go: cmd/link, cmd/cgo: internal linking fails if CGO_CFLAGS enables LTO

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

$ go version
go version devel +9eef49cfa6 Mon Jan 4 17:59:30 2021 +0000 linux/amd64

Does this issue reproduce with the latest release?

Yes, although the error is a bit different.

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

Ubuntu 20.04 or 20.10 (current devel series).

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/mwhudson/.cache/go-build"
GOENV="/home/mwhudson/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/mwhudson/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/mwhudson/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/mwhudson/src/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/mwhudson/src/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="devel +9eef49cfa6 Mon Jan 4 17:59:30 2021 +0000"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
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-build1258774523=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I ran a trivial os/user-using program with CFLAGS that caused gcc to create object files ready for link time optimization:

mwhudson@anduril:~/tmp$ cat user.go
package main

import (
	"fmt"
	"os/user"
)

func main() {
	u, _ := user.Current()
	fmt.Printf("username: %s\n", u.Name)
}
mwhudson@anduril:~/tmp$ CGO_CFLAGS='-g -flto -ffat-lto-objects' ~/src/go/bin/go run user.go

What did you expect to see?

username: Michael Hudson-Doyle

What did you see instead?

Errors of the form “loadelf: /home/mwhudson/.cache/go-build/1c/1cfde03a90c420f612c840a344f1de135898b62010e420c7b14c3e353c13c3d9-d(_x001.o): 67693: sym#26: ignoring symbol in section 5 (type 0)” and then a panic:

# command-line-arguments loadelf: /home/mwhudson/.cache/go-build/1c/1cfde03a90c420f612c840a344f1de135898b62010e420c7b14c3e353c13c3d9-d(_x001.o): 67693: sym#26: ignoring symbol in section 5 (type 0) loadelf: /home/mwhudson/.cache/go-build/1c/1cfde03a90c420f612c840a344f1de135898b62010e420c7b14c3e353c13c3d9-d(_x002.o): 67704: sym#44: ignoring symbol in section 5 (type 0) loadelf: /home/mwhudson/.cache/go-build/1c/1cfde03a90c420f612c840a344f1de135898b62010e420c7b14c3e353c13c3d9-d(_x003.o): 67712: sym#32: ignoring symbol in section 5 (type 0) loadelf: /home/mwhudson/.cache/go-build/1c/1cfde03a90c420f612c840a344f1de135898b62010e420c7b14c3e353c13c3d9-d(_x004.o): 67719: sym#29: ignoring symbol in section 4 (type 0) loadelf: /home/mwhudson/.cache/go-build/f8/f82d697d7b7630e244251862c642563a76958f85413b4848809324ae1c92be56-d(_x001.o): 67723: sym#24: ignoring symbol in section 4 (type 0) loadelf: /home/mwhudson/.cache/go-build/f8/f82d697d7b7630e244251862c642563a76958f85413b4848809324ae1c92be56-d(_x002.o): 67730: sym#29: ignoring symbol in section 4 (type 0) loadelf: /home/mwhudson/.cache/go-build/f8/f82d697d7b7630e244251862c642563a76958f85413b4848809324ae1c92be56-d(_x003.o): 67735: sym#26: ignoring symbol in section 5 (type 0) loadelf: /home/mwhudson/.cache/go-build/f8/f82d697d7b7630e244251862c642563a76958f85413b4848809324ae1c92be56-d(_x004.o): 67741: sym#27: ignoring symbol in section 5 (type 0) loadelf: /home/mwhudson/.cache/go-build/f8/f82d697d7b7630e244251862c642563a76958f85413b4848809324ae1c92be56-d(_x005.o): 67751: sym#38: ignoring symbol in section 5 (type 0) loadelf: /home/mwhudson/.cache/go-build/f8/f82d697d7b7630e244251862c642563a76958f85413b4848809324ae1c92be56-d(_x006.o): 67759: sym#31: ignoring symbol in section 5 (type 0) loadelf: /home/mwhudson/.cache/go-build/f8/f82d697d7b7630e244251862c642563a76958f85413b4848809324ae1c92be56-d(_x007.o): 67764: sym#27: ignoring symbol in section 5 (type 0) loadelf: /home/mwhudson/.cache/go-build/f8/f82d697d7b7630e244251862c642563a76958f85413b4848809324ae1c92be56-d(_x008.o): 67769: sym#27: ignoring symbol in section 5 (type 0) loadelf: /home/mwhudson/.cache/go-build/f8/f82d697d7b7630e244251862c642563a76958f85413b4848809324ae1c92be56-d(_x009.o): 67774: sym#26: ignoring symbol in section 5 (type 0) loadelf: /home/mwhudson/.cache/go-build/f8/f82d697d7b7630e244251862c642563a76958f85413b4848809324ae1c92be56-d(_x010.o): 67779: sym#26: ignoring symbol in section 5 (type 0) loadelf: /home/mwhudson/.cache/go-build/f8/f82d697d7b7630e244251862c642563a76958f85413b4848809324ae1c92be56-d(_x011.o): 67785: sym#27: ignoring symbol in section 5 (type 0) loadelf: /home/mwhudson/.cache/go-build/f8/f82d697d7b7630e244251862c642563a76958f85413b4848809324ae1c92be56-d(_x012.o): 67790: sym#34: ignoring symbol in section 5 (type 0) _cgo_callers: relocation target x_cgo_callers not defined _cgo_init: relocation target x_cgo_init not defined _cgo_mmap: relocation target x_cgo_mmap not defined _cgo_munmap: relocation target x_cgo_munmap not defined _cgo_notify_runtime_init_done: relocation target x_cgo_notify_runtime_init_done not defined /home/mwhudson/src/go/pkg/tool/linux_amd64/link: too many errors unexpected fault address 0x7f310460c000 fatal error: fault [signal SIGSEGV: segmentation violation code=0x1 addr=0x7f310460c000 pc=0x46db13]

