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_XSAVES))
20 xsave->header.xcomp_bv = mask | XCOMP_BV_COMPACTED_FORMAT;
21 }
22
xstate_get_host_group_perm(void)23 static inline u64 xstate_get_host_group_perm(void)
24 {
25 /* Pairs with WRITE_ONCE() in xstate_request_perm() */
26 return READ_ONCE(current->group_leader->thread.fpu.perm.__state_perm);
27 }
28
29 enum xstate_copy_mode {
30 XSTATE_COPY_FP,
31 XSTATE_COPY_FX,
32 XSTATE_COPY_XSAVE,
33 };
34
35 struct membuf;
36 extern void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate,
37 u32 pkru_val, enum xstate_copy_mode copy_mode);
38 extern void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
39 enum xstate_copy_mode mode);
40 extern int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf);
41 extern int copy_sigframe_from_user_to_xstate(struct fpstate *fpstate, const void __user *ubuf);
42
43
44 extern void fpu__init_cpu_xstate(void);
45 extern void fpu__init_system_xstate(unsigned int legacy_size);
46
47 extern void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr);
48
xfeatures_mask_supervisor(void)49 static inline u64 xfeatures_mask_supervisor(void)
50 {
51 return fpu_kernel_cfg.max_features & XFEATURE_MASK_SUPERVISOR_SUPPORTED;
52 }
53
xfeatures_mask_independent(void)54 static inline u64 xfeatures_mask_independent(void)
55 {
56 if (!cpu_feature_enabled(X86_FEATURE_ARCH_LBR))
57 return XFEATURE_MASK_INDEPENDENT & ~XFEATURE_MASK_LBR;
58
59 return XFEATURE_MASK_INDEPENDENT;
60 }
61
62 /* XSAVE/XRSTOR wrapper functions */
63
64 #ifdef CONFIG_X86_64
65 #define REX_PREFIX "0x48, "
66 #else
67 #define REX_PREFIX
68 #endif
69
70 /* These macros all use (%edi)/(%rdi) as the single memory argument. */
71 #define XSAVE ".byte " REX_PREFIX "0x0f,0xae,0x27"
72 #define XSAVEOPT ".byte " REX_PREFIX "0x0f,0xae,0x37"
73 #define XSAVES ".byte " REX_PREFIX "0x0f,0xc7,0x2f"
74 #define XRSTOR ".byte " REX_PREFIX "0x0f,0xae,0x2f"
75 #define XRSTORS ".byte " REX_PREFIX "0x0f,0xc7,0x1f"
76
77 /*
78 * After this @err contains 0 on success or the trap number when the
79 * operation raises an exception.
80 */
81 #define XSTATE_OP(op, st, lmask, hmask, err) \
82 asm volatile("1:" op "\n\t" \
83 "xor %[err], %[err]\n" \
84 "2:\n\t" \
85 _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_FAULT_MCE_SAFE) \
86 : [err] "=a" (err) \
87 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \
88 : "memory")
89
90 /*
91 * If XSAVES is enabled, it replaces XSAVEOPT because it supports a compact
92 * format and supervisor states in addition to modified optimization in
93 * XSAVEOPT.
94 *
95 * Otherwise, if XSAVEOPT is enabled, XSAVEOPT replaces XSAVE because XSAVEOPT
96 * supports modified optimization which is not supported by XSAVE.
97 *
98 * We use XSAVE as a fallback.
99 *
100 * The 661 label is defined in the ALTERNATIVE* macros as the address of the
101 * original instruction which gets replaced. We need to use it here as the
102 * address of the instruction where we might get an exception at.
103 */
104 #define XSTATE_XSAVE(st, lmask, hmask, err) \
105 asm volatile(ALTERNATIVE_2(XSAVE, \
106 XSAVEOPT, X86_FEATURE_XSAVEOPT, \
107 XSAVES, X86_FEATURE_XSAVES) \
108 "\n" \
109 "xor %[err], %[err]\n" \
110 "3:\n" \
111 ".pushsection .fixup,\"ax\"\n" \
112 "4: movl $-2, %[err]\n" \
113 "jmp 3b\n" \
114 ".popsection\n" \
115 _ASM_EXTABLE(661b, 4b) \
116 : [err] "=r" (err) \
117 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \
118 : "memory")
119
120 /*
121 * Use XRSTORS to restore context if it is enabled. XRSTORS supports compact
122 * XSAVE area format.
123 */
124 #define XSTATE_XRESTORE(st, lmask, hmask) \
125 asm volatile(ALTERNATIVE(XRSTOR, \
126 XRSTORS, X86_FEATURE_XSAVES) \
127 "\n" \
128 "3:\n" \
129 _ASM_EXTABLE_TYPE(661b, 3b, EX_TYPE_FPU_RESTORE) \
130 : \
131 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \
132 : "memory")
133
134 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_DEBUG_FPU)
135 extern void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor);
136 #else
xfd_validate_state(struct fpstate * fpstate,u64 mask,bool rstor)137 static inline void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor) { }
138 #endif
139
140 #ifdef CONFIG_X86_64
xfd_update_state(struct fpstate * fpstate)141 static inline void xfd_update_state(struct fpstate *fpstate)
142 {
143 if (fpu_state_size_dynamic()) {
144 u64 xfd = fpstate->xfd;
145
146 if (__this_cpu_read(xfd_state) != xfd) {
147 wrmsrl(MSR_IA32_XFD, xfd);
148 __this_cpu_write(xfd_state, xfd);
149 }
150 }
151 }
152 #else
xfd_update_state(struct fpstate * fpstate)153 static inline void xfd_update_state(struct fpstate *fpstate) { }
154 #endif
155
156 /*
157 * Save processor xstate to xsave area.
