gcc/config/bpf/bpf.h

   1 /* Definition of the eBPF target for GCC.
   2    Copyright (C) 2019-2021 Free Software Foundation, Inc.
   3
   4    This file is part of GCC.
   5
   6    GCC is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3, or (at your option)
   9    any later version.
  10
  11    GCC is distributed in the hope that it will be useful, but WITHOUT
  12    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  13    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  14    License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with GCC; see the file COPYING3.  If not see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef GCC_BPF_H
  21 #define GCC_BPF_H
  22
  23 /**** Controlling the Compilation Driver.  */
  24
  25 #define ASM_SPEC "%{mbig-endian:-EB} %{!mbig-endian:-EL} %{mxbpf:-mxbpf}"
  26 #define LINK_SPEC "%{mbig-endian:-EB} %{!mbig-endian:-EL}"
  27 #define LIB_SPEC ""
  28 #define STARTFILE_SPEC ""
  29
  30 /**** Run-time Target Specification.  */
  31
  32 #define TARGET_CPU_CPP_BUILTINS() bpf_target_macros (pfile)
  33
  34 /**** Storage Layout.  */
  35
  36 /* Endianness and word size.  */
  37 #define BITS_BIG_ENDIAN 0
  38 #define BYTES_BIG_ENDIAN (TARGET_BIG_ENDIAN)
  39 #define WORDS_BIG_ENDIAN (TARGET_BIG_ENDIAN)
  40 #define BITS_PER_WORD 64
  41 #define UNITS_PER_WORD 8
  42
  43 /* When storing an integer whose size is less than 64-bit in a
  44    register, promote it to a DImode.  */
  45 #define PROMOTE_MODE(M, UNSIGNEDP, TYPE)        \
  46   do                                            \
  47     {                                           \
  48       if (GET_MODE_CLASS (M) == MODE_INT        \
  49           && GET_MODE_SIZE (M) < 8)             \
  50         M = DImode;                             \
  51     } while (0)
  52
  53 /* Align argument parameters on the stack to 64-bit, at a minimum.  */
  54 #define PARM_BOUNDARY 64
  55
  56 /* The hardware enforces that the stack pointer should be aligned to
  57    64-bit at any time.  */
  58 #define STACK_BOUNDARY 64
  59
  60 /* Function entry points are aligned to 128 bits.  */
  61 #define FUNCTION_BOUNDARY 128
  62
  63 /* Maximum alignment required by data of any type.  */
  64 #define BIGGEST_ALIGNMENT 64
  65
  66 /* The best alignment to use in cases where we have a choice.  */
  67 #define FASTEST_ALIGNMENT 64
  68
  69 /* Use a fast alignment when storing arrays of chars in a local.  */
  70 #define LOCAL_ALIGNMENT(TYPE, ALIGN)                                    \
  71   (TREE_CODE (TYPE) == ARRAY_TYPE                                       \
  72    && TYPE_MODE (TREE_TYPE (TYPE)) == QImode                            \
  73    && (ALIGN) < FASTEST_ALIGNMENT ? FASTEST_ALIGNMENT : (ALIGN))
  74
  75 /* The load and store instructions won't work if the data is not in
  76    it's expected alignment.  */
  77 #define STRICT_ALIGNMENT 1
  78
  79 /* We use Pmode as the mode of the size increment operand in an
  80    `allocate_stack' pattern.  */
  81 #define STACK_SIZE_MODE Pmode
  82
  83 /**** Layout of Source Language Data Types.  */
  84
  85 #define INT_TYPE_SIZE         32
  86 #define SHORT_TYPE_SIZE       16
  87 #define LONG_TYPE_SIZE        64
  88 #define LONG_LONG_TYPE_SIZE   64
  89 #define CHAR_TYPE_SIZE         8
  90 #define FLOAT_TYPE_SIZE       32
  91 #define DOUBLE_TYPE_SIZE      64
  92 #define LONG_DOUBLE_TYPE_SIZE 64
  93
  94 #define INTPTR_TYPE     "long int"
  95 #define UINTPTR_TYPE    "long unsigned int"
  96 #define SIZE_TYPE       "long unsigned int"
  97 #define PTRDIFF_TYPE "long int"
