Source file src/cmd/link/internal/ld/xcoff.go

     1  // Copyright 2018 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package ld
     6  
     7  import (
     8  	"bytes"
     9  	"encoding/binary"
    10  	"fmt"
    11  	"math/bits"
    12  	"os"
    13  	"path/filepath"
    14  	"sort"
    15  	"strings"
    16  	"sync"
    17  
    18  	"cmd/internal/objabi"
    19  	"cmd/link/internal/loader"
    20  	"cmd/link/internal/sym"
    21  )
    22  
    23  // This file handles all algorithms related to XCOFF files generation.
    24  // Most of them are adaptations of the ones in  cmd/link/internal/pe.go
    25  // as PE and XCOFF are based on COFF files.
    26  // XCOFF files generated are 64 bits.
    27  
    28  const (
    29  	// Total amount of space to reserve at the start of the file
    30  	// for File Header, Auxiliary Header, and Section Headers.
    31  	// May waste some.
    32  	XCOFFHDRRESERVE = FILHSZ_64 + AOUTHSZ_EXEC64 + SCNHSZ_64*23
    33  
    34  	// base on dump -o, then rounded from 32B to 64B to
    35  	// match worst case elf text section alignment on ppc64.
    36  	XCOFFSECTALIGN int64 = 64
    37  
    38  	// XCOFF binaries should normally have all its sections position-independent.
    39  	// However, this is not yet possible for .text because of some R_ADDR relocations
    40  	// inside RODATA symbols.
    41  	// .data and .bss are position-independent so their address start inside an unreachable
    42  	// segment during execution to force segfault if something is wrong.
    43  	XCOFFTEXTBASE = 0x100000000 // Start of text address
    44  	XCOFFDATABASE = 0x200000000 // Start of data address
    45  )
    46  
    47  // File Header
    48  type XcoffFileHdr64 struct {
    49  	Fmagic   uint16 // Target machine
    50  	Fnscns   uint16 // Number of sections
    51  	Ftimedat int32  // Time and date of file creation
    52  	Fsymptr  uint64 // Byte offset to symbol table start
    53  	Fopthdr  uint16 // Number of bytes in optional header
    54  	Fflags   uint16 // Flags
    55  	Fnsyms   int32  // Number of entries in symbol table
    56  }
    57  
    58  const (
    59  	U64_TOCMAGIC = 0767 // AIX 64-bit XCOFF
    60  )
    61  
    62  // Flags that describe the type of the object file.
    63  const (
    64  	F_RELFLG    = 0x0001
    65  	F_EXEC      = 0x0002
    66  	F_LNNO      = 0x0004
    67  	F_FDPR_PROF = 0x0010
    68  	F_FDPR_OPTI = 0x0020
    69  	F_DSA       = 0x0040
    70  	F_VARPG     = 0x0100
    71  	F_DYNLOAD   = 0x1000
    72  	F_SHROBJ    = 0x2000
    73  	F_LOADONLY  = 0x4000
    74  )
    75  
    76  // Auxiliary Header
    77  type XcoffAoutHdr64 struct {
    78  	Omagic      int16    // Flags - Ignored If Vstamp Is 1
    79  	Ovstamp     int16    // Version
    80  	Odebugger   uint32   // Reserved For Debugger
    81  	Otextstart  uint64   // Virtual Address Of Text
    82  	Odatastart  uint64   // Virtual Address Of Data
    83  	Otoc        uint64   // Toc Address
    84  	Osnentry    int16    // Section Number For Entry Point
    85  	Osntext     int16    // Section Number For Text
    86  	Osndata     int16    // Section Number For Data
    87  	Osntoc      int16    // Section Number For Toc
    88  	Osnloader   int16    // Section Number For Loader
    89  	Osnbss      int16    // Section Number For Bss
    90  	Oalgntext   int16    // Max Text Alignment
    91  	Oalgndata   int16    // Max Data Alignment
    92  	Omodtype    [2]byte  // Module Type Field
    93  	Ocpuflag    uint8    // Bit Flags - Cputypes Of Objects
    94  	Ocputype    uint8    // Reserved for CPU type
    95  	Otextpsize  uint8    // Requested text page size
    96  	Odatapsize  uint8    // Requested data page size
    97  	Ostackpsize uint8    // Requested stack page size
    98  	Oflags      uint8    // Flags And TLS Alignment
    99  	Otsize      uint64   // Text Size In Bytes
   100  	Odsize      uint64   // Data Size In Bytes
   101  	Obsize      uint64   // Bss Size In Bytes
   102  	Oentry      uint64   // Entry Point Address
   103  	Omaxstack   uint64   // Max Stack Size Allowed
   104  	Omaxdata    uint64   // Max Data Size Allowed
   105  	Osntdata    int16    // Section Number For Tdata Section
   106  	Osntbss     int16    // Section Number For Tbss Section
   107  	Ox64flags   uint16   // Additional Flags For 64-Bit Objects
   108  	Oresv3a     int16    // Reserved
   109  	Oresv3      [2]int32 // Reserved
   110  }
   111  
   112  // Section Header
   113  type XcoffScnHdr64 struct {
   114  	Sname    [8]byte // Section Name
   115  	Spaddr   uint64  // Physical Address
   116  	Svaddr   uint64  // Virtual Address
   117  	Ssize    uint64  // Section Size
   118  	Sscnptr  uint64  // File Offset To Raw Data
   119  	Srelptr  uint64  // File Offset To Relocation
   120  	Slnnoptr uint64  // File Offset To Line Numbers
   121  	Snreloc  uint32  // Number Of Relocation Entries
   122  	Snlnno   uint32  // Number Of Line Number Entries
   123  	Sflags   uint32  // flags
   124  }
   125  
   126  // Flags defining the section type.
   127  const (
   128  	STYP_DWARF  = 0x0010
   129  	STYP_TEXT   = 0x0020
   130  	STYP_DATA   = 0x0040
   131  	STYP_BSS    = 0x0080
   132  	STYP_EXCEPT = 0x0100
   133  	STYP_INFO   = 0x0200
   134  	STYP_TDATA  = 0x0400
   135  	STYP_TBSS   = 0x0800
   136  	STYP_LOADER = 0x1000
   137  	STYP_DEBUG  = 0x2000
   138  	STYP_TYPCHK = 0x4000
   139  	STYP_OVRFLO = 0x8000
   140  )
   141  const (
   142  	SSUBTYP_DWINFO  = 0x10000 // DWARF info section
   143  	SSUBTYP_DWLINE  = 0x20000 // DWARF line-number section
   144  	SSUBTYP_DWPBNMS = 0x30000 // DWARF public names section
   145  	SSUBTYP_DWPBTYP = 0x40000 // DWARF public types section
   146  	SSUBTYP_DWARNGE = 0x50000 // DWARF aranges section
   147  	SSUBTYP_DWABREV = 0x60000 // DWARF abbreviation section
   148  	SSUBTYP_DWSTR   = 0x70000 // DWARF strings section
   149  	SSUBTYP_DWRNGES = 0x80000 // DWARF ranges section
   150  	SSUBTYP_DWLOC   = 0x90000 // DWARF location lists section
   151  	SSUBTYP_DWFRAME = 0xA0000 // DWARF frames section
   152  	SSUBTYP_DWMAC   = 0xB0000 // DWARF macros section
   153  )
   154  
   155  // Headers size
   156  const (
   157  	FILHSZ_32      = 20
   158  	FILHSZ_64      = 24
   159  	AOUTHSZ_EXEC32 = 72
   160  	AOUTHSZ_EXEC64 = 120
   161  	SCNHSZ_32      = 40
   162  	SCNHSZ_64      = 72
   163  	LDHDRSZ_32     = 32
   164  	LDHDRSZ_64     = 56
   165  	LDSYMSZ_64     = 24
   166  	RELSZ_64       = 14
   167  )
   168  
   169  // Type representing all XCOFF symbols.
   170  type xcoffSym any
   171  
   172  // Symbol Table Entry
   173  type XcoffSymEnt64 struct {
   174  	Nvalue  uint64 // Symbol value
   175  	Noffset uint32 // Offset of the name in string table or .debug section
   176  	Nscnum  int16  // Section number of symbol
   177  	Ntype   uint16 // Basic and derived type specification
   178  	Nsclass uint8  // Storage class of symbol
   179  	Nnumaux int8   // Number of auxiliary entries
   180  }
   181  
   182  const SYMESZ = 18
   183  
   184  const (
   185  	// Nscnum
   186  	N_DEBUG = -2
   187  	N_ABS   = -1
   188  	N_UNDEF = 0
   189  
   190  	//Ntype
   191  	SYM_V_INTERNAL  = 0x1000
   192  	SYM_V_HIDDEN    = 0x2000
   193  	SYM_V_PROTECTED = 0x3000
   194  	SYM_V_EXPORTED  = 0x4000
   195  	SYM_TYPE_FUNC   = 0x0020 // is function
   196  )
   197  
   198  // Storage Class.
   199  const (
   200  	C_NULL    = 0   // Symbol table entry marked for deletion
   201  	C_EXT     = 2   // External symbol
   202  	C_STAT    = 3   // Static symbol
   203  	C_BLOCK   = 100 // Beginning or end of inner block
   204  	C_FCN     = 101 // Beginning or end of function
   205  	C_FILE    = 103 // Source file name and compiler information
   206  	C_HIDEXT  = 107 // Unnamed external symbol
   207  	C_BINCL   = 108 // Beginning of include file
   208  	C_EINCL   = 109 // End of include file
   209  	C_WEAKEXT = 111 // Weak external symbol
   210  	C_DWARF   = 112 // DWARF symbol
   211  	C_GSYM    = 128 // Global variable
   212  	C_LSYM    = 129 // Automatic variable allocated on stack
   213  	C_PSYM    = 130 // Argument to subroutine allocated on stack
   214  	C_RSYM    = 131 // Register variable
   215  	C_RPSYM   = 132 // Argument to function or procedure stored in register
   216  	C_STSYM   = 133 // Statically allocated symbol
   217  	C_BCOMM   = 135 // Beginning of common block
   218  	C_ECOML   = 136 // Local member of common block
   219  	C_ECOMM   = 137 // End of common block
   220  	C_DECL    = 140 // Declaration of object
   221  	C_ENTRY   = 141 // Alternate entry
   222  	C_FUN     = 142 // Function or procedure
   223  	C_BSTAT   = 143 // Beginning of static block
   224  	C_ESTAT   = 144 // End of static block
   225  	C_GTLS    = 145 // Global thread-local variable
   226  	C_STTLS   = 146 // Static thread-local variable
   227  )
   228  
   229  // File Auxiliary Entry
   230  type XcoffAuxFile64 struct {
   231  	Xzeroes  uint32 // The name is always in the string table
   232  	Xoffset  uint32 // Offset in the string table
   233  	X_pad1   [6]byte
   234  	Xftype   uint8 // Source file string type
   235  	X_pad2   [2]byte
   236  	Xauxtype uint8 // Type of auxiliary entry
   237  }
   238  
   239  // Function Auxiliary Entry
   240  type XcoffAuxFcn64 struct {
   241  	Xlnnoptr uint64 // File pointer to line number
   242  	Xfsize   uint32 // Size of function in bytes
   243  	Xendndx  uint32 // Symbol table index of next entry
   244  	Xpad     uint8  // Unused
   245  	Xauxtype uint8  // Type of auxiliary entry
   246  }
   247  
   248  // csect Auxiliary Entry.
