1 files changed, 214 insertions, 0 deletions
diff --git a/src/cmd/link/internal/ld/asmb.go b/src/cmd/link/internal/ld/asmb.go
new file mode 100644
index 0000000..fda0439
--- /dev/null
+++ b/src/cmd/link/internal/ld/asmb.go
@@ -0,0 +1,214 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ld
+
+import (
+	"cmd/internal/objabi"
+	"cmd/link/internal/loader"
+	"cmd/link/internal/sym"
+	"fmt"
+	"runtime"
+	"sync"
+)
+
+// Assembling the binary is broken into two steps:
+//  - writing out the code/data/dwarf Segments, applying relocations on the fly
+//  - writing out the architecture specific pieces.
+// This function handles the first part.
+func asmb(ctxt *Link) {
+	// TODO(jfaller): delete me.
+	if thearch.Asmb != nil {
+		thearch.Asmb(ctxt, ctxt.loader)
+		return
+	}
+
+	if ctxt.IsELF {
+		Asmbelfsetup()
+	}
+
+	var wg sync.WaitGroup
+	sect := Segtext.Sections[0]
+	offset := sect.Vaddr - Segtext.Vaddr + Segtext.Fileoff
+	f := func(ctxt *Link, out *OutBuf, start, length int64) {
+		pad := thearch.CodePad
+		if pad == nil {
+			pad = zeros[:]
+		}
+		CodeblkPad(ctxt, out, start, length, pad)
+	}
+
+	if !thearch.WriteTextBlocks {
+		writeParallel(&wg, f, ctxt, offset, sect.Vaddr, sect.Length)
+		for _, sect := range Segtext.Sections[1:] {
+			offset := sect.Vaddr - Segtext.Vaddr + Segtext.Fileoff
+			writeParallel(&wg, datblk, ctxt, offset, sect.Vaddr, sect.Length)
+		}
+	} else {
+		// TODO why can't we handle all sections this way?
+		for _, sect := range Segtext.Sections {
+			offset := sect.Vaddr - Segtext.Vaddr + Segtext.Fileoff
+			// Handle additional text sections with Codeblk
+			if sect.Name == ".text" {
+				writeParallel(&wg, f, ctxt, offset, sect.Vaddr, sect.Length)
+			} else {
+				writeParallel(&wg, datblk, ctxt, offset, sect.Vaddr, sect.Length)
+			}
+		}
+	}
+
+	if Segrodata.Filelen > 0 {
+		writeParallel(&wg, datblk, ctxt, Segrodata.Fileoff, Segrodata.Vaddr, Segrodata.Filelen)
+	}
+
+	if Segrelrodata.Filelen > 0 {
+		writeParallel(&wg, datblk, ctxt, Segrelrodata.Fileoff, Segrelrodata.Vaddr, Segrelrodata.Filelen)
+	}
+
+	writeParallel(&wg, datblk, ctxt, Segdata.Fileoff, Segdata.Vaddr, Segdata.Filelen)
+
+	writeParallel(&wg, dwarfblk, ctxt, Segdwarf.Fileoff, Segdwarf.Vaddr, Segdwarf.Filelen)
+
+	wg.Wait()
+}
+
+// Assembling the binary is broken into two steps:
+//  - writing out the code/data/dwarf Segments
+//  - writing out the architecture specific pieces.
+// This function handles the second part.
+func asmb2(ctxt *Link) {
+	if thearch.Asmb2 != nil {
+		thearch.Asmb2(ctxt, ctxt.loader)
+		return
+	}
+
+	symSize = 0
+	spSize = 0
+	lcSize = 0
+
+	switch ctxt.HeadType {
+	default:
+		panic("unknown platform")
+
+	// Macho
+	case objabi.Hdarwin:
+		asmbMacho(ctxt)
+
+	// Plan9
+	case objabi.Hplan9:
+		asmbPlan9(ctxt)
+
+	// PE
+	case objabi.Hwindows:
+		asmbPe(ctxt)
+
+	// Xcoff
+	case objabi.Haix:
+		asmbXcoff(ctxt)
+
+	// Elf
+	case objabi.Hdragonfly,
+		objabi.Hfreebsd,
+		objabi.Hlinux,
+		objabi.Hnetbsd,
+		objabi.Hopenbsd,
+		objabi.Hsolaris:
+		asmbElf(ctxt)
+	}
+
+	if *FlagC {
+		fmt.Printf("textsize=%d\n", Segtext.Filelen)
+		fmt.Printf("datsize=%d\n", Segdata.Filelen)
+		fmt.Printf("bsssize=%d\n", Segdata.Length-Segdata.Filelen)
+		fmt.Printf("symsize=%d\n", symSize)
+		fmt.Printf("lcsize=%d\n", lcSize)
+		fmt.Printf("total=%d\n", Segtext.Filelen+Segdata.Length+uint64(symSize)+uint64(lcSize))
+	}
+}
+
+// writePlan9Header writes out the plan9 header at the present position in the OutBuf.
