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 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 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 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 59 static inline u64 xfeatures_mask_supervisor(void) 60 { 61 return fpu_kernel_cfg.max_features & XFEATURE_MASK_SUPERVISOR_SUPPORTED; 62 } 63 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 */ 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_PREFIX "0x48, " 98 #else 99 #define REX_PREFIX 100 #endif 101 102 /* These macros all use (%edi)/(%rdi) as the single memory argument. */ 103 #define XSAVE ".byte " REX_PREFIX "0x0f,0xae,0x27" 104 #define XSAVEOPT ".byte " REX_PREFIX "0x0f,0xae,0x37" 105 #define XSAVEC ".byte " REX_PREFIX "0x0f,0xc7,0x27" 106 #define XSAVES ".byte " REX_PREFIX "0x0f,0xc7,0x2f" 107 #define XRSTOR ".byte " REX_PREFIX "0x0f,0xae,0x2f" 108 #define XRSTORS ".byte " REX_PREFIX "0x0f,0xc7,0x1f" 109 110 /* 111 * After this @err contains 0 on success or the trap number when the 112 * operation raises an exception. 113 */ 114 #define XSTATE_OP(op, st, lmask, hmask, err) \ 115 asm volatile("1:" op "\n\t" \ 116 "xor %[err], %[err]\n" \ 117 "2:\n\t" \ 118 _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_FAULT_MCE_SAFE) \ 119 : [err] "=a" (err) \ 120 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ 121 : "memory") 122 123 /* 124 * If XSAVES is enabled, it replaces XSAVEC because it supports supervisor 125 * states in addition to XSAVEC. 126 * 127 * Otherwise if XSAVEC is enabled, it replaces XSAVEOPT because it supports 128 * compacted storage format in addition to XSAVEOPT. 129 * 130 * Otherwise, if XSAVEOPT is enabled, XSAVEOPT replaces XSAVE because XSAVEOPT 131 * supports modified optimization which is not supported by XSAVE. 132 * 133 * Use XSAVE as a fallback. 134 */ 135 #define XSTATE_XSAVE(st, lmask, hmask, err) \ 136 asm volatile("1: " ALTERNATIVE_3(XSAVE, \ 137 XSAVEOPT, X86_FEATURE_XSAVEOPT, \ 138 XSAVEC, X86_FEATURE_XSAVEC, \ 139 XSAVES, X86_FEATURE_XSAVES) \ 140 "\n" \ 141 "xor %[err], %[err]\n" \ 142 "3:\n" \ 143 _ASM_EXTABLE_TYPE_REG(1b, 3b, EX_TYPE_EFAULT_REG, %[err]) \ 144 : [err] "=r" (err) \ 145 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ 146 : "memory") 147 148 /* 149 * Use XRSTORS to restore context if it is enabled. XRSTORS supports compact 150 * XSAVE area format. 151 */ 152 #define XSTATE_XRESTORE(st, lmask, hmask) \ 153 asm volatile("1: " ALTERNATIVE(XRSTOR, \ 154 XRSTORS, X86_FEATURE_XSAVES) \ 155 "\n" \ 156 "3:\n" \ 157 _ASM_EXTABLE_TYPE(1b, 3b, EX_TYPE_FPU_RESTORE) \ 158 : \ 159 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ 160 : "memory") 161 162 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_DEBUG_FPU) 163 extern void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor); 164 #else 165 static inline void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor) { } 166 #endif 167 168 #ifdef CONFIG_X86_64 169 static inline void xfd_set_state(u64 xfd) 170 { 171 wrmsrl(MSR_IA32_XFD, xfd); 172 __this_cpu_write(xfd_state, xfd); 173 } 174 175 static inline void xfd_update_state(struct fpstate *fpstate) 176 { 177 if (fpu_state_size_dynamic()) { 178 u64 xfd = fpstate->xfd; 179 180 if (__this_cpu_read(xfd_state) != xfd) 181 xfd_set_state(xfd); 182 } 183 } 184 185 extern int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu); 186 #else 187 static inline void xfd_set_state(u64 xfd) { } 188 189 static inline void xfd_update_state(struct fpstate *fpstate) { } 190 191 static inline int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu) { 192 return -EPERM; 193 } 194 #endif 195 196 /* 197 * Save processor xstate to xsave area. 198 * 199 * Uses either XSAVE or XSAVEOPT or XSAVES depending on the CPU features 200 * and command line options. The choice is permanent until the next reboot. 201 */ 202 static inline void os_xsave(struct fpstate *fpstate) 203 { 204 u64 mask = fpstate->xfeatures; 205 u32 lmask = mask; 206 u32 hmask = mask >> 32; 207 int err; 208 209 WARN_ON_FPU(!alternatives_patched); 210 xfd_validate_state(fpstate, mask, false); 211 212 XSTATE_XSAVE(&fpstate->regs.xsave, lmask, hmask, err); 213 214 /* We should never fault when copying to a kernel buffer: */ 215 WARN_ON_FPU(err); 216 } 217 218 /* 219 * Restore processor xstate from xsave area. 220 * 221 * Uses XRSTORS when XSAVES is used, XRSTOR otherwise. 