   249  type XcoffAuxCSect64 struct {
   250  	Xscnlenlo uint32 // Lower 4 bytes of length or symbol table index
   251  	Xparmhash uint32 // Offset of parameter type-check string
   252  	Xsnhash   uint16 // .typchk section number
   253  	Xsmtyp    uint8  // Symbol alignment and type
   254  	Xsmclas   uint8  // Storage-mapping class
   255  	Xscnlenhi uint32 // Upper 4 bytes of length or symbol table index
   256  	Xpad      uint8  // Unused
   257  	Xauxtype  uint8  // Type of auxiliary entry
   258  }
   259  
   260  // DWARF Auxiliary Entry
   261  type XcoffAuxDWARF64 struct {
   262  	Xscnlen  uint64 // Length of this symbol section
   263  	X_pad    [9]byte
   264  	Xauxtype uint8 // Type of auxiliary entry
   265  }
   266  
   267  // Auxiliary type
   268  const (
   269  	_AUX_EXCEPT = 255
   270  	_AUX_FCN    = 254
   271  	_AUX_SYM    = 253
   272  	_AUX_FILE   = 252
   273  	_AUX_CSECT  = 251
   274  	_AUX_SECT   = 250
   275  )
   276  
   277  // Xftype field
   278  const (
   279  	XFT_FN = 0   // Source File Name
   280  	XFT_CT = 1   // Compile Time Stamp
   281  	XFT_CV = 2   // Compiler Version Number
   282  	XFT_CD = 128 // Compiler Defined Information/
   283  
   284  )
   285  
   286  // Symbol type field.
   287  const (
   288  	XTY_ER  = 0    // External reference
   289  	XTY_SD  = 1    // Section definition
   290  	XTY_LD  = 2    // Label definition
   291  	XTY_CM  = 3    // Common csect definition
   292  	XTY_WK  = 0x8  // Weak symbol
   293  	XTY_EXP = 0x10 // Exported symbol
   294  	XTY_ENT = 0x20 // Entry point symbol
   295  	XTY_IMP = 0x40 // Imported symbol
   296  )
   297  
   298  // Storage-mapping class.
   299  const (
   300  	XMC_PR     = 0  // Program code
   301  	XMC_RO     = 1  // Read-only constant
   302  	XMC_DB     = 2  // Debug dictionary table
   303  	XMC_TC     = 3  // TOC entry
   304  	XMC_UA     = 4  // Unclassified
   305  	XMC_RW     = 5  // Read/Write data
   306  	XMC_GL     = 6  // Global linkage
   307  	XMC_XO     = 7  // Extended operation
   308  	XMC_SV     = 8  // 32-bit supervisor call descriptor
   309  	XMC_BS     = 9  // BSS class
   310  	XMC_DS     = 10 // Function descriptor
   311  	XMC_UC     = 11 // Unnamed FORTRAN common
   312  	XMC_TC0    = 15 // TOC anchor
   313  	XMC_TD     = 16 // Scalar data entry in the TOC
   314  	XMC_SV64   = 17 // 64-bit supervisor call descriptor
   315  	XMC_SV3264 = 18 // Supervisor call descriptor for both 32-bit and 64-bit
   316  	XMC_TL     = 20 // Read/Write thread-local data
   317  	XMC_UL     = 21 // Read/Write thread-local data (.tbss)
   318  	XMC_TE     = 22 // TOC entry
   319  )
   320  
   321  // Loader Header
   322  type XcoffLdHdr64 struct {
   323  	Lversion int32  // Loader section version number
   324  	Lnsyms   int32  // Number of symbol table entries
   325  	Lnreloc  int32  // Number of relocation table entries
   326  	Listlen  uint32 // Length of import file ID string table
   327  	Lnimpid  int32  // Number of import file IDs
   328  	Lstlen   uint32 // Length of string table
   329  	Limpoff  uint64 // Offset to start of import file IDs
   330  	Lstoff   uint64 // Offset to start of string table
   331  	Lsymoff  uint64 // Offset to start of symbol table
   332  	Lrldoff  uint64 // Offset to start of relocation entries
   333  }
   334  
   335  // Loader Symbol
   336  type XcoffLdSym64 struct {
   337  	Lvalue  uint64 // Address field
   338  	Loffset uint32 // Byte offset into string table of symbol name
   339  	Lscnum  int16  // Section number containing symbol
   340  	Lsmtype int8   // Symbol type, export, import flags
   341  	Lsmclas int8   // Symbol storage class
   342  	Lifile  int32  // Import file ID; ordinal of import file IDs
   343  	Lparm   uint32 // Parameter type-check field
   344  }
   345  
   346  type xcoffLoaderSymbol struct {
   347  	sym    loader.Sym
   348  	smtype int8
   349  	smclas int8
   350  }
   351  
   352  type XcoffLdImportFile64 struct {
   353  	Limpidpath string
   354  	Limpidbase string
   355  	Limpidmem  string
   356  }
   357  
   358  type XcoffLdRel64 struct {
   359  	Lvaddr  uint64 // Address Field
   360  	Lrtype  uint16 // Relocation Size and Type
   361  	Lrsecnm int16  // Section Number being relocated
   362  	Lsymndx int32  // Loader-Section symbol table index
   363  }
   364  
   365  // xcoffLoaderReloc holds information about a relocation made by the loader.
   366  type xcoffLoaderReloc struct {
   367  	sym    loader.Sym
   368  	roff   int32
   369  	rtype  uint16
   370  	symndx int32
   371  }
   372  
   373  const (
   374  	XCOFF_R_POS = 0x00 // A(sym) Positive Relocation
   375  	XCOFF_R_NEG = 0x01 // -A(sym) Negative Relocation
   376  	XCOFF_R_REL = 0x02 // A(sym-*) Relative to self
   377  	XCOFF_R_TOC = 0x03 // A(sym-TOC) Relative to TOC
   378  	XCOFF_R_TRL = 0x12 // A(sym-TOC) TOC Relative indirect load.
   379  
   380  	XCOFF_R_TRLA = 0x13 // A(sym-TOC) TOC Rel load address. modifiable inst
   381  	XCOFF_R_GL   = 0x05 // A(external TOC of sym) Global Linkage
   382  	XCOFF_R_TCL  = 0x06 // A(local TOC of sym) Local object TOC address
   383  	XCOFF_R_RL   = 0x0C // A(sym) Pos indirect load. modifiable instruction
   384  	XCOFF_R_RLA  = 0x0D // A(sym) Pos Load Address. modifiable instruction
   385  	XCOFF_R_REF  = 0x0F // AL0(sym) Non relocating ref. No garbage collect
   386  	XCOFF_R_BA   = 0x08 // A(sym) Branch absolute. Cannot modify instruction
   387  	XCOFF_R_RBA  = 0x18 // A(sym) Branch absolute. modifiable instruction
   388  	XCOFF_R_BR   = 0x0A // A(sym-*) Branch rel to self. non modifiable
   389  	XCOFF_R_RBR  = 0x1A // A(sym-*) Branch rel to self. modifiable instr
   390  
   391  	XCOFF_R_TLS    = 0x20 // General-dynamic reference to TLS symbol
   392  	XCOFF_R_TLS_IE = 0x21 // Initial-exec reference to TLS symbol
   393  	XCOFF_R_TLS_LD = 0x22 // Local-dynamic reference to TLS symbol
   394  	XCOFF_R_TLS_LE = 0x23 // Local-exec reference to TLS symbol
   395  	XCOFF_R_TLSM   = 0x24 // Module reference to TLS symbol
   396  	XCOFF_R_TLSML  = 0x25 // Module reference to local (own) module
   397  
   398  	XCOFF_R_TOCU = 0x30 // Relative to TOC - high order bits
   399  	XCOFF_R_TOCL = 0x31 // Relative to TOC - low order bits
   400  )
   401  
   402  type XcoffLdStr64 struct {
   403  	size uint16
   404  	name string
   405  }
   406  
   407  // xcoffFile is used to build XCOFF file.
   408  type xcoffFile struct {
   409  	xfhdr           XcoffFileHdr64
   410  	xahdr           XcoffAoutHdr64
   411  	sections        []*XcoffScnHdr64
   412  	sectText        *XcoffScnHdr64
   413  	sectData        *XcoffScnHdr64
   414  	sectBss         *XcoffScnHdr64
   415  	stringTable     xcoffStringTable
   416  	sectNameToScnum map[string]int16
   417  	loaderSize      uint64
   418  	symtabOffset    int64                // offset to the start of symbol table
   419  	symbolCount     uint32               // number of symbol table records written
   420  	symtabSym       []xcoffSym           // XCOFF symbols for the symbol table
   421  	dynLibraries    map[string]int       // Dynamic libraries in .loader section. The integer represents its import file number (- 1)
   422  	loaderSymbols   []*xcoffLoaderSymbol // symbols inside .loader symbol table
   423  	loaderReloc     []*xcoffLoaderReloc  // Reloc that must be made inside loader
   424  	sync.Mutex                           // currently protect loaderReloc
   425  }
   426  
   427  // Var used by XCOFF Generation algorithms
   428  var (
   429  	xfile xcoffFile
   430  )
   431  
   432  // xcoffStringTable is a XCOFF string table.
   433  type xcoffStringTable struct {
   434  	strings    []string
   435  	stringsLen int
   436  }
   437  
   438  // size returns size of string table t.
   439  func (t *xcoffStringTable) size() int {
   440  	// string table starts with 4-byte length at the beginning
   441  	return t.stringsLen + 4
   442  }
   443  
   444  // add adds string str to string table t.
   445  func (t *xcoffStringTable) add(str string) int {
   446  	off := t.size()
   447  	t.strings = append(t.strings, str)
   448  	t.stringsLen += len(str) + 1 // each string will have 0 appended to it
   449  	return off
   450  }
   451  
   452  // write writes string table t into the output file.
