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runtime, cmd/internal/ld: initialize themoduledata slices directly

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This CL is quite conservative in some ways.  It continues to define
symbols that have no real purpose (e.g. epclntab).  These could be
deleted if there is no concern that external tools might look for them.

It would also now be possible to make some changes to the pcln data but
I get the impression that would definitely require some thought and
discussion.

Change-Id: Ib33cde07e4ec38ecc1d6c319a10138c9347933a3
Reviewed-on: https://go-review.googlesource.com/7616
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Michael Hudson-Doyle 2015-03-16 11:53:08 +13:00 committed by Ian Lance Taylor
parent c468f94672
commit 3a84e3305b
6 changed files with 58 additions and 54 deletions
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4
src/cmd/internal/ld/data.go
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@ -102,6 +102,10 @@ func Adduint64(ctxt *Link, s *LSym, v uint64) int64 {
return adduintxx(ctxt, s, v, 8)
}
func adduint(ctxt *Link, s *LSym, v uint64) int64 {
return adduintxx(ctxt, s, v, Thearch.Intsize)
}
func setuint8(ctxt *Link, s *LSym, r int64, v uint8) int64 {
return setuintxx(ctxt, s, r, uint64(v), 1)
}

15
src/cmd/internal/ld/pcln.go
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@ -202,6 +202,13 @@ func container(s *LSym) int {
var pclntab_zpcln Pcln
// These variables are used to initialize runtime.themoduledata, see symtab.go:symtab.
var pclntabNfunc int32
var pclntabFiletabOffset int32
var pclntabPclntabOffset int32
var pclntabFirstFunc *LSym
var pclntabLastFunc *LSym
func pclntab() {
funcdata_bytes := int64(0)
ftab := Linklookup(Ctxt, "runtime.pclntab", 0)
@ -222,11 +229,13 @@ func pclntab() {
}
}
pclntabNfunc = nfunc
Symgrow(Ctxt, ftab, 8+int64(Thearch.Ptrsize)+int64(nfunc)*2*int64(Thearch.Ptrsize)+int64(Thearch.Ptrsize)+4)
setuint32(Ctxt, ftab, 0, 0xfffffffb)
setuint8(Ctxt, ftab, 6, uint8(Thearch.Minlc))
setuint8(Ctxt, ftab, 7, uint8(Thearch.Ptrsize))
setuintxx(Ctxt, ftab, 8, uint64(nfunc), int64(Thearch.Ptrsize))
pclntabPclntabOffset = int32(8 + Thearch.Ptrsize)
nfunc = 0
var last *LSym
@ -246,6 +255,10 @@ func pclntab() {
pcln = &pclntab_zpcln
}
if pclntabFirstFunc == nil {
pclntabFirstFunc = Ctxt.Cursym
}
funcstart = int32(len(ftab.P))
funcstart += int32(-len(ftab.P)) & (int32(Thearch.Ptrsize) - 1)
@ -330,6 +343,7 @@ func pclntab() {
nfunc++
}
pclntabLastFunc = last
// Final entry of table is just end pc.
setaddrplus(Ctxt, ftab, 8+int64(Thearch.Ptrsize)+int64(nfunc)*2*int64(Thearch.Ptrsize), last, last.Size)
@ -337,6 +351,7 @@ func pclntab() {
start := int32(len(ftab.P))
start += int32(-len(ftab.P)) & (int32(Thearch.Ptrsize) - 1)
pclntabFiletabOffset = start
setuint32(Ctxt, ftab, 8+int64(Thearch.Ptrsize)+int64(nfunc)*2*int64(Thearch.Ptrsize)+int64(Thearch.Ptrsize), uint32(start))
Symgrow(Ctxt, ftab, int64(start)+(int64(Ctxt.Nhistfile)+1)*4)

