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Commit | Line | Data |
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dc1e35c6 SS |
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> | |
c37b5efe SS |
9 | #ifdef CONFIG_IA32_EMULATION |
10 | #include <asm/sigcontext32.h> | |
11 | #endif | |
6152e4b1 | 12 | #include <asm/xcr.h> |
dc1e35c6 SS |
13 | |
14 | /* | |
15 | * Supported feature mask by the CPU and the kernel. | |
16 | */ | |
6152e4b1 | 17 | u64 pcntxt_mask; |
dc1e35c6 | 18 | |
c37b5efe SS |
19 | struct _fpx_sw_bytes fx_sw_reserved; |
20 | #ifdef CONFIG_IA32_EMULATION | |
21 | struct _fpx_sw_bytes fx_sw_reserved_ia32; | |
22 | #endif | |
23 | ||
24 | /* | |
25 | * Check for the presence of extended state information in the | |
26 | * user fpstate pointer in the sigcontext. | |
27 | */ | |
28 | int check_for_xstate(struct i387_fxsave_struct __user *buf, | |
29 | void __user *fpstate, | |
30 | struct _fpx_sw_bytes *fx_sw_user) | |
31 | { | |
32 | int min_xstate_size = sizeof(struct i387_fxsave_struct) + | |
33 | sizeof(struct xsave_hdr_struct); | |
34 | unsigned int magic2; | |
35 | int err; | |
36 | ||
37 | err = __copy_from_user(fx_sw_user, &buf->sw_reserved[0], | |
38 | sizeof(struct _fpx_sw_bytes)); | |
39 | ||
40 | if (err) | |
41 | return err; | |
42 | ||
43 | /* | |
44 | * First Magic check failed. | |
45 | */ | |
46 | if (fx_sw_user->magic1 != FP_XSTATE_MAGIC1) | |
47 | return -1; | |
48 | ||
49 | /* | |
50 | * Check for error scenarios. | |
51 | */ | |
52 | if (fx_sw_user->xstate_size < min_xstate_size || | |
53 | fx_sw_user->xstate_size > xstate_size || | |
54 | fx_sw_user->xstate_size > fx_sw_user->extended_size) | |
55 | return -1; | |
56 | ||
57 | err = __get_user(magic2, (__u32 *) (((void *)fpstate) + | |
58 | fx_sw_user->extended_size - | |
59 | FP_XSTATE_MAGIC2_SIZE)); | |
60 | /* | |
61 | * Check for the presence of second magic word at the end of memory | |
62 | * layout. This detects the case where the user just copied the legacy | |
63 | * fpstate layout with out copying the extended state information | |
64 | * in the memory layout. | |
65 | */ | |
66 | if (err || magic2 != FP_XSTATE_MAGIC2) | |
67 | return -1; | |
68 | ||
69 | return 0; | |
70 | } | |
71 | ||
ab513701 SS |
72 | #ifdef CONFIG_X86_64 |
73 | /* | |
74 | * Signal frame handlers. | |
75 | */ | |
76 | ||
77 | int save_i387_xstate(void __user *buf) | |
78 | { | |
79 | struct task_struct *tsk = current; | |
80 | int err = 0; | |
81 | ||
82 | if (!access_ok(VERIFY_WRITE, buf, sig_xstate_size)) | |
83 | return -EACCES; | |
84 | ||
f65bc214 | 85 | BUG_ON(sig_xstate_size < xstate_size); |
ab513701 | 86 | |
c37b5efe | 87 | if ((unsigned long)buf % 64) |
ab513701 SS |
88 | printk("save_i387_xstate: bad fpstate %p\n", buf); |
89 | ||
90 | if (!used_math()) | |
91 | return 0; | |
92 | clear_used_math(); /* trigger finit */ | |
93 | if (task_thread_info(tsk)->status & TS_USEDFPU) { | |
ed405958 SS |
94 | /* |
95 | * Start with clearing the user buffer. This will present a | |
96 | * clean context for the bytes not touched by the fxsave/xsave. | |
97 | */ | |
9f482807 IM |
98 | err = __clear_user(buf, sig_xstate_size); |
99 | if (err) | |
100 | return err; | |
ed405958 | 101 | |
c37b5efe SS |
102 | if (task_thread_info(tsk)->status & TS_XSAVE) |
103 | err = xsave_user(buf); | |
104 | else | |
105 | err = fxsave_user(buf); | |
106 | ||
ab513701 SS |
107 | if (err) |
108 | return err; | |
109 | task_thread_info(tsk)->status &= ~TS_USEDFPU; | |
110 | stts(); | |
111 | } else { | |
112 | if (__copy_to_user(buf, &tsk->thread.xstate->fxsave, | |
113 | xstate_size)) | |
114 | return -1; | |
115 | } | |
c37b5efe SS |
116 | |
117 | if (task_thread_info(tsk)->status & TS_XSAVE) { | |
118 | struct _fpstate __user *fx = buf; | |
04944b79 SS |
119 | struct _xstate __user *x = buf; |
120 | u64 xstate_bv; | |
c37b5efe SS |
121 | |
122 | err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved, | |