   453  func (t *xcoffStringTable) write(out *OutBuf) {
   454  	out.Write32(uint32(t.size()))
   455  	for _, s := range t.strings {
   456  		out.WriteString(s)
   457  		out.Write8(0)
   458  	}
   459  }
   460  
   461  // write writes XCOFF section sect into the output file.
   462  func (sect *XcoffScnHdr64) write(ctxt *Link) {
   463  	binary.Write(ctxt.Out, binary.BigEndian, sect)
   464  	ctxt.Out.Write32(0) // Add 4 empty bytes at the end to match alignment
   465  }
   466  
   467  // addSection adds section to the XCOFF file f.
   468  func (f *xcoffFile) addSection(name string, addr uint64, size uint64, fileoff uint64, flags uint32) *XcoffScnHdr64 {
   469  	sect := &XcoffScnHdr64{
   470  		Spaddr:  addr,
   471  		Svaddr:  addr,
   472  		Ssize:   size,
   473  		Sscnptr: fileoff,
   474  		Sflags:  flags,
   475  	}
   476  	copy(sect.Sname[:], name) // copy string to [8]byte
   477  	f.sections = append(f.sections, sect)
   478  	f.sectNameToScnum[name] = int16(len(f.sections))
   479  	return sect
   480  }
   481  
   482  // addDwarfSection adds a dwarf section to the XCOFF file f.
   483  // This function is similar to addSection, but Dwarf section names
   484  // must be modified to conventional names and they are various subtypes.
   485  func (f *xcoffFile) addDwarfSection(s *sym.Section) *XcoffScnHdr64 {
   486  	newName, subtype := xcoffGetDwarfSubtype(s.Name)
   487  	return f.addSection(newName, 0, s.Length, s.Seg.Fileoff+s.Vaddr-s.Seg.Vaddr, STYP_DWARF|subtype)
   488  }
   489  
   490  // xcoffGetDwarfSubtype returns the XCOFF name of the DWARF section str
   491  // and its subtype constant.
   492  func xcoffGetDwarfSubtype(str string) (string, uint32) {
   493  	switch str {
   494  	default:
   495  		Exitf("unknown DWARF section name for XCOFF: %s", str)
   496  	case ".debug_abbrev":
   497  		return ".dwabrev", SSUBTYP_DWABREV
   498  	case ".debug_info":
   499  		return ".dwinfo", SSUBTYP_DWINFO
   500  	case ".debug_frame":
   501  		return ".dwframe", SSUBTYP_DWFRAME
   502  	case ".debug_line":
   503  		return ".dwline", SSUBTYP_DWLINE
   504  	case ".debug_loc":
   505  		return ".dwloc", SSUBTYP_DWLOC
   506  	case ".debug_pubnames":
   507  		return ".dwpbnms", SSUBTYP_DWPBNMS
   508  	case ".debug_pubtypes":
   509  		return ".dwpbtyp", SSUBTYP_DWPBTYP
   510  	case ".debug_ranges":
   511  		return ".dwrnges", SSUBTYP_DWRNGES
   512  	}
   513  	// never used
   514  	return "", 0
   515  }
   516  
   517  // getXCOFFscnum returns the XCOFF section number of a Go section.
   518  func (f *xcoffFile) getXCOFFscnum(sect *sym.Section) int16 {
   519  	switch sect.Seg {
   520  	case &Segtext:
   521  		return f.sectNameToScnum[".text"]
   522  	case &Segdata:
   523  		if sect.Name == ".noptrbss" || sect.Name == ".bss" {
   524  			return f.sectNameToScnum[".bss"]
   525  		}
   526  		if sect.Name == ".tbss" {
   527  			return f.sectNameToScnum[".tbss"]
   528  		}
   529  		return f.sectNameToScnum[".data"]
   530  	case &Segdwarf:
   531  		name, _ := xcoffGetDwarfSubtype(sect.Name)
   532  		return f.sectNameToScnum[name]
   533  	case &Segrelrodata:
   534  		return f.sectNameToScnum[".data"]
   535  	}
   536  	Errorf("getXCOFFscnum not implemented for section %s", sect.Name)
   537  	return -1
   538  }
   539  
   540  // Xcoffinit initialised some internal value and setups
   541  // already known header information.
   542  func Xcoffinit(ctxt *Link) {
   543  	xfile.dynLibraries = make(map[string]int)
   544  
   545  	HEADR = int32(Rnd(XCOFFHDRRESERVE, XCOFFSECTALIGN))
   546  	if *FlagRound != -1 {
   547  		Errorf("-R not available on AIX")
   548  	}
   549  	*FlagRound = XCOFFSECTALIGN
   550  	if *FlagTextAddr != -1 {
   551  		Errorf("-T not available on AIX")
   552  	}
   553  	*FlagTextAddr = Rnd(XCOFFTEXTBASE, *FlagRound) + int64(HEADR)
   554  }
   555  
   556  // SYMBOL TABLE
   557  
   558  // type records C_FILE information needed for genasmsym in XCOFF.
   559  type xcoffSymSrcFile struct {
   560  	name         string
   561  	file         *XcoffSymEnt64   // Symbol of this C_FILE
   562  	csectAux     *XcoffAuxCSect64 // Symbol for the current .csect
   563  	csectSymNb   uint64           // Symbol number for the current .csect
   564  	csectVAStart int64
   565  	csectVAEnd   int64
   566  }
   567  
   568  var (
   569  	currDwscnoff   = make(map[string]uint64) // Needed to create C_DWARF symbols
   570  	currSymSrcFile xcoffSymSrcFile
   571  	outerSymSize   = make(map[string]int64)
   572  )
   573  
   574  // xcoffUpdateOuterSize stores the size of outer symbols in order to have it
   575  // in the symbol table.
   576  func xcoffUpdateOuterSize(ctxt *Link, size int64, stype sym.SymKind) {
   577  	if size == 0 {
   578  		return
   579  	}
   580  	// TODO: use CarrierSymByType
   581  
   582  	ldr := ctxt.loader
   583  	switch stype {
   584  	default:
   585  		Errorf("unknown XCOFF outer symbol for type %s", stype.String())
   586  	case sym.SRODATA, sym.SRODATARELRO, sym.SFUNCTAB, sym.SSTRING:
   587  		// Nothing to do
   588  	case sym.STYPERELRO:
   589  		if ctxt.UseRelro() && (ctxt.BuildMode == BuildModeCArchive || ctxt.BuildMode == BuildModeCShared || ctxt.BuildMode == BuildModePIE) {
   590  			// runtime.types size must be removed, as it's a real symbol.
   591  			tsize := ldr.SymSize(ldr.Lookup("runtime.types", 0))
   592  			outerSymSize["typerel.*"] = size - tsize
   593  			return
   594  		}
   595  		fallthrough
   596  	case sym.STYPE:
   597  		if !ctxt.DynlinkingGo() {
   598  			// runtime.types size must be removed, as it's a real symbol.
   599  			tsize := ldr.SymSize(ldr.Lookup("runtime.types", 0))
   600  			outerSymSize["type:*"] = size - tsize
   601  		}
   602  	case sym.SGOSTRING:
   603  		outerSymSize["go:string.*"] = size
   604  	case sym.SGOFUNC:
   605  		if !ctxt.DynlinkingGo() {
   606  			outerSymSize["go:funcdesc"] = size
   607  		}
   608  	case sym.SGOFUNCRELRO:
   609  		outerSymSize["go:funcdescrel"] = size
   610  	case sym.SGCBITS:
   611  		outerSymSize["runtime.gcbits.*"] = size
   612  	case sym.SPCLNTAB:
   613  		// go:func.* size must be removed from pclntab,
   614  		// as it's a real symbol. Same for runtime.findfunctab.
   615  		fsize := ldr.SymSize(ldr.Lookup("go:func.*", 0))
   616  		fft := ldr.Lookup("runtime.findfunctab", 0)
   617  		fsize = Rnd(fsize, int64(symalign(ldr, fft)))
   618  		tsize := ldr.SymSize(fft)
   619  		outerSymSize["runtime.pclntab"] = size - (fsize + tsize)
   620  	}
   621  }
   622  
   623  // addSymbol writes a symbol or an auxiliary symbol entry on ctxt.out.
   624  func (f *xcoffFile) addSymbol(sym xcoffSym) {
   625  	f.symtabSym = append(f.symtabSym, sym)
   626  	f.symbolCount++
   627  }
   628  
   629  // xcoffAlign returns the log base 2 of the symbol's alignment.
   630  func xcoffAlign(ldr *loader.Loader, x loader.Sym, t SymbolType) uint8 {
   631  	align := ldr.SymAlign(x)
   632  	if align == 0 {
   633  		if t == TextSym {
   634  			align = int32(Funcalign)
   635  		} else {
   636  			align = symalign(ldr, x)
   637  		}
   638  	}
   639  	return logBase2(int(align))
   640  }
   641  
   642  // logBase2 returns the log in base 2 of a.
   643  func logBase2(a int) uint8 {
   644  	return uint8(bits.Len(uint(a)) - 1)
   645  }
   646  
   647  // Write symbols needed when a new file appeared:
   648  // - a C_FILE with one auxiliary entry for its name
   649  // - C_DWARF symbols to provide debug information
   650  // - a C_HIDEXT which will be a csect containing all of its functions
   651  // It needs several parameters to create .csect symbols such as its entry point and its section number.
   652  //
   653  // Currently, a new file is in fact a new package. It seems to be OK, but it might change
   654  // in the future.
   655  func (f *xcoffFile) writeSymbolNewFile(ctxt *Link, name string, firstEntry uint64, extnum int16) {
   656  	ldr := ctxt.loader
   657  	/* C_FILE */
   658  	s := &XcoffSymEnt64{
   659  		Noffset: uint32(f.stringTable.add(".file")),
   660  		Nsclass: C_FILE,
   661  		Nscnum:  N_DEBUG,
   662  		Ntype:   0, // Go isn't inside predefined language.
   663  		Nnumaux: 1,
   664  	}
   665  	f.addSymbol(s)
   666  	currSymSrcFile.file = s
   667  
   668  	// Auxiliary entry for file name.
   669  	auxf := &XcoffAuxFile64{
   670  		Xoffset:  uint32(f.stringTable.add(name)),
   671  		Xftype:   XFT_FN,
   672  		Xauxtype: _AUX_FILE,
   673  	}
   674  	f.addSymbol(auxf)
   675  
   676  	/* Dwarf */
   677  	for _, sect := range Segdwarf.Sections {
   678  		var dwsize uint64
   679  		if ctxt.LinkMode == LinkInternal {
   680  			// Find the size of this corresponding package DWARF compilation unit.
   681  			// This size is set during DWARF generation (see dwarf.go).