33
src/cmd/internal/ld/symtab.go
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@ -348,6 +348,8 @@ func symtab() {
symt.Size = 0
symt.Reachable = true
ntypelinks := 0
// assign specific types so that they sort together.
// within a type they sort by size, so the .* symbols
// just defined above will be first.
@ -363,6 +365,7 @@ func symtab() {
}
if strings.HasPrefix(s.Name, "go.typelink.") {
ntypelinks++
s.Type = STYPELINK
s.Hide = 1
s.Outer = symtypelink
@ -392,21 +395,29 @@ func symtab() {
// Information about the layout of the executable image for the
// runtime to use. Any changes here must be matched by changes to
// the definition of moduledata in runtime/symtab.go.
// This code uses several global variables that are set by pcln.go:pclntab.
moduledata := Linklookup(Ctxt, "runtime.themoduledata", 0)
moduledata.Type = SNOPTRDATA
moduledata.Size = 0 // truncate symbol back to 0 bytes to reinitialize
moduledata.Reachable = true
// Three slices (pclntable, ftab, filetab), uninitalized
moduledata.Size += int64((3 * 3 * Thearch.Ptrsize))
Symgrow(Ctxt, moduledata, moduledata.Size)
// Three uintptrs, initialized
// The pclntab slice
Addaddr(Ctxt, moduledata, Linklookup(Ctxt, "runtime.pclntab", 0))
Addaddr(Ctxt, moduledata, Linklookup(Ctxt, "runtime.epclntab", 0))
adduint(Ctxt, moduledata, uint64(Linklookup(Ctxt, "runtime.pclntab", 0).Size))
adduint(Ctxt, moduledata, uint64(Linklookup(Ctxt, "runtime.pclntab", 0).Size))
// The ftab slice
Addaddrplus(Ctxt, moduledata, Linklookup(Ctxt, "runtime.pclntab", 0), int64(pclntabPclntabOffset))
adduint(Ctxt, moduledata, uint64(pclntabNfunc+1))
adduint(Ctxt, moduledata, uint64(pclntabNfunc+1))
// The filetab slice
Addaddrplus(Ctxt, moduledata, Linklookup(Ctxt, "runtime.pclntab", 0), int64(pclntabFiletabOffset))
adduint(Ctxt, moduledata, uint64(Ctxt.Nhistfile))
adduint(Ctxt, moduledata, uint64(Ctxt.Nhistfile))
// findfunctab
Addaddr(Ctxt, moduledata, Linklookup(Ctxt, "runtime.findfunctab", 0))
// 2 more uintptrs (minpc, maxpc), uninitalized
moduledata.Size += int64(2 * Thearch.Ptrsize)
Symgrow(Ctxt, moduledata, moduledata.Size)
// more initialized uintptrs
// minpc, maxpc
Addaddr(Ctxt, moduledata, pclntabFirstFunc)
Addaddrplus(Ctxt, moduledata, pclntabLastFunc, pclntabLastFunc.Size)
// pointers to specific parts of the module
Addaddr(Ctxt, moduledata, Linklookup(Ctxt, "runtime.text", 0))
Addaddr(Ctxt, moduledata, Linklookup(Ctxt, "runtime.etext", 0))
Addaddr(Ctxt, moduledata, Linklookup(Ctxt, "runtime.noptrdata", 0))
@ -420,6 +431,8 @@ func symtab() {
Addaddr(Ctxt, moduledata, Linklookup(Ctxt, "runtime.end", 0))
Addaddr(Ctxt, moduledata, Linklookup(Ctxt, "runtime.gcdata", 0))
Addaddr(Ctxt, moduledata, Linklookup(Ctxt, "runtime.gcbss", 0))
// The typelinks slice
Addaddr(Ctxt, moduledata, Linklookup(Ctxt, "runtime.typelink", 0))
Addaddr(Ctxt, moduledata, Linklookup(Ctxt, "runtime.etypelink", 0))
adduint(Ctxt, moduledata, uint64(ntypelinks))
adduint(Ctxt, moduledata, uint64(ntypelinks))
}

2
src/runtime/proc1.go
View File

@ -51,7 +51,7 @@ func schedinit() {
framepointer_enabled = haveexperiment("framepointer")
tracebackinit()
symtabinit()
symtabverify()
stackinit()
mallocinit()
mcommoninit(_g_.m)

7
src/runtime/runtime1.go
View File

@ -427,12 +427,7 @@ func gomcache() *mcache {
//go:linkname reflect_typelinks reflect.typelinks
//go:nosplit
func reflect_typelinks() []*_type {
var ret []*_type
sp := (*slice)(unsafe.Pointer(&ret))
sp.array = (*byte)(unsafe.Pointer(themoduledata.typelink))
sp.len = uint((themoduledata.etypelink - themoduledata.typelink) / unsafe.Sizeof(ret[0]))
sp.cap = sp.len
return ret
return themoduledata.typelinks
}
// TODO: move back into mgc.go

