Source file src/cmd/internal/objabi/reloctype.go

     1  // Derived from Inferno utils/6l/l.h and related files.
     2  // https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/l.h
     3  //
     4  //	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
     5  //	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
     6  //	Portions Copyright © 1997-1999 Vita Nuova Limited
     7  //	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
     8  //	Portions Copyright © 2004,2006 Bruce Ellis
     9  //	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
    10  //	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
    11  //	Portions Copyright © 2009 The Go Authors. All rights reserved.
    12  //
    13  // Permission is hereby granted, free of charge, to any person obtaining a copy
    14  // of this software and associated documentation files (the "Software"), to deal
    15  // in the Software without restriction, including without limitation the rights
    16  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    17  // copies of the Software, and to permit persons to whom the Software is
    18  // furnished to do so, subject to the following conditions:
    19  //
    20  // The above copyright notice and this permission notice shall be included in
    21  // all copies or substantial portions of the Software.
    22  //
    23  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    24  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    25  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
    26  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    27  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    28  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    29  // THE SOFTWARE.
    30  
    31  package objabi
    32  
    33  type RelocType int16
    34  
    35  //go:generate stringer -type=RelocType
    36  const (
    37  	R_ADDR RelocType = 1 + iota
    38  	// R_ADDRPOWER relocates a pair of "D-form" instructions (instructions with 16-bit
    39  	// immediates in the low half of the instruction word), usually addis followed by
    40  	// another add or a load, inserting the "high adjusted" 16 bits of the address of
    41  	// the referenced symbol into the immediate field of the first instruction and the
    42  	// low 16 bits into that of the second instruction.
    43  	R_ADDRPOWER
    44  	// R_ADDRARM64 relocates an adrp, add pair to compute the address of the
    45  	// referenced symbol.
    46  	R_ADDRARM64
    47  	// R_ADDRMIPS (only used on mips/mips64) resolves to the low 16 bits of an external
    48  	// address, by encoding it into the instruction.
    49  	R_ADDRMIPS
    50  	// R_ADDROFF resolves to a 32-bit offset from the beginning of the section
    51  	// holding the data being relocated to the referenced symbol.
    52  	R_ADDROFF
    53  	R_SIZE
    54  	R_CALL
    55  	R_CALLARM
    56  	R_CALLARM64
    57  	R_CALLIND
    58  	R_CALLPOWER
    59  	// R_CALLMIPS (only used on mips64) resolves to non-PC-relative target address
    60  	// of a CALL (JAL) instruction, by encoding the address into the instruction.
    61  	R_CALLMIPS
    62  	R_CONST
    63  	R_PCREL
    64  	// R_TLS_LE, used on 386, amd64, and ARM, resolves to the offset of the
    65  	// thread-local symbol from the thread local base and is used to implement the
    66  	// "local exec" model for tls access (r.Sym is not set on intel platforms but is
    67  	// set to a TLS symbol -- runtime.tlsg -- in the linker when externally linking).
    68  	R_TLS_LE
    69  	// R_TLS_IE, used 386, amd64, and ARM resolves to the PC-relative offset to a GOT
    70  	// slot containing the offset from the thread-local symbol from the thread local
    71  	// base and is used to implemented the "initial exec" model for tls access (r.Sym
    72  	// is not set on intel platforms but is set to a TLS symbol -- runtime.tlsg -- in
    73  	// the linker when externally linking).
    74  	R_TLS_IE
    75  	R_GOTOFF
    76  	R_PLT0
    77  	R_PLT1
    78  	R_PLT2
    79  	R_USEFIELD
    80  	// R_USETYPE resolves to an *rtype, but no relocation is created. The
    81  	// linker uses this as a signal that the pointed-to type information
    82  	// should be linked into the final binary, even if there are no other
    83  	// direct references. (This is used for types reachable by reflection.)
    84  	R_USETYPE
    85  	// R_USEIFACE marks a type is converted to an interface in the function this
    86  	// relocation is applied to. The target is a type descriptor or an itab
    87  	// (in the latter case it refers to the concrete type contained in the itab).
    88  	// This is a marker relocation (0-sized), for the linker's reachabililty
    89  	// analysis.
    90  	R_USEIFACE
    91  	// R_USEIFACEMETHOD marks an interface method that is used in the function
    92  	// this relocation is applied to. The target is an interface type descriptor.
    93  	// The addend is the offset of the method in the type descriptor.
    94  	// This is a marker relocation (0-sized), for the linker's reachabililty
    95  	// analysis.