goroutine 129 [running]: runtime.throw(0x6dac2e, 0x5) /home/mwhudson/src/go/src/runtime/panic.go:1112 +0x72 fp=0xc00061fd18 sp=0xc00061fce8 pc=0x436e12 runtime.sigpanic() /home/mwhudson/src/go/src/runtime/signal_unix.go:737 +0x268 fp=0xc00061fd50 sp=0xc00061fd18 pc=0x44e4a8 runtime.memmove(0x7f310460baa0, 0x7f3104eb29b1, 0xa6a) /home/mwhudson/src/go/src/runtime/memmove_amd64.s:367 +0x433 fp=0xc00061fd58 sp=0xc00061fd50 pc=0x46db13 cmd/link/internal/ld.(*OutBuf).WriteSym(0xc00111e000, 0xc000128000, 0x3925, 0x2, 0xc0000b60c5, 0x1) /home/mwhudson/src/go/src/cmd/link/internal/ld/outbuf.go:300 +0x2bc fp=0xc00061fde8 sp=0xc00061fd58 pc=0x5ea7fc cmd/link/internal/ld.writeBlock(0xc00010e000, 0xc00111e000, 0xc000128000, 0xc000eae000, 0x5e2, 0x6a0, 0x40daa0, 0x9b4a5, 0xc0000b60c5, 0x1, …) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:952 +0x1a9 fp=0xc00061ff10 sp=0xc00061fde8 pc=0x589149 cmd/link/internal/ld.writeBlocks.func1(0xc00010e000, 0xc001114020, 0xc0000f40e0, 0xc00111e000, 0xc000128000, 0xc000eae000, 0x5e2, 0x6a0, 0x401000, 0x9b4a5, …) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:909 +0xb1 fp=0xc00061ff78 sp=0xc00061ff10 pc=0x608311 runtime.goexit() /home/mwhudson/src/go/src/runtime/asm_amd64.s:1367 +0x1 fp=0xc00061ff80 sp=0xc00061ff78 pc=0x46c901 created by cmd/link/internal/ld.writeBlocks /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:908 +0x565

goroutine 1 [semacquire]: sync.runtime_Semacquire(0xc0011a4038) /home/mwhudson/src/go/src/runtime/sema.go:56 +0x45 sync.(*WaitGroup).Wait(0xc0011a4030) /home/mwhudson/src/go/src/sync/waitgroup.go:130 +0x65 cmd/link/internal/ld.asmb(0xc00010e000) /home/mwhudson/src/go/src/cmd/link/internal/ld/asmb.go:73 +0x235 cmd/link/internal/ld.Main(0x87d2e0, 0x20, 0x20, 0x1, 0x7, 0x10, 0x0, 0x0, 0x6e663e, 0x1b, …) /home/mwhudson/src/go/src/cmd/link/internal/ld/main.go:331 +0x140e main.main() /home/mwhudson/src/go/src/cmd/link/main.go:68 +0x258

