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cmd/internal/obj, cmd/link, runtime: lots of TLS cleanup

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It's particularly nice to get rid of the android special cases in the linker.

Change-Id: I516363af7ce8a6b2f196fe49cb8887ac787a6dad
Reviewed-on: https://go-review.googlesource.com/14197
Run-TryBot: Michael Hudson-Doyle <michael.hudson@canonical.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Michael Hudson-Doyle 2015-09-02 11:23:15 +12:00
parent 1ef9b5a5b9
commit a5cb76243a
15 changed files with 27 additions and 132 deletions
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17
src/cmd/internal/obj/arm/asm5.go
View File

@ -739,9 +739,6 @@ func span5(ctxt *obj.Link, cursym *obj.LSym) {
* code references to be relocated too, and then
* perhaps we'd be able to parallelize the span loop above.
*/
if ctxt.Tlsg == nil {
ctxt.Tlsg = obj.Linklookup(ctxt, "runtime.tlsg", 0)
}
p = cursym.Text
ctxt.Autosize = int32(p.To.Offset + 4)
@ -1646,19 +1643,7 @@ func asmout(ctxt *obj.Link, p *obj.Prog, o *Optab, out []uint32) {
rel.Sym = p.To.Sym
rel.Add = p.To.Offset
// runtime.tlsg is special.
// Its "address" is the offset from the TLS thread pointer
// to the thread-local g and m pointers.
// Emit a TLS relocation instead of a standard one if its
// type is not explicitly set by runtime. This assumes that
// all references to runtime.tlsg should be accompanied with
// its type declaration if necessary.
if rel.Sym == ctxt.Tlsg && ctxt.Tlsg.Type == 0 {
rel.Type = obj.R_TLS
if ctxt.Flag_shared != 0 {
rel.Add += ctxt.Pc - p.Rel.Pc - 8 - int64(rel.Siz)
}
} else if ctxt.Flag_shared != 0 {
if ctxt.Flag_shared != 0 {
rel.Type = obj.R_PCREL
rel.Add += ctxt.Pc - p.Rel.Pc - 8
} else {

18
src/cmd/internal/obj/arm/obj5.go
View File

@ -129,24 +129,6 @@ func progedit(ctxt *obj.Link, p *obj.Prog) {
p.From.Offset = 0
}
}
if ctxt.Flag_shared != 0 {
// Shared libraries use R_ARM_TLS_IE32 instead of
// R_ARM_TLS_LE32, replacing the link time constant TLS offset in
// runtime.tlsg with an address to a GOT entry containing the
// offset. Rewrite $runtime.tlsg(SB) to runtime.tlsg(SB) to
// compensate.
if ctxt.Tlsg == nil {
ctxt.Tlsg = obj.Linklookup(ctxt, "runtime.tlsg", 0)
}
if p.From.Type == obj.TYPE_ADDR && p.From.Name == obj.NAME_EXTERN && p.From.Sym == ctxt.Tlsg {
p.From.Type = obj.TYPE_MEM
}
if p.To.Type == obj.TYPE_ADDR && p.To.Name == obj.NAME_EXTERN && p.To.Sym == ctxt.Tlsg {
p.To.Type = obj.TYPE_MEM
}
}
}
// Prog.mark

3
src/cmd/internal/obj/arm64/asm7.go
View File

@ -631,9 +631,6 @@ func span7(ctxt *obj.Link, cursym *obj.LSym) {
/*
* lay out the code, emitting code and data relocations.
*/
if ctxt.Tlsg == nil {
ctxt.Tlsg = obj.Linklookup(ctxt, "runtime.tlsg", 0)
}
obj.Symgrow(ctxt, cursym, cursym.Size)
bp := cursym.P
psz := int32(0)

26
src/cmd/internal/obj/link.go
View File

@ -414,23 +414,16 @@ const (
R_CALLPOWER
R_CONST
R_PCREL
// R_TLS (only used on arm currently, and not on android and darwin where tlsg is
// a regular variable) resolves to data needed to access the thread-local g. It is
// interpreted differently depending on toolchain flags to implement either the
// "local exec" or "inital exec" model for tls access.
// TODO(mwhudson): change to use R_TLS_LE or R_TLS_IE as appropriate, not having
// R_TLS do double duty.
R_TLS
// R_TLS_LE (only used on 386 and amd64 currently) resolves to the offset of the
// thread-local g from the thread local base and is used to implement the "local
// exec" model for tls access (r.Sym is not set by the compiler for this case but
// is set to Tlsg in the linker when externally linking).
// R_TLS_LE, used on 386, amd64, and ARM, resolves to the offset of the
// thread-local symbol from the thread local base and is used to implement the
// "local exec" model for tls access (r.Sym is not set on intel platforms but is
// set to a TLS symbol -- runtime.tlsg -- in the linker when externally linking).
R_TLS_LE
// R_TLS_IE (only used on 386 and amd64 currently) resolves to the PC-relative
// offset to a GOT slot containing the offset the thread-local g from the thread
// local base and is used to implemented the "initial exec" model for tls access
// (r.Sym is not set by the compiler for this case but is set to Tlsg in the
// linker when externally linking).
// R_TLS_IE, used 386, amd64, and ARM resolves to the PC-relative offset to a GOT
// slot containing the offset from the thread-local symbol from the thread local
// base and is used to implemented the "initial exec" model for tls access (r.Sym
// is not set on intel platforms but is set to a TLS symbol -- runtime.tlsg -- in
// the linker when externally linking).
R_TLS_IE
R_GOTOFF
R_PLT0
@ -505,7 +498,6 @@ type Link struct {
Sym_divu *LSym
Sym_mod *LSym
Sym_modu *LSym
Tlsg *LSym
Plan9privates *LSym
Curp *Prog
Printp *Prog

