*
385 * Drop the current fpu which clears used_math(). This ensures
386 * that any context-switch during the copy of the new state,
387 * avoids the intermediate state from getting restored/saved.
388 * Thus avoiding the new restored state from getting corrupted.
389 * We will be ready to restore/save the state only after
390 * set_used_math() is again set.
391 */
392 drop_fpu(tsk);
393
394 if (__copy_from_user(xsave, buf_fx, state_size) ||
395 __copy_from_user(&env, buf, sizeof(env))) {
396 err = -1;
397 } else {
398 sanitize_restored_xstate(tsk, &env, xstate_bv, fx_only);
399 set_used_math();
400 }
401
402 if (use_eager_fpu())
403 math_state_restore();
404
405 return err;
406 } else {
407 /*
408 * For 64-bit frames and 32-bit fsave frames, restore the user
409 * state to the registers directly (with exceptions handled).
410 */
411 user_fpu_begin();
412 if (restore_user_xstate(buf_fx, xstate_bv, fx_only)) {
413 drop_init_fpu(tsk);
414 return -1;
415 }
416 }
417
418 return 0;
419}
420
421/*
422 * Prepare the SW reserved portion of the fxsave memory layout, indicating
423 * the presence of the extended state information in the memory layout
424 * pointed by the fpstate pointer in the sigcontext.
425 * This will be saved when ever the FP and extended state context is
426 * saved on the user stack during the signal handler delivery to the user.
427 */
428static void prepare_fx_sw_frame(void)
429{
430 int fsave_header_size = sizeof(struct i387_fsave_struct);
431 int size = xstate_size + FP_XSTATE_MAGIC2_SIZE;
432
433 if (config_enabled(CONFIG_X86_32))
434 size += fsave_header_size;
435
436 fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
437 fx_sw_reserved.extended_size = size;
438 fx_sw_reserved.xstate_bv = pcntxt_mask;
439 fx_sw_reserved.xstate_size = xstate_size;
440
441 if (config_enabled(CONFIG_IA32_EMULATION)) {
442 fx_sw_reserved_ia32 = fx_sw_reserved;
443 fx_sw_reserved_ia32.extended_size += fsave_header_size;
444 }
445}
446
447/*
448 * Enable the extended processor state save/restore feature
449 */
450static inline void xstate_enable(void)
451{
452 set_in_cr4(X86_CR4_OSXSAVE);
453 xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask);
454}
455
456/*
457 * Record the offsets and sizes of different state managed by the xsave
458 * memory layout.
459 */
460static void __init setup_xstate_features(void)
461{
462 int eax, ebx, ecx, edx, leaf = 0x2;
463
464 xstate_features = fls64(pcntxt_mask);
465 xstate_offsets = alloc_bootmem(xstate_features * sizeof(int));
466 xstate_sizes = alloc_bootmem(xstate_features * sizeof(int));
467
468 do {
469 cpuid_count(XSTATE_CPUID, leaf, &eax, &ebx, &ecx, &edx);
470
471 if (eax == 0)
472 break;
473
474 xstate_offsets[leaf] = ebx;
475 xstate_sizes[leaf] = eax;
476
477 leaf++;
478 } while (1);
479}
480
481/*
482 * setup the xstate image representing the init state
483 */
484static void __init setup_init_fpu_buf(void)
485{
486 /*
487 * Setup init_xstate_buf to represent the init state of
488 * all the features managed by the xsave
489 */
490 init_xstate_buf = alloc_bootmem_align(xstate_size,
491 __alignof__(struct xsave_struct));
492 fx_finit(&init_xstate_buf->i387);
493
494 if (!cpu_has_xsave)
495 return;
496
497 setup_xstate_features();
498
499 /*
500 * Init all the features state with header_bv being 0x0
501 */
502 xrstor_state(init_xstate_buf, -1);
503 /*
504 * Dump the init state again. This is to identify the init state
505 * of any feature which is not represented by all zero's.
