1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __X86_KERNEL_FPU_XSTATE_H
3 #define __X86_KERNEL_FPU_XSTATE_H
4
5 #include <asm/cpufeature.h>
6 #include <asm/fpu/xstate.h>
7 #include <asm/fpu/xcr.h>
8
9 #ifdef CONFIG_X86_64
10 DECLARE_PER_CPU(u64, xfd_state);
11 #endif
12
xstate_init_xcomp_bv(struct xregs_state * xsave,u64 mask)13 static inline void xstate_init_xcomp_bv(struct xregs_state *xsave, u64 mask)
14 {
15 /*
16 * XRSTORS requires these bits set in xcomp_bv, or it will
17 * trigger #GP:
18 */
19 if (cpu_feature_enabled(X86_FEATURE_XCOMPACTED))
20 xsave->header.xcomp_bv = mask | XCOMP_BV_COMPACTED_FORMAT;
21 }
22
xstate_get_group_perm(bool guest)23 static inline u64 xstate_get_group_perm(bool guest)
24 {
25 struct fpu *fpu = ¤t->group_leader->thread.fpu;
26 struct fpu_state_perm *perm;
27
28 /* Pairs with WRITE_ONCE() in xstate_request_perm() */
29 perm = guest ? &fpu->guest_perm : &fpu->perm;
30 return READ_ONCE(perm->__state_perm);
31 }
32
xstate_get_host_group_perm(void)33 static inline u64 xstate_get_host_group_perm(void)
34 {
35 return xstate_get_group_perm(false);
36 }
37
38 enum xstate_copy_mode {
39 XSTATE_COPY_FP,
40 XSTATE_COPY_FX,
41 XSTATE_COPY_XSAVE,
42 };
43
44 struct membuf;
45 extern void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate,
46 u64 xfeatures, u32 pkru_val,
47 enum xstate_copy_mode copy_mode);
48 extern void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
49 enum xstate_copy_mode mode);
50 extern int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u32 *pkru);
51 extern int copy_sigframe_from_user_to_xstate(struct task_struct *tsk, const void __user *ubuf);
52
53
54 extern void fpu__init_cpu_xstate(void);
55 extern void fpu__init_system_xstate(unsigned int legacy_size);
56
57 extern void __user *get_xsave_addr_user(struct xregs_state __user *xsave, int xfeature_nr);
58
xfeatures_mask_supervisor(void)59 static inline u64 xfeatures_mask_supervisor(void)
60 {
61 return fpu_kernel_cfg.max_features & XFEATURE_MASK_SUPERVISOR_SUPPORTED;
62 }
63
xfeatures_mask_independent(void)64 static inline u64 xfeatures_mask_independent(void)
65 {
66 if (!cpu_feature_enabled(X86_FEATURE_ARCH_LBR))
67 return fpu_kernel_cfg.independent_features & ~XFEATURE_MASK_LBR;
68
69 return fpu_kernel_cfg.independent_features;
70 }
71
72 /*
73 * Update the value of PKRU register that was already pushed onto the signal frame.
74 */
update_pkru_in_sigframe(struct xregs_state __user * buf,u64 mask,u32 pkru)75 static inline int update_pkru_in_sigframe(struct xregs_state __user *buf, u64 mask, u32 pkru)
76 {
77 u64 xstate_bv;
78 int err;
79
80 if (unlikely(!cpu_feature_enabled(X86_FEATURE_OSPKE)))
81 return 0;
82
83 /* Mark PKRU as in-use so that it is restored correctly. */
84 xstate_bv = (mask & xfeatures_in_use()) | XFEATURE_MASK_PKRU;
85
86 err = __put_user(xstate_bv, &buf->header.xfeatures);
87 if (err)
88 return err;
89
90 /* Update PKRU value in the userspace xsave buffer. */
91 return __put_user(pkru, (unsigned int __user *)get_xsave_addr_user(buf, XFEATURE_PKRU));
92 }
93
94 /* XSAVE/XRSTOR wrapper functions */
95
96 #ifdef CONFIG_X86_64
97 #define REX_SUFFIX "64"
98 #else
99 #define REX_SUFFIX
100 #endif
101
102 #define XSAVE "xsave" REX_SUFFIX " %[xa]"
103 #define XSAVEOPT "xsaveopt" REX_SUFFIX " %[xa]"
104 #define XSAVEC "xsavec" REX_SUFFIX " %[xa]"
105 #define XSAVES "xsaves" REX_SUFFIX " %[xa]"
106 #define XRSTOR "xrstor" REX_SUFFIX " %[xa]"
107 #define XRSTORS "xrstors" REX_SUFFIX " %[xa]"
108
109 /*
110 * After this @err contains 0 on success or the trap number when the
111 * operation raises an exception.
