runtime, cmd/internal/ld: initialize themoduledata slices directly
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>
diff --git a/src/cmd/internal/ld/data.go b/src/cmd/internal/ld/data.go
index bc2021a..e674514 100644
--- a/src/cmd/internal/ld/data.go
+++ b/src/cmd/internal/ld/data.go
@@ -102,6 +102,10 @@
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)
}
diff --git a/src/cmd/internal/ld/pcln.go b/src/cmd/internal/ld/pcln.go
index 0250ca0..65ca0c3 100644
--- a/src/cmd/internal/ld/pcln.go
+++ b/src/cmd/internal/ld/pcln.go
@@ -202,6 +202,13 @@
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 @@
}
}
+ 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 @@
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 @@
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 @@
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)
diff --git a/src/cmd/internal/ld/symtab.go b/src/cmd/internal/ld/symtab.go
index c5b32fd2..4e1bfc6 100644
--- a/src/cmd/internal/ld/symtab.go
+++ b/src/cmd/internal/ld/symtab.go
@@ -348,6 +348,8 @@
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 @@
}
if strings.HasPrefix(s.Name, "go.typelink.") {
+ ntypelinks++
s.Type = STYPELINK
s.Hide = 1
s.Outer = symtypelink
@@ -392,21 +395,29 @@
// 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 @@
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))
}
diff --git a/src/runtime/proc1.go b/src/runtime/proc1.go
index b8ea36c..772fa09 100644
--- a/src/runtime/proc1.go
+++ b/src/runtime/proc1.go
@@ -51,7 +51,7 @@
framepointer_enabled = haveexperiment("framepointer")
tracebackinit()
- symtabinit()
+ symtabverify()
stackinit()
mallocinit()
mcommoninit(_g_.m)
diff --git a/src/runtime/runtime1.go b/src/runtime/runtime1.go
index 072a585..5fddc58 100644
--- a/src/runtime/runtime1.go
+++ b/src/runtime/runtime1.go
@@ -427,12 +427,7 @@
//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
diff --git a/src/runtime/symtab.go b/src/runtime/symtab.go
index 689a336..8ee80c8 100644
--- a/src/runtime/symtab.go
+++ b/src/runtime/symtab.go
@@ -33,11 +33,11 @@
// 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 @@
noptrbss, enoptrbss uintptr
end, gcdata, gcbss uintptr
- typelink, etypelink uintptr
+ typelinks []*_type
}
var themoduledata moduledata // linker symbol
@@ -72,30 +72,19 @@
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 @@
}
}
- // 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
