// Inferno utils/5l/asm.c
// https://bitbucket.org/inferno-os/inferno-os/src/default/utils/5l/asm.c
//
//	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
//	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
//	Portions Copyright © 1997-1999 Vita Nuova Limited
//	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
//	Portions Copyright © 2004,2006 Bruce Ellis
//	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
//	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
//	Portions Copyright © 2009 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package s390x

import (
	"cmd/internal/objabi"
	"cmd/link/internal/ld"
	"debug/elf"
	"fmt"
)

// gentext generates assembly to append the local moduledata to the global
// moduledata linked list at initialization time. This is only done if the runtime
// is in a different module.
//
// <go.link.addmoduledata>:
// 	larl  %r2, <local.moduledata>
// 	jg    <runtime.addmoduledata@plt>
//	undef
//
// The job of appending the moduledata is delegated to runtime.addmoduledata.
func gentext(ctxt *ld.Link) {
	if !ctxt.DynlinkingGo() {
		return
	}
	addmoduledata := ctxt.Syms.Lookup("runtime.addmoduledata", 0)
	if addmoduledata.Type == ld.STEXT && ld.Buildmode != ld.BuildmodePlugin {
		// we're linking a module containing the runtime -> no need for
		// an init function
		return
	}
	addmoduledata.Attr |= ld.AttrReachable
	initfunc := ctxt.Syms.Lookup("go.link.addmoduledata", 0)
	initfunc.Type = ld.STEXT
	initfunc.Attr |= ld.AttrLocal
	initfunc.Attr |= ld.AttrReachable

	// larl %r2, <local.moduledata>
	ld.Adduint8(ctxt, initfunc, 0xc0)
	ld.Adduint8(ctxt, initfunc, 0x20)
	lmd := ld.Addrel(initfunc)
	lmd.Off = int32(initfunc.Size)
	lmd.Siz = 4
	lmd.Sym = ctxt.Moduledata
	lmd.Type = objabi.R_PCREL
	lmd.Variant = ld.RV_390_DBL
	lmd.Add = 2 + int64(lmd.Siz)
	ld.Adduint32(ctxt, initfunc, 0)

	// jg <runtime.addmoduledata[@plt]>
	ld.Adduint8(ctxt, initfunc, 0xc0)
	ld.Adduint8(ctxt, initfunc, 0xf4)
	rel := ld.Addrel(initfunc)
	rel.Off = int32(initfunc.Size)
	rel.Siz = 4
	rel.Sym = ctxt.Syms.Lookup("runtime.addmoduledata", 0)
	rel.Type = objabi.R_CALL
	rel.Variant = ld.RV_390_DBL
	rel.Add = 2 + int64(rel.Siz)
	ld.Adduint32(ctxt, initfunc, 0)

	// undef (for debugging)
	ld.Adduint32(ctxt, initfunc, 0)
	if ld.Buildmode == ld.BuildmodePlugin {
		ctxt.Textp = append(ctxt.Textp, addmoduledata)
	}
	ctxt.Textp = append(ctxt.Textp, initfunc)
	initarray_entry := ctxt.Syms.Lookup("go.link.addmoduledatainit", 0)
	initarray_entry.Attr |= ld.AttrLocal
	initarray_entry.Attr |= ld.AttrReachable
	initarray_entry.Type = ld.SINITARR
	ld.Addaddr(ctxt, initarray_entry, initfunc)
}

func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) bool {
	targ := r.Sym

	switch r.Type {
	default:
		if r.Type >= 256 {
			ld.Errorf(s, "unexpected relocation type %d", r.Type)
			return false
		}

		// Handle relocations found in ELF object files.
	case 256 + ld.R_390_12,
		256 + ld.R_390_GOT12:
		ld.Errorf(s, "s390x 12-bit relocations have not been implemented (relocation type %d)", r.Type-256)
		return false

	case 256 + ld.R_390_8,
		256 + ld.R_390_16,
		256 + ld.R_390_32,
		256 + ld.R_390_64:
		if targ.Type == ld.SDYNIMPORT {
			ld.Errorf(s, "unexpected R_390_nn relocation for dynamic symbol %s", targ.Name)
		}
		r.Type = objabi.R_ADDR
		return true

