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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 | ||
85 | BUILD_BUG_ON(sizeof(struct user_i387_struct) != | |
86 | sizeof(tsk->thread.xstate->fxsave)); | |
87 | ||
c37b5efe | 88 | if ((unsigned long)buf % 64) |
ab513701 SS |
89 | printk("save_i387_xstate: bad fpstate %p\n", buf); |
90 | ||
91 | if (!used_math()) | |
92 | return 0; | |
93 | clear_used_math(); /* trigger finit */ | |
94 | if (task_thread_info(tsk)->status & TS_USEDFPU) { | |
c37b5efe SS |
95 | if (task_thread_info(tsk)->status & TS_XSAVE) |
96 | err = xsave_user(buf); | |
97 | else | |
98 | err = fxsave_user(buf); | |
99 | ||
ab513701 SS |
100 | if (err) |
101 | return err; | |
102 | task_thread_info(tsk)->status &= ~TS_USEDFPU; | |
103 | stts(); | |
104 | } else { | |
105 | if (__copy_to_user(buf, &tsk->thread.xstate->fxsave, | |
106 | xstate_size)) | |
107 | return -1; | |
108 | } | |
c37b5efe SS |
109 | |
110 | if (task_thread_info(tsk)->status & TS_XSAVE) { | |
111 | struct _fpstate __user *fx = buf; | |
112 | ||
113 | err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved, | |
114 | sizeof(struct _fpx_sw_bytes)); | |
115 | ||
116 | err |= __put_user(FP_XSTATE_MAGIC2, | |
117 | (__u32 __user *) (buf + sig_xstate_size | |
118 | - FP_XSTATE_MAGIC2_SIZE)); | |
119 | } | |
120 | ||
ab513701 SS |
121 | return 1; |
122 | } | |
123 | ||
c37b5efe SS |
124 | /* |
125 | * Restore the extended state if present. Otherwise, restore the FP/SSE | |
126 | * state. | |
127 | */ | |
128 | int restore_user_xstate(void __user *buf) | |
129 | { | |
130 | struct _fpx_sw_bytes fx_sw_user; | |
6152e4b1 | 131 | u64 mask; |
c37b5efe SS |
132 | int err; |
133 | ||
134 | if (((unsigned long)buf % 64) || | |
135 | check_for_xstate(buf, buf, &fx_sw_user)) | |
136 | goto fx_only; | |
137 | ||
6152e4b1 | 138 | mask = fx_sw_user.xstate_bv; |
c37b5efe SS |
139 | |
140 | /* | |
141 | * restore the state passed by the user. | |
142 | */ | |
6152e4b1 | 143 | err = xrestore_user(buf, mask); |
c37b5efe SS |
144 | if (err) |
145 | return err; | |
146 | ||
147 | /* | |
148 | * init the state skipped by the user. | |
149 | */ | |
6152e4b1 | 150 | mask = pcntxt_mask & ~mask; |
c37b5efe | 151 | |
6152e4b1 | 152 | xrstor_state(init_xstate_buf, mask); |
c37b5efe SS |
153 | |
154 | return 0; | |
155 | ||
156 | fx_only: | |
157 | /* | |
158 | * couldn't find the extended state information in the | |
159 | * memory layout. Restore just the FP/SSE and init all | |
160 | * the other extended state. | |
161 | */ | |
6152e4b1 | 162 | xrstor_state(init_xstate_buf, pcntxt_mask & ~XSTATE_FPSSE); |
c37b5efe SS |
163 | return fxrstor_checking((__force struct i387_fxsave_struct *)buf); |
164 | } | |
165 | ||
ab513701 SS |
166 | /* |
167 | * This restores directly out of user space. Exceptions are handled. | |
168 | */ | |
169 | int restore_i387_xstate(void __user *buf) | |
170 | { | |
171 | struct task_struct *tsk = current; | |
c37b5efe | 172 | int err = 0; |
ab513701 SS |
173 | |
174 | if (!buf) { | |
c37b5efe SS |
175 | if (used_math()) |
176 | goto clear; | |
ab513701 SS |
177 | return 0; |
178 | } else | |
179 | if (!access_ok(VERIFY_READ, buf, sig_xstate_size)) | |
180 | return -EACCES; | |
181 | ||
182 | if (!used_math()) { | |
183 | err = init_fpu(tsk); | |
184 | if (err) | |
185 | return err; | |
186 | } | |
187 | ||
188 | if (!(task_thread_info(current)->status & TS_USEDFPU)) { | |
189 | clts(); | |
190 | task_thread_info(current)->status |= TS_USEDFPU; | |
191 | } | |
c37b5efe SS |
192 | if (task_thread_info(tsk)->status & TS_XSAVE) |
193 | err = restore_user_xstate(buf); | |
194 | else | |
195 | err = fxrstor_checking((__force struct i387_fxsave_struct *) | |
196 | buf); | |
ab513701 SS |
197 | if (unlikely(err)) { |
198 | /* | |
199 | * Encountered an error while doing the restore from the | |
200 | * user buffer, clear the fpu state. | |