112 *
113 * The [xa] input parameter below represents the struct xregs_state pointer
114 * and the asm symbolic name for the argument used in the XSAVE/XRSTOR insns
115 * above.
116 */
117 #define XSTATE_OP(op, st, lmask, hmask, err) \
118 asm volatile("1:" op "\n\t" \
119 "xor %[err], %[err]\n" \
120 "2:\n" \
121 _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_FAULT_MCE_SAFE) \
122 : [err] "=a" (err) \
123 : [xa] "m" (*(st)), "a" (lmask), "d" (hmask) \
124 : "memory")
125
126 /*
127 * If XSAVES is enabled, it replaces XSAVEC because it supports supervisor
128 * states in addition to XSAVEC.
129 *
130 * Otherwise if XSAVEC is enabled, it replaces XSAVEOPT because it supports
131 * compacted storage format in addition to XSAVEOPT.
132 *
133 * Otherwise, if XSAVEOPT is enabled, XSAVEOPT replaces XSAVE because XSAVEOPT
134 * supports modified optimization which is not supported by XSAVE.
135 *
136 * Use XSAVE as a fallback.
137 */
138 #define XSTATE_XSAVE(st, lmask, hmask, err) \
139 asm volatile("1: " ALTERNATIVE_3(XSAVE, \
140 XSAVEOPT, X86_FEATURE_XSAVEOPT, \
141 XSAVEC, X86_FEATURE_XSAVEC, \
142 XSAVES, X86_FEATURE_XSAVES) \
143 "\n\t" \
144 "xor %[err], %[err]\n" \
145 "3:\n" \
146 _ASM_EXTABLE_TYPE_REG(1b, 3b, EX_TYPE_EFAULT_REG, %[err]) \
147 : [err] "=r" (err) \
148 : [xa] "m" (*(st)), "a" (lmask), "d" (hmask) \
149 : "memory")
150
151 /*
152 * Use XRSTORS to restore context if it is enabled. XRSTORS supports compact
153 * XSAVE area format.
154 */
155 #define XSTATE_XRESTORE(st, lmask, hmask) \
156 asm volatile("1: " ALTERNATIVE(XRSTOR, \
157 XRSTORS, X86_FEATURE_XSAVES) \
158 "\n" \
159 "3:\n" \
160 _ASM_EXTABLE_TYPE(1b, 3b, EX_TYPE_FPU_RESTORE) \
161 : \
162 : [xa] "m" (*(st)), "a" (lmask), "d" (hmask) \
163 : "memory")
164
165 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_DEBUG_FPU)
166 extern void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor);
167 #else
xfd_validate_state(struct fpstate * fpstate,u64 mask,bool rstor)168 static inline void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor) { }
169 #endif
170
171 #ifdef CONFIG_X86_64
xfd_set_state(u64 xfd)172 static inline void xfd_set_state(u64 xfd)
173 {
174 wrmsrl(MSR_IA32_XFD, xfd);
175 __this_cpu_write(xfd_state, xfd);
176 }
177
xfd_update_state(struct fpstate * fpstate)178 static inline void xfd_update_state(struct fpstate *fpstate)
179 {
180 if (fpu_state_size_dynamic()) {
181 u64 xfd = fpstate->xfd;
182
183 if (__this_cpu_read(xfd_state) != xfd)
184 xfd_set_state(xfd);
185 }
186 }
187
188 extern int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu);
189 #else
xfd_set_state(u64 xfd)190 static inline void xfd_set_state(u64 xfd) { }
191
xfd_update_state(struct fpstate * fpstate)192 static inline void xfd_update_state(struct fpstate *fpstate) { }
193
__xfd_enable_feature(u64 which,struct fpu_guest * guest_fpu)194 static inline int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu) {
195 return -EPERM;
196 }
197 #endif
198
199 /*
200 * Save processor xstate to xsave area.
201 *
202 * Uses either XSAVE or XSAVEOPT or XSAVES depending on the CPU features
203 * and command line options. The choice is permanent until the next reboot.
204 */
os_xsave(struct fpstate * fpstate)205 static inline void os_xsave(struct fpstate *fpstate)
206 {
207 u64 mask = fpstate->xfeatures;
208 u32 lmask = mask;
209 u32 hmask = mask >> 32;
210 int err;
211
212 WARN_ON_FPU(!alternatives_patched);
213 xfd_validate_state(fpstate, mask, false);
214
215 XSTATE_XSAVE(&fpstate->regs.xsave, lmask, hmask, err);
216
217 /* We should never fault when copying to a kernel buffer: */
218 WARN_ON_FPU(err);
219 }
220
221 /*
222 * Restore processor xstate from xsave area.
