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cmd/asm: NOP function crashes asm when building for arm64 #20348

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stapelberg opened this issue May 12, 2017 · 2 comments
Closed

cmd/asm: NOP function crashes asm when building for arm64 #20348

stapelberg opened this issue May 12, 2017 · 2 comments
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FrozenDueToAge NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
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@stapelberg
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Please answer these questions before submitting your issue. Thanks!

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

go version devel +380aa884b8 Fri May 12 18:08:12 2017 +0000 linux/amd64

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

GOARCH="arm64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/michael/go"
GORACE=""
GOROOT="/tmp/upstream-go"
GOTOOLDIR="/tmp/upstream-go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build622527587=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="0"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"

What did you do?

$ head -50 repro.go repro_arm64.s 
==> repro.go <==
package main

func stub()

func main() {
        stub()
}

==> repro_arm64.s <==
TEXT ·stub(SB),$0-0
        NOP

I ran GOARCH=arm64 go build on an amd64 host machine.

What did you expect to see?

I think the definition of ·stub is invalid, as it’s missing a RET instruction. Still, the assembler shouldn’t crash, should it?

What did you see instead?

$ GOARCH=arm64 /tmp/upstream-go/bin/go build         
# asm-crash-repro
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0xaa pc=0x4f7760]

goroutine 1 [running]:
cmd/internal/obj/arm64.preprocess(0xc42007a100, 0xc4200a6000, 0xc42004e380)
        /tmp/upstream-go/src/cmd/internal/obj/arm64/obj7.go:469 +0x210
cmd/internal/obj.Flushplist(0xc42007a100, 0xc420045e50, 0xc42004e380)
        /tmp/upstream-go/src/cmd/internal/obj/plist.go:106 +0x692
main.main()
        /tmp/upstream-go/src/cmd/asm/main.go:75 +0x5d1

This issue is reproducible with go1.8.1.
@andybons
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@ianlancetaylor @josharian

@andybons andybons added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Apr 11, 2018
@andybons andybons added this to the Unplanned milestone Apr 11, 2018
@gopherbot
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Change https://golang.org/cl/106457 mentions this issue: cmd/internal/obj/arm64: don't crash on trailing NOP

@golang golang locked and limited conversation to collaborators Apr 11, 2019
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