  98
  99 #define SIG_ATOMIC_TYPE "char"
 100
 101 #define INT8_TYPE "char"
 102 #define INT16_TYPE "short int"
 103 #define INT32_TYPE "int"
 104 #define INT64_TYPE "long int"
 105 #define UINT8_TYPE "unsigned char"
 106 #define UINT16_TYPE "short unsigned int"
 107 #define UINT32_TYPE "unsigned int"
 108 #define UINT64_TYPE "long unsigned int"
 109
 110 #define INT_LEAST8_TYPE INT8_TYPE
 111 #define INT_LEAST16_TYPE INT16_TYPE
 112 #define INT_LEAST32_TYPE INT32_TYPE
 113 #define INT_LEAST64_TYPE INT64_TYPE
 114 #define UINT_LEAST8_TYPE UINT8_TYPE
 115 #define UINT_LEAST16_TYPE UINT16_TYPE
 116 #define UINT_LEAST32_TYPE UINT32_TYPE
 117 #define UINT_LEAST64_TYPE UINT64_TYPE
 118
 119 #define INT_FAST8_TYPE INT8_TYPE
 120 #define INT_FAST16_TYPE INT16_TYPE
 121 #define INT_FAST32_TYPE INT32_TYPE
 122 #define INT_FAST64_TYPE INT64_TYPE
 123 #define UINT_FAST8_TYPE UINT8_TYPE
 124 #define UINT_FAST16_TYPE UINT16_TYPE
 125 #define UINT_FAST32_TYPE UINT32_TYPE
 126 #define UINT_FAST64_TYPE UINT64_TYPE
 127
 128 /* `char' is signed by default, like in x86.  */
 129 #define DEFAULT_SIGNED_CHAR 1
 130
 131 /* `wchar_t' is a signed 32-bit type.  The second constant is used by
 132    cpp, which can't use WCHAR_TYPE.  */
 133 #define WCHAR_TYPE "int"
 134 #define WCHAR_TYPE_SIZE 32
 135
 136 /* `wint_t' is a signed 32-bit type.  */
 137 #define WINT_TYPE "int"
 138 #define WINT_TYPE_SIZE 32
 139
 140 /**** Register Usage.  */
 141
 142 /*** Basic Characteristics of Registers.  */
 143
 144 #define BPF_R0  0
 145 #define BPF_R1  1
 146 #define BPF_R2  2
 147 #define BPF_R3  3
 148 #define BPF_R4  4
 149 #define BPF_R5  5
 150 #define BPF_R6  6
 151 #define BPF_CTX BPF_R6
 152 #define BPF_R7  7
 153 #define BPF_R8  8
 154 #define BPF_R9  9
 155 #define BPF_SP BPF_R9
 156 #define BPF_R10 10
 157 #define BPF_FP  BPF_R10
 158 /* 11 is not a real eBPF hard register and is eliminated or not used
 159    in the final assembler.  See below.  */
 160
 161 #define FIRST_PSEUDO_REGISTER 12
 162
 163 /* The registers %r0..%r8 are available for general allocation.
 164    %r9 is the pseudo-stack pointer.
 165    %r10 is the stack frame, which is read-only.
 166    %r11 (__arg__) is a fake register that always gets eliminated.  */
 167 #define FIXED_REGISTERS                         \
 168   {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1}
 169
 170 /* %r0..%r5 are clobbered by function calls.  */
 171 #define CALL_USED_REGISTERS                             \
 172   {1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1}
 173
 174 /**** Register Classes.  */
 175
 176 enum reg_class
 177 {
 178   NO_REGS,              /* no registers in set.  */
 179   ALL_REGS,             /* all registers.  */
 180   LIM_REG_CLASSES       /* max value + 1.  */
 181 };
 182
 183 #define N_REG_CLASSES (int) LIM_REG_CLASSES
 184 #define GENERAL_REGS ALL_REGS
 185
 186 /* An initializer containing the names of the register classes as C
 187    string constants.  These names are used in writing some of the
 188    debugging dumps.  */
 189 #define REG_CLASS_NAMES                         \
 190 {                                               \
 191   "NO_REGS",                                    \
 192   "ALL_REGS"                                    \
 193 }
 194
 195 /* An initializer containing the contents of the register classes, as
 196    integers which are bit masks.  The Nth integer specifies the
 197    contents of class N.  The way the integer MASK is interpreted is
 198    that register R is in the class if `MASK & (1 << R)' is 1.