   682  			dwsize = getDwsectCUSize(sect.Name, name)
   683  			// .debug_abbrev is common to all packages and not found with the previous function
   684  			if sect.Name == ".debug_abbrev" {
   685  				dwsize = uint64(ldr.SymSize(sect.Sym))
   686  
   687  			}
   688  		} else {
   689  			// There is only one .FILE with external linking.
   690  			dwsize = sect.Length
   691  		}
   692  
   693  		// get XCOFF name
   694  		name, _ := xcoffGetDwarfSubtype(sect.Name)
   695  		s := &XcoffSymEnt64{
   696  			Nvalue:  currDwscnoff[sect.Name],
   697  			Noffset: uint32(f.stringTable.add(name)),
   698  			Nsclass: C_DWARF,
   699  			Nscnum:  f.getXCOFFscnum(sect),
   700  			Nnumaux: 1,
   701  		}
   702  
   703  		if currSymSrcFile.csectAux == nil {
   704  			// Dwarf relocations need the symbol number of .dw* symbols.
   705  			// It doesn't need to know it for each package, one is enough.
   706  			// currSymSrcFile.csectAux == nil means first package.
   707  			ldr.SetSymDynid(sect.Sym, int32(f.symbolCount))
   708  
   709  			if sect.Name == ".debug_frame" && ctxt.LinkMode != LinkExternal {
   710  				// CIE size must be added to the first package.
   711  				dwsize += 48
   712  			}
   713  		}
   714  
   715  		f.addSymbol(s)
   716  
   717  		// update the DWARF section offset in this file
   718  		if sect.Name != ".debug_abbrev" {
   719  			currDwscnoff[sect.Name] += dwsize
   720  		}
   721  
   722  		// Auxiliary dwarf section
   723  		auxd := &XcoffAuxDWARF64{
   724  			Xscnlen:  dwsize,
   725  			Xauxtype: _AUX_SECT,
   726  		}
   727  
   728  		f.addSymbol(auxd)
   729  	}
   730  
   731  	/* .csect */
   732  	// Check if extnum is in text.
   733  	// This is temporary and only here to check if this algorithm is correct.
   734  	if extnum != 1 {
   735  		Exitf("XCOFF symtab: A new file was detected with its first symbol not in .text")
   736  	}
   737  
   738  	currSymSrcFile.csectSymNb = uint64(f.symbolCount)
   739  
   740  	// No offset because no name
   741  	s = &XcoffSymEnt64{
   742  		Nvalue:  firstEntry,
   743  		Nscnum:  extnum,
   744  		Nsclass: C_HIDEXT,
   745  		Ntype:   0, // check visibility ?
   746  		Nnumaux: 1,
   747  	}
   748  	f.addSymbol(s)
   749  
   750  	aux := &XcoffAuxCSect64{
   751  		Xsmclas:  XMC_PR,
   752  		Xsmtyp:   XTY_SD | logBase2(Funcalign)<<3,
   753  		Xauxtype: _AUX_CSECT,
   754  	}
   755  	f.addSymbol(aux)
   756  
   757  	currSymSrcFile.csectAux = aux
   758  	currSymSrcFile.csectVAStart = int64(firstEntry)
   759  	currSymSrcFile.csectVAEnd = int64(firstEntry)
   760  }
   761  
   762  // Update values for the previous package.
   763  //   - Svalue of the C_FILE symbol: if it is the last one, this Svalue must be -1
   764  //   - Xsclen of the csect symbol.
   765  func (f *xcoffFile) updatePreviousFile(ctxt *Link, last bool) {
   766  	// first file
   767  	if currSymSrcFile.file == nil {
   768  		return
   769  	}
   770  
   771  	// Update C_FILE
   772  	cfile := currSymSrcFile.file
   773  	if last {
   774  		cfile.Nvalue = 0xFFFFFFFFFFFFFFFF
   775  	} else {
   776  		cfile.Nvalue = uint64(f.symbolCount)
   777  	}
   778  
   779  	// update csect scnlen in this auxiliary entry
   780  	aux := currSymSrcFile.csectAux
   781  	csectSize := currSymSrcFile.csectVAEnd - currSymSrcFile.csectVAStart
   782  	aux.Xscnlenlo = uint32(csectSize & 0xFFFFFFFF)
   783  	aux.Xscnlenhi = uint32(csectSize >> 32)
   784  }
   785  
   786  // Write symbol representing a .text function.
   787  // The symbol table is split with C_FILE corresponding to each package
   788  // and not to each source file as it should be.
   789  func (f *xcoffFile) writeSymbolFunc(ctxt *Link, x loader.Sym) []xcoffSym {
   790  	// New XCOFF symbols which will be written.
   791  	syms := []xcoffSym{}
   792  
   793  	// Check if a new file is detected.
   794  	ldr := ctxt.loader
   795  	name := ldr.SymName(x)
   796  	if strings.Contains(name, "-tramp") || strings.HasPrefix(name, "runtime.text.") {
   797  		// Trampoline don't have a FILE so there are considered
   798  		// in the current file.
   799  		// Same goes for runtime.text.X symbols.
   800  	} else if ldr.SymPkg(x) == "" { // Undefined global symbol
   801  		// If this happens, the algorithm must be redone.
   802  		if currSymSrcFile.name != "" {
   803  			Exitf("undefined global symbol found inside another file")
   804  		}
   805  	} else {
   806  		// Current file has changed. New C_FILE, C_DWARF, etc must be generated.
   807  		if currSymSrcFile.name != ldr.SymPkg(x) {
   808  			if ctxt.LinkMode == LinkInternal {
   809  				// update previous file values
   810  				xfile.updatePreviousFile(ctxt, false)
   811  				currSymSrcFile.name = ldr.SymPkg(x)
   812  				f.writeSymbolNewFile(ctxt, ldr.SymPkg(x), uint64(ldr.SymValue(x)), xfile.getXCOFFscnum(ldr.SymSect(x)))
   813  			} else {
   814  				// With external linking, ld will crash if there is several
   815  				// .FILE and DWARF debugging enable, somewhere during
   816  				// the relocation phase.
   817  				// Therefore, all packages are merged under a fake .FILE
   818  				// "go_functions".
   819  				// TODO(aix); remove once ld has been fixed or the triggering
   820  				// relocation has been found and fixed.
   821  				if currSymSrcFile.name == "" {
   822  					currSymSrcFile.name = ldr.SymPkg(x)
   823  					f.writeSymbolNewFile(ctxt, "go_functions", uint64(ldr.SymValue(x)), xfile.getXCOFFscnum(ldr.SymSect(x)))
   824  				}
   825  			}
   826  
   827  		}
   828  	}
   829  
   830  	name = ldr.SymExtname(x)
   831  	name = mangleABIName(ctxt, ldr, x, name)
   832  
   833  	s := &XcoffSymEnt64{
   834  		Nsclass: C_EXT,
   835  		Noffset: uint32(xfile.stringTable.add(name)),
   836  		Nvalue:  uint64(ldr.SymValue(x)),
   837  		Nscnum:  f.getXCOFFscnum(ldr.SymSect(x)),
   838  		Ntype:   SYM_TYPE_FUNC,
   839  		Nnumaux: 2,
   840  	}
   841  
   842  	if ldr.IsFileLocal(x) || ldr.AttrVisibilityHidden(x) || ldr.AttrLocal(x) {
   843  		s.Nsclass = C_HIDEXT
   844  	}
   845  
   846  	ldr.SetSymDynid(x, int32(xfile.symbolCount))
   847  	syms = append(syms, s)
   848  
   849  	// Keep track of the section size by tracking the VA range. Individual
   850  	// alignment differences may introduce a few extra bytes of padding
   851  	// which are not fully accounted for by ldr.SymSize(x).
   852  	sv := ldr.SymValue(x) + ldr.SymSize(x)
   853  	if currSymSrcFile.csectVAEnd < sv {
   854  		currSymSrcFile.csectVAEnd = sv
   855  	}
   856  
   857  	// create auxiliary entries
   858  	a2 := &XcoffAuxFcn64{
   859  		Xfsize:   uint32(ldr.SymSize(x)),
   860  		Xlnnoptr: 0,                     // TODO
   861  		Xendndx:  xfile.symbolCount + 3, // this symbol + 2 aux entries
   862  		Xauxtype: _AUX_FCN,
   863  	}
   864  	syms = append(syms, a2)
   865  
   866  	a4 := &XcoffAuxCSect64{
   867  		Xscnlenlo: uint32(currSymSrcFile.csectSymNb & 0xFFFFFFFF),
   868  		Xscnlenhi: uint32(currSymSrcFile.csectSymNb >> 32),
   869  		Xsmclas:   XMC_PR, // Program Code
   870  		Xsmtyp:    XTY_LD, // label definition (based on C)
   871  		Xauxtype:  _AUX_CSECT,
   872  	}
   873  	a4.Xsmtyp |= xcoffAlign(ldr, x, TextSym) << 3
   874  
   875  	syms = append(syms, a4)
   876  	return syms
   877  }
   878  
   879  // put function used by genasmsym to write symbol table.
   880  func putaixsym(ctxt *Link, x loader.Sym, t SymbolType) {
   881  	// All XCOFF symbols generated by this GO symbols
   882  	// Can be a symbol entry or an auxiliary entry
   883  	syms := []xcoffSym{}
   884  
   885  	ldr := ctxt.loader
   886  	name := ldr.SymName(x)
   887  	if t == UndefinedSym {
   888  		name = ldr.SymExtname(x)
   889  	}
   890  
   891  	switch t {
   892  	default:
   893  		return
   894  
   895  	case TextSym:
   896  		if ldr.SymPkg(x) != "" || strings.Contains(name, "-tramp") || strings.HasPrefix(name, "runtime.text.") {
   897  			// Function within a file
   898  			syms = xfile.writeSymbolFunc(ctxt, x)
   899  		} else {
   900  			// Only runtime.text and runtime.etext come through this way
   901  			if name != "runtime.text" && name != "runtime.etext" && name != "go:buildid" {
   902  				Exitf("putaixsym: unknown text symbol %s", name)
   903  			}
   904  			s := &XcoffSymEnt64{
   905  				Nsclass: C_HIDEXT,
   906  				Noffset: uint32(xfile.stringTable.add(name)),
   907  				Nvalue:  uint64(ldr.SymValue(x)),
   908  				Nscnum:  xfile.getXCOFFscnum(ldr.SymSect(x)),
   909  				Ntype:   SYM_TYPE_FUNC,
   910  				Nnumaux: 1,
   911  			}
   912  			ldr.SetSymDynid(x, int32(xfile.symbolCount))
   913  			syms = append(syms, s)
   914  
   915  			size := uint64(ldr.SymSize(x))
   916  			a4 := &XcoffAuxCSect64{
   917  				Xauxtype:  _AUX_CSECT,
   918  				Xscnlenlo: uint32(size & 0xFFFFFFFF),
   919  				Xscnlenhi: uint32(size >> 32),
   920  				Xsmclas:   XMC_PR,
   921  				Xsmtyp:    XTY_SD,
   922  			}
   923  			a4.Xsmtyp |= xcoffAlign(ldr, x, TextSym) << 3
   924  			syms = append(syms, a4)
   925  		}
   926  
   927  	case DataSym, BSSSym:
   928  		s := &XcoffSymEnt64{
   929  			Nsclass: C_EXT,
   930  			Noffset: uint32(xfile.stringTable.add(name)),
   931  			Nvalue:  uint64(ldr.SymValue(x)),
   932  			Nscnum:  xfile.getXCOFFscnum(ldr.SymSect(x)),
   933  			Nnumaux: 1,
   934  		}
   935  
   936  		if ldr.IsFileLocal(x) || ldr.AttrVisibilityHidden(x) || ldr.AttrLocal(x) {
   937  			// There is more symbols in the case of a global data
   938  			// which are related to the assembly generated
   939  			// to access such symbols.