222 */ 223 static inline void os_xrstor(struct fpstate *fpstate, u64 mask) 224 { 225 u32 lmask = mask; 226 u32 hmask = mask >> 32; 227 228 xfd_validate_state(fpstate, mask, true); 229 XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask); 230 } 231 232 /* Restore of supervisor state. Does not require XFD */ 233 static inline void os_xrstor_supervisor(struct fpstate *fpstate) 234 { 235 u64 mask = xfeatures_mask_supervisor(); 236 u32 lmask = mask; 237 u32 hmask = mask >> 32; 238 239 XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask); 240 } 241 242 /* 243 * XSAVE itself always writes all requested xfeatures. Removing features 244 * from the request bitmap reduces the features which are written. 245 * Generate a mask of features which must be written to a sigframe. The 246 * unset features can be optimized away and not written. 247 * 248 * This optimization is user-visible. Only use for states where 249 * uninitialized sigframe contents are tolerable, like dynamic features. 250 * 251 * Users of buffers produced with this optimization must check XSTATE_BV 252 * to determine which features have been optimized out. 253 */ 254 static inline u64 xfeatures_need_sigframe_write(void) 255 { 256 u64 xfeaures_to_write; 257 258 /* In-use features must be written: */ 259 xfeaures_to_write = xfeatures_in_use(); 260 261 /* Also write all non-optimizable sigframe features: */ 262 xfeaures_to_write |= XFEATURE_MASK_USER_SUPPORTED & 263 ~XFEATURE_MASK_SIGFRAME_INITOPT; 264 265 return xfeaures_to_write; 266 } 267 268 /* 269 * Save xstate to user space xsave area. 270 * 271 * We don't use modified optimization because xrstor/xrstors might track 272 * a different application. 273 * 274 * We don't use compacted format xsave area for backward compatibility for 275 * old applications which don't understand the compacted format of the 276 * xsave area. 277 * 278 * The caller has to zero buf::header before calling this because XSAVE* 279 * does not touch the reserved fields in the header. 280 */ 281 static inline int xsave_to_user_sigframe(struct xregs_state __user *buf, u32 pkru) 282 { 283 /* 284 * Include the features which are not xsaved/rstored by the kernel 285 * internally, e.g. PKRU. That's user space ABI and also required 286 * to allow the signal handler to modify PKRU. 287 */ 288 struct fpstate *fpstate = current->thread.fpu.fpstate; 289 u64 mask = fpstate->user_xfeatures; 290 u32 lmask; 291 u32 hmask; 292 int err; 293 294 /* Optimize away writing unnecessary xfeatures: */ 295 if (fpu_state_size_dynamic()) 296 mask &= xfeatures_need_sigframe_write(); 297 298 lmask = mask; 299 hmask = mask >> 32; 300 xfd_validate_state(fpstate, mask, false); 301 302 stac(); 303 XSTATE_OP(XSAVE, buf, lmask, hmask, err); 304 clac(); 305 306 if (!err) 307 err = update_pkru_in_sigframe(buf, mask, pkru); 308 309 return err; 310 } 311 312 /* 313 * Restore xstate from user space xsave area. 314 */ 315 static inline int xrstor_from_user_sigframe(struct xregs_state __user *buf, u64 mask) 316 { 317 struct xregs_state *xstate = ((__force struct xregs_state *)buf); 318 u32 lmask = mask; 319 u32 hmask = mask >> 32; 320 int err; 321 322 xfd_validate_state(current->thread.fpu.fpstate, mask, true); 323 324 stac(); 325 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err); 326 clac(); 327 328 return err; 329 } 330 331 /* 332 * Restore xstate from kernel space xsave area, return an error code instead of 333 * an exception. 334 */ 335 static inline int os_xrstor_safe(struct fpstate *fpstate, u64 mask) 336 { 337 struct xregs_state *xstate = &fpstate->regs.xsave; 338 u32 lmask = mask; 339 u32 hmask = mask >> 32; 340 int err; 341 342 /* Ensure that XFD is up to date */ 343 xfd_update_state(fpstate); 344 345 if (cpu_feature_enabled(X86_FEATURE_XSAVES)) 346 XSTATE_OP(XRSTORS, xstate, lmask, hmask, err); 347 else 348 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err); 349 350 return err; 351 } 352 353 354 #endif 355