	case 256 + ld.R_390_PC16,
		256 + ld.R_390_PC32,
		256 + ld.R_390_PC64:
		if targ.Type == ld.SDYNIMPORT {
			ld.Errorf(s, "unexpected R_390_PCnn relocation for dynamic symbol %s", targ.Name)
		}
		if targ.Type == 0 || targ.Type == ld.SXREF {
			ld.Errorf(s, "unknown symbol %s in pcrel", targ.Name)
		}
		r.Type = objabi.R_PCREL
		r.Add += int64(r.Siz)
		return true

	case 256 + ld.R_390_GOT16,
		256 + ld.R_390_GOT32,
		256 + ld.R_390_GOT64:
		ld.Errorf(s, "unimplemented S390x relocation: %v", r.Type-256)
		return true

	case 256 + ld.R_390_PLT16DBL,
		256 + ld.R_390_PLT32DBL:
		r.Type = objabi.R_PCREL
		r.Variant = ld.RV_390_DBL
		r.Add += int64(r.Siz)
		if targ.Type == ld.SDYNIMPORT {
			addpltsym(ctxt, targ)
			r.Sym = ctxt.Syms.Lookup(".plt", 0)
			r.Add += int64(targ.Plt)
		}
		return true

	case 256 + ld.R_390_PLT32,
		256 + ld.R_390_PLT64:
		r.Type = objabi.R_PCREL
		r.Add += int64(r.Siz)
		if targ.Type == ld.SDYNIMPORT {
			addpltsym(ctxt, targ)
			r.Sym = ctxt.Syms.Lookup(".plt", 0)
			r.Add += int64(targ.Plt)
		}
		return true

	case 256 + ld.R_390_COPY:
		ld.Errorf(s, "unimplemented S390x relocation: %v", r.Type-256)
		return false

	case 256 + ld.R_390_GLOB_DAT:
		ld.Errorf(s, "unimplemented S390x relocation: %v", r.Type-256)
		return false

	case 256 + ld.R_390_JMP_SLOT:
		ld.Errorf(s, "unimplemented S390x relocation: %v", r.Type-256)
		return false

	case 256 + ld.R_390_RELATIVE:
		ld.Errorf(s, "unimplemented S390x relocation: %v", r.Type-256)
		return false

	case 256 + ld.R_390_GOTOFF:
		if targ.Type == ld.SDYNIMPORT {
			ld.Errorf(s, "unexpected R_390_GOTOFF relocation for dynamic symbol %s", targ.Name)
		}
		r.Type = objabi.R_GOTOFF
		return true

	case 256 + ld.R_390_GOTPC:
		r.Type = objabi.R_PCREL
		r.Sym = ctxt.Syms.Lookup(".got", 0)
		r.Add += int64(r.Siz)
		return true

	case 256 + ld.R_390_PC16DBL,
		256 + ld.R_390_PC32DBL:
		r.Type = objabi.R_PCREL
		r.Variant = ld.RV_390_DBL
		r.Add += int64(r.Siz)
		if targ.Type == ld.SDYNIMPORT {
			ld.Errorf(s, "unexpected R_390_PCnnDBL relocation for dynamic symbol %s", targ.Name)
		}
		return true

	case 256 + ld.R_390_GOTPCDBL:
		r.Type = objabi.R_PCREL
		r.Variant = ld.RV_390_DBL
		r.Sym = ctxt.Syms.Lookup(".got", 0)
		r.Add += int64(r.Siz)
		return true

	case 256 + ld.R_390_GOTENT:
		addgotsym(ctxt, targ)

		r.Type = objabi.R_PCREL
		r.Variant = ld.RV_390_DBL
		r.Sym = ctxt.Syms.Lookup(".got", 0)
		r.Add += int64(targ.Got)
		r.Add += int64(r.Siz)
		return true
	}
	// Handle references to ELF symbols from our own object files.
	if targ.Type != ld.SDYNIMPORT {
		return true
	}

	return false
}

func elfreloc1(ctxt *ld.Link, r *ld.Reloc, sectoff int64) int {
	ld.Thearch.Vput(uint64(sectoff))

	elfsym := r.Xsym.ElfsymForReloc()
	switch r.Type {
	default:
		return -1

	case objabi.R_TLS_LE:
		switch r.Siz {
		default:
			return -1
		case 4:
			// WARNING - silently ignored by linker in ELF64
			ld.Thearch.Vput(ld.R_390_TLS_LE32 | uint64(elfsym)<<32)
		case 8:
			// WARNING - silently ignored by linker in ELF32
			ld.Thearch.Vput(ld.R_390_TLS_LE64 | uint64(elfsym)<<32)
		}

