arch/x86/include/uapi/asm/sigcontext.h

   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' embeds
 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 */