    96  	R_USEIFACEMETHOD
    97  	// R_USENAMEDMETHOD marks that methods with a specific name must not be eliminated.
    98  	// The target is a symbol containing the name of a method called via a generic
    99  	// interface or looked up via MethodByName("F").
   100  	R_USENAMEDMETHOD
   101  	// R_METHODOFF resolves to a 32-bit offset from the beginning of the section
   102  	// holding the data being relocated to the referenced symbol.
   103  	// It is a variant of R_ADDROFF used when linking from the uncommonType of a
   104  	// *rtype, and may be set to zero by the linker if it determines the method
   105  	// text is unreachable by the linked program.
   106  	R_METHODOFF
   107  	// R_KEEP tells the linker to keep the referred-to symbol in the final binary
   108  	// if the symbol containing the R_KEEP relocation is in the final binary.
   109  	R_KEEP
   110  	R_POWER_TOC
   111  	R_GOTPCREL
   112  	// R_JMPMIPS (only used on mips64) resolves to non-PC-relative target address
   113  	// of a JMP instruction, by encoding the address into the instruction.
   114  	// The stack nosplit check ignores this since it is not a function call.
   115  	R_JMPMIPS
   116  
   117  	// R_DWARFSECREF resolves to the offset of the symbol from its section.
   118  	// Target of relocation must be size 4 (in current implementation).
   119  	R_DWARFSECREF
   120  
   121  	// R_DWARFFILEREF resolves to an index into the DWARF .debug_line
   122  	// file table for the specified file symbol. Must be applied to an
   123  	// attribute of form DW_FORM_data4.
   124  	R_DWARFFILEREF
   125  
   126  	// Platform dependent relocations. Architectures with fixed width instructions
   127  	// have the inherent issue that a 32-bit (or 64-bit!) displacement cannot be
   128  	// stuffed into a 32-bit instruction, so an address needs to be spread across
   129  	// several instructions, and in turn this requires a sequence of relocations, each
   130  	// updating a part of an instruction. This leads to relocation codes that are
   131  	// inherently processor specific.
   132  
   133  	// Arm64.
   134  
   135  	// Set a MOV[NZ] immediate field to bits [15:0] of the offset from the thread
   136  	// local base to the thread local variable defined by the referenced (thread
   137  	// local) symbol. Error if the offset does not fit into 16 bits.
   138  	R_ARM64_TLS_LE
   139  
   140  	// Relocates an ADRP; LD64 instruction sequence to load the offset between
   141  	// the thread local base and the thread local variable defined by the
   142  	// referenced (thread local) symbol from the GOT.
   143  	R_ARM64_TLS_IE
   144  
   145  	// R_ARM64_GOTPCREL relocates an adrp, ld64 pair to compute the address of the GOT
   146  	// slot of the referenced symbol.
   147  	R_ARM64_GOTPCREL
   148  
   149  	// R_ARM64_GOT resolves a GOT-relative instruction sequence, usually an adrp
   150  	// followed by another ld instruction.
   151  	R_ARM64_GOT
   152  
   153  	// R_ARM64_PCREL resolves a PC-relative addresses instruction sequence, usually an
   154  	// adrp followed by another add instruction.
   155  	R_ARM64_PCREL
   156  
   157  	// R_ARM64_PCREL_LDST8 resolves a PC-relative addresses instruction sequence, usually an
   158  	// adrp followed by a LD8 or ST8 instruction.
   159  	R_ARM64_PCREL_LDST8
   160  
   161  	// R_ARM64_PCREL_LDST16 resolves a PC-relative addresses instruction sequence, usually an
   162  	// adrp followed by a LD16 or ST16 instruction.
   163  	R_ARM64_PCREL_LDST16
   164  
   165  	// R_ARM64_PCREL_LDST32 resolves a PC-relative addresses instruction sequence, usually an
   166  	// adrp followed by a LD32 or ST32 instruction.
   167  	R_ARM64_PCREL_LDST32
   168  
   169  	// R_ARM64_PCREL_LDST64 resolves a PC-relative addresses instruction sequence, usually an
   170  	// adrp followed by a LD64 or ST64 instruction.
   171  	R_ARM64_PCREL_LDST64
   172  
   173  	// R_ARM64_LDST8 sets a LD/ST immediate value to bits [11:0] of a local address.
   174  	R_ARM64_LDST8
   175  
   176  	// R_ARM64_LDST16 sets a LD/ST immediate value to bits [11:1] of a local address.
