Unable to access function arguments and local variables for linkshared binary

[ManojKumarChauhan]

What version of Go are you using (go version)?

$ go version
1.15

Does this issue reproduce with the latest release?

Yes with every version of go

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOENV="/root/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/root/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/root/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="/usr/bin/gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build531678036=/tmp/go-build -gno-record-gcc-switches"

What did you do?

Using dyninst, I tried to access local variables and arguments of a function which is part of a go binary compiled with linkshared option. To get local variables, dyninst uses libdw library to find all the modules. It uses dwarf_nextcu function of libdw to find all the modules of binary.
When I compile a go binary using "go build filename.go" then dwarf_nextcu finds all the modules (almost 118) and dyninst is able to access local variables and arguments of any function.
But when I compile a go binary with linkshared option "go build -linkshared filename.go" then dwarf_nextcu finds only 5 modules. Due to that, dyninst is not able to access any variable of a function.

When I contact libdw team, they checked the symbols of both the binaries and gave a response.

//go binary without linkshared
$ eu-readelf --debug-dump=info wrapecho.txt | grep producer | sort | uniq -c
1 producer (string) "GNU AS 2.25"
147 producer (string) "Go cmd/compile go1.15.1"
2 producer (strp) "GNU C11 6.5.0 20181026"
16 producer (strp) "GNU C 4.9.2"

//go binry with linkshared
$ eu-readelf --debug-dump=info wrapecho_linkshared.txt | grep producer | sort | uniq -c
1 producer (string) "GNU AS 2.26.1"
18 producer (strp) "GNU C11 6.5.0 20181026"

Response from libdw team:
"So the information you want to extract from them is simply not there for the Go compiler generated functions. This is probably a bug you should produce to the Go language team or Ubuntu (if it is specific to their packaging)."

Is this a bug in go or there is any other way to read the symbols.

What did you expect to see?

I should be able to access variables of a function of go linkshared binary

What did you see instead?

Could not access variable of a function.

[cherrymui]

I believe currently debug info generation is not enabled for shared libraries. See #38378. I think we can close this and combine it into that issue. Thanks.