3
src/cmd/internal/obj/mips/asm0.go
View File

@ -504,9 +504,6 @@ func span9(ctxt *obj.Link, cursym *obj.LSym) {
/*
* lay out the code, emitting code and data relocations.
*/
if ctxt.Tlsg == nil {
ctxt.Tlsg = obj.Linklookup(ctxt, "runtime.tlsg", 0)
}
obj.Symgrow(ctxt, cursym, cursym.Size)

3
src/cmd/internal/obj/ppc64/asm9.go
View File

@ -504,9 +504,6 @@ func span9(ctxt *obj.Link, cursym *obj.LSym) {
/*
* lay out the code, emitting code and data relocations.
*/
if ctxt.Tlsg == nil {
ctxt.Tlsg = obj.Linklookup(ctxt, "runtime.tlsg", 0)
}
obj.Symgrow(ctxt, cursym, cursym.Size)

4
src/cmd/internal/obj/x86/obj6.go
View File

@ -435,10 +435,6 @@ func nacladdr(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) {
}
func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
if ctxt.Tlsg == nil {
ctxt.Tlsg = obj.Linklookup(ctxt, "runtime.tlsg", 0)
}
if ctxt.Headtype == obj.Hplan9 && ctxt.Plan9privates == nil {
ctxt.Plan9privates = obj.Linklookup(ctxt, "_privates", 0)
}

13
src/cmd/link/internal/arm/asm.go
View File

@ -223,17 +223,6 @@ func elfreloc1(r *ld.Reloc, sectoff int64) int {
return -1
}
case obj.R_TLS:
if r.Siz == 4 {
if ld.Buildmode == ld.BuildmodeCShared {
ld.Thearch.Lput(ld.R_ARM_TLS_IE32 | uint32(elfsym)<<8)
} else {
ld.Thearch.Lput(ld.R_ARM_TLS_LE32 | uint32(elfsym)<<8)
}
} else {
return -1
}
case obj.R_TLS_LE:
ld.Thearch.Lput(ld.R_ARM_TLS_LE32 | uint32(elfsym)<<8)
@ -345,7 +334,7 @@ func archreloc(r *ld.Reloc, s *ld.LSym, val *int64) int {
rs = rs.Outer
}
if rs.Type != obj.SHOSTOBJ && rs.Sect == nil {
if rs.Type != obj.SHOSTOBJ && rs.Type != obj.SDYNIMPORT && rs.Sect == nil {
ld.Diag("missing section for %s", rs.Name)
}
r.Xsym = rs

25
src/cmd/link/internal/ld/data.go
View File

@ -362,11 +362,6 @@ func relocsym(s *LSym) {
Diag("unreachable sym in relocation: %s %s", s.Name, r.Sym.Name)
}
// Android emulates runtime.tlsg as a regular variable.
if r.Type == obj.R_TLS && goos == "android" {
r.Type = obj.R_ADDR
}
switch r.Type {
default:
switch siz {
@ -385,26 +380,6 @@ func relocsym(s *LSym) {
Diag("unknown reloc %d", r.Type)
}
case obj.R_TLS:
if Linkmode == LinkExternal && Iself && HEADTYPE != obj.Hopenbsd {
r.Done = 0
r.Sym = Ctxt.Tlsg
r.Xsym = Ctxt.Tlsg
r.Xadd = r.Add
o = r.Add
break
}
if Linkmode == LinkInternal && Iself && Thearch.Thechar == '5' {
panic("should no longer get here")
break
}
r.Done = 0
o = 0
if Thearch.Thechar != '6' {
o = r.Add
}
case obj.R_TLS_LE:
if Linkmode == LinkExternal && Iself && HEADTYPE != obj.Hopenbsd {
r.Done = 0

6
src/cmd/link/internal/ld/elf.go
View File

@ -1506,9 +1506,7 @@ func elfshbits(sect *Section) *ElfShdr {
sh.flags |= SHF_WRITE
}
if sect.Name == ".tbss" {
if goos != "android" {
sh.flags |= SHF_TLS // no TLS on android
}
sh.flags |= SHF_TLS
sh.type_ = SHT_NOBITS
}
@ -1517,7 +1515,7 @@ func elfshbits(sect *Section) *ElfShdr {
}
sh.addralign = uint64(sect.Align)
sh.size = sect.Length
if sect.Name != ".tbss" || goos == "android" {
if sect.Name != ".tbss" {
sh.off = sect.Seg.Fileoff + sect.Vaddr - sect.Seg.Vaddr
}