123 | sizeof(struct _fpx_sw_bytes)); | |
124 | ||
125 | err |= __put_user(FP_XSTATE_MAGIC2, | |
126 | (__u32 __user *) (buf + sig_xstate_size | |
127 | - FP_XSTATE_MAGIC2_SIZE)); | |
04944b79 SS |
128 | |
129 | /* | |
130 | * Read the xstate_bv which we copied (directly from the cpu or | |
131 | * from the state in task struct) to the user buffers and | |
132 | * set the FP/SSE bits. | |
133 | */ | |
134 | err |= __get_user(xstate_bv, &x->xstate_hdr.xstate_bv); | |
135 | ||
136 | /* | |
137 | * For legacy compatible, we always set FP/SSE bits in the bit | |
138 | * vector while saving the state to the user context. This will | |
139 | * enable us capturing any changes(during sigreturn) to | |
140 | * the FP/SSE bits by the legacy applications which don't touch | |
141 | * xstate_bv in the xsave header. | |
142 | * | |
143 | * xsave aware apps can change the xstate_bv in the xsave | |
144 | * header as well as change any contents in the memory layout. | |
145 | * xrestore as part of sigreturn will capture all the changes. | |
146 | */ | |
147 | xstate_bv |= XSTATE_FPSSE; | |
148 | ||
149 | err |= __put_user(xstate_bv, &x->xstate_hdr.xstate_bv); | |
150 | ||
f364eada SS |
151 | if (err) |
152 | return err; | |
c37b5efe SS |
153 | } |
154 | ||
ab513701 SS |
155 | return 1; |
156 | } | |
157 | ||
c37b5efe SS |
158 | /* |
159 | * Restore the extended state if present. Otherwise, restore the FP/SSE | |
160 | * state. | |
161 | */ | |
7820b756 | 162 | static int restore_user_xstate(void __user *buf) |
c37b5efe SS |
163 | { |
164 | struct _fpx_sw_bytes fx_sw_user; | |
6152e4b1 | 165 | u64 mask; |
c37b5efe SS |
166 | int err; |
167 | ||
168 | if (((unsigned long)buf % 64) || | |
169 | check_for_xstate(buf, buf, &fx_sw_user)) | |
170 | goto fx_only; | |
171 | ||
6152e4b1 | 172 | mask = fx_sw_user.xstate_bv; |
c37b5efe SS |
173 | |
174 | /* | |
175 | * restore the state passed by the user. | |
176 | */ | |
6152e4b1 | 177 | err = xrestore_user(buf, mask); |
c37b5efe SS |
178 | if (err) |
179 | return err; | |
180 | ||
181 | /* | |
182 | * init the state skipped by the user. | |
183 | */ | |
6152e4b1 | 184 | mask = pcntxt_mask & ~mask; |
c37b5efe | 185 | |
6152e4b1 | 186 | xrstor_state(init_xstate_buf, mask); |
c37b5efe SS |
187 | |
188 | return 0; | |
189 | ||
190 | fx_only: | |
191 | /* | |
192 | * couldn't find the extended state information in the | |
193 | * memory layout. Restore just the FP/SSE and init all | |
194 | * the other extended state. | |
195 | */ | |
6152e4b1 | 196 | xrstor_state(init_xstate_buf, pcntxt_mask & ~XSTATE_FPSSE); |
c37b5efe SS |
197 | return fxrstor_checking((__force struct i387_fxsave_struct *)buf); |
198 | } | |
199 | ||
ab513701 SS |
200 | /* |
201 | * This restores directly out of user space. Exceptions are handled. | |
202 | */ | |
203 | int restore_i387_xstate(void __user *buf) | |
204 | { | |
205 | struct task_struct *tsk = current; | |
c37b5efe | 206 | int err = 0; |
ab513701 SS |
207 | |
208 | if (!buf) { | |
c37b5efe SS |
209 | if (used_math()) |
210 | goto clear; | |
ab513701 SS |
211 | return 0; |
212 | } else | |
213 | if (!access_ok(VERIFY_READ, buf, sig_xstate_size)) | |
214 | return -EACCES; | |
215 | ||
216 | if (!used_math()) { | |
217 | err = init_fpu(tsk); | |
218 | if (err) | |
219 | return err; | |
220 | } | |
221 | ||
222 | if (!(task_thread_info(current)->status & TS_USEDFPU)) { | |
223 | clts(); | |
224 | task_thread_info(current)->status |= TS_USEDFPU; | |
225 | } | |
c37b5efe SS |
226 | if (task_thread_info(tsk)->status & TS_XSAVE) |
227 | err = restore_user_xstate(buf); | |
228 | else | |
229 | err = fxrstor_checking((__force struct i387_fxsave_struct *) | |
230 | buf); | |
ab513701 SS |
231 | if (unlikely(err)) { |
232 | /* | |
233 | * Encountered an error while doing the restore from the | |
234 | * user buffer, clear the fpu state. | |
235 | */ | |
c37b5efe | 236 | clear: |
ab513701 SS |
