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_XSAVES)) 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 u32 pkru_val, enum xstate_copy_mode copy_mode); 47 extern void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk, 48 enum xstate_copy_mode mode); 49 extern int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf); 50 extern int copy_sigframe_from_user_to_xstate(struct fpstate *fpstate, const void __user *ubuf); 51 52 53 extern void fpu__init_cpu_xstate(void); 54 extern void fpu__init_system_xstate(unsigned int legacy_size); 55 56 extern void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr); 57 58 static inline u64 xfeatures_mask_supervisor(void) 59 { 60 return fpu_kernel_cfg.max_features & XFEATURE_MASK_SUPERVISOR_SUPPORTED; 61 } 62 63 static inline u64 xfeatures_mask_independent(void) 64 { 65 if (!cpu_feature_enabled(X86_FEATURE_ARCH_LBR)) 66 return XFEATURE_MASK_INDEPENDENT & ~XFEATURE_MASK_LBR; 67 68 return XFEATURE_MASK_INDEPENDENT; 69 } 70 71 /* XSAVE/XRSTOR wrapper functions */ 72 73 #ifdef CONFIG_X86_64 74 #define REX_PREFIX "0x48, " 75 #else 76 #define REX_PREFIX 77 #endif 78 79 /* These macros all use (%edi)/(%rdi) as the single memory argument. */ 80 #define XSAVE ".byte " REX_PREFIX "0x0f,0xae,0x27" 81 #define XSAVEOPT ".byte " REX_PREFIX "0x0f,0xae,0x37" 82 #define XSAVES ".byte " REX_PREFIX "0x0f,0xc7,0x2f" 83 #define XRSTOR ".byte " REX_PREFIX "0x0f,0xae,0x2f" 84 #define XRSTORS ".byte " REX_PREFIX "0x0f,0xc7,0x1f" 85 86 /* 87 * After this @err contains 0 on success or the trap number when the 88 * operation raises an exception. 89 */ 90 #define XSTATE_OP(op, st, lmask, hmask, err) \ 91 asm volatile("1:" op "\n\t" \ 92 "xor %[err], %[err]\n" \ 93 "2:\n\t" \ 94 _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_FAULT_MCE_SAFE) \ 95 : [err] "=a" (err) \ 96 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ 97 : "memory") 98 99 /* 100 * If XSAVES is enabled, it replaces XSAVEOPT because it supports a compact 101 * format and supervisor states in addition to modified optimization in 102 * XSAVEOPT. 103 * 104 * Otherwise, if XSAVEOPT is enabled, XSAVEOPT replaces XSAVE because XSAVEOPT 105 * supports modified optimization which is not supported by XSAVE. 106 * 107 * We use XSAVE as a fallback. 108 * 109 * The 661 label is defined in the ALTERNATIVE* macros as the address of the 110 * original instruction which gets replaced. We need to use it here as the 111 * address of the instruction where we might get an exception at. 112 */ 113 #define XSTATE_XSAVE(st, lmask, hmask, err) \ 114 asm volatile(ALTERNATIVE_2(XSAVE, \ 115 XSAVEOPT, X86_FEATURE_XSAVEOPT, \ 116 XSAVES, X86_FEATURE_XSAVES) \ 117 "\n" \ 118 "xor %[err], %[err]\n" \ 119 "3:\n" \ 120 _ASM_EXTABLE_TYPE_REG(661b, 3b, EX_TYPE_EFAULT_REG, %[err]) \ 121 : [err] "=r" (err) \ 122 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ 123 : "memory") 124 125 /* 126 * Use XRSTORS to restore context if it is enabled. XRSTORS supports compact 127 * XSAVE area format. 128 */ 129 #define XSTATE_XRESTORE(st, lmask, hmask) \ 130 asm volatile(ALTERNATIVE(XRSTOR, \ 131 XRSTORS, X86_FEATURE_XSAVES) \ 132 "\n" \ 133 "3:\n" \ 134 _ASM_EXTABLE_TYPE(661b, 3b, EX_TYPE_FPU_RESTORE) \ 135 : \ 136 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ 137 : "memory") 138 139 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_DEBUG_FPU) 140 extern void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor); 141 #else 142 static inline void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor) { } 143 #endif 144 145 #ifdef CONFIG_X86_64 146 static inline void xfd_update_state(struct fpstate *fpstate) 147 { 148 if (fpu_state_size_dynamic()) { 149 u64 xfd = fpstate->xfd; 150 151 if (__this_cpu_read(xfd_state) != xfd) { 152 wrmsrl(MSR_IA32_XFD, xfd); 153 __this_cpu_write(xfd_state, xfd); 154 } 155 } 156 } 157 158 extern int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu); 159 #else 160 static inline void xfd_update_state(struct fpstate *fpstate) { } 161 162 static inline int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu) { 163 return -EPERM; 164 } 165 #endif 166 167 /* 168 * Save processor xstate to xsave area. 169 * 170 * Uses either XSAVE or XSAVEOPT or XSAVES depending on the CPU features 171 * and command line options. The choice is permanent until the next reboot. 