goroutine 24 [semacquire]: sync.runtime_Semacquire(0xc001230008) /home/mwhudson/src/go/src/runtime/sema.go:56 +0x45 sync.(*WaitGroup).Wait(0xc001230000) /home/mwhudson/src/go/src/sync/waitgroup.go:130 +0x65 cmd/link/internal/ld.writeBlocks(0xc00010e000, 0xc00119eb60, 0xc0000f40e0, 0xc000128000, 0xc0011c2218, 0x4e5, 0x4e5, 0x53f000, 0x15ca0, 0x8bd260, …) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:924 +0x736 cmd/link/internal/ld.writeDatblkToOutBuf(…) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:1006 cmd/link/internal/ld.datblk(0xc00010e000, 0xc00119eb60, 0x53f000, 0x15ca0) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:994 +0xad cmd/link/internal/ld.writeParallel.func1(0xc0011a4030, 0x6f23a8, 0xc00010e000, 0xc00119eb60, 0x53f000, 0x15ca0) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:988 +0x7a created by cmd/link/internal/ld.writeParallel /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:986 +0x152

goroutine 23 [runnable]: cmd/link/internal/loader.(*Loader).SubSym(…) /home/mwhudson/src/go/src/cmd/link/internal/loader/loader.go:1740 cmd/link/internal/loader.(*Loader).AttrSubSymbol(…) /home/mwhudson/src/go/src/cmd/link/internal/loader/loader.go:1161 cmd/link/internal/ld.writeBlocks(0xc00010e000, 0xc00119eaf0, 0xc0000f40e0, 0xc000128000, 0xc0011b6008, 0x1d27, 0x1d27, 0x49d000, 0xa1028, 0x8bd260, …) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:858 +0x785 cmd/link/internal/ld.writeDatblkToOutBuf(…) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:1006 cmd/link/internal/ld.datblk(0xc00010e000, 0xc00119eaf0, 0x49d000, 0xa1028) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:994 +0xad cmd/link/internal/ld.writeParallel.func1(0xc0011a4030, 0x6f23a8, 0xc00010e000, 0xc00119eaf0, 0x49d000, 0xa1028) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:988 +0x7a created by cmd/link/internal/ld.writeParallel /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:986 +0x152

goroutine 21 [semacquire]: sync.runtime_Semacquire(0xc001114028) /home/mwhudson/src/go/src/runtime/sema.go:56 +0x45 sync.(*WaitGroup).Wait(0xc001114020) /home/mwhudson/src/go/src/sync/waitgroup.go:130 +0x65 cmd/link/internal/ld.writeBlocks(0xc00010e000, 0xc00119ea10, 0xc0000f40e0, 0xc000128000, 0xc000eae000, 0x5e2, 0x6a0, 0x401000, 0x9b4a5, 0xc0000b60c5, …) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:924 +0x736 cmd/link/internal/ld.CodeblkPad(…) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:834 cmd/link/internal/ld.asmb.func1(0xc00010e000, 0xc00119ea10, 0x401000, 0x9b4a5) /home/mwhudson/src/go/src/cmd/link/internal/ld/asmb.go:39 +0xd3 cmd/link/internal/ld.writeParallel.func1(0xc0011a4030, 0x6f23a0, 0xc00010e000, 0xc00119ea10, 0x401000, 0x9b4a5) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:988 +0x7a created by cmd/link/internal/ld.writeParallel /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:986 +0x152

goroutine 113 [runnable]: os.Exit(0x2) /home/mwhudson/src/go/src/os/proc.go:62 +0x73 cmd/link/internal/ld.Exit(0x2) /home/mwhudson/src/go/src/cmd/link/internal/ld/util.go:31 +0x8a cmd/link/internal/ld.Exitf(0x6dfa23, 0xf, 0x0, 0x0, 0x0) /home/mwhudson/src/go/src/cmd/link/internal/ld/util.go:38 +0x106 cmd/link/internal/ld.afterErrorAction() /home/mwhudson/src/go/src/cmd/link/internal/ld/util.go:49 +0x7a cmd/link/internal/loader.(*ErrorReporter).Errorf(0xc00010e010, 0xa5e0, 0x6e8fde, 0x20, 0xc001225ae0, 0x1, 0x1) /home/mwhudson/src/go/src/cmd/link/internal/loader/loader.go:2619 +0x143 cmd/link/internal/ld.(*ErrorReporter).errorUnresolved(0xc00010e010, 0xc000128000, 0xa5e0, 0xa5df) /home/mwhudson/src/go/src/cmd/link/internal/ld/errors.go:63 +0x4e9 cmd/link/internal/ld.(*relocSymState).relocsym(0xc001225ea0, 0xa5e0, 0x7f310474b4c0, 0x8, 0x7b40) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:199 +0x338a cmd/link/internal/ld.writeBlock(0xc00010e000, 0xc001232000, 0xc000128000, 0xc0011c2218, 0x4e5, 0x4e5, 0x54d4c0, 0x15ca0, 0x8bd260, 0x200, …) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:953 +0x1e7 cmd/link/internal/ld.writeBlocks.func1(0xc00010e000, 0xc001230000, 0xc0000f40e0, 0xc001232000, 0xc000128000, 0xc0011c2218, 0x4e5, 0x4e5, 0x53f000, 0x15ca0, …) /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:909 +0xb1 created by cmd/link/internal/ld.writeBlocks /home/mwhudson/src/go/src/cmd/link/internal/ld/data.go:908 +0x565