158 *
159 * Uses either XSAVE or XSAVEOPT or XSAVES depending on the CPU features
160 * and command line options. The choice is permanent until the next reboot.
161 */
os_xsave(struct fpstate * fpstate)162 static inline void os_xsave(struct fpstate *fpstate)
163 {
164 u64 mask = fpstate->xfeatures;
165 u32 lmask = mask;
166 u32 hmask = mask >> 32;
167 int err;
168
169 WARN_ON_FPU(!alternatives_patched);
170 xfd_validate_state(fpstate, mask, false);
171
172 XSTATE_XSAVE(&fpstate->regs.xsave, lmask, hmask, err);
173
174 /* We should never fault when copying to a kernel buffer: */
175 WARN_ON_FPU(err);
176 }
177
178 /*
179 * Restore processor xstate from xsave area.
180 *
181 * Uses XRSTORS when XSAVES is used, XRSTOR otherwise.
182 */
os_xrstor(struct fpstate * fpstate,u64 mask)183 static inline void os_xrstor(struct fpstate *fpstate, u64 mask)
184 {
185 u32 lmask = mask;
186 u32 hmask = mask >> 32;
187
188 xfd_validate_state(fpstate, mask, true);
189 XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask);
190 }
191
192 /* Restore of supervisor state. Does not require XFD */
os_xrstor_supervisor(struct fpstate * fpstate)193 static inline void os_xrstor_supervisor(struct fpstate *fpstate)
194 {
195 u64 mask = xfeatures_mask_supervisor();
196 u32 lmask = mask;
197 u32 hmask = mask >> 32;
198
199 XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask);
200 }
201
202 /*
203 * XSAVE itself always writes all requested xfeatures. Removing features
204 * from the request bitmap reduces the features which are written.
205 * Generate a mask of features which must be written to a sigframe. The
206 * unset features can be optimized away and not written.
207 *
208 * This optimization is user-visible. Only use for states where
209 * uninitialized sigframe contents are tolerable, like dynamic features.
210 *
211 * Users of buffers produced with this optimization must check XSTATE_BV
212 * to determine which features have been optimized out.
213 */
xfeatures_need_sigframe_write(void)214 static inline u64 xfeatures_need_sigframe_write(void)
215 {
216 u64 xfeaures_to_write;
217
218 /* In-use features must be written: */
219 xfeaures_to_write = xfeatures_in_use();
220
221 /* Also write all non-optimizable sigframe features: */
222 xfeaures_to_write |= XFEATURE_MASK_USER_SUPPORTED &
223 ~XFEATURE_MASK_SIGFRAME_INITOPT;
224
225 return xfeaures_to_write;
226 }
227
228 /*
229 * Save xstate to user space xsave area.
230 *
231 * We don't use modified optimization because xrstor/xrstors might track
232 * a different application.
233 *
234 * We don't use compacted format xsave area for backward compatibility for
235 * old applications which don't understand the compacted format of the
236 * xsave area.
237 *
238 * The caller has to zero buf::header before calling this because XSAVE*
239 * does not touch the reserved fields in the header.
240 */
xsave_to_user_sigframe(struct xregs_state __user * buf)241 static inline int xsave_to_user_sigframe(struct xregs_state __user *buf)
242 {
243 /*
244 * Include the features which are not xsaved/rstored by the kernel
245 * internally, e.g. PKRU. That's user space ABI and also required
246 * to allow the signal handler to modify PKRU.
247 */
248 struct fpstate *fpstate = current->thread.fpu.fpstate;
249 u64 mask = fpstate->user_xfeatures;
250 u32 lmask;
251 u32 hmask;
252 int err;
253
254 /* Optimize away writing unnecessary xfeatures: */
255 if (fpu_state_size_dynamic())
256 mask &= xfeatures_need_sigframe_write();
257
258 lmask = mask;
259 hmask = mask >> 32;
260 xfd_validate_state(fpstate, mask, false);
261
262 stac();
263 XSTATE_OP(XSAVE, buf, lmask, hmask, err);
264 clac();
265
266 return err;
267 }
268
269 /*
270 * Restore xstate from user space xsave area.
271 */
xrstor_from_user_sigframe(struct xregs_state __user * buf,u64 mask)272 static inline int xrstor_from_user_sigframe(struct xregs_state __user *buf, u64 mask)
273 {
274 struct xregs_state *xstate = ((__force struct xregs_state *)buf);
275 u32 lmask = mask;
276 u32 hmask = mask >> 32;
277 int err;
278
279 xfd_validate_state(current->thread.fpu.fpstate, mask, true);
280
281 stac();
282 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
283 clac();
284
285 return err;
286 }
287
288 /*
289 * Restore xstate from kernel space xsave area, return an error code instead of
290 * an exception.
291 */
os_xrstor_safe(struct fpstate * fpstate,u64 mask)292 static inline int os_xrstor_safe(struct fpstate *fpstate, u64 mask)
293 {
294 struct xregs_state *xstate = &fpstate->regs.xsave;
295 u32 lmask = mask;
296 u32 hmask = mask >> 32;
297 int err;
298
299 /* Ensure that XFD is up to date */
300 xfd_update_state(fpstate);
301
302 if (cpu_feature_enabled(X86_FEATURE_XSAVES))
303 XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
304 else
305 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
306
307 return err;
308 }
309
310
311 #endif
312