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 *get_xsave_addr(struct xregs_state *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 /* XSAVE/XRSTOR wrapper functions */ 73 74 #ifdef CONFIG_X86_64 75 #define REX_PREFIX "0x48, " 76 #else 77 #define REX_PREFIX 78 #endif 79 80 /* These macros all use (%edi)/(%rdi) as the single memory argument. */ 81 #define XSAVE ".byte " REX_PREFIX "0x0f,0xae,0x27" 82 #define XSAVEOPT ".byte " REX_PREFIX "0x0f,0xae,0x37" 83 #define XSAVEC ".byte " REX_PREFIX "0x0f,0xc7,0x27" 84 #define XSAVES ".byte " REX_PREFIX "0x0f,0xc7,0x2f" 85 #define XRSTOR ".byte " REX_PREFIX "0x0f,0xae,0x2f" 86 #define XRSTORS ".byte " REX_PREFIX "0x0f,0xc7,0x1f" 87 88 /* 89 * After this @err contains 0 on success or the trap number when the 90 * operation raises an exception. 91 */ 92 #define XSTATE_OP(op, st, lmask, hmask, err) \ 93 asm volatile("1:" op "\n\t" \ 94 "xor %[err], %[err]\n" \ 95 "2:\n\t" \ 96 _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_FAULT_MCE_SAFE) \ 97 : [err] "=a" (err) \ 98 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ 99 : "memory") 100 101 /* 102 * If XSAVES is enabled, it replaces XSAVEC because it supports supervisor 103 * states in addition to XSAVEC. 104 * 105 * Otherwise if XSAVEC is enabled, it replaces XSAVEOPT because it supports 106 * compacted storage format in addition to XSAVEOPT. 107 * 108 * Otherwise, if XSAVEOPT is enabled, XSAVEOPT replaces XSAVE because XSAVEOPT 109 * supports modified optimization which is not supported by XSAVE. 110 * 111 * We use XSAVE as a fallback. 112 * 113 * The 661 label is defined in the ALTERNATIVE* macros as the address of the 114 * original instruction which gets replaced. We need to use it here as the 115 * address of the instruction where we might get an exception at. 116 */ 117 #define XSTATE_XSAVE(st, lmask, hmask, err) \ 118 asm volatile(ALTERNATIVE_3(XSAVE, \ 119 XSAVEOPT, X86_FEATURE_XSAVEOPT, \ 120 XSAVEC, X86_FEATURE_XSAVEC, \ 121 XSAVES, X86_FEATURE_XSAVES) \ 122 "\n" \ 123 "xor %[err], %[err]\n" \ 124 "3:\n" \ 125 _ASM_EXTABLE_TYPE_REG(661b, 3b, EX_TYPE_EFAULT_REG, %[err]) \ 126 : [err] "=r" (err) \ 127 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ 128 : "memory") 129 130 /* 131 * Use XRSTORS to restore context if it is enabled. XRSTORS supports compact 132 * XSAVE area format. 133 */ 134 #define XSTATE_XRESTORE(st, lmask, hmask) \ 135 asm volatile(ALTERNATIVE(XRSTOR, \ 136 XRSTORS, X86_FEATURE_XSAVES) \ 137 "\n" \ 138 "3:\n" \ 139 _ASM_EXTABLE_TYPE(661b, 3b, EX_TYPE_FPU_RESTORE) \ 140 : \ 141 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ 142 : "memory") 143 144 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_DEBUG_FPU) 145 extern void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor); 146 #else 147 static inline void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor) { } 148 #endif 149 150 #ifdef CONFIG_X86_64 151 static inline void xfd_set_state(u64 xfd) 152 { 153 wrmsrl(MSR_IA32_XFD, xfd); 154 __this_cpu_write(xfd_state, xfd); 155 } 156 157 static inline void xfd_update_state(struct fpstate *fpstate) 158 { 159 if (fpu_state_size_dynamic()) { 160 u64 xfd = fpstate->xfd; 161 162 if (__this_cpu_read(xfd_state) != xfd) 163 xfd_set_state(xfd); 164 } 165 } 166 167 extern int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu); 168 #else 169 static inline void xfd_set_state(u64 xfd) { } 170 171 static inline void xfd_update_state(struct fpstate *fpstate) { } 172 173 static inline int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu) { 174 return -EPERM; 175 } 176 #endif 177 178 /* 179 * Save processor xstate to xsave area. 180 * 181 * Uses either XSAVE or XSAVEOPT or XSAVES depending on the CPU features 182 * and command line options. The choice is permanent until the next reboot. 183 */ 184 static inline void os_xsave(struct fpstate *fpstate) 185 { 186 u64 mask = fpstate->xfeatures; 187 u32 lmask = mask; 188 u32 hmask = mask >> 32; 189 int err; 190 191 WARN_ON_FPU(!alternatives_patched); 192 xfd_validate_state(fpstate, mask, false); 193 194 XSTATE_XSAVE(&fpstate->regs.xsave, lmask, hmask, err); 195 196 /* We should never fault when copying to a kernel buffer: */ 197 WARN_ON_FPU(err); 198 } 199 200 /* 201 * Restore processor xstate from xsave area. 202 * 203 * Uses XRSTORS when XSAVES is used, XRSTOR otherwise. 