   940  			// But as Golang as its own way to check if a symbol is
   941  			// global or local (the capital letter), we don't need to
   942  			// implement them yet.
   943  			s.Nsclass = C_HIDEXT
   944  		}
   945  
   946  		ldr.SetSymDynid(x, int32(xfile.symbolCount))
   947  		syms = append(syms, s)
   948  
   949  		// Create auxiliary entry
   950  
   951  		// Normally, size should be the size of csect containing all
   952  		// the data and bss symbols of one file/package.
   953  		// However, it's easier to just have a csect for each symbol.
   954  		// It might change
   955  		size := uint64(ldr.SymSize(x))
   956  		a4 := &XcoffAuxCSect64{
   957  			Xauxtype:  _AUX_CSECT,
   958  			Xscnlenlo: uint32(size & 0xFFFFFFFF),
   959  			Xscnlenhi: uint32(size >> 32),
   960  		}
   961  
   962  		if ty := ldr.SymType(x); ty >= sym.STYPE && ty <= sym.SPCLNTAB {
   963  			if ctxt.IsExternal() && strings.HasPrefix(ldr.SymSect(x).Name, ".data.rel.ro") {
   964  				// During external linking, read-only datas with relocation
   965  				// must be in .data.
   966  				a4.Xsmclas = XMC_RW
   967  			} else {
   968  				// Read only data
   969  				a4.Xsmclas = XMC_RO
   970  			}
   971  		} else if /*ty == sym.SDATA &&*/ strings.HasPrefix(ldr.SymName(x), "TOC.") && ctxt.IsExternal() {
   972  			a4.Xsmclas = XMC_TC
   973  		} else if ldr.SymName(x) == "TOC" {
   974  			a4.Xsmclas = XMC_TC0
   975  		} else {
   976  			a4.Xsmclas = XMC_RW
   977  		}
   978  		if t == DataSym {
   979  			a4.Xsmtyp |= XTY_SD
   980  		} else {
   981  			a4.Xsmtyp |= XTY_CM
   982  		}
   983  
   984  		a4.Xsmtyp |= xcoffAlign(ldr, x, t) << 3
   985  
   986  		syms = append(syms, a4)
   987  
   988  	case UndefinedSym:
   989  		if ty := ldr.SymType(x); ty != sym.SDYNIMPORT && ty != sym.SHOSTOBJ && ty != sym.SUNDEFEXT {
   990  			return
   991  		}
   992  		s := &XcoffSymEnt64{
   993  			Nsclass: C_EXT,
   994  			Noffset: uint32(xfile.stringTable.add(name)),
   995  			Nnumaux: 1,
   996  		}
   997  		ldr.SetSymDynid(x, int32(xfile.symbolCount))
   998  		syms = append(syms, s)
   999  
  1000  		a4 := &XcoffAuxCSect64{
  1001  			Xauxtype: _AUX_CSECT,
  1002  			Xsmclas:  XMC_DS,
  1003  			Xsmtyp:   XTY_ER | XTY_IMP,
  1004  		}
  1005  
  1006  		if ldr.SymName(x) == "__n_pthreads" {
  1007  			// Currently, all imported symbols made by cgo_import_dynamic are
  1008  			// syscall functions, except __n_pthreads which is a variable.
  1009  			// TODO(aix): Find a way to detect variables imported by cgo.
  1010  			a4.Xsmclas = XMC_RW
  1011  		}
  1012  
  1013  		syms = append(syms, a4)
  1014  
  1015  	case TLSSym:
  1016  		s := &XcoffSymEnt64{
  1017  			Nsclass: C_EXT,
  1018  			Noffset: uint32(xfile.stringTable.add(name)),
  1019  			Nscnum:  xfile.getXCOFFscnum(ldr.SymSect(x)),
  1020  			Nvalue:  uint64(ldr.SymValue(x)),
  1021  			Nnumaux: 1,
  1022  		}
  1023  
  1024  		ldr.SetSymDynid(x, int32(xfile.symbolCount))
  1025  		syms = append(syms, s)
  1026  
  1027  		size := uint64(ldr.SymSize(x))
  1028  		a4 := &XcoffAuxCSect64{
  1029  			Xauxtype:  _AUX_CSECT,
  1030  			Xsmclas:   XMC_UL,
  1031  			Xsmtyp:    XTY_CM,
  1032  			Xscnlenlo: uint32(size & 0xFFFFFFFF),
  1033  			Xscnlenhi: uint32(size >> 32),
  1034  		}
  1035  
  1036  		syms = append(syms, a4)
  1037  	}
  1038  
  1039  	for _, s := range syms {
  1040  		xfile.addSymbol(s)
  1041  	}
  1042  }
  1043  
  1044  // Generate XCOFF Symbol table.
  1045  // It will be written in out file in Asmbxcoff, because it must be
  1046  // at the very end, especially after relocation sections which needs symbols' index.
  1047  func (f *xcoffFile) asmaixsym(ctxt *Link) {
  1048  	ldr := ctxt.loader
  1049  	// Get correct size for symbols wrapping others symbols like go.string.*
  1050  	// sym.Size can be used directly as the symbols have already been written.
  1051  	for name, size := range outerSymSize {
  1052  		sym := ldr.Lookup(name, 0)
  1053  		if sym == 0 {
  1054  			Errorf("unknown outer symbol with name %s", name)
  1055  		} else {
  1056  			s := ldr.MakeSymbolUpdater(sym)
  1057  			s.SetSize(size)
  1058  		}
  1059  	}
  1060  
  1061  	// These symbols won't show up in the first loop below because we
  1062  	// skip sym.STEXT symbols. Normal sym.STEXT symbols are emitted by walking textp.
  1063  	s := ldr.Lookup("runtime.text", 0)
  1064  	if ldr.SymType(s).IsText() {
  1065  		// We've already included this symbol in ctxt.Textp on AIX with external linker.
  1066  		// See data.go:/textaddress
  1067  		if !ctxt.IsExternal() {
  1068  			putaixsym(ctxt, s, TextSym)
  1069  		}
  1070  	}
  1071  
  1072  	n := 1
  1073  	// Generate base addresses for all text sections if there are multiple
  1074  	for _, sect := range Segtext.Sections[1:] {
  1075  		if sect.Name != ".text" || ctxt.IsExternal() {
  1076  			// On AIX, runtime.text.X are symbols already in the symtab.
  1077  			break
  1078  		}
  1079  		s = ldr.Lookup(fmt.Sprintf("runtime.text.%d", n), 0)
  1080  		if s == 0 {
  1081  			break
  1082  		}
  1083  		if ldr.SymType(s).IsText() {
  1084  			putaixsym(ctxt, s, TextSym)
  1085  		}
  1086  		n++
  1087  	}
  1088  
  1089  	s = ldr.Lookup("runtime.etext", 0)
  1090  	if ldr.SymType(s).IsText() {
  1091  		// We've already included this symbol in ctxt.Textp
  1092  		// on AIX with external linker.
  1093  		// See data.go:/textaddress
  1094  		if !ctxt.IsExternal() {
  1095  			putaixsym(ctxt, s, TextSym)
  1096  		}
  1097  	}
  1098  
  1099  	shouldBeInSymbolTable := func(s loader.Sym, name string) bool {
  1100  		if ldr.AttrNotInSymbolTable(s) {
  1101  			return false
  1102  		}
  1103  		if (name == "" || name[0] == '.') && !ldr.IsFileLocal(s) && name != ".TOC." {
  1104  			return false
  1105  		}
  1106  		return true
  1107  	}
  1108  
  1109  	for s, nsym := loader.Sym(1), loader.Sym(ldr.NSym()); s < nsym; s++ {
  1110  		if !shouldBeInSymbolTable(s, ldr.SymName(s)) {
  1111  			continue
  1112  		}
  1113  		st := ldr.SymType(s)
  1114  		switch {
  1115  		case st == sym.STLSBSS:
  1116  			if ctxt.IsExternal() {
  1117  				putaixsym(ctxt, s, TLSSym)
  1118  			}
  1119  
  1120  		case st == sym.SBSS, st == sym.SNOPTRBSS, st == sym.SLIBFUZZER_8BIT_COUNTER, st == sym.SCOVERAGE_COUNTER:
  1121  			if ldr.AttrReachable(s) {
  1122  				data := ldr.Data(s)
  1123  				if len(data) > 0 {
  1124  					ldr.Errorf(s, "should not be bss (size=%d type=%v special=%v)", len(data), ldr.SymType(s), ldr.AttrSpecial(s))
  1125  				}
  1126  				putaixsym(ctxt, s, BSSSym)
  1127  			}
  1128  
  1129  		case st >= sym.SELFRXSECT && st < sym.SFirstUnallocated: // data sections handled in dodata
  1130  			if ldr.AttrReachable(s) {
  1131  				putaixsym(ctxt, s, DataSym)
  1132  			}
  1133  
  1134  		case st == sym.SUNDEFEXT:
  1135  			putaixsym(ctxt, s, UndefinedSym)
  1136  
  1137  		case st == sym.SDYNIMPORT:
  1138  			if ldr.AttrReachable(s) {
  1139  				putaixsym(ctxt, s, UndefinedSym)
  1140  			}
  1141  		}
  1142  	}
  1143  
  1144  	for _, s := range ctxt.Textp {
  1145  		putaixsym(ctxt, s, TextSym)
  1146  	}
  1147  
  1148  	if ctxt.Debugvlog != 0 {
  1149  		ctxt.Logf("symsize = %d\n", uint32(symSize))
  1150  	}
  1151  	xfile.updatePreviousFile(ctxt, true)
  1152  }
  1153  
  1154  func (f *xcoffFile) genDynSym(ctxt *Link) {
  1155  	ldr := ctxt.loader
  1156  	var dynsyms []loader.Sym
  1157  	for s := loader.Sym(1); s < loader.Sym(ldr.NSym()); s++ {
  1158  		if !ldr.AttrReachable(s) {
  1159  			continue
  1160  		}
  1161  		if t := ldr.SymType(s); t != sym.SHOSTOBJ && t != sym.SDYNIMPORT {
  1162  			continue
  1163  		}
  1164  		dynsyms = append(dynsyms, s)
  1165  	}
  1166  
  1167  	for _, s := range dynsyms {
  1168  		f.adddynimpsym(ctxt, s)
  1169  
  1170  		if _, ok := f.dynLibraries[ldr.SymDynimplib(s)]; !ok {
  1171  			f.dynLibraries[ldr.SymDynimplib(s)] = len(f.dynLibraries)
  1172  		}
  1173  	}
  1174  }
  1175  
  1176  // (*xcoffFile)adddynimpsym adds the dynamic symbol "s" to a XCOFF file.
