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cmd/link,runtime: remove relocations from stkobjs

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Use an offset from go.func.* instead.
This removes the last relocation from funcdata symbols,
which lets us simplify that code.

size      before    after     Δ       %
addr2line 3683218   3680706   -2512   -0.068%
api       4951074   4944850   -6224   -0.126%
asm       4744258   4757586   +13328  +0.281%
buildid   2419986   2418546   -1440   -0.060%
cgo       4218306   4197346   -20960  -0.497%
compile   22132066  22076882  -55184  -0.249%
cover     4432834   4411362   -21472  -0.484%
dist      3111202   3091346   -19856  -0.638%
doc       3583602   3563234   -20368  -0.568%
fix       3023922   3020658   -3264   -0.108%
link      6188034   6164642   -23392  -0.378%
nm        3665826   3646818   -19008  -0.519%
objdump   4015234   4012450   -2784   -0.069%
pack      2155010   2153554   -1456   -0.068%
pprof     13044178  13011522  -32656  -0.250%
test2json 2402146   2383906   -18240  -0.759%
trace     9765410   9736514   -28896  -0.296%
vet       6681250   6655058   -26192  -0.392%
total     104217556 103926980 -290576 -0.279%

relocs    before  after   Δ       %
addr2line 25563   25066   -497    -1.944%
api       18409   17176   -1233   -6.698%
asm       18903   18271   -632    -3.343%
buildid   9513    9233    -280    -2.943%
cgo       17103   16222   -881    -5.151%
compile   64825   60421   -4404   -6.794%
cover     19464   18479   -985    -5.061%
dist      10798   10135   -663    -6.140%
doc       13503   12735   -768    -5.688%
fix       11465   10820   -645    -5.626%
link      23214   21849   -1365   -5.880%
nm        25480   24987   -493    -1.935%
objdump   26610   26057   -553    -2.078%
pack      7951    7665    -286    -3.597%
pprof     63964   60761   -3203   -5.008%
test2json 8735    8389    -346    -3.961%
trace     39639   37180   -2459   -6.203%
vet       25970   24044   -1926   -7.416%
total     431108  409489  -21619  -5.015%

Change-Id: I43c26196a008da6d1cb3a782eea2f428778bd569
Reviewed-on: https://go-review.googlesource.com/c/go/+/353138
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This commit is contained in:
Josh Bleecher Snyder 2021-09-27 14:27:20 -07:00
parent ae83301ab2
commit 3100dc1a7f
8 changed files with 69 additions and 60 deletions
Download patch file Download diff file Expand all files Collapse all files

2
src/cmd/compile/internal/liveness/plive.go
View file

@ -1443,7 +1443,7 @@ func (lv *liveness) emitStackObjects() *obj.LSym {
}
off = objw.Uint32(x, off, uint32(sz))
off = objw.Uint32(x, off, uint32(ptrdata))
off = objw.SymPtr(x, off, lsym, 0)
off = objw.SymPtrOff(x, off, lsym)
}
if base.Flag.Live != 0 {

5
src/cmd/link/internal/ld/data.go
View file

@ -1367,6 +1367,11 @@ func (state *dodataState) makeRelroForSharedLib(target *Link) {
// the relro data.
isRelro = true
}
case sym.SGOFUNC:
// The only SGOFUNC symbols that contain relocations are .stkobj,
// and their relocations are of type objabi.R_ADDROFF,
// which always get resolved during linking.
isRelro = false
}
if isRelro {
state.setSymType(s, symnrelro)

22
src/cmd/link/internal/ld/pcln.go
View file

@ -711,7 +711,7 @@ func writeFuncs(ctxt *Link, sb *loader.SymbolBuilder, funcs []loader.Sym, inlSym
ldr := ctxt.loader
deferReturnSym := ldr.Lookup("runtime.deferreturn", abiInternalVer)
gofunc := ldr.Lookup("go.func.*", 0)
gofuncrel := ldr.Lookup("go.funcrel.*", 0)
gofuncBase := ldr.SymValue(gofunc)
textStart := ldr.SymValue(ldr.Lookup("runtime.text", 0))
funcdata := []loader.Sym{}
var pcsp, pcfile, pcline, pcinline loader.Sym
@ -813,24 +813,10 @@ func writeFuncs(ctxt *Link, sb *loader.SymbolBuilder, funcs []loader.Sym, inlSym
continue
}
outer := ldr.OuterSym(fdsym)
if outer == 0 {
panic(fmt.Sprintf("no carrier sym for symbol %s (funcdata %s#%d)", ldr.SymName(fdsym), ldr.SymName(s), j))
if outer := ldr.OuterSym(fdsym); outer != gofunc {
panic(fmt.Sprintf("bad carrier sym for symbol %s (funcdata %s#%d), want go.func.* got %s", ldr.SymName(fdsym), ldr.SymName(s), j, ldr.SymName(outer)))
}
rel := uint32(ldr.SymValue(fdsym) - ldr.SymValue(outer))
// Record gofunc vs gofuncrel in bottom bit. See runtime/symtab.go:funcdata.
// TODO: The only symbols that in gofuncrel are .stkobj symbols.
// Remove those relocations, and simplify this.
rel <<= 1
switch outer {
case gofunc:
case gofuncrel:
rel |= 1
default:
panic(fmt.Sprintf("expected symbol %s (funcdata %s#%d) to be placed in go.func.* or go.funcrel.*, got %s (%d)",
ldr.SymName(fdsym), ldr.SymName(s), j, ldr.SymName(outer), outer))
}
sb.SetUint32(ctxt.Arch, int64(dataoff), rel)
sb.SetUint32(ctxt.Arch, int64(dataoff), uint32(ldr.SymValue(fdsym)-gofuncBase))
}
}
}

