1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ 2 #ifndef _UAPI_ASM_X86_SIGCONTEXT_H 3 #define _UAPI_ASM_X86_SIGCONTEXT_H 4 5 /* 6 * Linux signal context definitions. The sigcontext includes a complex 7 * hierarchy of CPU and FPU state, available to user-space (on the stack) when 8 * a signal handler is executed. 9 * 10 * As over the years this ABI grew from its very simple roots towards 11 * supporting more and more CPU state organically, some of the details (which 12 * were rather clever hacks back in the days) became a bit quirky by today. 13 * 14 * The current ABI includes flexible provisions for future extensions, so we 15 * won't have to grow new quirks for quite some time. Promise! 16 */ 17 18 #include <linux/compiler.h> 19 #include <linux/types.h> 20 21 #define FP_XSTATE_MAGIC1 0x46505853U 22 #define FP_XSTATE_MAGIC2 0x46505845U 23 #define FP_XSTATE_MAGIC2_SIZE sizeof(FP_XSTATE_MAGIC2) 24 25 /* 26 * Bytes 464..511 in the current 512-byte layout of the FXSAVE/FXRSTOR frame 27 * are reserved for SW usage. On CPUs supporting XSAVE/XRSTOR, these bytes are 28 * used to extend the fpstate pointer in the sigcontext, which now includes the 29 * extended state information along with fpstate information. 30 * 31 * If sw_reserved.magic1 == FP_XSTATE_MAGIC1 then there's a 32 * sw_reserved.extended_size bytes large extended context area present. (The 33 * last 32-bit word of this extended area (at the 34 * fpstate+extended_size-FP_XSTATE_MAGIC2_SIZE address) is set to 35 * FP_XSTATE_MAGIC2 so that you can sanity check your size calculations.) 36 * 37 * This extended area typically grows with newer CPUs that have larger and 38 * larger XSAVE areas. 39 */ 40 struct _fpx_sw_bytes { 41 /* 42 * If set to FP_XSTATE_MAGIC1 then this is an xstate context. 43 * 0 if a legacy frame. 44 */ 45 __u32 magic1; 46 47 /* 48 * Total size of the fpstate area: 49 * 50 * - if magic1 == 0 then it's sizeof(struct _fpstate) 51 * - if magic1 == FP_XSTATE_MAGIC1 then it's sizeof(struct _xstate) 52 * plus extensions (if any) 53 */ 54 __u32 extended_size; 55 56 /* 57 * Feature bit mask (including FP/SSE/extended state) that is present 58 * in the memory layout: 59 */ 60 __u64 xfeatures; 61 62 /* 63 * Actual XSAVE state size, based on the xfeatures saved in the layout. 64 * 'extended_size' is greater than 'xstate_size': 65 */ 66 __u32 xstate_size; 67 68 /* For future use: */ 69 __u32 padding[7]; 70 }; 71 72 /* 73 * As documented in the iBCS2 standard: 74 * 75 * The first part of "struct _fpstate" is just the normal i387 hardware setup, 76 * the extra "status" word is used to save the coprocessor status word before 77 * entering the handler. 78 * 79 * The FPU state data structure has had to grow to accommodate the extended FPU 80 * state required by the Streaming SIMD Extensions. There is no documented 81 * standard to accomplish this at the moment. 82 */ 83 84 /* 10-byte legacy floating point register: */ 85 struct _fpreg { 86 __u16 significand[4]; 87 __u16 exponent; 88 }; 89 90 /* 16-byte floating point register: */ 91 struct _fpxreg { 92 __u16 significand[4]; 93 __u16 exponent; 94 __u16 padding[3]; 95 }; 96 97 /* 16-byte XMM register: */ 98 struct _xmmreg { 99 __u32 element[4]; 100 }; 101 102 #define X86_FXSR_MAGIC 0x0000 103 104 /* 105 * The 32-bit FPU frame: 106 */ 107 struct _fpstate_32 { 108 /* Legacy FPU environment: */ 109 __u32 cw; 110 __u32 sw; 111 __u32 tag; 112 __u32 ipoff; 113 __u32 cssel; 114 __u32 dataoff; 115 __u32 datasel; 116 struct _fpreg _st[8]; 