 199
 200    In eBPF all the hard registers are considered general-purpose
 201    integer registers.  */
 202 #define REG_CLASS_CONTENTS                      \
 203 {                                               \
 204    0x00000000, /* NO_REGS */                    \
 205    0x00000fff, /* ALL_REGS */                   \
 206 }
 207
 208 /* A C expression whose value is a register class containing hard
 209    register REGNO.  In general there is more that one such class;
 210    choose a class which is "minimal", meaning that no smaller class
 211    also contains the register.  */
 212 #define REGNO_REG_CLASS(REGNO) GENERAL_REGS
 213
 214 /* A macro whose definition is the name of the class to which a
 215    valid base register must belong.  A base register is one used in
 216    an address which is the register value plus a displacement.  */
 217 #define BASE_REG_CLASS GENERAL_REGS
 218
 219 /* A macro whose definition is the name of the class to which a
 220    valid index register must belong.  An index register is one used
 221    in an address where its value is either multiplied by a scale
 222    factor or added to another register (as well as added to a
 223    displacement).  */
 224 #define INDEX_REG_CLASS NO_REGS
 225
 226 /* C expression which is nonzero if register number REGNO is suitable
 227    for use as a base register in operand addresses.  In eBPF every
 228    hard register can be used for this purpose.  */
 229 #define REGNO_OK_FOR_BASE_P(REGNO)                      \
 230   ((REGNO) < FIRST_PSEUDO_REGISTER)
 231
 232 /* C expression which is nonzero if register number REGNO is suitable
 233    for use as an index register in operand addresses.  */
 234 #define REGNO_OK_FOR_INDEX_P(REGNO) false
 235
 236 /**** Debugging Info ****/
 237
 238 /* We cannot support DWARF2 because of the limitations of eBPF.  */
 239
 240 /* elfos.h insists in using DWARF.  Undo that here.  */
 241 #ifdef DWARF2_DEBUGGING_INFO
 242 # undef DWARF2_DEBUGGING_INFO
 243 #endif
 244 #ifdef PREFERRED_DEBUGGING_TYPE
 245 # undef PREFERRED_DEBUGGING_TYPE
 246 #endif
 247
 248 #define DBX_DEBUGGING_INFO
 249
 250 /**** Stack Layout and Calling Conventions.  */
 251
 252 /*** Basic Stack Layout.  */
 253
 254 #define STACK_GROWS_DOWNWARD 1
 255 #define FRAME_GROWS_DOWNWARD 1
 256
 257 /* The argument pointer always points to the first argument.  */
 258 #define FIRST_PARM_OFFSET(FNDECL) 0
 259
 260 /* Unsupported.  */
 261 #define RETURN_ADDR_RTX(count, frame) const0_rtx
 262
 263 /*** Registers That Address the Stack Frame.  */
 264
 265 #define FRAME_POINTER_REGNUM 10
 266 #define STACK_POINTER_REGNUM 9
 267 #define ARG_POINTER_REGNUM 11
 268 #define STATIC_CHAIN_REGNUM 8
 269
 270 /*** Registers elimination.  */
 271
 272 #define ELIMINABLE_REGS                                 \
 273   {{ ARG_POINTER_REGNUM, FRAME_POINTER_REGNUM },        \
 274    { ARG_POINTER_REGNUM, STACK_POINTER_REGNUM }}
 275
 276 /* Define the offset between two registers, one to be eliminated, and
 277    the other its replacement, at the start of a routine.  */
 278 #define INITIAL_ELIMINATION_OFFSET(FROM, TO, OFFSET)            \
 279   do                                                            \
 280     {                                                           \
 281       (OFFSET) = bpf_initial_elimination_offset ((FROM), (TO)); \
 282     } while (0)
