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 static inline u64 xfeatures_mask_supervisor(void) 58 { 59 return fpu_kernel_cfg.max_features & XFEATURE_MASK_SUPERVISOR_SUPPORTED; 60 } 61 62 static inline u64 xfeatures_mask_independent(void) 63 { 64 if (!cpu_feature_enabled(X86_FEATURE_ARCH_LBR)) 65 return fpu_kernel_cfg.independent_features & ~XFEATURE_MASK_LBR; 66 67 return fpu_kernel_cfg.independent_features; 68 } 69 70 /* XSAVE/XRSTOR wrapper functions */ 71 72 #ifdef CONFIG_X86_64 73 #define REX_PREFIX "0x48, " 74 #else 75 #define REX_PREFIX 76 #endif 77 78 /* These macros all use (%edi)/(%rdi) as the single memory argument. */ 79 #define XSAVE ".byte " REX_PREFIX "0x0f,0xae,0x27" 80 #define XSAVEOPT ".byte " REX_PREFIX "0x0f,0xae,0x37" 81 #define XSAVEC ".byte " REX_PREFIX "0x0f,0xc7,0x27" 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 XSAVEC because it supports supervisor 101 * states in addition to XSAVEC. 102 * 103 * Otherwise if XSAVEC is enabled, it replaces XSAVEOPT because it supports 104 * compacted storage format in addition to XSAVEOPT. 105 * 106 * Otherwise, if XSAVEOPT is enabled, XSAVEOPT replaces XSAVE because XSAVEOPT 107 * supports modified optimization which is not supported by XSAVE. 108 * 109 * Use XSAVE as a fallback. 110 */ 111 #define XSTATE_XSAVE(st, lmask, hmask, err) \ 112 asm volatile("1: " ALTERNATIVE_3(XSAVE, \ 113 XSAVEOPT, X86_FEATURE_XSAVEOPT, \ 114 XSAVEC, X86_FEATURE_XSAVEC, \ 115 XSAVES, X86_FEATURE_XSAVES) \ 116 "\n" \ 117 "xor %[err], %[err]\n" \ 118 "3:\n" \ 119 _ASM_EXTABLE_TYPE_REG(1b, 3b, EX_TYPE_EFAULT_REG, %[err]) \ 120 : [err] "=r" (err) \ 121 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ 122 : "memory") 123 124 /* 125 * Use XRSTORS to restore context if it is enabled. XRSTORS supports compact 126 * XSAVE area format. 127 */ 128 #define XSTATE_XRESTORE(st, lmask, hmask) \ 129 asm volatile("1: " ALTERNATIVE(XRSTOR, \ 130 XRSTORS, X86_FEATURE_XSAVES) \ 131 "\n" \ 132 "3:\n" \ 133 _ASM_EXTABLE_TYPE(1b, 3b, EX_TYPE_FPU_RESTORE) \ 134 : \ 135 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ 136 : "memory") 137 138 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_DEBUG_FPU) 139 extern void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor); 140 #else 141 static inline void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor) { } 142 #endif 143 144 #ifdef CONFIG_X86_64 145 static inline void xfd_set_state(u64 xfd) 146 { 147 wrmsrl(MSR_IA32_XFD, xfd); 148 __this_cpu_write(xfd_state, xfd); 149 } 150 151 static inline void xfd_update_state(struct fpstate *fpstate) 152 { 153 if (fpu_state_size_dynamic()) { 154 u64 xfd = fpstate->xfd; 155 156 if (__this_cpu_read(xfd_state) != xfd) 157 xfd_set_state(xfd); 158 } 159 } 160 161 extern int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu); 162 #else 163 static inline void xfd_set_state(u64 xfd) { } 164 165 static inline void xfd_update_state(struct fpstate *fpstate) { } 166 167 static inline int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu) { 168 return -EPERM; 169 } 170 #endif 171 172 /* 173 * Save processor xstate to xsave area. 174 * 175 * Uses either XSAVE or XSAVEOPT or XSAVES depending on the CPU features 176 * and command line options. The choice is permanent until the next reboot. 177 */ 178 static inline void os_xsave(struct fpstate *fpstate) 179 { 180 u64 mask = fpstate->xfeatures; 181 u32 lmask = mask; 182 u32 hmask = mask >> 32; 183 int err; 184 185 WARN_ON_FPU(!alternatives_patched); 186 xfd_validate_state(fpstate, mask, false); 187 188 XSTATE_XSAVE(&fpstate->regs.xsave, lmask, hmask, err); 189 190 /* We should never fault when copying to a kernel buffer: */ 191 WARN_ON_FPU(err); 192 } 193 194 /* 195 * Restore processor xstate from xsave area. 196 * 197 * Uses XRSTORS when XSAVES is used, XRSTOR otherwise. 