117 __u16 status; 118 __u16 magic; /* 0xffff: regular FPU data only */ 119 /* 0x0000: FXSR FPU data */ 120 121 /* FXSR FPU environment */ 122 __u32 _fxsr_env[6]; /* FXSR FPU env is ignored */ 123 __u32 mxcsr; 124 __u32 reserved; 125 struct _fpxreg _fxsr_st[8]; /* FXSR FPU reg data is ignored */ 126 struct _xmmreg _xmm[8]; /* First 8 XMM registers */ 127 union { 128 __u32 padding1[44]; /* Second 8 XMM registers plus padding */ 129 __u32 padding[44]; /* Alias name for old user-space */ 130 }; 131 132 union { 133 __u32 padding2[12]; 134 struct _fpx_sw_bytes sw_reserved; /* Potential extended state is encoded here */ 135 }; 136 }; 137 138 /* 139 * The 64-bit FPU frame. (FXSAVE format and later) 140 * 141 * Note1: If sw_reserved.magic1 == FP_XSTATE_MAGIC1 then the structure is 142 * larger: 'struct _xstate'. Note that 'struct _xstate' embedds 143 * 'struct _fpstate' so that you can always assume the _fpstate portion 144 * exists so that you can check the magic value. 145 * 146 * Note2: Reserved fields may someday contain valuable data. Always 147 * save/restore them when you change signal frames. 148 */ 149 struct _fpstate_64 { 150 __u16 cwd; 151 __u16 swd; 152 /* Note this is not the same as the 32-bit/x87/FSAVE twd: */ 153 __u16 twd; 154 __u16 fop; 155 __u64 rip; 156 __u64 rdp; 157 __u32 mxcsr; 158 __u32 mxcsr_mask; 159 __u32 st_space[32]; /* 8x FP registers, 16 bytes each */ 160 __u32 xmm_space[64]; /* 16x XMM registers, 16 bytes each */ 161 __u32 reserved2[12]; 162 union { 163 __u32 reserved3[12]; 164 struct _fpx_sw_bytes sw_reserved; /* Potential extended state is encoded here */ 165 }; 166 }; 167 168 #ifdef __i386__ 169 # define _fpstate _fpstate_32 170 #else 171 # define _fpstate _fpstate_64 172 #endif 173 174 struct _header { 175 __u64 xfeatures; 176 __u64 reserved1[2]; 177 __u64 reserved2[5]; 178 }; 179 180 struct _ymmh_state { 181 /* 16x YMM registers, 16 bytes each: */ 182 __u32 ymmh_space[64]; 183 }; 184 185 /* 186 * Extended state pointed to by sigcontext::fpstate. 187 * 188 * In addition to the fpstate, information encoded in _xstate::xstate_hdr 189 * indicates the presence of other extended state information supported 190 * by the CPU and kernel: 191 */ 192 struct _xstate { 193 struct _fpstate fpstate; 194 struct _header xstate_hdr; 195 struct _ymmh_state ymmh; 196 /* New processor state extensions go here: */ 197 }; 198 199 /* 200 * The 32-bit signal frame: 201 */ 202 struct sigcontext_32 { 203 __u16 gs, __gsh; 204 __u16 fs, __fsh; 205 __u16 es, __esh; 206 __u16 ds, __dsh; 207 __u32 di; 208 __u32 si; 209 __u32 bp; 210 __u32 sp; 211 __u32 bx; 212 __u32 dx; 213 __u32 cx; 214 __u32 ax; 215 __u32 trapno; 216 __u32 err; 217 __u32 ip; 218 __u16 cs, __csh; 219 __u32 flags; 220 __u32 sp_at_signal; 221 __u16 ss, __ssh; 222 223 /* 224 * fpstate is really (struct _fpstate *) or (struct _xstate *) 225 * depending on the FP_XSTATE_MAGIC1 encoded in the SW reserved 226 * bytes of (struct _fpstate) and FP_XSTATE_MAGIC2 present at the end 227 * of extended memory layout. See comments at the definition of 228 * (struct _fpx_sw_bytes) 229 */ 230 __u32 fpstate; /* Zero when no FPU/extended context */ 231 __u32 oldmask; 232 __u32 cr2; 233 }; 234 235 /* 236 * The 64-bit signal frame: 237 */ 238 struct sigcontext_64 { 239 __u64 r8; 240 __u64 r9; 241 __u64 r10; 242 __u64 r11; 243 __u64 r12; 244 __u64 r13; 245 __u64 r14; 246 __u64 r15; 247 __u64 di; 248 __u64 si; 249 __u64 bp; 250 __u64 bx; 251 __u64 dx; 252 __u64 ax; 253 __u64 cx; 254 __u64 sp; 