11
src/cmd/link/internal/ld/symtab.go
View file

@ -569,13 +569,8 @@ func (ctxt *Link) symtab(pcln *pclntab) []sym.SymKind {
strings.HasSuffix(name, ".args_stackmap"),
strings.HasSuffix(name, ".stkobj"):
ldr.SetAttrNotInSymbolTable(s, true)
if ctxt.UseRelro() && strings.HasSuffix(name, ".stkobj") {
symGroupType[s] = sym.SGOFUNCRELRO
ldr.SetCarrierSym(s, symgofuncrel)
} else {
symGroupType[s] = sym.SGOFUNC
ldr.SetCarrierSym(s, symgofunc)
}
if ctxt.Debugvlog != 0 {
align := ldr.SymAlign(s)
liveness += (ldr.SymSize(s) + int64(align) - 1) &^ (int64(align) - 1)
@ -676,12 +671,8 @@ func (ctxt *Link) symtab(pcln *pclntab) []sym.SymKind {
moduledata.AddAddr(ctxt.Arch, ldr.Lookup("runtime.gcbss", 0))
moduledata.AddAddr(ctxt.Arch, ldr.Lookup("runtime.types", 0))
moduledata.AddAddr(ctxt.Arch, ldr.Lookup("runtime.etypes", 0))
moduledata.AddAddr(ctxt.Arch, ldr.Lookup("runtime.rodata", 0))
moduledata.AddAddr(ctxt.Arch, ldr.Lookup("go.func.*", 0))
if gofuncrel := ldr.Lookup("go.funcrel.*", 0); gofuncrel != 0 {
moduledata.AddAddr(ctxt.Arch, gofuncrel)
} else {
moduledata.AddUint(ctxt.Arch, 0)
}
if ctxt.IsAIX() && ctxt.IsExternal() {
// Add R_XCOFFREF relocation to prevent ld's garbage collection of

7
src/runtime/mgcmark.go
View file

@ -803,7 +803,7 @@ func scanstack(gp *g, gcw *gcWork) {
println()
printunlock()
}
gcdata := r.gcdata
gcdata := r.gcdata()
var s *mspan
if r.useGCProg() {
// This path is pretty unlikely, an object large enough
@ -923,7 +923,8 @@ func scanframeworker(frame *stkframe, state *stackScanState, gcw *gcWork) {
// varp is 0 for defers, where there are no locals.
// In that case, there can't be a pointer to its args, either.
// (And all args would be scanned above anyway.)
for i, obj := range objs {
for i := range objs {
obj := &objs[i]
off := obj.off
base := frame.varp // locals base pointer
if off >= 0 {
@ -937,7 +938,7 @@ func scanframeworker(frame *stkframe, state *stackScanState, gcw *gcWork) {
if stackTraceDebug {
println("stkobj at", hex(ptr), "of size", obj.size)
}
state.addObject(ptr, &objs[i])
state.addObject(ptr, obj)
}
}
}

1
src/runtime/proc.go
View file

@ -687,6 +687,7 @@ func schedinit() {
modulesinit() // provides activeModules
typelinksinit() // uses maps, activeModules
itabsinit() // uses activeModules
stkobjinit() // must run before GC starts
sigsave(&_g_.m.sigmask)
initSigmask = _g_.m.sigmask