   177  	R_ARM64_LDST16
   178  
   179  	// R_ARM64_LDST32 sets a LD/ST immediate value to bits [11:2] of a local address.
   180  	R_ARM64_LDST32
   181  
   182  	// R_ARM64_LDST64 sets a LD/ST immediate value to bits [11:3] of a local address.
   183  	R_ARM64_LDST64
   184  
   185  	// R_ARM64_LDST128 sets a LD/ST immediate value to bits [11:4] of a local address.
   186  	R_ARM64_LDST128
   187  
   188  	// PPC64.
   189  
   190  	// R_POWER_TLS_LE is used to implement the "local exec" model for tls
   191  	// access. It resolves to the offset of the thread-local symbol from the
   192  	// thread pointer (R13) and is split against a pair of instructions to
   193  	// support a 32 bit displacement.
   194  	R_POWER_TLS_LE
   195  
   196  	// R_POWER_TLS_IE is used to implement the "initial exec" model for tls access. It
   197  	// relocates a D-form, DS-form instruction sequence like R_ADDRPOWER_DS. It
   198  	// inserts to the offset of GOT slot for the thread-local symbol from the TOC (the
   199  	// GOT slot is filled by the dynamic linker with the offset of the thread-local
   200  	// symbol from the thread pointer (R13)).
   201  	R_POWER_TLS_IE
   202  
   203  	// R_POWER_TLS marks an X-form instruction such as "ADD R3,R13,R4" as completing
   204  	// a sequence of GOT-relative relocations to compute a TLS address. This can be
   205  	// used by the system linker to to rewrite the GOT-relative TLS relocation into a
   206  	// simpler thread-pointer relative relocation. See table 3.26 and 3.28 in the
   207  	// ppc64 elfv2 1.4 ABI on this transformation.  Likewise, the second argument
   208  	// (usually called RB in X-form instructions) is assumed to be R13.
   209  	R_POWER_TLS
   210  
   211  	// R_POWER_TLS_IE_PCREL34 is similar to R_POWER_TLS_IE, but marks a single MOVD
   212  	// which has been assembled as a single prefixed load doubleword without using the
   213  	// TOC.
   214  	R_POWER_TLS_IE_PCREL34
   215  
   216  	// R_POWER_TLS_LE_TPREL34 is similar to R_POWER_TLS_LE, but computes an offset from
   217  	// the thread pointer in one prefixed instruction.
   218  	R_POWER_TLS_LE_TPREL34
   219  
   220  	// R_ADDRPOWER_DS is similar to R_ADDRPOWER above, but assumes the second
   221  	// instruction is a "DS-form" instruction, which has an immediate field occupying
   222  	// bits [15:2] of the instruction word. Bits [15:2] of the address of the
   223  	// relocated symbol are inserted into this field; it is an error if the last two
   224  	// bits of the address are not 0.
   225  	R_ADDRPOWER_DS
   226  
   227  	// R_ADDRPOWER_GOT relocates a D-form + DS-form instruction sequence by inserting
   228  	// a relative displacement of referenced symbol's GOT entry to the TOC pointer.
   229  	R_ADDRPOWER_GOT
   230  
   231  	// R_ADDRPOWER_GOT_PCREL34 is identical to R_ADDRPOWER_GOT, but uses a PC relative
   232  	// sequence to generate a GOT symbol addresses.
   233  	R_ADDRPOWER_GOT_PCREL34
   234  
   235  	// R_ADDRPOWER_PCREL relocates two D-form instructions like R_ADDRPOWER, but
   236  	// inserts the displacement from the place being relocated to the address of the
   237  	// relocated symbol instead of just its address.
   238  	R_ADDRPOWER_PCREL
   239  
   240  	// R_ADDRPOWER_TOCREL relocates two D-form instructions like R_ADDRPOWER, but
   241  	// inserts the offset from the TOC to the address of the relocated symbol
   242  	// rather than the symbol's address.
   243  	R_ADDRPOWER_TOCREL
   244  
   245  	// R_ADDRPOWER_TOCREL_DS relocates a D-form, DS-form instruction sequence like
   246  	// R_ADDRPOWER_DS but inserts the offset from the TOC to the address of the
   247  	// relocated symbol rather than the symbol's address.
   248  	R_ADDRPOWER_TOCREL_DS
   249  
   250  	// R_ADDRPOWER_D34 relocates a single prefixed D-form load/store operation.  All
   251  	// prefixed forms are D form. The high 18 bits are stored in the prefix,
   252  	// and the low 16 are stored in the suffix. The address is absolute.