172 */ 173 static inline void os_xsave(struct fpstate *fpstate) 174 { 175 u64 mask = fpstate->xfeatures; 176 u32 lmask = mask; 177 u32 hmask = mask >> 32; 178 int err; 179 180 WARN_ON_FPU(!alternatives_patched); 181 xfd_validate_state(fpstate, mask, false); 182 183 XSTATE_XSAVE(&fpstate->regs.xsave, lmask, hmask, err); 184 185 /* We should never fault when copying to a kernel buffer: */ 186 WARN_ON_FPU(err); 187 } 188 189 /* 190 * Restore processor xstate from xsave area. 191 * 192 * Uses XRSTORS when XSAVES is used, XRSTOR otherwise. 193 */ 194 static inline void os_xrstor(struct fpstate *fpstate, u64 mask) 195 { 196 u32 lmask = mask; 197 u32 hmask = mask >> 32; 198 199 xfd_validate_state(fpstate, mask, true); 200 XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask); 201 } 202 203 /* Restore of supervisor state. Does not require XFD */ 204 static inline void os_xrstor_supervisor(struct fpstate *fpstate) 205 { 206 u64 mask = xfeatures_mask_supervisor(); 207 u32 lmask = mask; 208 u32 hmask = mask >> 32; 209 210 XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask); 211 } 212 213 /* 214 * XSAVE itself always writes all requested xfeatures. Removing features 215 * from the request bitmap reduces the features which are written. 216 * Generate a mask of features which must be written to a sigframe. The 217 * unset features can be optimized away and not written. 218 * 219 * This optimization is user-visible. Only use for states where 220 * uninitialized sigframe contents are tolerable, like dynamic features. 221 * 222 * Users of buffers produced with this optimization must check XSTATE_BV 223 * to determine which features have been optimized out. 224 */ 225 static inline u64 xfeatures_need_sigframe_write(void) 226 { 227 u64 xfeaures_to_write; 228 229 /* In-use features must be written: */ 230 xfeaures_to_write = xfeatures_in_use(); 231 232 /* Also write all non-optimizable sigframe features: */ 233 xfeaures_to_write |= XFEATURE_MASK_USER_SUPPORTED & 234 ~XFEATURE_MASK_SIGFRAME_INITOPT; 235 236 return xfeaures_to_write; 237 } 238 239 /* 240 * Save xstate to user space xsave area. 241 * 242 * We don't use modified optimization because xrstor/xrstors might track 243 * a different application. 244 * 245 * We don't use compacted format xsave area for backward compatibility for 246 * old applications which don't understand the compacted format of the 247 * xsave area. 248 * 249 * The caller has to zero buf::header before calling this because XSAVE* 250 * does not touch the reserved fields in the header. 251 */ 252 static inline int xsave_to_user_sigframe(struct xregs_state __user *buf) 253 { 254 /* 255 * Include the features which are not xsaved/rstored by the kernel 256 * internally, e.g. PKRU. That's user space ABI and also required 257 * to allow the signal handler to modify PKRU. 258 */ 259 struct fpstate *fpstate = current->thread.fpu.fpstate; 260 u64 mask = fpstate->user_xfeatures; 261 u32 lmask; 262 u32 hmask; 263 int err; 264 265 /* Optimize away writing unnecessary xfeatures: */ 266 if (fpu_state_size_dynamic()) 267 mask &= xfeatures_need_sigframe_write(); 268 269 lmask = mask; 270 hmask = mask >> 32; 271 xfd_validate_state(fpstate, mask, false); 272 273 stac(); 274 XSTATE_OP(XSAVE, buf, lmask, hmask, err); 275 clac(); 276 277 return err; 278 } 279 280 /* 281 * Restore xstate from user space xsave area. 282 */ 283 static inline int xrstor_from_user_sigframe(struct xregs_state __user *buf, u64 mask) 284 { 285 struct xregs_state *xstate = ((__force struct xregs_state *)buf); 286 u32 lmask = mask; 287 u32 hmask = mask >> 32; 288 int err; 289 290 xfd_validate_state(current->thread.fpu.fpstate, mask, true); 291 292 stac(); 293 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err); 294 clac(); 295 296 return err; 297 } 298 299 /* 300 * Restore xstate from kernel space xsave area, return an error code instead of 301 * an exception. 302 */ 303 static inline int os_xrstor_safe(struct fpstate *fpstate, u64 mask) 304 { 305 struct xregs_state *xstate = &fpstate->regs.xsave; 306 u32 lmask = mask; 307 u32 hmask = mask >> 32; 308 int err; 309 310 /* Ensure that XFD is up to date */ 311 xfd_update_state(fpstate); 312 313 if (cpu_feature_enabled(X86_FEATURE_XSAVES)) 314 XSTATE_OP(XRSTORS, xstate, lmask, hmask, err); 315 else 316 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err); 317 318 return err; 319 } 320 321 322 #endif 323