25
src/cmd/link/internal/ld/lib.go
View File

@ -307,7 +307,7 @@ func (mode *BuildMode) Set(s string) error {
}
*mode = BuildmodeCShared
case "shared":
if goos != "linux" || goarch != "amd64" {
if goos != "linux" || (goarch != "amd64" && goarch != "arm") {
return badmode()
}
*mode = BuildmodeShared
@ -549,17 +549,14 @@ func loadlib() {
tlsg := Linklookup(Ctxt, "runtime.tlsg", 0)
// For most ports, runtime.tlsg is a placeholder symbol for TLS
// relocation. However, the Android and Darwin arm ports need it
// to be a real variable.
//
// TODO(crawshaw): android should require leaving the tlsg->type
// alone (as the runtime-provided SNOPTRBSS) just like darwin/arm.
// But some other part of the linker is expecting STLSBSS.
if tlsg.Type != obj.SDYNIMPORT && (goos != "darwin" || Thearch.Thechar != '5') {
// runtime.tlsg is used for external linking on platforms that do not define
// a variable to hold g in assembly (currently only intel).
if tlsg.Type == 0 {
tlsg.Type = obj.STLSBSS
tlsg.Size = int64(Thearch.Ptrsize)
} else if tlsg.Type != obj.SDYNIMPORT {
Diag("internal error: runtime declared tlsg variable %d", tlsg.Type)
}
tlsg.Size = int64(Thearch.Ptrsize)
tlsg.Reachable = true
Ctxt.Tlsg = tlsg
@ -1821,13 +1818,7 @@ func genasmsym(put func(*LSym, string, int, int64, int64, int, *LSym)) {
case obj.STLSBSS:
if Linkmode == LinkExternal && HEADTYPE != obj.Hopenbsd {
var type_ int
if goos == "android" {
type_ = 'B'
} else {
type_ = 't'
}
put(s, s.Name, type_, Symaddr(s), s.Size, int(s.Version), s.Gotype)
put(s, s.Name, 't', Symaddr(s), s.Size, int(s.Version), s.Gotype)
}
}
}

4
src/runtime/asm_arm64.s
View File

@ -36,9 +36,9 @@ TEXT runtime·rt0_go(SB),NOSPLIT,$0
MRS_TPIDR_R0 // load TLS base pointer
MOVD R0, R3 // arg 3: TLS base pointer
#ifdef TLSG_IS_VARIABLE
MOVD $runtime·tls_g(SB), R2 // arg 2: tlsg
MOVD $runtime·tls_g(SB), R2 // arg 2: &tls_g
#else
MOVD $0x10, R2 // arg 2: tlsg TODO(minux): hardcoded for linux
MOVD 0, R2 // arg 2: not used when using platform's TLS
#endif
MOVD $setg_gcc<>(SB), R1 // arg 1: setg
MOVD g, R0 // arg 0: G

3
src/runtime/tls_arm.s
View File

@ -58,9 +58,6 @@ TEXT runtime·load_g(SB),NOSPLIT,$0
// See save_g
MRC 15, 0, R0, C13, C0, 3 // fetch TLS base pointer
BIC $3, R0 // Darwin/ARM might return unaligned pointer
// $runtime.tlsg(SB) is a special linker symbol.
// It is the offset from the TLS base pointer to our
// thread-local storage for g.
MOVW runtime·tls_g(SB), R11
ADD R11, R0
MOVW 0(R0), g

3
src/runtime/tls_arm64.s
View File

@ -53,8 +53,5 @@ nocgo:
RET
#ifdef TLSG_IS_VARIABLE
// The runtime.tlsg name is being handled specially in the
// linker. As we just need a regular variable here, don't
// use that name.
GLOBL runtime·tls_g+0(SB), NOPTR, $8
#endif

6
src/runtime/tls_ppc64x.s
View File

@ -30,7 +30,7 @@ TEXT runtime·save_g(SB),NOSPLIT,$-8-0
// $runtime.tlsg(SB) is a special linker symbol.
// It is the offset from the start of TLS to our
// thread-local storage for g.
MOVD $runtime·tlsg(SB), R31
MOVD $runtime·tls_g(SB), R31
ADD R13, R31
// The actual TLS base is 0x7000 below R13
SUB $0x7000, R31
@ -51,10 +51,12 @@ nocgo:
//
// NOTE: _cgo_topofstack assumes this only clobbers g (R30), and R31.
TEXT runtime·load_g(SB),NOSPLIT,$-8-0
MOVD $runtime·tlsg(SB), R31
MOVD $runtime·tls_g(SB), R31
// R13 is the C ABI TLS base pointer + 0x7000
ADD R13, R31
SUB $0x7000, R31
MOVD 0(R31), g
RET
GLOBL runtime·tls_g+0(SB), TLSBSS, $8