   253  	R_ADDRPOWER_D34
   254  
   255  	// R_ADDRPOWER_PCREL34 relates a single prefixed D-form load/store/add operation.
   256  	// All prefixed forms are D form. The resulting address is relative to the
   257  	// PC. It is a signed 34 bit offset.
   258  	R_ADDRPOWER_PCREL34
   259  
   260  	// RISC-V.
   261  
   262  	// R_RISCV_JAL resolves a 20 bit offset for a J-type instruction.
   263  	R_RISCV_JAL
   264  
   265  	// R_RISCV_JAL_TRAMP is the same as R_RISCV_JAL but denotes the use of a
   266  	// trampoline, which we may be able to avoid during relocation. These are
   267  	// only used by the linker and are not emitted by the compiler or assembler.
   268  	R_RISCV_JAL_TRAMP
   269  
   270  	// R_RISCV_CALL resolves a 32 bit PC-relative address for an AUIPC + JALR
   271  	// instruction pair.
   272  	R_RISCV_CALL
   273  
   274  	// R_RISCV_PCREL_ITYPE resolves a 32 bit PC-relative address for an
   275  	// AUIPC + I-type instruction pair.
   276  	R_RISCV_PCREL_ITYPE
   277  
   278  	// R_RISCV_PCREL_STYPE resolves a 32 bit PC-relative address for an
   279  	// AUIPC + S-type instruction pair.
   280  	R_RISCV_PCREL_STYPE
   281  
   282  	// R_RISCV_TLS_IE resolves a 32 bit TLS initial-exec address for an
   283  	// AUIPC + I-type instruction pair.
   284  	R_RISCV_TLS_IE
   285  
   286  	// R_RISCV_TLS_LE resolves a 32 bit TLS local-exec address for a
   287  	// LUI + I-type instruction sequence.
   288  	R_RISCV_TLS_LE
   289  
   290  	// R_RISCV_GOT_HI20 resolves the high 20 bits of a 32-bit PC-relative GOT
   291  	// address.
   292  	R_RISCV_GOT_HI20
   293  
   294  	// R_RISCV_PCREL_HI20 resolves the high 20 bits of a 32-bit PC-relative
   295  	// address.
   296  	R_RISCV_PCREL_HI20
   297  
   298  	// R_RISCV_PCREL_LO12_I resolves the low 12 bits of a 32-bit PC-relative
   299  	// address using an I-type instruction.
   300  	R_RISCV_PCREL_LO12_I
   301  
   302  	// R_RISCV_PCREL_LO12_S resolves the low 12 bits of a 32-bit PC-relative
   303  	// address using an S-type instruction.
   304  	R_RISCV_PCREL_LO12_S
   305  
   306  	// R_RISCV_BRANCH resolves a 12-bit PC-relative branch offset.
   307  	R_RISCV_BRANCH
   308  
   309  	// R_RISCV_RVC_BRANCH resolves an 8-bit PC-relative offset for a CB-type
   310  	// instruction.
   311  	R_RISCV_RVC_BRANCH
   312  
   313  	// R_RISCV_RVC_JUMP resolves an 11-bit PC-relative offset for a CJ-type
   314  	// instruction.
   315  	R_RISCV_RVC_JUMP
   316  
   317  	// R_PCRELDBL relocates s390x 2-byte aligned PC-relative addresses.
   318  	// TODO(mundaym): remove once variants can be serialized - see issue 14218.
   319  	R_PCRELDBL
   320  
   321  	// Loong64.
   322  
   323  	// R_ADDRLOONG64 resolves to the low 12 bits of an external address, by encoding
   324  	// it into the instruction.
   325  	R_ADDRLOONG64
   326  
   327  	// R_ADDRLOONG64U resolves to the sign-adjusted "upper" 20 bits (bit 5-24) of an
   328  	// external address, by encoding it into the instruction.
   329  	R_ADDRLOONG64U
   330  
   331  	// R_ADDRLOONG64TLS resolves to the low 12 bits of a TLS address (offset from
   332  	// thread pointer), by encoding it into the instruction.
   333  	R_ADDRLOONG64TLS
   334  
   335  	// R_ADDRLOONG64TLSU resolves to the high 20 bits of a TLS address (offset from
   336  	// thread pointer), by encoding it into the instruction.
   337  	R_ADDRLOONG64TLSU
   338  
   339  	// R_CALLLOONG64 resolves to non-PC-relative target address of a CALL (BL/JIRL)
   340  	// instruction, by encoding the address into the instruction.