About this issue

Original URL
State: open
Created 3 years ago
Comments: 15 (10 by maintainers)

Commits related to this issue

cmd/link, cmd/cgo: support -flto in CFLAGS The linker now accepts unrecognized object files in external linking mode. These objects will simply be passed to the external linker. This permits using -f... — committed to golang/go by ianlancetaylor 3 years ago
www-apps/mattermost-server: bump to 6.4.2 bump 6.3 branch to 6.3.5 bump 6.2 branch to 6.2.5 bump 5.37 branch to 5.37.9 Also strip LTO from CGO_CFLAGS per https://github.com/golang/go/issues/43505 — committed to matoro/overlay by matoro 2 years ago
Disable lto to fix build It looks like that golang applications currently fails[1] to build with lto enabled on CGO_CFLAGS/CGO_CXXFLAGS. Disabling lto until there is a fix from upstream golang. Refe... — committed to archlinux/aur by dbermond 2 years ago

Most upvoted comments

I just upgraded to 1.17 and am still seeing this during a build when LTO is enabled, so it does not seem to have been fixed in this release.

mkdir -p $WORK/b001/exe/
cd .
/usr/lib/go/pkg/tool/linux_amd64/link -o $WORK/b001/exe/a.out -importcfg $WORK/b001/importcfg.link -installsuffix shared -buildmode=pie -buildid=m1qr5vgOOA5hGhQ61dg-/
tUdJ4RLJL5nvSqQ-3szr/Nevd-K5g6UJJGBtmKWHk/m1qr5vgOOA5hGhQ61dg- -s -w -X github.com/mattermost/mattermost-server/model.BuildNumber=5.38.2 -X "github.com/mattermost/mat
termost-server/model.BuildDate=Fri Aug 27 03:46:00 PM UTC 2021" -X github.com/mattermost/mattermost-server/model.BuildHash=cc3edaef3420b785e8e0889edfc122881fc147dc -X
 github.com/mattermost/mattermost-server/model.BuildHashEnterprise=none -X github.com/mattermost/mattermost-server/model.BuildEnterpriseReady=false -extld=x86_64-pc-l
inux-gnu-gcc $WORK/b001/_pkg_.a
# github.com/mattermost/mattermost-server/v5/cmd/mattermost
_cgo_callers: relocation target x_cgo_callers not defined
_cgo_init: relocation target x_cgo_init not defined
_cgo_mmap: relocation target x_cgo_mmap not defined
_cgo_munmap: relocation target x_cgo_munmap not defined
_cgo_notify_runtime_init_done: relocation target x_cgo_notify_runtime_init_done not defined
_cgo_sigaction: relocation target x_cgo_sigaction not defined
_cgo_thread_start: relocation target x_cgo_thread_start not defined
net._cgo_3c1cec0c9a4e_C2func_getaddrinfo: relocation target _cgo_3c1cec0c9a4e_C2func_getaddrinfo not defined
net._cgo_3c1cec0c9a4e_C2func_getnameinfo: relocation target _cgo_3c1cec0c9a4e_C2func_getnameinfo not defined
net._cgo_3c1cec0c9a4e_Cfunc_freeaddrinfo: relocation target _cgo_3c1cec0c9a4e_Cfunc_freeaddrinfo not defined
net._cgo_3c1cec0c9a4e_Cfunc_gai_strerror: relocation target _cgo_3c1cec0c9a4e_Cfunc_gai_strerror not defined
os/user._cgo_aacb17fbab05_Cfunc__Cmalloc: relocation target _cgo_aacb17fbab05_Cfunc__Cmalloc not defined
os/user._cgo_aacb17fbab05_Cfunc_free: relocation target _cgo_aacb17fbab05_Cfunc_free not defined
os/user._cgo_aacb17fbab05_Cfunc_mygetgrgid_r: relocation target _cgo_aacb17fbab05_Cfunc_mygetgrgid_r not defined
os/user._cgo_aacb17fbab05_Cfunc_mygetpwuid_r: relocation target _cgo_aacb17fbab05_Cfunc_mygetpwuid_r not defined
os/user._cgo_aacb17fbab05_Cfunc_realloc: relocation target _cgo_aacb17fbab05_Cfunc_realloc not defined
os/user._cgo_aacb17fbab05_Cfunc_sysconf: relocation target _cgo_aacb17fbab05_Cfunc_sysconf not defined
runtime._cgo_setenv: relocation target x_cgo_setenv not defined
runtime._cgo_unsetenv: relocation target x_cgo_unsetenv not defined
runtime.cgo_yield: relocation target _cgo_yield not defined
.rela: relocation target _cgo_yield not defined
/usr/lib/go/pkg/tool/linux_amd64/link: too many errors
unexpected fault address 0x7f353fd7d000
fatal error: fault
[signal SIGSEGV: segmentation violation code=0x1 addr=0x7f353fd7d000 pc=0x490fcc]
 
