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all: use ":" for compiler generated symbols

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As it can't appear in user package paths.

There is a hack for handling "go:buildid" and "type:*" on windows/386.

Previously, windows/386 requires underscore prefix on external symbols,
but that's only applied for SHOSTOBJ/SUNDEFEXT or cgo export symbols.
"go.buildid" is STEXT, "type.*" is STYPE, thus they are not prefixed
with underscore.

In external linking mode, the external linker can't resolve them as
external symbols. But we are lucky that they have "." in their name,
so the external linker see them as Forwarder RVA exports. See:

 - https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#export-address-table
 - https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=ld/pe-dll.c;h=e7b82ba6ffadf74dc1b9ee71dc13d48336941e51;hb=HEAD#l972)

This CL changes "." to ":" in symbols name, so theses symbols can not be
found by external linker anymore. So a hacky way is adding the
underscore prefix for these 2 symbols. I don't have enough knowledge to
verify whether adding the underscore for all STEXT/STYPE symbols are
fine, even if it could be, that would be done in future CL.

Fixes #37762

Change-Id: I92eaaf24c0820926a36e0530fdb07b07af1fcc35
Reviewed-on: https://go-review.googlesource.com/c/go/+/317917
Reviewed-by: Than McIntosh <thanm@google.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
This commit is contained in:
Cuong Manh Le 2021-05-08 00:45:06 +07:00
parent 5639fcae7f
commit 0f8dffd0aa
37 changed files with 283 additions and 231 deletions
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20
src/cmd/link/internal/ld/lib.go
View file

@ -926,24 +926,24 @@ func (ctxt *Link) mangleTypeSym() {
// typeSymbolMangle mangles the given symbol name into something shorter.
//
// Keep the type.. prefix, which parts of the linker (like the
// Keep the type:. prefix, which parts of the linker (like the
// DWARF generator) know means the symbol is not decodable.
// Leave type.runtime. symbols alone, because other parts of
// Leave type:runtime. symbols alone, because other parts of
// the linker manipulates them.
func typeSymbolMangle(name string) string {
if !strings.HasPrefix(name, "type.") {
if !strings.HasPrefix(name, "type:") {
return name
}
if strings.HasPrefix(name, "type.runtime.") {
if strings.HasPrefix(name, "type:runtime.") {
return name
}
if len(name) <= 14 && !strings.Contains(name, "@") { // Issue 19529
return name
}
hash := notsha256.Sum256([]byte(name))
prefix := "type."
prefix := "type:"
if name[5] == '.' {
prefix = "type.."
prefix = "type:."
}
return prefix + base64.StdEncoding.EncodeToString(hash[:6])
}
@ -2319,11 +2319,11 @@ func ldshlibsyms(ctxt *Link, shlib string) {
continue
}
// Symbols whose names start with "type." are compiler
// generated, so make functions with that prefix internal.
// Symbols whose names start with "type:" are compiler generated,
// so make functions with that prefix internal.
ver := 0
symname := elfsym.Name // (unmangled) symbol name
if elf.ST_TYPE(elfsym.Info) == elf.STT_FUNC && strings.HasPrefix(elfsym.Name, "type.") {
if elf.ST_TYPE(elfsym.Info) == elf.STT_FUNC && strings.HasPrefix(elfsym.Name, "type:") {
ver = abiInternalVer
} else if buildcfg.Experiment.RegabiWrappers && elf.ST_TYPE(elfsym.Info) == elf.STT_FUNC {
// Demangle the ABI name. Keep in sync with symtab.go:mangleABIName.
@ -2357,7 +2357,7 @@ func ldshlibsyms(ctxt *Link, shlib string) {
// The decodetype_* functions in decodetype.go need access to
// the type data.
sname := l.SymName(s)
if strings.HasPrefix(sname, "type.") && !strings.HasPrefix(sname, "type..") {
if strings.HasPrefix(sname, "type:") && !strings.HasPrefix(sname, "type:.") {
su.SetData(readelfsymboldata(ctxt, f, &elfsym))
}
}