   341  	R_CALLLOONG64
   342  
   343  	// R_LOONG64_TLS_IE_PCREL_HI and R_LOONG64_TLS_IE_LO relocates a pcalau12i, ld.d
   344  	// pair to compute the address of the GOT slot of the tls symbol.
   345  	R_LOONG64_TLS_IE_PCREL_HI
   346  	R_LOONG64_TLS_IE_LO
   347  
   348  	// R_LOONG64_GOT_HI and R_LOONG64_GOT_LO resolves a GOT-relative instruction sequence,
   349  	// usually an pcalau12i followed by another ld or addi instruction.
   350  	R_LOONG64_GOT_HI
   351  	R_LOONG64_GOT_LO
   352  
   353  	// R_JMPLOONG64 resolves to non-PC-relative target address of a JMP instruction,
   354  	// by encoding the address into the instruction.
   355  	R_JMPLOONG64
   356  
   357  	// R_ADDRMIPSU (only used on mips/mips64) resolves to the sign-adjusted "upper" 16
   358  	// bits (bit 16-31) of an external address, by encoding it into the instruction.
   359  	R_ADDRMIPSU
   360  	// R_ADDRMIPSTLS (only used on mips64) resolves to the low 16 bits of a TLS
   361  	// address (offset from thread pointer), by encoding it into the instruction.
   362  	R_ADDRMIPSTLS
   363  
   364  	// R_ADDRCUOFF resolves to a pointer-sized offset from the start of the
   365  	// symbol's DWARF compile unit.
   366  	R_ADDRCUOFF
   367  
   368  	// R_WASMIMPORT resolves to the index of the WebAssembly function import.
   369  	R_WASMIMPORT
   370  
   371  	// R_XCOFFREF (only used on aix/ppc64) prevents garbage collection by ld
   372  	// of a symbol. This isn't a real relocation, it can be placed in anywhere
   373  	// in a symbol and target any symbols.
   374  	R_XCOFFREF
   375  
   376  	// R_PEIMAGEOFF resolves to a 32-bit offset from the start address of where
   377  	// the executable file is mapped in memory.
   378  	R_PEIMAGEOFF
   379  
   380  	// R_INITORDER specifies an ordering edge between two inittask records.
   381  	// (From one p..inittask record to another one.)
   382  	// This relocation does not apply any changes to the actual data, it is
   383  	// just used in the linker to order the inittask records appropriately.
   384  	R_INITORDER
   385  
   386  	// R_WEAK marks the relocation as a weak reference.
   387  	// A weak relocation does not make the symbol it refers to reachable,
   388  	// and is only honored by the linker if the symbol is in some other way
   389  	// reachable.
   390  	R_WEAK = -1 << 15
   391  
   392  	R_WEAKADDR    = R_WEAK | R_ADDR
   393  	R_WEAKADDROFF = R_WEAK | R_ADDROFF
   394  )
   395  
   396  // IsDirectCall reports whether r is a relocation for a direct call.
   397  // A direct call is a CALL instruction that takes the target address
   398  // as an immediate. The address is embedded into the instruction(s), possibly
   399  // with limited width. An indirect call is a CALL instruction that takes
   400  // the target address in register or memory.
   401  func (r RelocType) IsDirectCall() bool {
   402  	switch r {
   403  	case R_CALL, R_CALLARM, R_CALLARM64, R_CALLLOONG64, R_CALLMIPS, R_CALLPOWER,
   404  		R_RISCV_CALL, R_RISCV_JAL, R_RISCV_JAL_TRAMP:
   405  		return true
   406  	}
   407  	return false
   408  }
   409  
   410  // IsDirectJump reports whether r is a relocation for a direct jump.
   411  // A direct jump is a JMP instruction that takes the target address
   412  // as an immediate. The address is embedded into the instruction, possibly
   413  // with limited width. An indirect jump is a JMP instruction that takes
   414  // the target address in register or memory.
   415  func (r RelocType) IsDirectJump() bool {
   416  	switch r {
   417  	case R_JMPMIPS:
   418  		return true
   419  	case R_JMPLOONG64:
   420  		return true
   421  	}
   422  	return false
   423  }
   424  
   425  // IsDirectCallOrJump reports whether r is a relocation for a direct
   426  // call or a direct jump.
   427  func (r RelocType) IsDirectCallOrJump() bool {
   428  	return r.IsDirectCall() || r.IsDirectJump()
   429  }
   430  

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