goroutine 134 [running]:
runtime.throw({0x66cc67, 0xc000612000})
        /usr/lib/go/src/runtime/panic.go:1198 +0x71 fp=0xc000ebaa30 sp=0xc000ebaa00 pc=0x434271
runtime.sigpanic()
        /usr/lib/go/src/runtime/signal_unix.go:742 +0x2f6 fp=0xc000ebaa80 sp=0xc000ebaa30 pc=0x44a696
encoding/binary.littleEndian.PutUint32(...)
        /usr/lib/go/src/encoding/binary/binary.go:73
encoding/binary.(*littleEndian).PutUint32(0x866320, {0x7f353fd7d000, 0x4fe35b, 0x38e}, 0xc89d00)
        <autogenerated>:1 +0x2c fp=0xc000ebaaa0 sp=0xc000ebaa80 pc=0x490fcc
cmd/link/internal/loader.(*SymbolBuilder).setUintXX(0x634e40, 0xca32, 0x24be7, 0x60, 0x60)
        /usr/lib/go/src/cmd/link/internal/loader/symbolbuilder.go:246 +0x15a fp=0xc000ebaae0 sp=0xc000ebaaa0 pc=0x503b9a
cmd/link/internal/loader.(*SymbolBuilder).SetUint32(...)
        /usr/lib/go/src/cmd/link/internal/loader/symbolbuilder.go:279
cmd/link/internal/ld.writeFuncs(0xc000182000, 0xc000042180, {0xc004636000, 0x10df6, 0x5ab252}, 0x684e20, {0xc005e80000, 0x10df6, 0x4fbd07}, {0xc004bd8000, ...}, ...)
        /usr/lib/go/src/cmd/link/internal/ld/pcln.go:780 +0x43a fp=0xc000ebacd0 sp=0xc000ebaae0 pc=0x5b073a
cmd/link/internal/ld.(*pclntab).generateFunctab.func1(0xc000182000, 0x1511a2)
        /usr/lib/go/src/cmd/link/internal/ld/pcln.go:565 +0x1ef fp=0xc000ebadd8 sp=0xc000ebacd0 pc=0x5af08f
cmd/link/internal/ld.writeBlock(0xc000182000, 0x1, 0xc000612000, {0xc004a185e8, 0x2172, 0x516}, 0x516, 0x0, {0x867280, 0x200, ...})
        /usr/lib/go/src/cmd/link/internal/ld/data.go:997 +0x3e5 fp=0xc000ebaf08 sp=0xc000ebadd8 pc=0x555e45
cmd/link/internal/ld.writeBlocks.func1(0xc002274a00, 0x516, {0xc004a185e8, 0x800000000010800, 0x18}, 0xc0041bc0e0, 0xc004600000, {0x867280, 0x200, 0x200})
        /usr/lib/go/src/cmd/link/internal/ld/data.go:951 +0x76 fp=0xc000ebaf80 sp=0xc000ebaf08 pc=0x5559d6
cmd/link/internal/ld.writeBlocks·dwrap·2()
        /usr/lib/go/src/cmd/link/internal/ld/data.go:954 +0x63 fp=0xc000ebafe0 sp=0xc000ebaf80 pc=0x555923
runtime.goexit()
        /usr/lib/go/src/runtime/asm_amd64.s:1581 +0x1 fp=0xc000ebafe8 sp=0xc000ebafe0 pc=0x463be1
created by cmd/link/internal/ld.writeBlocks
        /usr/lib/go/src/cmd/link/internal/ld/data.go:950 +0x585

matoro on Aug 27, 2021