 283
 284 /*** Passing Function Arguments on the Stack.  */
 285
 286 /* The eBPF ABI doesn't support passing arguments on the stack.  Only
 287    in the first five registers.  Code in bpf.c assures the stack is
 288    never used when passing arguments.  However, we still have to
 289    define the constants below.  */
 290
 291 /* If nonzero, push insns will be used to pass outgoing arguments.  */
 292 #define PUSH_ARGS 0
 293
 294 /* If nonzero, function arguments will be evaluated from last to
 295    first, rather than from first to last.  */
 296 #define PUSH_ARGS_REVERSED 1
 297
 298 /* Allocate stack space for arguments at the beginning of each
 299    function.  */
 300 #define ACCUMULATE_OUTGOING_ARGS 1
 301
 302 /*** Passing Arguments in Registers.  */
 303
 304 /* Use an integer in order to keep track of the number of arguments
 305    passed to a function in integer registers, up to
 306    MAX_ARGS_IN_REGISTERS.  */
 307 #define CUMULATIVE_ARGS int
 308
 309 /* INIT_CUMULATIVE_ARGS initializes a variable CUM of type
 310    CUMULATIVE_ARGS for a call to a function whose data type is FNTYPE.
 311    For a library call, FNTYPE is 0.  */
 312 #define INIT_CUMULATIVE_ARGS(CUM,FNTYPE,LIBNAME,FNDECL,N_NAMED_ARGS) \
 313   memset (&(CUM), 0, sizeof (CUM))
 314
 315 /* Nonzero if N is the number of a hard register in which function
 316    arguments are sometimes passed.  */
 317 #define FUNCTION_ARG_REGNO_P(N) ((N) >= 1 && (N) <= 5)
 318
 319 /*** How Scalar Function Values are Returned.  */
 320
 321 /* Define how to find the value returned by a library function
 322    assuming the value has mode MODE.  This is always %r0 for eBPF.  */
 323 #define LIBCALL_VALUE(MODE)  \
 324   gen_rtx_REG ((MODE), 0)
 325
 326 /*** Generating Code for Profiling.  */
 327
 328 /* We do not support profiling yet, so do not call `mcount'.  */
 329 #define FUNCTION_PROFILER(FILE, LABELNO) do { } while (0)
 330
 331 /*** Function Entry and Exit.  */
 332
 333 /* We do not require an accurate stack pointer at function return.
 334    This is because the stack pointer's original value is initialized
 335    from the frame pointer, rather than decreased, to satisfy the
 336    kernel's verifier.  Thus, we have to save the stack pointer in
 337    function prologue and restore it in function epilogue.  If
 338    EXIT_IGNORE_STACK is not set, then superfluous instructions are
 339    generated to save and restore the stack pointer after and before
 340    the function epilogue, respectively.  */
 341 #define EXIT_IGNORE_STACK 1
 342
 343 /**** Support for Nested Functions.  */
 344
 345 /* We have to define TRAMPOLINE_SIZE even if we don't ever generate
 346    them.  Set to 64 arbitrarily.  */
 347 #define TRAMPOLINE_SIZE 64
 348
 349 /**** Addressing Modes.  */
 350
 351 /* Maximum number of registers that can appear in a valid memory
 352    address.  */
 353 #define MAX_REGS_PER_ADDRESS 1
 354
 355 /* 1 if X is an rtx for a constant that is a valid address.  */
 356
 357 #define CONSTANT_ADDRESS_P(X) 0
 358
 359 /**** Describing Relative Costs of Operations.  */
 360
 361 /* Cost of a branch instruction.  A value of 1 is the default.  */
 362 #define BRANCH_COST(SPEED_P,PREDICTABLE_P) 1
 363
 364 /* The SPARC port says: Nonzero if access to memory by bytes is slow
 365    and undesirable.  For RISC chips, it means that access to memory by
 366    bytes is no better than access by words when possible, so grab a
 367    whole word and maybe make use of that.  */
 368 #define SLOW_BYTE_ACCESS 1
 369
 370 /* Threshold of number of scalar memory-to-memory move instructions,
 371    _below_ which a sequence of insns should be generated instead of a
 372    string move insn or a library call.  */
 373 #define MOVE_RATIO(speed) 128
 374
 375 /* Threshold of number of scalar move instructions, _below_ which a
 376    sequence of insns should be generated to clear memory instead of a
 377    string clear insn or a library call.  */
 378 #define CLEAR_RATIO(speed) 128
 379
 380 /* Threshold of number of scalar move instructions, _below_ which a
 381    sequence of insns should be generated to set memory to a constant
 382    value, instead of a block set insn or a library call.  */
 383 #define SET_RATIO(speed) 128
 384
 385 /* True if it is as good or better to call a constant function address
 386    than to call an address kept in a register.  */
 387 #define NO_FUNCTION_CSE 1
 388
 389 /**** Dividing the Output into Sections.  */
 390
 391 #define TEXT_SECTION_ASM_OP "\t.text"
 392 #define DATA_SECTION_ASM_OP "\t.data"
 393 #define BSS_SECTION_ASM_OP "\t.bss"
 394
 395 /**** Defining the Output Assembler Language.  */
 396
 397 /*** The Overall Framework of an Assembler File.  */
 398
 399 #define ASM_COMMENT_START ";"
 400
 401 /* Output to assembler file text saying following lines
 402    may contain character constants, extra white space, comments, etc.  */
 403
 404 #ifndef ASM_APP_ON
 405 #define ASM_APP_ON " #APP\n"
 406 #endif
 407
 408 /* Output to assembler file text saying following lines
 409    no longer contain unusual constructs.  */
 410
 411 #ifndef ASM_APP_OFF
 412 #define ASM_APP_OFF " #NO_APP\n"