	case objabi.R_TLS_IE:
		switch r.Siz {
		default:
			return -1
		case 4:
			ld.Thearch.Vput(ld.R_390_TLS_IEENT | uint64(elfsym)<<32)
		}

	case objabi.R_ADDR:
		switch r.Siz {
		default:
			return -1
		case 4:
			ld.Thearch.Vput(ld.R_390_32 | uint64(elfsym)<<32)
		case 8:
			ld.Thearch.Vput(ld.R_390_64 | uint64(elfsym)<<32)
		}

	case objabi.R_GOTPCREL:
		if r.Siz == 4 {
			ld.Thearch.Vput(ld.R_390_GOTENT | uint64(elfsym)<<32)
		} else {
			return -1
		}

	case objabi.R_PCREL, objabi.R_PCRELDBL, objabi.R_CALL:
		elfrel := ld.R_390_NONE
		isdbl := r.Variant&ld.RV_TYPE_MASK == ld.RV_390_DBL
		// TODO(mundaym): all DBL style relocations should be
		// signalled using the variant - see issue 14218.
		switch r.Type {
		case objabi.R_PCRELDBL, objabi.R_CALL:
			isdbl = true
		}
		if r.Xsym.Type == ld.SDYNIMPORT && (r.Xsym.ElfType == elf.STT_FUNC || r.Type == objabi.R_CALL) {
			if isdbl {
				switch r.Siz {
				case 2:
					elfrel = ld.R_390_PLT16DBL
				case 4:
					elfrel = ld.R_390_PLT32DBL
				}
			} else {
				switch r.Siz {
				case 4:
					elfrel = ld.R_390_PLT32
				case 8:
					elfrel = ld.R_390_PLT64
				}
			}
		} else {
			if isdbl {
				switch r.Siz {
				case 2:
					elfrel = ld.R_390_PC16DBL
				case 4:
					elfrel = ld.R_390_PC32DBL
				}
			} else {
				switch r.Siz {
				case 2:
					elfrel = ld.R_390_PC16
				case 4:
					elfrel = ld.R_390_PC32
				case 8:
					elfrel = ld.R_390_PC64
				}
			}
		}
		if elfrel == ld.R_390_NONE {
			return -1 // unsupported size/dbl combination
		}
		ld.Thearch.Vput(uint64(elfrel) | uint64(elfsym)<<32)
	}

	ld.Thearch.Vput(uint64(r.Xadd))
	return 0
}

func elfsetupplt(ctxt *ld.Link) {
	plt := ctxt.Syms.Lookup(".plt", 0)
	got := ctxt.Syms.Lookup(".got", 0)
	if plt.Size == 0 {
		// stg     %r1,56(%r15)
		ld.Adduint8(ctxt, plt, 0xe3)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0xf0)
		ld.Adduint8(ctxt, plt, 0x38)
		ld.Adduint8(ctxt, plt, 0x00)
		ld.Adduint8(ctxt, plt, 0x24)
		// larl    %r1,_GLOBAL_OFFSET_TABLE_
		ld.Adduint8(ctxt, plt, 0xc0)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Addpcrelplus(ctxt, plt, got, 6)
		// mvc     48(8,%r15),8(%r1)
		ld.Adduint8(ctxt, plt, 0xd2)
		ld.Adduint8(ctxt, plt, 0x07)
		ld.Adduint8(ctxt, plt, 0xf0)
		ld.Adduint8(ctxt, plt, 0x30)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x08)
		// lg      %r1,16(%r1)
		ld.Adduint8(ctxt, plt, 0xe3)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x00)
		ld.Adduint8(ctxt, plt, 0x04)
		// br      %r1
		ld.Adduint8(ctxt, plt, 0x07)
		ld.Adduint8(ctxt, plt, 0xf1)
		// nopr    %r0
		ld.Adduint8(ctxt, plt, 0x07)
		ld.Adduint8(ctxt, plt, 0x00)
		// nopr    %r0
		ld.Adduint8(ctxt, plt, 0x07)
		ld.Adduint8(ctxt, plt, 0x00)
		// nopr    %r0
		ld.Adduint8(ctxt, plt, 0x07)
		ld.Adduint8(ctxt, plt, 0x00)