255 __u64 ip; 256 __u64 flags; 257 __u16 cs; 258 __u16 gs; 259 __u16 fs; 260 __u16 ss; 261 __u64 err; 262 __u64 trapno; 263 __u64 oldmask; 264 __u64 cr2; 265 266 /* 267 * fpstate is really (struct _fpstate *) or (struct _xstate *) 268 * depending on the FP_XSTATE_MAGIC1 encoded in the SW reserved 269 * bytes of (struct _fpstate) and FP_XSTATE_MAGIC2 present at the end 270 * of extended memory layout. See comments at the definition of 271 * (struct _fpx_sw_bytes) 272 */ 273 __u64 fpstate; /* Zero when no FPU/extended context */ 274 __u64 reserved1[8]; 275 }; 276 277 /* 278 * Create the real 'struct sigcontext' type: 279 */ 280 #ifdef __KERNEL__ 281 # ifdef __i386__ 282 # define sigcontext sigcontext_32 283 # else 284 # define sigcontext sigcontext_64 285 # endif 286 #endif 287 288 /* 289 * The old user-space sigcontext definition, just in case user-space still 290 * relies on it. The kernel definition (in asm/sigcontext.h) has unified 291 * field names but otherwise the same layout. 292 */ 293 #ifndef __KERNEL__ 294 295 #define _fpstate_ia32 _fpstate_32 296 #define sigcontext_ia32 sigcontext_32 297 298 299 # ifdef __i386__ 300 struct sigcontext { 301 __u16 gs, __gsh; 302 __u16 fs, __fsh; 303 __u16 es, __esh; 304 __u16 ds, __dsh; 305 __u32 edi; 306 __u32 esi; 307 __u32 ebp; 308 __u32 esp; 309 __u32 ebx; 310 __u32 edx; 311 __u32 ecx; 312 __u32 eax; 313 __u32 trapno; 314 __u32 err; 315 __u32 eip; 316 __u16 cs, __csh; 317 __u32 eflags; 318 __u32 esp_at_signal; 319 __u16 ss, __ssh; 320 struct _fpstate __user *fpstate; 321 __u32 oldmask; 322 __u32 cr2; 323 }; 324 # else /* __x86_64__: */ 325 struct sigcontext { 326 __u64 r8; 327 __u64 r9; 328 __u64 r10; 329 __u64 r11; 330 __u64 r12; 331 __u64 r13; 332 __u64 r14; 333 __u64 r15; 334 __u64 rdi; 335 __u64 rsi; 336 __u64 rbp; 337 __u64 rbx; 338 __u64 rdx; 339 __u64 rax; 340 __u64 rcx; 341 __u64 rsp; 342 __u64 rip; 343 __u64 eflags; /* RFLAGS */ 344 __u16 cs; 345 346 /* 347 * Prior to 2.5.64 ("[PATCH] x86-64 updates for 2.5.64-bk3"), 348 * Linux saved and restored fs and gs in these slots. This 349 * was counterproductive, as fsbase and gsbase were never 350 * saved, so arch_prctl was presumably unreliable. 351 * 352 * These slots should never be reused without extreme caution: 353 * 354 * - Some DOSEMU versions stash fs and gs in these slots manually, 355 * thus overwriting anything the kernel expects to be preserved 356 * in these slots. 357 * 358 * - If these slots are ever needed for any other purpose, 359 * there is some risk that very old 64-bit binaries could get 360 * confused. I doubt that many such binaries still work, 361 * though, since the same patch in 2.5.64 also removed the 362 * 64-bit set_thread_area syscall, so it appears that there 363 * is no TLS API beyond modify_ldt that works in both pre- 364 * and post-2.5.64 kernels. 365 * 366 * If the kernel ever adds explicit fs, gs, fsbase, and gsbase 367 * save/restore, it will most likely need to be opt-in and use 368 * different context slots. 369 */ 370 __u16 gs; 371 __u16 fs; 372 union { 373 __u16 ss; /* If UC_SIGCONTEXT_SS */ 374 __u16 __pad0; /* Alias name for old (!UC_SIGCONTEXT_SS) user-space */ 375 }; 376 __u64 err; 377 __u64 trapno; 378 __u64 oldmask; 379 __u64 cr2; 380 struct _fpstate __user *fpstate; /* Zero when no FPU context */ 381 # ifdef __ILP32__ 382 __u32 __fpstate_pad; 383 # endif 384 __u64 reserved1[8]; 385 }; 386 # endif /* __x86_64__ */ 387 #endif /* !__KERNEL__ */ 388 389 #endif /* _UAPI_ASM_X86_SIGCONTEXT_H */ 390