506 */
507 xsave_state(init_xstate_buf, -1);
508}
509
510static enum { AUTO, ENABLE, DISABLE } eagerfpu = AUTO;
511static int __init eager_fpu_setup(char *s)
512{
513 if (!strcmp(s, "on"))
514 eagerfpu = ENABLE;
515 else if (!strcmp(s, "off"))
516 eagerfpu = DISABLE;
517 else if (!strcmp(s, "auto"))
518 eagerfpu = AUTO;
519 return 1;
520}
521__setup("eagerfpu=", eager_fpu_setup);
522
523/*
524 * Enable and initialize the xsave feature.
525 */
526static void __init xstate_enable_boot_cpu(void)
527{
528 unsigned int eax, ebx, ecx, edx;
529
530 if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
531 WARN(1, KERN_ERR "XSTATE_CPUID missing\n");
532 return;
533 }
534
535 cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
536 pcntxt_mask = eax + ((u64)edx << 32);
537
538 if ((pcntxt_mask & XSTATE_FPSSE) != XSTATE_FPSSE) {
539 pr_err("FP/SSE not shown under xsave features 0x%llx\n",
540 pcntxt_mask);
541 BUG();
542 }
543
544 /*
545 * Support only the state known to OS.
546 */
547 pcntxt_mask = pcntxt_mask & XCNTXT_MASK;
548
549 xstate_enable();
550
551 /*
552 * Recompute the context size for enabled features
553 */
554 cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
555 xstate_size = ebx;
556
557 update_regset_xstate_info(xstate_size, pcntxt_mask);
558 prepare_fx_sw_frame();
559 setup_init_fpu_buf();
560
561 /* Auto enable eagerfpu for xsaveopt */
562 if (cpu_has_xsaveopt && eagerfpu != DISABLE)
563 eagerfpu = ENABLE;
564
565 if (pcntxt_mask & XSTATE_EAGER) {
566 if (eagerfpu == DISABLE) {
567 pr_err("eagerfpu not present, disabling some xstate features: 0x%llx\n",
568 pcntxt_mask & XSTATE_EAGER);
569 pcntxt_mask &= ~XSTATE_EAGER;
570 } else {
571 eagerfpu = ENABLE;
572 }
573 }
574
575 pr_info("enabled xstate_bv 0x%llx, cntxt size 0x%x\n",
576 pcntxt_mask, xstate_size);
577}
578
579/*
580 * For the very first instance, this calls xstate_enable_boot_cpu();
581 * for all subsequent instances, this calls xstate_enable().
582 *
583 * This is somewhat obfuscated due to the lack of powerful enough
584 * overrides for the section checks.
585 */
586void xsave_init(void)
587{
588 static __refdata void (*next_func)(void) = xstate_enable_boot_cpu;
589 void (*this_func)(void);
590
591 if (!cpu_has_xsave)
592 return;
593
594 this_func = next_func;
595 next_func = xstate_enable;
596 this_func();
597}
598
599static inline void __init eager_fpu_init_bp(void)
600{
601 current->thread.fpu.state =
602 alloc_bootmem_align(xstate_size, __alignof__(struct xsave_struct));
603 if (!init_xstate_buf)
604 setup_init_fpu_buf();
605}
606
607void eager_fpu_init(void)
608{
609 static __refdata void (*boot_func)(void) = eager_fpu_init_bp;
610
611 clear_used_math();
612 current_thread_info()->status = 0;
613
614 if (eagerfpu == ENABLE)
615 setup_force_cpu_cap(X86_FEATURE_EAGER_FPU);
616
617 if (!cpu_has_eager_fpu) {
618 stts();
619 return;
620 }
621
622 if (boot_func) {
623 boot_func();
624 boot_func = NULL;
625 }
626
627 /*
628 * This is same as math_state_restore(). But use_xsave() is
629 * not yet patched to use math_state_restore().
630 */
631 init_fpu(current);
632 __thread_fpu_begin(current);
633 if (cpu_has_xsave)
634 xrstor_state(init_xstate_buf, -1);
635 else
636 fxrstor_checking(&init_xstate_buf->i387);
637}