		// assume got->size == 0 too
		ld.Addaddrplus(ctxt, got, ctxt.Syms.Lookup(".dynamic", 0), 0)

		ld.Adduint64(ctxt, got, 0)
		ld.Adduint64(ctxt, got, 0)
	}
}

func machoreloc1(s *ld.Symbol, r *ld.Reloc, sectoff int64) int {
	return -1
}

func archreloc(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol, val *int64) int {
	if ld.Linkmode == ld.LinkExternal {
		return -1
	}

	switch r.Type {
	case objabi.R_CONST:
		*val = r.Add
		return 0

	case objabi.R_GOTOFF:
		*val = ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0))
		return 0
	}

	return -1
}

func archrelocvariant(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol, t int64) int64 {
	switch r.Variant & ld.RV_TYPE_MASK {
	default:
		ld.Errorf(s, "unexpected relocation variant %d", r.Variant)
		return t

	case ld.RV_NONE:
		return t

	case ld.RV_390_DBL:
		if (t & 1) != 0 {
			ld.Errorf(s, "%s+%v is not 2-byte aligned", r.Sym.Name, r.Sym.Value)
		}
		return t >> 1
	}
}

func addpltsym(ctxt *ld.Link, s *ld.Symbol) {
	if s.Plt >= 0 {
		return
	}

	ld.Adddynsym(ctxt, s)

	if ld.Iself {
		plt := ctxt.Syms.Lookup(".plt", 0)
		got := ctxt.Syms.Lookup(".got", 0)
		rela := ctxt.Syms.Lookup(".rela.plt", 0)
		if plt.Size == 0 {
			elfsetupplt(ctxt)
		}
		// larl    %r1,_GLOBAL_OFFSET_TABLE_+index

		ld.Adduint8(ctxt, plt, 0xc0)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Addpcrelplus(ctxt, plt, got, got.Size+6) // need variant?

		// add to got: pointer to current pos in plt
		ld.Addaddrplus(ctxt, got, plt, plt.Size+8) // weird but correct
		// lg      %r1,0(%r1)
		ld.Adduint8(ctxt, plt, 0xe3)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x00)
		ld.Adduint8(ctxt, plt, 0x00)
		ld.Adduint8(ctxt, plt, 0x04)
		// br      %r1
		ld.Adduint8(ctxt, plt, 0x07)
		ld.Adduint8(ctxt, plt, 0xf1)
		// basr    %r1,%r0
		ld.Adduint8(ctxt, plt, 0x0d)
		ld.Adduint8(ctxt, plt, 0x10)
		// lgf     %r1,12(%r1)
		ld.Adduint8(ctxt, plt, 0xe3)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x0c)
		ld.Adduint8(ctxt, plt, 0x00)
		ld.Adduint8(ctxt, plt, 0x14)
		// jg .plt
		ld.Adduint8(ctxt, plt, 0xc0)
		ld.Adduint8(ctxt, plt, 0xf4)

		ld.Adduint32(ctxt, plt, uint32(-((plt.Size - 2) >> 1))) // roll-your-own relocation
		//.plt index
		ld.Adduint32(ctxt, plt, uint32(rela.Size)) // rela size before current entry

		// rela
		ld.Addaddrplus(ctxt, rela, got, got.Size-8)

		ld.Adduint64(ctxt, rela, ld.ELF64_R_INFO(uint32(s.Dynid), ld.R_390_JMP_SLOT))
		ld.Adduint64(ctxt, rela, 0)

		s.Plt = int32(plt.Size - 32)

	} else {
		ld.Errorf(s, "addpltsym: unsupported binary format")
	}
}

func addgotsym(ctxt *ld.Link, s *ld.Symbol) {
	if s.Got >= 0 {
		return
	}

	ld.Adddynsym(ctxt, s)
	got := ctxt.Syms.Lookup(".got", 0)
	s.Got = int32(got.Size)
	ld.Adduint64(ctxt, got, 0)

	if ld.Iself {
		rela := ctxt.Syms.Lookup(".rela", 0)
		ld.Addaddrplus(ctxt, rela, got, int64(s.Got))
		ld.Adduint64(ctxt, rela, ld.ELF64_R_INFO(uint32(s.Dynid), ld.R_390_GLOB_DAT))
		ld.Adduint64(ctxt, rela, 0)
	} else {
		ld.Errorf(s, "addgotsym: unsupported binary format")
	}
}