  1177  // A new symbol named s.Extname() is created to be the actual dynamic symbol
  1178  // in the .loader section and in the symbol table as an External Reference.
  1179  // The symbol "s" is transformed to SXCOFFTOC to end up in .data section.
  1180  // However, there is no writing protection on those symbols and
  1181  // it might need to be added.
  1182  // TODO(aix): Handles dynamic symbols without library.
  1183  func (f *xcoffFile) adddynimpsym(ctxt *Link, s loader.Sym) {
  1184  	// Check that library name is given.
  1185  	// Pattern is already checked when compiling.
  1186  	ldr := ctxt.loader
  1187  	if ctxt.IsInternal() && ldr.SymDynimplib(s) == "" {
  1188  		ctxt.Errorf(s, "imported symbol must have a given library")
  1189  	}
  1190  
  1191  	sb := ldr.MakeSymbolUpdater(s)
  1192  	sb.SetReachable(true)
  1193  	sb.SetType(sym.SXCOFFTOC)
  1194  
  1195  	// Create new dynamic symbol
  1196  	extsym := ldr.CreateSymForUpdate(ldr.SymExtname(s), 0)
  1197  	extsym.SetType(sym.SDYNIMPORT)
  1198  	extsym.SetDynimplib(ldr.SymDynimplib(s))
  1199  	extsym.SetExtname(ldr.SymExtname(s))
  1200  	extsym.SetDynimpvers(ldr.SymDynimpvers(s))
  1201  
  1202  	// Add loader symbol
  1203  	lds := &xcoffLoaderSymbol{
  1204  		sym:    extsym.Sym(),
  1205  		smtype: XTY_IMP,
  1206  		smclas: XMC_DS,
  1207  	}
  1208  	if ldr.SymName(s) == "__n_pthreads" {
  1209  		// Currently, all imported symbols made by cgo_import_dynamic are
  1210  		// syscall functions, except __n_pthreads which is a variable.
  1211  		// TODO(aix): Find a way to detect variables imported by cgo.
  1212  		lds.smclas = XMC_RW
  1213  	}
  1214  	f.loaderSymbols = append(f.loaderSymbols, lds)
  1215  
  1216  	// Relocation to retrieve the external address
  1217  	sb.AddBytes(make([]byte, 8))
  1218  	r, _ := sb.AddRel(objabi.R_ADDR)
  1219  	r.SetSym(extsym.Sym())
  1220  	r.SetSiz(uint8(ctxt.Arch.PtrSize))
  1221  	// TODO: maybe this could be
  1222  	// sb.SetSize(0)
  1223  	// sb.SetData(nil)
  1224  	// sb.AddAddr(ctxt.Arch, extsym.Sym())
  1225  	// If the size is not 0 to begin with, I don't think the added 8 bytes
  1226  	// of zeros are necessary.
  1227  }
  1228  
  1229  // Xcoffadddynrel adds a dynamic relocation in a XCOFF file.
  1230  // This relocation will be made by the loader.
  1231  func Xcoffadddynrel(target *Target, ldr *loader.Loader, syms *ArchSyms, s loader.Sym, r loader.Reloc, rIdx int) bool {
  1232  	if target.IsExternal() {
  1233  		return true
  1234  	}
  1235  	if ldr.SymType(s) <= sym.SPCLNTAB {
  1236  		ldr.Errorf(s, "cannot have a relocation to %s in a text section symbol", ldr.SymName(r.Sym()))
  1237  		return false
  1238  	}
  1239  
  1240  	xldr := &xcoffLoaderReloc{
  1241  		sym:  s,
  1242  		roff: r.Off(),
  1243  	}
  1244  	targ := r.Sym()
  1245  	var targType sym.SymKind
  1246  	if targ != 0 {
  1247  		targType = ldr.SymType(targ)
  1248  	}
  1249  
  1250  	switch r.Type() {
  1251  	default:
  1252  		ldr.Errorf(s, "unexpected .loader relocation to symbol: %s (type: %s)", ldr.SymName(targ), r.Type().String())
  1253  		return false
  1254  	case objabi.R_ADDR:
  1255  		if ldr.SymType(s) == sym.SXCOFFTOC && targType == sym.SDYNIMPORT {
  1256  			// Imported symbol relocation
  1257  			for i, dynsym := range xfile.loaderSymbols {
  1258  				if ldr.SymName(dynsym.sym) == ldr.SymName(targ) {
  1259  					xldr.symndx = int32(i + 3) // +3 because of 3 section symbols
  1260  					break
  1261  				}
  1262  			}
  1263  		} else if t := ldr.SymType(s); t.IsDATA() || t.IsNOPTRDATA() || t == sym.SBUILDINFO || t == sym.SXCOFFTOC || t == sym.SMODULEDATA {
  1264  			switch ldr.SymSect(targ).Seg {
  1265  			default:
  1266  				ldr.Errorf(s, "unknown segment for .loader relocation with symbol %s", ldr.SymName(targ))
  1267  			case &Segtext:
  1268  			case &Segrodata:
  1269  				xldr.symndx = 0 // .text
  1270  			case &Segdata:
  1271  				if targType == sym.SBSS || targType == sym.SNOPTRBSS {
  1272  					xldr.symndx = 2 // .bss
  1273  				} else {
  1274  					xldr.symndx = 1 // .data
  1275  				}
  1276  			}
  1277  
  1278  		} else {
  1279  			ldr.Errorf(s, "unexpected type for .loader relocation R_ADDR for symbol %s: %s to %s", ldr.SymName(targ), ldr.SymType(s), ldr.SymType(targ))
  1280  			return false
  1281  		}
  1282  
  1283  		xldr.rtype = 0x3F<<8 + XCOFF_R_POS
  1284  	}
  1285  
  1286  	xfile.Lock()
  1287  	xfile.loaderReloc = append(xfile.loaderReloc, xldr)
  1288  	xfile.Unlock()
  1289  	return true
  1290  }
  1291  
  1292  func (ctxt *Link) doxcoff() {
  1293  	ldr := ctxt.loader
  1294  
  1295  	// TOC
  1296  	toc := ldr.CreateSymForUpdate("TOC", 0)
  1297  	toc.SetType(sym.SXCOFFTOC)
  1298  	toc.SetVisibilityHidden(true)
  1299  
  1300  	// Add entry point to .loader symbols.
  1301  	ep := ldr.Lookup(*flagEntrySymbol, 0)
  1302  	if ep == 0 || !ldr.AttrReachable(ep) {
  1303  		Exitf("wrong entry point")
  1304  	}
  1305  
  1306  	xfile.loaderSymbols = append(xfile.loaderSymbols, &xcoffLoaderSymbol{
  1307  		sym:    ep,
  1308  		smtype: XTY_ENT | XTY_SD,
  1309  		smclas: XMC_DS,
  1310  	})
  1311  
  1312  	xfile.genDynSym(ctxt)
  1313  
  1314  	for s := loader.Sym(1); s < loader.Sym(ldr.NSym()); s++ {
  1315  		if strings.HasPrefix(ldr.SymName(s), "TOC.") {
  1316  			sb := ldr.MakeSymbolUpdater(s)
  1317  			sb.SetType(sym.SXCOFFTOC)
  1318  		}
  1319  	}
  1320  
  1321  	if ctxt.IsExternal() {
  1322  		// Change rt0_go name to match name in runtime/cgo:main().
  1323  		rt0 := ldr.Lookup("runtime.rt0_go", 0)
  1324  		ldr.SetSymExtname(rt0, "runtime_rt0_go")
  1325  
  1326  		nsym := loader.Sym(ldr.NSym())
  1327  		for s := loader.Sym(1); s < nsym; s++ {
  1328  			if !ldr.AttrCgoExport(s) {
  1329  				continue
  1330  			}
  1331  			if ldr.IsFileLocal(s) {
  1332  				panic("cgo_export on static symbol")
  1333  			}
  1334  
  1335  			if ldr.SymType(s).IsText() {
  1336  				// On AIX, an exported function must have two symbols:
  1337  				// - a .text symbol which must start with a ".".
  1338  				// - a .data symbol which is a function descriptor.
  1339  				name := ldr.SymExtname(s)
  1340  				ldr.SetSymExtname(s, "."+name)
  1341  
  1342  				desc := ldr.MakeSymbolUpdater(ldr.CreateExtSym(name, 0))
  1343  				desc.SetReachable(true)
  1344  				desc.SetType(sym.SNOPTRDATA)
  1345  				desc.AddAddr(ctxt.Arch, s)
  1346  				desc.AddAddr(ctxt.Arch, toc.Sym())
  1347  				desc.AddUint64(ctxt.Arch, 0)
  1348  			}
  1349  		}
  1350  	}
  1351  }
  1352  
  1353  // Loader section
  1354  // Currently, this section is created from scratch when assembling the XCOFF file
  1355  // according to information retrieved in xfile object.
  1356  
  1357  // Create loader section and returns its size.
  1358  func Loaderblk(ctxt *Link, off uint64) {
  1359  	xfile.writeLdrScn(ctxt, off)
  1360  }
  1361  
  1362  func (f *xcoffFile) writeLdrScn(ctxt *Link, globalOff uint64) {
  1363  	var symtab []*XcoffLdSym64
  1364  	var strtab []*XcoffLdStr64
  1365  	var importtab []*XcoffLdImportFile64
  1366  	var reloctab []*XcoffLdRel64
  1367  	var dynimpreloc []*XcoffLdRel64
  1368  
  1369  	// As the string table is updated in any loader subsection,
  1370  	//  its length must be computed at the same time.