223 *
224 * Uses XRSTORS when XSAVES is used, XRSTOR otherwise.
225 */
os_xrstor(struct fpstate * fpstate,u64 mask)226 static inline void os_xrstor(struct fpstate *fpstate, u64 mask)
227 {
228 u32 lmask = mask;
229 u32 hmask = mask >> 32;
230
231 xfd_validate_state(fpstate, mask, true);
232 XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask);
233 }
234
235 /* Restore of supervisor state. Does not require XFD */
os_xrstor_supervisor(struct fpstate * fpstate)236 static inline void os_xrstor_supervisor(struct fpstate *fpstate)
237 {
238 u64 mask = xfeatures_mask_supervisor();
239 u32 lmask = mask;
240 u32 hmask = mask >> 32;
241
242 XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask);
243 }
244
245 /*
246 * XSAVE itself always writes all requested xfeatures. Removing features
247 * from the request bitmap reduces the features which are written.
248 * Generate a mask of features which must be written to a sigframe. The
249 * unset features can be optimized away and not written.
250 *
251 * This optimization is user-visible. Only use for states where
252 * uninitialized sigframe contents are tolerable, like dynamic features.
253 *
254 * Users of buffers produced with this optimization must check XSTATE_BV
255 * to determine which features have been optimized out.
256 */
xfeatures_need_sigframe_write(void)257 static inline u64 xfeatures_need_sigframe_write(void)
258 {
259 u64 xfeaures_to_write;
260
261 /* In-use features must be written: */
262 xfeaures_to_write = xfeatures_in_use();
263
264 /* Also write all non-optimizable sigframe features: */
265 xfeaures_to_write |= XFEATURE_MASK_USER_SUPPORTED &
266 ~XFEATURE_MASK_SIGFRAME_INITOPT;
267
268 return xfeaures_to_write;
269 }
270
271 /*
272 * Save xstate to user space xsave area.
273 *
274 * We don't use modified optimization because xrstor/xrstors might track
275 * a different application.
276 *
277 * We don't use compacted format xsave area for backward compatibility for
278 * old applications which don't understand the compacted format of the
279 * xsave area.
280 *
281 * The caller has to zero buf::header before calling this because XSAVE*
282 * does not touch the reserved fields in the header.
283 */
xsave_to_user_sigframe(struct xregs_state __user * buf,u32 pkru)284 static inline int xsave_to_user_sigframe(struct xregs_state __user *buf, u32 pkru)
285 {
286 /*
287 * Include the features which are not xsaved/rstored by the kernel
288 * internally, e.g. PKRU. That's user space ABI and also required
289 * to allow the signal handler to modify PKRU.
290 */
291 struct fpstate *fpstate = current->thread.fpu.fpstate;
292 u64 mask = fpstate->user_xfeatures;
293 u32 lmask;
294 u32 hmask;
295 int err;
296
297 /* Optimize away writing unnecessary xfeatures: */
298 if (fpu_state_size_dynamic())
299 mask &= xfeatures_need_sigframe_write();
300
301 lmask = mask;
302 hmask = mask >> 32;
303 xfd_validate_state(fpstate, mask, false);
304
305 stac();
306 XSTATE_OP(XSAVE, buf, lmask, hmask, err);
307 clac();
308
309 if (!err)
310 err = update_pkru_in_sigframe(buf, mask, pkru);
311
312 return err;
313 }
314
315 /*
316 * Restore xstate from user space xsave area.
317 */
xrstor_from_user_sigframe(struct xregs_state __user * buf,u64 mask)318 static inline int xrstor_from_user_sigframe(struct xregs_state __user *buf, u64 mask)
319 {
320 struct xregs_state *xstate = ((__force struct xregs_state *)buf);
321 u32 lmask = mask;
322 u32 hmask = mask >> 32;
323 int err;
324
325 xfd_validate_state(current->thread.fpu.fpstate, mask, true);
326
327 stac();
328 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
329 clac();
330
331 return err;
332 }
333
334 /*
335 * Restore xstate from kernel space xsave area, return an error code instead of
336 * an exception.
337 */
os_xrstor_safe(struct fpstate * fpstate,u64 mask)338 static inline int os_xrstor_safe(struct fpstate *fpstate, u64 mask)
339 {
340 struct xregs_state *xstate = &fpstate->regs.xsave;
341 u32 lmask = mask;
342 u32 hmask = mask >> 32;
343 int err;
344
345 /* Ensure that XFD is up to date */
346 xfd_update_state(fpstate);
347
348 if (cpu_feature_enabled(X86_FEATURE_XSAVES))
349 XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
350 else
351 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
352
353 return err;
354 }
355
356
357 #endif
358