+func writePlan9Header(buf *OutBuf, magic uint32, entry int64, is64Bit bool) {
+	if is64Bit {
+		magic |= 0x00008000
+	}
+	buf.Write32b(magic)
+	buf.Write32b(uint32(Segtext.Filelen))
+	buf.Write32b(uint32(Segdata.Filelen))
+	buf.Write32b(uint32(Segdata.Length - Segdata.Filelen))
+	buf.Write32b(uint32(symSize))
+	if is64Bit {
+		buf.Write32b(uint32(entry &^ 0x80000000))
+	} else {
+		buf.Write32b(uint32(entry))
+	}
+	buf.Write32b(uint32(spSize))
+	buf.Write32b(uint32(lcSize))
+	// amd64 includes the entry at the beginning of the symbol table.
+	if is64Bit {
+		buf.Write64b(uint64(entry))
+	}
+}
+
+// asmbPlan9 assembles a plan 9 binary.
+func asmbPlan9(ctxt *Link) {
+	if !*FlagS {
+		*FlagS = true
+		symo := int64(Segdata.Fileoff + Segdata.Filelen)
+		ctxt.Out.SeekSet(symo)
+		asmbPlan9Sym(ctxt)
+	}
+	ctxt.Out.SeekSet(0)
+	writePlan9Header(ctxt.Out, thearch.Plan9Magic, Entryvalue(ctxt), thearch.Plan9_64Bit)
+}
+
+// sizeExtRelocs precomputes the size needed for the reloc records,
+// sets the size and offset for relocation records in each section,
+// and mmap the output buffer with the proper size.
+func sizeExtRelocs(ctxt *Link, relsize uint32) {
+	if relsize == 0 {
+		panic("sizeExtRelocs: relocation size not set")
+	}
+	var sz int64
+	for _, seg := range Segments {
+		for _, sect := range seg.Sections {
+			sect.Reloff = uint64(ctxt.Out.Offset() + sz)
+			sect.Rellen = uint64(relsize * sect.Relcount)
+			sz += int64(sect.Rellen)
+		}
+	}
+	filesz := ctxt.Out.Offset() + sz
+	ctxt.Out.Mmap(uint64(filesz))
+}
+
+// relocSectFn wraps the function writing relocations of a section
+// for parallel execution. Returns the wrapped function and a wait
+// group for which the caller should wait.
+func relocSectFn(ctxt *Link, relocSect func(*Link, *OutBuf, *sym.Section, []loader.Sym)) (func(*Link, *sym.Section, []loader.Sym), *sync.WaitGroup) {
+	var fn func(ctxt *Link, sect *sym.Section, syms []loader.Sym)
+	var wg sync.WaitGroup
+	var sem chan int
+	if ctxt.Out.isMmapped() {
+		// Write sections in parallel.
+		sem = make(chan int, 2*runtime.GOMAXPROCS(0))
+		fn = func(ctxt *Link, sect *sym.Section, syms []loader.Sym) {
+			wg.Add(1)
+			sem <- 1
+			out, err := ctxt.Out.View(sect.Reloff)
+			if err != nil {
+				panic(err)
+			}
+			go func() {
+				relocSect(ctxt, out, sect, syms)
+				wg.Done()
+				<-sem
+			}()
+		}
+	} else {
+		// We cannot Mmap. Write sequentially.
+		fn = func(ctxt *Link, sect *sym.Section, syms []loader.Sym) {
+			relocSect(ctxt, ctxt.Out, sect, syms)
+		}
+	}
+	return fn, &wg
+}