Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

cmd/link: relocation error on ppc64le musl with cgo and CGO_CFLAGS=-Os #52336

Closed
nmeum opened this issue Apr 13, 2022 · 9 comments
Closed

cmd/link: relocation error on ppc64le musl with cgo and CGO_CFLAGS=-Os #52336

nmeum opened this issue Apr 13, 2022 · 9 comments
Labels
arch-ppc64x NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
Milestone

Comments

@nmeum
Copy link

nmeum commented Apr 13, 2022

This is a follow-up for #51787.

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

$ go version
go version go1.18.1 linux/ppc64le

Does this issue reproduce with the latest release?

Yes.

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

go env Output
$ go env
GO111MODULE=""
GOARCH="ppc64le"
GOBIN=""
GOCACHE="/home/buildozer/.cache/go-build"
GOENV="/home/buildozer/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="ppc64le"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/buildozer/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/buildozer/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/lib/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go/pkg/tool/linux_ppc64le"
GOVCS=""
GOVERSION="go1.18.1"
GCCGO="gccgo"
GOPPC64="power8"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build1359095760=/tmp/go-build -gno-record-gcc-switches"

What did you do?

This is issue we encountered when packaging Go software for Alpine Linux Edge ppc64le. On all other architectures, supported by Alpine, the affected Go software builds fine but on ppc64le it fails with a relocation error (which makes me think that this is related to #51787).

This issue only seems to appear with -Os in the CGO_CFLAGS environment variable (keep in mind though many wrappers around go build, e.g. Makefiles, set CGO_FLAGS=$CFLAGS). Without setting CGO_CFLAGS the software builds fine.

For example:

$ git clone https://github.com/maximbaz/yubikey-touch-detector
$ cd yubikey-touch-detector
$ CGO_CFLAGS=-Os go build -v

I have not yet been able to produce a minimal example but this seems to affect a lot of software #51787 (comment) has more examples. Let me know if you need me to provide more information.

What did you expect to see?

A successful build.

What did you see instead?

os/user
net
crypto/x509
github.com/godbus/dbus/v5
crypto/tls
github.com/esiqveland/notify
github.com/coreos/go-systemd/v22/activation
github.com/maximbaz/yubikey-touch-detector/notifier
github.com/maximbaz/yubikey-touch-detector/detector
github.com/maximbaz/yubikey-touch-detector
# github.com/maximbaz/yubikey-touch-detector
net(.text): relocation target _savegpr0_28 not defined
net(.text): relocation target _restgpr0_28 not defined
net(.text): relocation target _savegpr0_29 not defined
net(.text): relocation target _restgpr0_29 not defined
runtime/cgo(.text): relocation target _restgpr0_30 not defined
runtime/cgo(.text): relocation target _restgpr0_31 not defined
runtime/cgo(.text): relocation target _savegpr0_23 not defined
runtime/cgo(.text): relocation target _restgpr0_23 not defined
runtime/cgo(.text): relocation target _restgpr0_30 not defined
runtime/cgo(.text): relocation target _savegpr0_29 not defined
runtime/cgo(.text): relocation target _restgpr0_29 not defined
runtime/cgo(.text): relocation target _savegpr0_25 not defined
runtime/cgo(.text): relocation target _restgpr0_25 not defined
runtime/cgo(.text): relocation target _savegpr0_28 not defined
runtime/cgo(.text): relocation target _restgpr0_28 not defined
runtime/cgo(.text): relocation target _restgpr0_31 not defined
os/user(.text): relocation target _restgpr0_30 not defined
os/user(.text): relocation target _savegpr0_29 not defined
os/user(.text): relocation target _restgpr0_29 not defined

CC: @pmur, @cherrymui

@cherrymui cherrymui changed the title cmd/go: relocation error on ppc64le musl with cgo and CGO_CFLAGS=-Os cmd/link: relocation error on ppc64le musl with cgo and CGO_CFLAGS=-Os Apr 13, 2022
@cherrymui
Copy link
Member

cherrymui commented Apr 13, 2022

Without setting CGO_CFLAGS the software builds fine.

Interesting. Presumably this causes the C compiler to emit symbols (like _savegpr0_28) that the Go linker doesn't currently handle.

A workaround is to try go build -ldflags=-linkmode=external. Would that be an option?

On #51787 (comment) you also mentioned "unexpected trampoline for shared or dynamic linking" errors. When/how could that happen? Could you provide the command line for that one? Thanks.

@nmeum
Copy link
Author

nmeum commented Apr 13, 2022

A workaround is to try go build -ldflags=-linkmode=external. Would that be an option?

That does seem to work, yes.

On #51787 (comment) you also mentioned "unexpected trampoline for shared or dynamic linking" errors. When/how could that happen? Could you provide the command line for that one? Thanks.

I debugged this a bit further and since it seems that different flags are needed to reproduce the two I decided to create two separate issues. I hope that's ok. The other issue is #52337.

algitbot pushed a commit to alpinelinux/aports that referenced this issue Apr 13, 2022
This re-enables 866f2e1. While Go
1.18.1 fixed the initial linking error we encountered with Go 1.18
on ppc64le it seems there are two more regressions with -buildmode=pie
and CGO_CFLAGS=-Os. See:

* golang/go#52336
* golang/go#52337

Forcing external link mode seems to be a workaround for now.

Fixes #13692
@dmitshur dmitshur added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Apr 14, 2022
@dmitshur dmitshur added this to the Backlog milestone Apr 14, 2022
@pmur
Copy link
Contributor

pmur commented Apr 15, 2022

This is a PPC64 (and likely -Os) only quirk. binutils ld generates these symbols. Also, I noticed the project in question uses a makefile which explicitly requests external linking. @nmeum is alpine using the project supplied makefile?

@Cherry should I be matching this behavior in the internal linker? These functions are part of the PPC64 ELF ABIs.

@cherrymui
Copy link
Member

cherrymui commented Apr 15, 2022

I think it is okay to require external linking for some C compiler flags. However, it would be nice to support ones that are system default. How complex that would be to add the support? Thanks.

@nmeum
Copy link
Author

nmeum commented Apr 16, 2022

This is a PPC64 (and likely -Os) only quirk. binutils ld generates these symbols. Also, I noticed the project in question uses a makefile which explicitly requests external linking. @nmeum is alpine using the project supplied makefile?

Yep, Alpine is using CFLAGS=-Os by default and uses the Makefile provided by the project which sets CGO_CFLAGS=$CFLAGS. It is not just this particular project though, we seem to have quite a few Go packages in Alpine which sets CGO_CFLAGS in a similar manner.

@pmur
Copy link
Contributor

pmur commented Apr 18, 2022

I think it is feasible support generating those ABI functions when linking internally. I'll make a patch.

@gopherbot
Copy link

gopherbot commented Apr 18, 2022

Change https://go.dev/cl/400796 mentions this issue: cmd/link: generate ABI save/restore functions if needed

@gopherbot
Copy link

gopherbot commented Apr 18, 2022

Change https://go.dev/cl/400796 mentions this issue: cmd/link: generate PPC64 ABI save/restore functions if needed

@gopherbot
Copy link

gopherbot commented Apr 19, 2022

Change https://go.dev/cl/401114 mentions this issue: cmd/link: generate ABI register save/restore functions if needed

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
arch-ppc64x NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
Projects
None yet
Development

No branches or pull requests

5 participants