func asmb(ctxt *ld.Link) {
	if ctxt.Debugvlog != 0 {
		ctxt.Logf("%5.2f asmb\n", ld.Cputime())
	}

	if ld.Iself {
		ld.Asmbelfsetup()
	}

	sect := ld.Segtext.Sections[0]
	ld.Cseek(int64(sect.Vaddr - ld.Segtext.Vaddr + ld.Segtext.Fileoff))
	ld.Codeblk(ctxt, int64(sect.Vaddr), int64(sect.Length))
	for _, sect = range ld.Segtext.Sections[1:] {
		ld.Cseek(int64(sect.Vaddr - ld.Segtext.Vaddr + ld.Segtext.Fileoff))
		ld.Datblk(ctxt, int64(sect.Vaddr), int64(sect.Length))
	}

	if ld.Segrodata.Filelen > 0 {
		if ctxt.Debugvlog != 0 {
			ctxt.Logf("%5.2f rodatblk\n", ld.Cputime())
		}
		ld.Cseek(int64(ld.Segrodata.Fileoff))
		ld.Datblk(ctxt, int64(ld.Segrodata.Vaddr), int64(ld.Segrodata.Filelen))
	}
	if ld.Segrelrodata.Filelen > 0 {
		if ctxt.Debugvlog != 0 {
			ctxt.Logf("%5.2f rodatblk\n", ld.Cputime())
		}
		ld.Cseek(int64(ld.Segrelrodata.Fileoff))
		ld.Datblk(ctxt, int64(ld.Segrelrodata.Vaddr), int64(ld.Segrelrodata.Filelen))
	}

	if ctxt.Debugvlog != 0 {
		ctxt.Logf("%5.2f datblk\n", ld.Cputime())
	}

	ld.Cseek(int64(ld.Segdata.Fileoff))
	ld.Datblk(ctxt, int64(ld.Segdata.Vaddr), int64(ld.Segdata.Filelen))

	ld.Cseek(int64(ld.Segdwarf.Fileoff))
	ld.Dwarfblk(ctxt, int64(ld.Segdwarf.Vaddr), int64(ld.Segdwarf.Filelen))

	/* output symbol table */
	ld.Symsize = 0

	ld.Lcsize = 0
	symo := uint32(0)
	if !*ld.FlagS {
		if !ld.Iself {
			ld.Errorf(nil, "unsupported executable format")
		}
		if ctxt.Debugvlog != 0 {
			ctxt.Logf("%5.2f sym\n", ld.Cputime())
		}
		symo = uint32(ld.Segdwarf.Fileoff + ld.Segdwarf.Filelen)
		symo = uint32(ld.Rnd(int64(symo), int64(*ld.FlagRound)))

		ld.Cseek(int64(symo))
		if ctxt.Debugvlog != 0 {
			ctxt.Logf("%5.2f elfsym\n", ld.Cputime())
		}
		ld.Asmelfsym(ctxt)
		ld.Cflush()
		ld.Cwrite(ld.Elfstrdat)

		if ctxt.Debugvlog != 0 {
			ctxt.Logf("%5.2f dwarf\n", ld.Cputime())
		}

		if ld.Linkmode == ld.LinkExternal {
			ld.Elfemitreloc(ctxt)
		}
	}

	if ctxt.Debugvlog != 0 {
		ctxt.Logf("%5.2f header\n", ld.Cputime())
	}
	ld.Cseek(0)
	switch ld.Headtype {
	default:
		ld.Errorf(nil, "unsupported operating system")
	case objabi.Hlinux:
		ld.Asmbelf(ctxt, int64(symo))
	}

	ld.Cflush()
	if *ld.FlagC {
		fmt.Printf("textsize=%d\n", ld.Segtext.Filelen)
		fmt.Printf("datsize=%d\n", ld.Segdata.Filelen)
		fmt.Printf("bsssize=%d\n", ld.Segdata.Length-ld.Segdata.Filelen)
		fmt.Printf("symsize=%d\n", ld.Symsize)
		fmt.Printf("lcsize=%d\n", ld.Lcsize)
		fmt.Printf("total=%d\n", ld.Segtext.Filelen+ld.Segdata.Length+uint64(ld.Symsize)+uint64(ld.Lcsize))
	}
}