204 */ 205 static inline void os_xrstor(struct fpstate *fpstate, u64 mask) 206 { 207 u32 lmask = mask; 208 u32 hmask = mask >> 32; 209 210 xfd_validate_state(fpstate, mask, true); 211 XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask); 212 } 213 214 /* Restore of supervisor state. Does not require XFD */ 215 static inline void os_xrstor_supervisor(struct fpstate *fpstate) 216 { 217 u64 mask = xfeatures_mask_supervisor(); 218 u32 lmask = mask; 219 u32 hmask = mask >> 32; 220 221 XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask); 222 } 223 224 /* 225 * XSAVE itself always writes all requested xfeatures. Removing features 226 * from the request bitmap reduces the features which are written. 227 * Generate a mask of features which must be written to a sigframe. The 228 * unset features can be optimized away and not written. 229 * 230 * This optimization is user-visible. Only use for states where 231 * uninitialized sigframe contents are tolerable, like dynamic features. 232 * 233 * Users of buffers produced with this optimization must check XSTATE_BV 234 * to determine which features have been optimized out. 235 */ 236 static inline u64 xfeatures_need_sigframe_write(void) 237 { 238 u64 xfeaures_to_write; 239 240 /* In-use features must be written: */ 241 xfeaures_to_write = xfeatures_in_use(); 242 243 /* Also write all non-optimizable sigframe features: */ 244 xfeaures_to_write |= XFEATURE_MASK_USER_SUPPORTED & 245 ~XFEATURE_MASK_SIGFRAME_INITOPT; 246 247 return xfeaures_to_write; 248 } 249 250 /* 251 * Save xstate to user space xsave area. 252 * 253 * We don't use modified optimization because xrstor/xrstors might track 254 * a different application. 255 * 256 * We don't use compacted format xsave area for backward compatibility for 257 * old applications which don't understand the compacted format of the 258 * xsave area. 259 * 260 * The caller has to zero buf::header before calling this because XSAVE* 261 * does not touch the reserved fields in the header. 262 */ 263 static inline int xsave_to_user_sigframe(struct xregs_state __user *buf) 264 { 265 /* 266 * Include the features which are not xsaved/rstored by the kernel 267 * internally, e.g. PKRU. That's user space ABI and also required 268 * to allow the signal handler to modify PKRU. 269 */ 270 struct fpstate *fpstate = current->thread.fpu.fpstate; 271 u64 mask = fpstate->user_xfeatures; 272 u32 lmask; 273 u32 hmask; 274 int err; 275 276 /* Optimize away writing unnecessary xfeatures: */ 277 if (fpu_state_size_dynamic()) 278 mask &= xfeatures_need_sigframe_write(); 279 280 lmask = mask; 281 hmask = mask >> 32; 282 xfd_validate_state(fpstate, mask, false); 283 284 stac(); 285 XSTATE_OP(XSAVE, buf, lmask, hmask, err); 286 clac(); 287 288 return err; 289 } 290 291 /* 292 * Restore xstate from user space xsave area. 293 */ 294 static inline int xrstor_from_user_sigframe(struct xregs_state __user *buf, u64 mask) 295 { 296 struct xregs_state *xstate = ((__force struct xregs_state *)buf); 297 u32 lmask = mask; 298 u32 hmask = mask >> 32; 299 int err; 300 301 xfd_validate_state(current->thread.fpu.fpstate, mask, true); 302 303 stac(); 304 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err); 305 clac(); 306 307 return err; 308 } 309 310 /* 311 * Restore xstate from kernel space xsave area, return an error code instead of 312 * an exception. 313 */ 314 static inline int os_xrstor_safe(struct fpstate *fpstate, u64 mask) 315 { 316 struct xregs_state *xstate = &fpstate->regs.xsave; 317 u32 lmask = mask; 318 u32 hmask = mask >> 32; 319 int err; 320 321 /* Ensure that XFD is up to date */ 322 xfd_update_state(fpstate); 323 324 if (cpu_feature_enabled(X86_FEATURE_XSAVES)) 325 XSTATE_OP(XRSTORS, xstate, lmask, hmask, err); 326 else 327 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err); 328 329 return err; 330 } 331 332 333 #endif 334