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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 | */ | |
98 | __clear_user(buf, sig_xstate_size); | |
99 | ||
c37b5efe SS |
100 | if (task_thread_info(tsk)->status & TS_XSAVE) |
101 | err = xsave_user(buf); | |
102 | else | |
103 | err = fxsave_user(buf); | |
104 | ||
ab513701 SS |
105 | if (err) |
106 | return err; | |
107 | task_thread_info(tsk)->status &= ~TS_USEDFPU; | |
108 | stts(); | |
109 | } else { | |
110 | if (__copy_to_user(buf, &tsk->thread.xstate->fxsave, | |
111 | xstate_size)) | |
112 | return -1; | |
113 | } | |
c37b5efe SS |
114 | |
115 | if (task_thread_info(tsk)->status & TS_XSAVE) { | |
116 | struct _fpstate __user *fx = buf; | |
117 | ||
118 | err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved, | |
119 | sizeof(struct _fpx_sw_bytes)); | |
120 | ||
121 | err |= __put_user(FP_XSTATE_MAGIC2, | |
122 | (__u32 __user *) (buf + sig_xstate_size | |
123 | - FP_XSTATE_MAGIC2_SIZE)); | |
124 | } | |
125 | ||
ab513701 SS |
126 | return 1; |
127 | } | |
128 | ||
c37b5efe SS |
129 | /* |
130 | * Restore the extended state if present. Otherwise, restore the FP/SSE | |
131 | * state. | |
132 | */ | |
133 | int restore_user_xstate(void __user *buf) | |
134 | { | |
135 | struct _fpx_sw_bytes fx_sw_user; | |
6152e4b1 | 136 | u64 mask; |
c37b5efe SS |
137 | int err; |
138 | ||
139 | if (((unsigned long)buf % 64) || | |
140 | check_for_xstate(buf, buf, &fx_sw_user)) | |
141 | goto fx_only; | |
142 | ||
6152e4b1 | 143 | mask = fx_sw_user.xstate_bv; |
c37b5efe SS |
144 | |
145 | /* | |
146 | * restore the state passed by the user. | |
147 | */ | |
6152e4b1 | 148 | err = xrestore_user(buf, mask); |
c37b5efe SS |
149 | if (err) |
150 | return err; | |
151 | ||
152 | /* | |
153 | * init the state skipped by the user. | |
154 | */ | |
6152e4b1 | 155 | mask = pcntxt_mask & ~mask; |
c37b5efe | 156 | |
6152e4b1 | 157 | xrstor_state(init_xstate_buf, mask); |
c37b5efe SS |
158 | |
159 | return 0; | |
160 | ||
161 | fx_only: | |
162 | /* | |
163 | * couldn't find the extended state information in the | |
164 | * memory layout. Restore just the FP/SSE and init all | |
165 | * the other extended state. | |
166 | */ | |
6152e4b1 | 167 | xrstor_state(init_xstate_buf, pcntxt_mask & ~XSTATE_FPSSE); |
c37b5efe SS |
168 | return fxrstor_checking((__force struct i387_fxsave_struct *)buf); |
169 | } | |
170 | ||
ab513701 SS |
171 | /* |
172 | * This restores directly out of user space. Exceptions are handled. | |
173 | */ | |
174 | int restore_i387_xstate(void __user *buf) | |
175 | { | |
176 | struct task_struct *tsk = current; | |
c37b5efe | 177 | int err = 0; |
ab513701 SS |
178 | |
179 | if (!buf) { | |
c37b5efe SS |
180 | if (used_math()) |
181 | goto clear; | |
ab513701 SS |
182 | return 0; |
183 | } else | |
184 | if (!access_ok(VERIFY_READ, buf, sig_xstate_size)) | |
185 | return -EACCES; | |
186 | ||
187 | if (!used_math()) { | |
188 | err = init_fpu(tsk); | |
189 | if (err) | |
190 | return err; | |
191 | } | |
192 | ||
193 | if (!(task_thread_info(current)->status & TS_USEDFPU)) { | |
194 | clts(); | |
195 | task_thread_info(current)->status |= TS_USEDFPU; | |
196 | } | |
c37b5efe SS |
197 | if (task_thread_info(tsk)->status & TS_XSAVE) |
198 | err = restore_user_xstate(buf); | |
199 | else | |
200 | err = fxrstor_checking((__force struct i387_fxsave_struct *) | |
201 | buf); | |
ab513701 SS |
202 | if (unlikely(err)) { |
203 | /* | |
204 | * Encountered an error while doing the restore from the | |
205 | * user buffer, clear the fpu state. | |
206 | */ | |
c37b5efe | 207 | clear: |
ab513701 SS |
208 | clear_fpu(tsk); |
209 | clear_used_math(); | |
210 | } | |
211 | return err; | |
212 | } | |
213 | #endif | |