198 */ 199 static inline void os_xrstor(struct fpstate *fpstate, u64 mask) 200 { 201 u32 lmask = mask; 202 u32 hmask = mask >> 32; 203 204 xfd_validate_state(fpstate, mask, true); 205 XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask); 206 } 207 208 /* Restore of supervisor state. Does not require XFD */ 209 static inline void os_xrstor_supervisor(struct fpstate *fpstate) 210 { 211 u64 mask = xfeatures_mask_supervisor(); 212 u32 lmask = mask; 213 u32 hmask = mask >> 32; 214 215 XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask); 216 } 217 218 /* 219 * XSAVE itself always writes all requested xfeatures. Removing features 220 * from the request bitmap reduces the features which are written. 221 * Generate a mask of features which must be written to a sigframe. The 222 * unset features can be optimized away and not written. 223 * 224 * This optimization is user-visible. Only use for states where 225 * uninitialized sigframe contents are tolerable, like dynamic features. 226 * 227 * Users of buffers produced with this optimization must check XSTATE_BV 228 * to determine which features have been optimized out. 229 */ 230 static inline u64 xfeatures_need_sigframe_write(void) 231 { 232 u64 xfeaures_to_write; 233 234 /* In-use features must be written: */ 235 xfeaures_to_write = xfeatures_in_use(); 236 237 /* Also write all non-optimizable sigframe features: */ 238 xfeaures_to_write |= XFEATURE_MASK_USER_SUPPORTED & 239 ~XFEATURE_MASK_SIGFRAME_INITOPT; 240 241 return xfeaures_to_write; 242 } 243 244 /* 245 * Save xstate to user space xsave area. 246 * 247 * We don't use modified optimization because xrstor/xrstors might track 248 * a different application. 249 * 250 * We don't use compacted format xsave area for backward compatibility for 251 * old applications which don't understand the compacted format of the 252 * xsave area. 253 * 254 * The caller has to zero buf::header before calling this because XSAVE* 255 * does not touch the reserved fields in the header. 256 */ 257 static inline int xsave_to_user_sigframe(struct xregs_state __user *buf) 258 { 259 /* 260 * Include the features which are not xsaved/rstored by the kernel 261 * internally, e.g. PKRU. That's user space ABI and also required 262 * to allow the signal handler to modify PKRU. 263 */ 264 struct fpstate *fpstate = current->thread.fpu.fpstate; 265 u64 mask = fpstate->user_xfeatures; 266 u32 lmask; 267 u32 hmask; 268 int err; 269 270 /* Optimize away writing unnecessary xfeatures: */ 271 if (fpu_state_size_dynamic()) 272 mask &= xfeatures_need_sigframe_write(); 273 274 lmask = mask; 275 hmask = mask >> 32; 276 xfd_validate_state(fpstate, mask, false); 277 278 stac(); 279 XSTATE_OP(XSAVE, buf, lmask, hmask, err); 280 clac(); 281 282 return err; 283 } 284 285 /* 286 * Restore xstate from user space xsave area. 287 */ 288 static inline int xrstor_from_user_sigframe(struct xregs_state __user *buf, u64 mask) 289 { 290 struct xregs_state *xstate = ((__force struct xregs_state *)buf); 291 u32 lmask = mask; 292 u32 hmask = mask >> 32; 293 int err; 294 295 xfd_validate_state(current->thread.fpu.fpstate, mask, true); 296 297 stac(); 298 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err); 299 clac(); 300 301 return err; 302 } 303 304 /* 305 * Restore xstate from kernel space xsave area, return an error code instead of 306 * an exception. 307 */ 308 static inline int os_xrstor_safe(struct fpstate *fpstate, u64 mask) 309 { 310 struct xregs_state *xstate = &fpstate->regs.xsave; 311 u32 lmask = mask; 312 u32 hmask = mask >> 32; 313 int err; 314 315 /* Ensure that XFD is up to date */ 316 xfd_update_state(fpstate); 317 318 if (cpu_feature_enabled(X86_FEATURE_XSAVES)) 319 XSTATE_OP(XRSTORS, xstate, lmask, hmask, err); 320 else 321 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err); 322 323 return err; 324 } 325 326 327 #endif 328