Go: strings: SIGILL on s390x on z196

Created on 9 Sep 2016 · 10Comments · Source: golang/go

Please answer these questions before submitting your issue. Thanks!

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

1.7 or 1.7.1

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

unname -a says "Linux zelenka 3.16.0-4-s390x #1 SMP Debian 3.16.36-1+deb8u1 (2016-09-03) s390x GNU/Linux". This has been seen on https://db.debian.org/machines.cgi?host=zelenka and https://db.debian.org/machines.cgi?host=zandonai, a Debian porter and build box respectively. /proc/cpuinfo has "processor 0: version = FF, identification = 06A18A, machine = 2817".

It doesn't happen on a z13 running Ubuntu 16.10.

What did you do?

./all.bash

What did you expect to see?

tests passing

What did you see instead?

SIGILL: illegal instruction
PC=0x755be m=4

goroutine 52 [running]:
runtime.checkvectorfacility()
    /«PKGBUILDDIR»/src/runtime/asm_s390x.s:35 +0x4e fp=0xc42003cd78 sp=0xc42003cd50
created by testing.(*T).Run
    /«PKGBUILDDIR»/src/testing/testing.go:646 +0x376

goroutine 1 [chan receive]:
testing.(*T).Run(0xc42004acc0, 0x185eca, 0xf, 0x19e300, 0x10000000003f372)
    /«PKGBUILDDIR»/src/testing/testing.go:647 +0x3a0
testing.RunTests.func1(0xc420070000)
    /«PKGBUILDDIR»/src/testing/testing.go:793 +0xe6
testing.tRunner(0xc420070000, 0xc42003edb8)
    /«PKGBUILDDIR»/src/testing/testing.go:610 +0xd8
testing.RunTests(0x19db20, 0x238520, 0x31, 0x31, 0x100000000000c03)
    /«PKGBUILDDIR»/src/testing/testing.go:799 +0x3da
testing.(*M).Run(0xc42003ef08, 0xf)
    /«PKGBUILDDIR»/src/testing/testing.go:743 +0x88
main.main()
    strings/_test/_testmain.go:292 +0x14c

r0   0x1    r1   0x40
r2   0xc42003cda0   r3   0xc4202855c0
r4   0x11   r5   0x6e
r6   0xc4202855c0   r7   0x1
r8   0xc4202855d1   r9   0x6e
r10  0x40   r11  0x1b8cb54
r12  0x3fffd27faa0  r13  0xc420001380
r14  0x78afc    r15  0xc42003cd50
pc   0x755be    link 0x78afc
FAIL    strings 0.155s

(full log at https://buildd.debian.org/status/fetch.php?pkg=golang-1.7&arch=s390x&ver=1.7.1-1&stamp=1473301050)

FrozenDueToAge

Source

mwhudson

👍1

Most helpful comment

Done.

bradfitz on 9 Sep 2016

👍3 ❤1

All 10 comments

paging @mundaym

mwhudson on 9 Sep 2016

Oh yes, we don't think this happened at the time of the 1.7 release, so it's possible the configuration of the machine has changed somehow recently?

mwhudson on 9 Sep 2016

(Although at the time, we were hitting #16780 as well, so tests were disabled during the package build on s390x and thus it's hard to say for sure whether our memory is accurate. :innocent:)

tianon on 9 Sep 2016

I think the memory needs to cleared before the STFLE instruction.

Do you have a z196 you can test on? Could you try the following patch?

--- a/src/runtime/asm_s390x.s
+++ b/src/runtime/asm_s390x.s
@@ -20,6 +20,7 @@ TEXT runtime·checkvectorfacility(SB),NOSPLIT,$32-0
        MOVD    $2, R0
        MOVD    R1, tmp-32(SP)
        MOVD    $x-24(SP), R1
+       XC      $24, 0(R1), 0(R1)
 //      STFLE   0(R1)
        WORD    $0xB2B01000
        MOVBZ   z-8(SP), R1

mundaym on 9 Sep 2016

👍1

@mundaym that was incredibly fast :+1:

I've applied that patch against 1.7.1 and tested on the zelenka machine @mwhudson referenced above, and the strings test now passes successfully (ok strings 0.147s). :metal:

tianon on 9 Sep 2016

👍1

For completeness I let the tests finish, and got all the way to ALL TESTS PASSED. :green_heart:

tianon on 9 Sep 2016

CL https://golang.org/cl/28850 mentions this issue.