214 | ||
c37b5efe SS |
215 | /* |
216 | * Prepare the SW reserved portion of the fxsave memory layout, indicating | |
217 | * the presence of the extended state information in the memory layout | |
218 | * pointed by the fpstate pointer in the sigcontext. | |
219 | * This will be saved when ever the FP and extended state context is | |
220 | * saved on the user stack during the signal handler delivery to the user. | |
221 | */ | |
222 | void prepare_fx_sw_frame(void) | |
223 | { | |
224 | int size_extended = (xstate_size - sizeof(struct i387_fxsave_struct)) + | |
225 | FP_XSTATE_MAGIC2_SIZE; | |
226 | ||
227 | sig_xstate_size = sizeof(struct _fpstate) + size_extended; | |
228 | ||
229 | #ifdef CONFIG_IA32_EMULATION | |
230 | sig_xstate_ia32_size = sizeof(struct _fpstate_ia32) + size_extended; | |
231 | #endif | |
232 | ||
233 | memset(&fx_sw_reserved, 0, sizeof(fx_sw_reserved)); | |
234 | ||
235 | fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1; | |
236 | fx_sw_reserved.extended_size = sig_xstate_size; | |
6152e4b1 | 237 | fx_sw_reserved.xstate_bv = pcntxt_mask; |
c37b5efe SS |
238 | fx_sw_reserved.xstate_size = xstate_size; |
239 | #ifdef CONFIG_IA32_EMULATION | |
240 | memcpy(&fx_sw_reserved_ia32, &fx_sw_reserved, | |
241 | sizeof(struct _fpx_sw_bytes)); | |
242 | fx_sw_reserved_ia32.extended_size = sig_xstate_ia32_size; | |
243 | #endif | |
244 | } | |
245 | ||
dc1e35c6 SS |
246 | /* |
247 | * Represents init state for the supported extended state. | |
248 | */ | |
249 | struct xsave_struct *init_xstate_buf; | |
250 | ||
3c1c7f10 SS |
251 | #ifdef CONFIG_X86_64 |
252 | unsigned int sig_xstate_size = sizeof(struct _fpstate); | |
253 | #endif | |
254 | ||
dc1e35c6 SS |
255 | /* |
256 | * Enable the extended processor state save/restore feature | |
257 | */ | |
258 | void __cpuinit xsave_init(void) | |
259 | { | |
260 | if (!cpu_has_xsave) | |
261 | return; | |
262 | ||
263 | set_in_cr4(X86_CR4_OSXSAVE); | |
264 | ||
265 | /* | |
266 | * Enable all the features that the HW is capable of | |
267 | * and the Linux kernel is aware of. | |
dc1e35c6 | 268 | */ |
6152e4b1 | 269 | xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask); |
dc1e35c6 SS |
270 | } |
271 | ||
272 | /* | |
273 | * setup the xstate image representing the init state | |
274 | */ | |
275 | void setup_xstate_init(void) | |
276 | { | |
277 | init_xstate_buf = alloc_bootmem(xstate_size); | |
278 | init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT; | |
279 | } | |
280 | ||
281 | /* | |
282 | * Enable and initialize the xsave feature. | |
283 | */ | |
284 | void __init xsave_cntxt_init(void) | |
285 | { | |
286 | unsigned int eax, ebx, ecx, edx; | |
287 | ||
288 | cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx); | |
6152e4b1 | 289 | pcntxt_mask = eax + ((u64)edx << 32); |
dc1e35c6 | 290 | |
6152e4b1 PA |
291 | if ((pcntxt_mask & XSTATE_FPSSE) != XSTATE_FPSSE) { |
292 | printk(KERN_ERR "FP/SSE not shown under xsave features 0x%llx\n", | |
293 | pcntxt_mask); | |
dc1e35c6 SS |
294 | BUG(); |
295 | } | |
296 | ||
297 | /* | |
298 | * for now OS knows only about FP/SSE | |
299 | */ | |
6152e4b1 | 300 | pcntxt_mask = pcntxt_mask & XCNTXT_MASK; |
dc1e35c6 SS |
301 | xsave_init(); |
302 | ||
303 | /* | |
304 | * Recompute the context size for enabled features | |
305 | */ | |
306 | cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx); | |
dc1e35c6 SS |
307 | xstate_size = ebx; |
308 | ||
c37b5efe SS |
309 | prepare_fx_sw_frame(); |
310 | ||
dc1e35c6 SS |
311 | setup_xstate_init(); |
312 | ||
6152e4b1 | 313 | printk(KERN_INFO "xsave/xrstor: enabled xstate_bv 0x%llx, " |
dc1e35c6 | 314 | "cntxt size 0x%x\n", |
6152e4b1 | 315 | pcntxt_mask, xstate_size); |
dc1e35c6 | 316 | } |