51
src/runtime/symtab.go
View File

@ -33,11 +33,11 @@ const (
// image. It is written by the linker. Any changes here must be
// matched changes to the code in cmd/internal/ld/symtab.go:symtab.
type moduledata struct {
pclntable []byte
ftab []functab
filetab []uint32
pclntab, epclntab, findfunctab uintptr
minpc, maxpc uintptr
pclntable []byte
ftab []functab
filetab []uint32
findfunctab uintptr
minpc, maxpc uintptr
text, etext uintptr
noptrdata, enoptrdata uintptr
@ -46,7 +46,7 @@ type moduledata struct {
noptrbss, enoptrbss uintptr
end, gcdata, gcbss uintptr
typelink, etypelink uintptr
typelinks []*_type
}
var themoduledata moduledata // linker symbol
@ -72,30 +72,19 @@ type findfuncbucket struct {
subbuckets [16]byte
}
func symtabinit() {
func symtabverify() {
// See golang.org/s/go12symtab for header: 0xfffffffb,
// two zero bytes, a byte giving the PC quantum,
// and a byte giving the pointer width in bytes.
pcln := (*[8]byte)(unsafe.Pointer(themoduledata.pclntab))
pcln32 := (*[2]uint32)(unsafe.Pointer(themoduledata.pclntab))
pcln := *(**[8]byte)(unsafe.Pointer(&themoduledata.pclntable))
pcln32 := *(**[2]uint32)(unsafe.Pointer(&themoduledata.pclntable))
if pcln32[0] != 0xfffffffb || pcln[4] != 0 || pcln[5] != 0 || pcln[6] != _PCQuantum || pcln[7] != ptrSize {
println("runtime: function symbol table header:", hex(pcln32[0]), hex(pcln[4]), hex(pcln[5]), hex(pcln[6]), hex(pcln[7]))
throw("invalid function symbol table\n")
}
// pclntable is all bytes of pclntab symbol.
sp := (*sliceStruct)(unsafe.Pointer(&themoduledata.pclntable))
sp.array = unsafe.Pointer(themoduledata.pclntab)
sp.len = int(uintptr(unsafe.Pointer(themoduledata.epclntab)) - uintptr(unsafe.Pointer(themoduledata.pclntab)))
sp.cap = sp.len
// ftab is lookup table for function by program counter.
nftab := int(*(*uintptr)(add(unsafe.Pointer(pcln), 8)))
p := add(unsafe.Pointer(pcln), 8+ptrSize)
sp = (*sliceStruct)(unsafe.Pointer(&themoduledata.ftab))
sp.array = p
sp.len = nftab + 1
sp.cap = sp.len
nftab := len(themoduledata.ftab) - 1
for i := 0; i < nftab; i++ {
// NOTE: ftab[nftab].entry is legal; it is the address beyond the final function.
if themoduledata.ftab[i].entry > themoduledata.ftab[i+1].entry {
@ -113,22 +102,10 @@ func symtabinit() {
}
}
// The ftab ends with a half functab consisting only of
// 'entry', followed by a uint32 giving the pcln-relative
// offset of the file table.
sp = (*sliceStruct)(unsafe.Pointer(&themoduledata.filetab))
end := unsafe.Pointer(&themoduledata.ftab[nftab].funcoff) // just beyond ftab
fileoffset := *(*uint32)(end)
sp.array = unsafe.Pointer(&themoduledata.pclntable[fileoffset])
// length is in first element of array.
// set len to 1 so we can get first element.
sp.len = 1
sp.cap = 1
sp.len = int(themoduledata.filetab[0])
sp.cap = sp.len
themoduledata.minpc = themoduledata.ftab[0].entry
themoduledata.maxpc = themoduledata.ftab[nftab].entry
if themoduledata.minpc != themoduledata.ftab[0].entry ||
themoduledata.maxpc != themoduledata.ftab[nftab].entry {
throw("minpc or maxpc invalid")
}
}
// FuncForPC returns a *Func describing the function that contains the