  1371  	stlen := uint32(0)
  1372  
  1373  	// Loader Header
  1374  	hdr := &XcoffLdHdr64{
  1375  		Lversion: 2,
  1376  		Lsymoff:  LDHDRSZ_64,
  1377  	}
  1378  
  1379  	ldr := ctxt.loader
  1380  	/* Symbol table */
  1381  	for _, s := range f.loaderSymbols {
  1382  		lds := &XcoffLdSym64{
  1383  			Loffset: stlen + 2,
  1384  			Lsmtype: s.smtype,
  1385  			Lsmclas: s.smclas,
  1386  		}
  1387  		sym := s.sym
  1388  		switch s.smtype {
  1389  		default:
  1390  			ldr.Errorf(sym, "unexpected loader symbol type: 0x%x", s.smtype)
  1391  		case XTY_ENT | XTY_SD:
  1392  			lds.Lvalue = uint64(ldr.SymValue(sym))
  1393  			lds.Lscnum = f.getXCOFFscnum(ldr.SymSect(sym))
  1394  		case XTY_IMP:
  1395  			lds.Lifile = int32(f.dynLibraries[ldr.SymDynimplib(sym)] + 1)
  1396  		}
  1397  		ldstr := &XcoffLdStr64{
  1398  			size: uint16(len(ldr.SymName(sym)) + 1), // + null terminator
  1399  			name: ldr.SymName(sym),
  1400  		}
  1401  		stlen += uint32(2 + ldstr.size) // 2 = sizeof ldstr.size
  1402  		symtab = append(symtab, lds)
  1403  		strtab = append(strtab, ldstr)
  1404  
  1405  	}
  1406  
  1407  	hdr.Lnsyms = int32(len(symtab))
  1408  	hdr.Lrldoff = hdr.Lsymoff + uint64(24*hdr.Lnsyms) // 24 = sizeof one symbol
  1409  	off := hdr.Lrldoff                                // current offset is the same of reloc offset
  1410  
  1411  	/* Reloc */
  1412  	// Ensure deterministic order
  1413  	sort.Slice(f.loaderReloc, func(i, j int) bool {
  1414  		r1, r2 := f.loaderReloc[i], f.loaderReloc[j]
  1415  		if r1.sym != r2.sym {
  1416  			return r1.sym < r2.sym
  1417  		}
  1418  		if r1.roff != r2.roff {
  1419  			return r1.roff < r2.roff
  1420  		}
  1421  		if r1.rtype != r2.rtype {
  1422  			return r1.rtype < r2.rtype
  1423  		}
  1424  		return r1.symndx < r2.symndx
  1425  	})
  1426  
  1427  	ep := ldr.Lookup(*flagEntrySymbol, 0)
  1428  	xldr := &XcoffLdRel64{
  1429  		Lvaddr:  uint64(ldr.SymValue(ep)),
  1430  		Lrtype:  0x3F00,
  1431  		Lrsecnm: f.getXCOFFscnum(ldr.SymSect(ep)),
  1432  		Lsymndx: 0,
  1433  	}
  1434  	off += 16
  1435  	reloctab = append(reloctab, xldr)
  1436  
  1437  	off += uint64(16 * len(f.loaderReloc))
  1438  	for _, r := range f.loaderReloc {
  1439  		symp := r.sym
  1440  		if symp == 0 {
  1441  			panic("unexpected 0 sym value")
  1442  		}
  1443  		xldr = &XcoffLdRel64{
  1444  			Lvaddr:  uint64(ldr.SymValue(symp) + int64(r.roff)),
  1445  			Lrtype:  r.rtype,
  1446  			Lsymndx: r.symndx,
  1447  		}
  1448  
  1449  		if ldr.SymSect(symp) != nil {
  1450  			xldr.Lrsecnm = f.getXCOFFscnum(ldr.SymSect(symp))
  1451  		}
  1452  
  1453  		reloctab = append(reloctab, xldr)
  1454  	}
  1455  
  1456  	off += uint64(16 * len(dynimpreloc))
  1457  	reloctab = append(reloctab, dynimpreloc...)
  1458  
  1459  	hdr.Lnreloc = int32(len(reloctab))
  1460  	hdr.Limpoff = off
  1461  
  1462  	/* Import */
  1463  	// Default import: /usr/lib:/lib
  1464  	ldimpf := &XcoffLdImportFile64{
  1465  		Limpidpath: "/usr/lib:/lib",
  1466  	}
  1467  	off += uint64(len(ldimpf.Limpidpath) + len(ldimpf.Limpidbase) + len(ldimpf.Limpidmem) + 3) // + null delimiter
  1468  	importtab = append(importtab, ldimpf)
  1469  
  1470  	// The map created by adddynimpsym associates the name to a number
  1471  	// This number represents the librairie index (- 1) in this import files section
  1472  	// Therefore, they must be sorted before being put inside the section
  1473  	libsOrdered := make([]string, len(f.dynLibraries))
  1474  	for key, val := range f.dynLibraries {
  1475  		if libsOrdered[val] != "" {
  1476  			continue
  1477  		}
  1478  		libsOrdered[val] = key
  1479  	}
  1480  
  1481  	for _, lib := range libsOrdered {
  1482  		// lib string is defined as base.a/mem.o or path/base.a/mem.o
  1483  		n := strings.Split(lib, "/")
  1484  		path := ""
  1485  		base := n[len(n)-2]
  1486  		mem := n[len(n)-1]
  1487  		if len(n) > 2 {
  1488  			path = lib[:len(lib)-len(base)-len(mem)-2]
  1489  
  1490  		}
  1491  		ldimpf = &XcoffLdImportFile64{
  1492  			Limpidpath: path,
  1493  			Limpidbase: base,
  1494  			Limpidmem:  mem,
  1495  		}
  1496  		off += uint64(len(ldimpf.Limpidpath) + len(ldimpf.Limpidbase) + len(ldimpf.Limpidmem) + 3) // + null delimiter
  1497  		importtab = append(importtab, ldimpf)
  1498  	}
  1499  
  1500  	hdr.Lnimpid = int32(len(importtab))
  1501  	hdr.Listlen = uint32(off - hdr.Limpoff)
  1502  	hdr.Lstoff = off
  1503  	hdr.Lstlen = stlen
  1504  
  1505  	/* Writing */
  1506  	ctxt.Out.SeekSet(int64(globalOff))
  1507  	binary.Write(ctxt.Out, ctxt.Arch.ByteOrder, hdr)
  1508  
  1509  	for _, s := range symtab {
  1510  		binary.Write(ctxt.Out, ctxt.Arch.ByteOrder, s)
  1511  
  1512  	}
  1513  	for _, r := range reloctab {
  1514  		binary.Write(ctxt.Out, ctxt.Arch.ByteOrder, r)
  1515  	}
  1516  	for _, f := range importtab {
  1517  		ctxt.Out.WriteString(f.Limpidpath)
  1518  		ctxt.Out.Write8(0)
  1519  		ctxt.Out.WriteString(f.Limpidbase)
  1520  		ctxt.Out.Write8(0)
  1521  		ctxt.Out.WriteString(f.Limpidmem)
  1522  		ctxt.Out.Write8(0)
  1523  	}
  1524  	for _, s := range strtab {
  1525  		ctxt.Out.Write16(s.size)
  1526  		ctxt.Out.WriteString(s.name)
  1527  		ctxt.Out.Write8(0) // null terminator
  1528  	}
  1529  
  1530  	f.loaderSize = off + uint64(stlen)
  1531  }
  1532  
  1533  // XCOFF assembling and writing file
  1534  
  1535  func (f *xcoffFile) writeFileHeader(ctxt *Link) {
  1536  	// File header
  1537  	f.xfhdr.Fmagic = U64_TOCMAGIC
  1538  	f.xfhdr.Fnscns = uint16(len(f.sections))
  1539  	f.xfhdr.Ftimedat = 0
  1540  
  1541  	if !*FlagS {
  1542  		f.xfhdr.Fsymptr = uint64(f.symtabOffset)
  1543  		f.xfhdr.Fnsyms = int32(f.symbolCount)
  1544  	}
  1545  
  1546  	if ctxt.BuildMode == BuildModeExe && ctxt.LinkMode == LinkInternal {
  1547  		ldr := ctxt.loader
  1548  		f.xfhdr.Fopthdr = AOUTHSZ_EXEC64
  1549  		f.xfhdr.Fflags = F_EXEC
  1550  
  1551  		// auxiliary header
  1552  		f.xahdr.Ovstamp = 1 // based on dump -o
  1553  		f.xahdr.Omagic = 0x10b
  1554  		copy(f.xahdr.Omodtype[:], "1L")
  1555  		entry := ldr.Lookup(*flagEntrySymbol, 0)
  1556  		f.xahdr.Oentry = uint64(ldr.SymValue(entry))
  1557  		f.xahdr.Osnentry = f.getXCOFFscnum(ldr.SymSect(entry))
  1558  		toc := ldr.Lookup("TOC", 0)
  1559  		f.xahdr.Otoc = uint64(ldr.SymValue(toc))
  1560  		f.xahdr.Osntoc = f.getXCOFFscnum(ldr.SymSect(toc))
  1561  
  1562  		f.xahdr.Oalgntext = int16(logBase2(int(XCOFFSECTALIGN)))
  1563  		f.xahdr.Oalgndata = 0x5
  1564  
  1565  		binary.Write(ctxt.Out, binary.BigEndian, &f.xfhdr)
  1566  		binary.Write(ctxt.Out, binary.BigEndian, &f.xahdr)
  1567  	} else {
  1568  		f.xfhdr.Fopthdr = 0
  1569  		binary.Write(ctxt.Out, binary.BigEndian, &f.xfhdr)
  1570  	}
  1571  
  1572  }
  1573  
  1574  func xcoffwrite(ctxt *Link) {
  1575  	ctxt.Out.SeekSet(0)
  1576  
  1577  	xfile.writeFileHeader(ctxt)
  1578  
  1579  	for _, sect := range xfile.sections {
  1580  		sect.write(ctxt)
  1581  	}
  1582  }
  1583  
  1584  // Generate XCOFF assembly file.