 413 #endif
 414
 415 /*** Output of Data.  */
 416
 417 /*** Output of Uninitialized Variables.  */
 418
 419 /* A C statement (sans semicolon) to output to the stdio stream
 420    FILE the assembler definition of uninitialized global DECL named
 421    NAME whose size is SIZE bytes and alignment is ALIGN bytes.
 422    Try to use asm_output_aligned_bss to implement this macro.  */
 423
 424 #define ASM_OUTPUT_ALIGNED_BSS(FILE, DECL, NAME, SIZE, ALIGN)   \
 425   do {                                                          \
 426     ASM_OUTPUT_ALIGNED_LOCAL (FILE, NAME, SIZE, ALIGN);         \
 427   } while (0)
 428
 429 /*** Output and Generation of Labels.  */
 430
 431 /* Globalizing directive for a label.  */
 432 #define GLOBAL_ASM_OP "\t.global\t"
 433
 434 /* This is how to store into the string LABEL
 435    the symbol_ref name of an internal numbered label where
 436    PREFIX is the class of label and NUM is the number within the class.
 437    This is suitable for output with `assemble_name'.  */
 438
 439 #undef ASM_GENERATE_INTERNAL_LABEL
 440 #define ASM_GENERATE_INTERNAL_LABEL(LABEL,PREFIX,NUM)                   \
 441   sprintf ((LABEL), "*%s%s%ld", (LOCAL_LABEL_PREFIX), (PREFIX), (long)(NUM))
 442
 443 /*** Output of Assembler Instructions.  */
 444
 445 #define REGISTER_NAMES                                          \
 446   { "%r0", "%r1", "%r2", "%r3", "%r4", "%r5", "%r6", "%r7",     \
 447     "%r8", "%r9", "%fp", "__arg__" }
 448
 449 #define ADDITIONAL_REGISTER_NAMES               \
 450   { { "%a", 0 }, { "%ctx", 6 }, { "%r10" , 10 } }
 451
 452 #define LOCAL_LABEL_PREFIX "."
 453 #define USER_LABEL_PREFIX  ""
 454
 455 #define PRINT_OPERAND(STREAM,X,CODE)            \
 456   bpf_print_operand ((STREAM),(X),(CODE))
 457
 458 #define PRINT_OPERAND_ADDRESS(STREAM,X)         \
 459   bpf_print_operand_address ((STREAM), (X))
 460
 461 /*** Assembler Commands for Alignment.  */
 462
 463 /* This is how to output an assembler line that says to advance the
 464    location counter to a multiple of 2**LOG bytes.  */
 465 #define ASM_OUTPUT_ALIGN(STREAM,LOG)            \
 466   fprintf (STREAM, "\t.align\t%d\n", (LOG))
 467
 468 /**** Miscellaneous Parameters.  */
 469
 470 /* Specify the machine mode that this machine uses for the index in
 471    the tablejump instruction.  */
 472 #define CASE_VECTOR_MODE DImode
 473
 474 /* Define if operations between registers with integral mode smaller
 475    than a word are always performed on the entire register.  */
 476 #define WORD_REGISTER_OPERATIONS 1
 477
 478 /* C expression indicating when insns that read memory in MEM_MODE, an
 479    integral mode narrower than a word, set the bits outsize of
 480    MEM_MODE to be either the sign-extension or the zero-extension of
 481    the data read.  */
 482 #define LOAD_EXTEND_OP(MODE) ZERO_EXTEND
 483
 484 /* The maximum number of bytes that a single instruction can move
 485    quickly between memory and registers or between two memory
 486    locations.  */
 487 #define MOVE_MAX 8
 488
 489 /* An alias for the machine mode for pointers.  */
 490 #define Pmode DImode
 491
 492 /* An alias for the machine mode used for memory references to
 493    functions being called, in 'call' RTL expressions.  */
 494 #define FUNCTION_MODE Pmode
 495
 496 /* No libm on eBPF (for now.)  */
 497 #define MATH_LIBRARY ""
 498
 499 /**** libgcc settings.  */
 500
 501 /* Iterating over the global constructors and destructors and
 502    executing them requires the ability of doing indirect calls.
 503
 504    eBPF doesn't support indirect calls, so no chance of supporting
 505    constructors and destructors.  */
 506 #define DO_GLOBAL_CTORS_BODY                    \
 507   do { } while (0)
 508 #define DO_GLOBAL_DTORS_BODY                    \
 509   do { } while (0)
 510
 511 #endif /* ! GCC_BPF_H */