62
src/runtime/stack.go
View file

@ -691,7 +691,8 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
// Adjust pointers in all stack objects (whether they are live or not).
// See comments in mgcmark.go:scanframeworker.
if frame.varp != 0 {
for _, obj := range objs {
for i := range objs {
obj := &objs[i]
off := obj.off
base := frame.varp // locals base pointer
if off >= 0 {
@ -705,7 +706,7 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
continue
}
ptrdata := obj.ptrdata()
gcdata := obj.gcdata
gcdata := obj.gcdata()
var s *mspan
if obj.useGCProg() {
// See comments in mgcmark.go:scanstack
@ -1321,7 +1322,7 @@ func getStackMap(frame *stkframe, cache *pcvalueCache, debug bool) (locals, args
// We don't actually use argmap in this case, but we need to fake the stack object
// record for these frames which contain an internal/abi.RegArgs at a hard-coded offset.
// This offset matches the assembly code on amd64 and arm64.
objs = methodValueCallFrameObjs
objs = methodValueCallFrameObjs[:]
} else {
p := funcdata(f, _FUNCDATA_StackObjects)
if p != nil {
@ -1340,22 +1341,32 @@ func getStackMap(frame *stkframe, cache *pcvalueCache, debug bool) (locals, args
return
}
var (
abiRegArgsEface interface{} = abi.RegArgs{}
abiRegArgsType *_type = efaceOf(&abiRegArgsEface)._type
methodValueCallFrameObjs = []stackObjectRecord{
{
var methodValueCallFrameObjs [1]stackObjectRecord // initialized in stackobjectinit
func stkobjinit() {
var abiRegArgsEface interface{} = abi.RegArgs{}
abiRegArgsType := efaceOf(&abiRegArgsEface)._type
if abiRegArgsType.kind&kindGCProg != 0 {
throw("abiRegArgsType needs GC Prog, update methodValueCallFrameObjs")
}
// Set methodValueCallFrameObjs[0].gcdataoff so that
// stackObjectRecord.gcdata() will work correctly with it.
ptr := uintptr(unsafe.Pointer(&methodValueCallFrameObjs[0]))
var mod *moduledata
for datap := &firstmoduledata; datap != nil; datap = datap.next {
if datap.gofunc <= ptr && ptr < datap.end {
mod = datap
break
}
}
if mod == nil {
throw("methodValueCallFrameObjs is not in a module")
}
methodValueCallFrameObjs[0] = stackObjectRecord{
off: -int32(alignUp(abiRegArgsType.size, 8)), // It's always the highest address local.
size: int32(abiRegArgsType.size),
_ptrdata: int32(abiRegArgsType.ptrdata),
gcdata: abiRegArgsType.gcdata,
},
}
)
func init() {
if abiRegArgsType.kind&kindGCProg != 0 {
throw("abiRegArgsType needs GC Prog, update methodValueCallFrameObjs")
gcdataoff: uint32(uintptr(unsafe.Pointer(abiRegArgsType.gcdata)) - mod.rodata),
}
}
@ -1368,7 +1379,7 @@ type stackObjectRecord struct {
off int32
size int32
_ptrdata int32 // ptrdata, or -ptrdata is GC prog is used
gcdata *byte // pointer map or GC prog of the type
gcdataoff uint32 // offset to gcdata from moduledata.rodata
}
func (r *stackObjectRecord) useGCProg() bool {
@ -1383,6 +1394,23 @@ func (r *stackObjectRecord) ptrdata() uintptr {
return uintptr(x)
}
// gcdata returns pointer map or GC prog of the type.
func (r *stackObjectRecord) gcdata() *byte {
ptr := uintptr(unsafe.Pointer(r))
var mod *moduledata
for datap := &firstmoduledata; datap != nil; datap = datap.next {
if datap.gofunc <= ptr && ptr < datap.end {
mod = datap
break
}
}
// If you get a panic here due to a nil mod,
// you may have made a copy of a stackObjectRecord.
// You must use the original pointer.
res := mod.rodata + uintptr(r.gcdataoff)
return (*byte)(unsafe.Pointer(res))
}
// This is exported as ABI0 via linkname so obj can call it.
//
//go:nosplit

9
src/runtime/symtab.go
View file

@ -427,7 +427,8 @@ type moduledata struct {
noptrbss, enoptrbss uintptr
end, gcdata, gcbss uintptr
types, etypes uintptr
gofunc, gofuncrel uintptr // go.func.*, go.funcrel.*
rodata uintptr
gofunc uintptr // go.func.*
textsectmap []textsect
typelinks []int32 // offsets from types
@ -1092,11 +1093,7 @@ func funcdata(f funcInfo, i uint8) unsafe.Pointer {
if off == ^uint32(0) {
return nil
}
base := f.datap.gofunc
if off&1 != 0 {
base = f.datap.gofuncrel
}
return unsafe.Pointer(base + uintptr(off>>1))
return unsafe.Pointer(f.datap.gofunc + uintptr(off))
}
// step advances to the next pc, value pair in the encoded table.