  1585  func asmbXcoff(ctxt *Link) {
  1586  	ctxt.Out.SeekSet(0)
  1587  	fileoff := int64(Segdwarf.Fileoff + Segdwarf.Filelen)
  1588  	fileoff = Rnd(fileoff, *FlagRound)
  1589  
  1590  	xfile.sectNameToScnum = make(map[string]int16)
  1591  
  1592  	// Add sections
  1593  	s := xfile.addSection(".text", Segtext.Vaddr, Segtext.Length, Segtext.Fileoff, STYP_TEXT)
  1594  	xfile.xahdr.Otextstart = s.Svaddr
  1595  	xfile.xahdr.Osntext = xfile.sectNameToScnum[".text"]
  1596  	xfile.xahdr.Otsize = s.Ssize
  1597  	xfile.sectText = s
  1598  
  1599  	segdataVaddr := Segdata.Vaddr
  1600  	segdataFilelen := Segdata.Filelen
  1601  	segdataFileoff := Segdata.Fileoff
  1602  	segbssFilelen := Segdata.Length - Segdata.Filelen
  1603  	if len(Segrelrodata.Sections) > 0 {
  1604  		// Merge relro segment to data segment as
  1605  		// relro data are inside data segment on AIX.
  1606  		segdataVaddr = Segrelrodata.Vaddr
  1607  		segdataFileoff = Segrelrodata.Fileoff
  1608  		segdataFilelen = Segdata.Vaddr + Segdata.Filelen - Segrelrodata.Vaddr
  1609  	}
  1610  
  1611  	s = xfile.addSection(".data", segdataVaddr, segdataFilelen, segdataFileoff, STYP_DATA)
  1612  	xfile.xahdr.Odatastart = s.Svaddr
  1613  	xfile.xahdr.Osndata = xfile.sectNameToScnum[".data"]
  1614  	xfile.xahdr.Odsize = s.Ssize
  1615  	xfile.sectData = s
  1616  
  1617  	s = xfile.addSection(".bss", segdataVaddr+segdataFilelen, segbssFilelen, 0, STYP_BSS)
  1618  	xfile.xahdr.Osnbss = xfile.sectNameToScnum[".bss"]
  1619  	xfile.xahdr.Obsize = s.Ssize
  1620  	xfile.sectBss = s
  1621  
  1622  	if ctxt.LinkMode == LinkExternal {
  1623  		var tbss *sym.Section
  1624  		for _, s := range Segdata.Sections {
  1625  			if s.Name == ".tbss" {
  1626  				tbss = s
  1627  				break
  1628  			}
  1629  		}
  1630  		s = xfile.addSection(".tbss", tbss.Vaddr, tbss.Length, 0, STYP_TBSS)
  1631  	}
  1632  
  1633  	// add dwarf sections
  1634  	for _, sect := range Segdwarf.Sections {
  1635  		xfile.addDwarfSection(sect)
  1636  	}
  1637  
  1638  	// add and write remaining sections
  1639  	if ctxt.LinkMode == LinkInternal {
  1640  		// Loader section
  1641  		if ctxt.BuildMode == BuildModeExe {
  1642  			Loaderblk(ctxt, uint64(fileoff))
  1643  			s = xfile.addSection(".loader", 0, xfile.loaderSize, uint64(fileoff), STYP_LOADER)
  1644  			xfile.xahdr.Osnloader = xfile.sectNameToScnum[".loader"]
  1645  
  1646  			// Update fileoff for symbol table
  1647  			fileoff += int64(xfile.loaderSize)
  1648  		}
  1649  	}
  1650  
  1651  	// Create Symbol table
  1652  	xfile.asmaixsym(ctxt)
  1653  
  1654  	if ctxt.LinkMode == LinkExternal {
  1655  		xfile.emitRelocations(ctxt, fileoff)
  1656  	}
  1657  
  1658  	// Write Symbol table
  1659  	xfile.symtabOffset = ctxt.Out.Offset()
  1660  	for _, s := range xfile.symtabSym {
  1661  		binary.Write(ctxt.Out, ctxt.Arch.ByteOrder, s)
  1662  	}
  1663  	// write string table
  1664  	xfile.stringTable.write(ctxt.Out)
  1665  
  1666  	// write headers
  1667  	xcoffwrite(ctxt)
  1668  }
  1669  
  1670  // emitRelocations emits relocation entries for go.o in external linking.
  1671  func (f *xcoffFile) emitRelocations(ctxt *Link, fileoff int64) {
  1672  	ctxt.Out.SeekSet(fileoff)
  1673  	for ctxt.Out.Offset()&7 != 0 {
  1674  		ctxt.Out.Write8(0)
  1675  	}
  1676  
  1677  	ldr := ctxt.loader
  1678  	// relocsect relocates symbols from first in section sect, and returns
  1679  	// the total number of relocations emitted.
  1680  	relocsect := func(sect *sym.Section, syms []loader.Sym, base uint64) uint32 {
  1681  		// ctxt.Logf("%s 0x%x\n", sect.Name, sect.Vaddr)
  1682  		// If main section has no bits, nothing to relocate.
  1683  		if sect.Vaddr >= sect.Seg.Vaddr+sect.Seg.Filelen {
  1684  			return 0
  1685  		}
  1686  		sect.Reloff = uint64(ctxt.Out.Offset())
  1687  		for i, s := range syms {
  1688  			if !ldr.AttrReachable(s) {
  1689  				continue
  1690  			}
  1691  			if uint64(ldr.SymValue(s)) >= sect.Vaddr {
  1692  				syms = syms[i:]
  1693  				break
  1694  			}
  1695  		}
  1696  		eaddr := int64(sect.Vaddr + sect.Length)
  1697  		for _, s := range syms {
  1698  			if !ldr.AttrReachable(s) {
  1699  				continue
  1700  			}
  1701  			if ldr.SymValue(s) >= eaddr {
  1702  				break
  1703  			}
  1704  
  1705  			// Compute external relocations on the go, and pass to Xcoffreloc1 to stream out.
  1706  			// Relocation must be ordered by address, so create a list of sorted indices.
  1707  			relocs := ldr.Relocs(s)
  1708  			sorted := make([]int, relocs.Count())
  1709  			for i := 0; i < relocs.Count(); i++ {
  1710  				sorted[i] = i
  1711  			}
  1712  			sort.Slice(sorted, func(i, j int) bool {
  1713  				return relocs.At(sorted[i]).Off() < relocs.At(sorted[j]).Off()
  1714  			})
  1715  
  1716  			for _, ri := range sorted {
  1717  				r := relocs.At(ri)
  1718  				rr, ok := extreloc(ctxt, ldr, s, r)
  1719  				if !ok {
  1720  					continue
  1721  				}
  1722  				if rr.Xsym == 0 {
  1723  					ldr.Errorf(s, "missing xsym in relocation")
  1724  					continue
  1725  				}
  1726  				if ldr.SymDynid(rr.Xsym) < 0 {
  1727  					ldr.Errorf(s, "reloc %s to non-coff symbol %s (outer=%s) %d %d", r.Type(), ldr.SymName(r.Sym()), ldr.SymName(rr.Xsym), ldr.SymType(r.Sym()), ldr.SymDynid(rr.Xsym))
  1728  				}
  1729  				if !thearch.Xcoffreloc1(ctxt.Arch, ctxt.Out, ldr, s, rr, int64(uint64(ldr.SymValue(s)+int64(r.Off()))-base)) {
  1730  					ldr.Errorf(s, "unsupported obj reloc %d(%s)/%d to %s", r.Type(), r.Type(), r.Siz(), ldr.SymName(r.Sym()))
  1731  				}
  1732  			}
  1733  		}
  1734  		sect.Rellen = uint64(ctxt.Out.Offset()) - sect.Reloff
  1735  		return uint32(sect.Rellen) / RELSZ_64
  1736  	}
  1737  	sects := []struct {
  1738  		xcoffSect *XcoffScnHdr64
  1739  		segs      []*sym.Segment
  1740  	}{
  1741  		{f.sectText, []*sym.Segment{&Segtext}},
  1742  		{f.sectData, []*sym.Segment{&Segrelrodata, &Segdata}},
  1743  	}
  1744  	for _, s := range sects {
  1745  		s.xcoffSect.Srelptr = uint64(ctxt.Out.Offset())
  1746  		n := uint32(0)
  1747  		for _, seg := range s.segs {
  1748  			for _, sect := range seg.Sections {
  1749  				if sect.Name == ".text" {
  1750  					n += relocsect(sect, ctxt.Textp, 0)
  1751  				} else {
  1752  					n += relocsect(sect, ctxt.datap, 0)
  1753  				}
  1754  			}
  1755  		}
  1756  		s.xcoffSect.Snreloc += n
  1757  	}
  1758  
  1759  dwarfLoop:
  1760  	for i := 0; i < len(Segdwarf.Sections); i++ {
  1761  		sect := Segdwarf.Sections[i]
  1762  		si := dwarfp[i]
  1763  		if si.secSym() != sect.Sym ||
  1764  			ldr.SymSect(si.secSym()) != sect {
  1765  			panic("inconsistency between dwarfp and Segdwarf")
  1766  		}
  1767  		for _, xcoffSect := range f.sections {
  1768  			_, subtyp := xcoffGetDwarfSubtype(sect.Name)
  1769  			if xcoffSect.Sflags&0xF0000 == subtyp {
  1770  				xcoffSect.Srelptr = uint64(ctxt.Out.Offset())
  1771  				xcoffSect.Snreloc = relocsect(sect, si.syms, sect.Vaddr)
  1772  				continue dwarfLoop
  1773  			}
  1774  		}
  1775  		Errorf("emitRelocations: could not find %q section", sect.Name)
  1776  	}
  1777  }
  1778  
  1779  // xcoffCreateExportFile creates a file with exported symbols for
  1780  // -Wl,-bE option.
  1781  // ld won't export symbols unless they are listed in an export file.
  1782  func xcoffCreateExportFile(ctxt *Link) (fname string) {
  1783  	fname = filepath.Join(*flagTmpdir, "export_file.exp")
  1784  	var buf bytes.Buffer
  1785  
  1786  	ldr := ctxt.loader
  1787  	for s := range ldr.ForAllCgoExportStatic() {
  1788  		extname := ldr.SymExtname(s)
  1789  		if !strings.HasPrefix(extname, "._cgoexp_") {
  1790  			continue
  1791  		}
  1792  		if ldr.IsFileLocal(s) {
  1793  			continue // Only export non-static symbols
  1794  		}
  1795  
  1796  		// Retrieve the name of the initial symbol
  1797  		// exported by cgo.
  1798  		// The corresponding Go symbol is:
  1799  		// _cgoexp_hashcode_symname.
  1800  		name := strings.SplitN(extname, "_", 4)[3]
  1801  
  1802  		buf.Write([]byte(name + "\n"))
  1803  	}
  1804  
  1805  	err := os.WriteFile(fname, buf.Bytes(), 0666)
  1806  	if err != nil {
  1807  		Errorf("WriteFile %s failed: %v", fname, err)
  1808  	}
  1809  
  1810  	return fname
  1811  }
  1812  

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