237 | clear_fpu(tsk); |
238 | clear_used_math(); | |
239 | } | |
240 | return err; | |
241 | } | |
242 | #endif | |
243 | ||
c37b5efe SS |
244 | /* |
245 | * Prepare the SW reserved portion of the fxsave memory layout, indicating | |
246 | * the presence of the extended state information in the memory layout | |
247 | * pointed by the fpstate pointer in the sigcontext. | |
248 | * This will be saved when ever the FP and extended state context is | |
249 | * saved on the user stack during the signal handler delivery to the user. | |
250 | */ | |
8bcad30f | 251 | static void prepare_fx_sw_frame(void) |
c37b5efe SS |
252 | { |
253 | int size_extended = (xstate_size - sizeof(struct i387_fxsave_struct)) + | |
254 | FP_XSTATE_MAGIC2_SIZE; | |
255 | ||
256 | sig_xstate_size = sizeof(struct _fpstate) + size_extended; | |
257 | ||
258 | #ifdef CONFIG_IA32_EMULATION | |
259 | sig_xstate_ia32_size = sizeof(struct _fpstate_ia32) + size_extended; | |
260 | #endif | |
261 | ||
262 | memset(&fx_sw_reserved, 0, sizeof(fx_sw_reserved)); | |
263 | ||
264 | fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1; | |
265 | fx_sw_reserved.extended_size = sig_xstate_size; | |
6152e4b1 | 266 | fx_sw_reserved.xstate_bv = pcntxt_mask; |
c37b5efe SS |
267 | fx_sw_reserved.xstate_size = xstate_size; |
268 | #ifdef CONFIG_IA32_EMULATION | |
269 | memcpy(&fx_sw_reserved_ia32, &fx_sw_reserved, | |
270 | sizeof(struct _fpx_sw_bytes)); | |
271 | fx_sw_reserved_ia32.extended_size = sig_xstate_ia32_size; | |
272 | #endif | |
273 | } | |
274 | ||
dc1e35c6 SS |
275 | /* |
276 | * Represents init state for the supported extended state. | |
277 | */ | |
278 | struct xsave_struct *init_xstate_buf; | |
279 | ||
3c1c7f10 SS |
280 | #ifdef CONFIG_X86_64 |
281 | unsigned int sig_xstate_size = sizeof(struct _fpstate); | |
282 | #endif | |
283 | ||
dc1e35c6 SS |
284 | /* |
285 | * Enable the extended processor state save/restore feature | |
286 | */ | |
287 | void __cpuinit xsave_init(void) | |
288 | { | |
289 | if (!cpu_has_xsave) | |
290 | return; | |
291 | ||
292 | set_in_cr4(X86_CR4_OSXSAVE); | |
293 | ||
294 | /* | |
295 | * Enable all the features that the HW is capable of | |
296 | * and the Linux kernel is aware of. | |
dc1e35c6 | 297 | */ |
6152e4b1 | 298 | xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask); |
dc1e35c6 SS |
299 | } |
300 | ||
301 | /* | |
302 | * setup the xstate image representing the init state | |
303 | */ | |
a19aac85 | 304 | static void __init setup_xstate_init(void) |
dc1e35c6 SS |
305 | { |
306 | init_xstate_buf = alloc_bootmem(xstate_size); | |
307 | init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT; | |
308 | } | |
309 | ||
310 | /* | |
311 | * Enable and initialize the xsave feature. | |
312 | */ | |
bfe085f6 | 313 | void __ref xsave_cntxt_init(void) |
dc1e35c6 SS |
314 | { |
315 | unsigned int eax, ebx, ecx, edx; | |
316 | ||
317 | cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx); | |
6152e4b1 | 318 | pcntxt_mask = eax + ((u64)edx << 32); |
dc1e35c6 | 319 | |
6152e4b1 PA |
320 | if ((pcntxt_mask & XSTATE_FPSSE) != XSTATE_FPSSE) { |
321 | printk(KERN_ERR "FP/SSE not shown under xsave features 0x%llx\n", | |
322 | pcntxt_mask); | |
dc1e35c6 SS |
323 | BUG(); |
324 | } | |
325 | ||
326 | /* | |
327 | * for now OS knows only about FP/SSE | |
328 | */ | |
6152e4b1 | 329 | pcntxt_mask = pcntxt_mask & XCNTXT_MASK; |
dc1e35c6 SS |
330 | xsave_init(); |
331 | ||
332 | /* | |
333 | * Recompute the context size for enabled features | |
334 | */ | |
335 | cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx); | |
dc1e35c6 SS |
336 | xstate_size = ebx; |
337 | ||
c37b5efe SS |
338 | prepare_fx_sw_frame(); |
339 | ||
dc1e35c6 SS |
340 | setup_xstate_init(); |
341 | ||
6152e4b1 | 342 | printk(KERN_INFO "xsave/xrstor: enabled xstate_bv 0x%llx, " |
dc1e35c6 | 343 | "cntxt size 0x%x\n", |
6152e4b1 | 344 | pcntxt_mask, xstate_size); |
dc1e35c6 | 345 | } |