201 | */ | |
c37b5efe | 202 | clear: |
ab513701 SS |
203 | clear_fpu(tsk); |
204 | clear_used_math(); | |
205 | } | |
206 | return err; | |
207 | } | |
208 | #endif | |
209 | ||
c37b5efe SS |
210 | /* |
211 | * Prepare the SW reserved portion of the fxsave memory layout, indicating | |
212 | * the presence of the extended state information in the memory layout | |
213 | * pointed by the fpstate pointer in the sigcontext. | |
214 | * This will be saved when ever the FP and extended state context is | |
215 | * saved on the user stack during the signal handler delivery to the user. | |
216 | */ | |
217 | void prepare_fx_sw_frame(void) | |
218 | { | |
219 | int size_extended = (xstate_size - sizeof(struct i387_fxsave_struct)) + | |
220 | FP_XSTATE_MAGIC2_SIZE; | |
221 | ||
222 | sig_xstate_size = sizeof(struct _fpstate) + size_extended; | |
223 | ||
224 | #ifdef CONFIG_IA32_EMULATION | |
225 | sig_xstate_ia32_size = sizeof(struct _fpstate_ia32) + size_extended; | |
226 | #endif | |
227 | ||
228 | memset(&fx_sw_reserved, 0, sizeof(fx_sw_reserved)); | |
229 | ||
230 | fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1; | |
231 | fx_sw_reserved.extended_size = sig_xstate_size; | |
6152e4b1 | 232 | fx_sw_reserved.xstate_bv = pcntxt_mask; |
c37b5efe SS |
233 | fx_sw_reserved.xstate_size = xstate_size; |
234 | #ifdef CONFIG_IA32_EMULATION | |
235 | memcpy(&fx_sw_reserved_ia32, &fx_sw_reserved, | |
236 | sizeof(struct _fpx_sw_bytes)); | |
237 | fx_sw_reserved_ia32.extended_size = sig_xstate_ia32_size; | |
238 | #endif | |
239 | } | |
240 | ||
dc1e35c6 SS |
241 | /* |
242 | * Represents init state for the supported extended state. | |
243 | */ | |
244 | struct xsave_struct *init_xstate_buf; | |
245 | ||
3c1c7f10 SS |
246 | #ifdef CONFIG_X86_64 |
247 | unsigned int sig_xstate_size = sizeof(struct _fpstate); | |
248 | #endif | |
249 | ||
dc1e35c6 SS |
250 | /* |
251 | * Enable the extended processor state save/restore feature | |
252 | */ | |
253 | void __cpuinit xsave_init(void) | |
254 | { | |
255 | if (!cpu_has_xsave) | |
256 | return; | |
257 | ||
258 | set_in_cr4(X86_CR4_OSXSAVE); | |
259 | ||
260 | /* | |
261 | * Enable all the features that the HW is capable of | |
262 | * and the Linux kernel is aware of. | |
dc1e35c6 | 263 | */ |
6152e4b1 | 264 | xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask); |
dc1e35c6 SS |
265 | } |
266 | ||
267 | /* | |
268 | * setup the xstate image representing the init state | |
269 | */ | |
270 | void setup_xstate_init(void) | |
271 | { | |
272 | init_xstate_buf = alloc_bootmem(xstate_size); | |
273 | init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT; | |
274 | } | |
275 | ||
276 | /* | |
277 | * Enable and initialize the xsave feature. | |
278 | */ | |
279 | void __init xsave_cntxt_init(void) | |
280 | { | |
281 | unsigned int eax, ebx, ecx, edx; | |
282 | ||
283 | cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx); | |
6152e4b1 | 284 | pcntxt_mask = eax + ((u64)edx << 32); |
dc1e35c6 | 285 | |
6152e4b1 PA |
286 | if ((pcntxt_mask & XSTATE_FPSSE) != XSTATE_FPSSE) { |
287 | printk(KERN_ERR "FP/SSE not shown under xsave features 0x%llx\n", | |
288 | pcntxt_mask); | |
dc1e35c6 SS |
289 | BUG(); |
290 | } | |
291 | ||
292 | /* | |
293 | * for now OS knows only about FP/SSE | |
294 | */ | |
6152e4b1 | 295 | pcntxt_mask = pcntxt_mask & XCNTXT_MASK; |
dc1e35c6 SS |
296 | xsave_init(); |
297 | ||
298 | /* | |
299 | * Recompute the context size for enabled features | |
300 | */ | |
301 | cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx); | |
dc1e35c6 SS |
302 | xstate_size = ebx; |
303 | ||
c37b5efe SS |
304 | prepare_fx_sw_frame(); |
305 | ||
dc1e35c6 SS |
306 | setup_xstate_init(); |
307 | ||
6152e4b1 | 308 | printk(KERN_INFO "xsave/xrstor: enabled xstate_bv 0x%llx, " |
dc1e35c6 | 309 | "cntxt size 0x%x\n", |
6152e4b1 | 310 | pcntxt_mask, xstate_size); |
dc1e35c6 | 311 | } |