Help needed for a BPF kernel issue with S390

From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Ilya Leoshkevich <iii@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>
Cc: "bpf@vger.kernel.org" <bpf@vger.kernel.org>,
	"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>
Subject: Help needed for a BPF kernel issue with S390
Date: Sat, 24 Feb 2024 08:07:09 +0000	[thread overview]
Message-ID: <c2d90fe3-9d8a-4f64-8136-126cf556d08f@csgroup.eu> (raw)

Hello,

I'm seeking your help with an issue reported by BPF CI tests on a core 
BPF patch I provided to improve security in link with 
https://github.com/KSPP/linux/issues/7

I submitted patch 
https://patchwork.kernel.org/project/netdevbpf/patch/135feeafe6fe8d412e90865622e9601403c42be5.1708253445.git.christophe.leroy@csgroup.eu/

As you can see in the checks list, I get "bpf/vmtest-bpf-next-VM_Test-14 
	fail 	Logs for s390x-gcc / test (test_progs, false, 360) / test_progs 
on s390x with gcc "

The output is the one below.

Could you help me understand and fix the issue on S390 ?

Thanks
Christophe

Output:

...
   #262     reg_bounds_rand_ranges_u64_u64:OK
   #263     resolve_btfids:OK
   Caught signal #11!
   Stack trace:
   ./test_progs(crash_handler+0x40)[0x2aa090c5ca8]
   linux-vdso64.so.1(__kernel_sigreturn+0x0)[0x3ffc78ce488]
   ./test_progs(ring_buffer__poll+0xc6)[0x2aa0912bbe6]
   ./test_progs(+0x283490)[0x2aa08f83490]
   /lib/s390x-linux-gnu/libpthread.so.0(+0x7e66)[0x3ffb8c07e66]
   /lib/s390x-linux-gnu/libc.so.6(+0xfcd46)[0x3ffb8afcd46]
   [0x0]

   test_progs[116] is installing a program with bpf_probe_write_user 
helper that may corrupt user memory!

   User process fault: interruption code 003b ilc:2 in 
test_progs[2aa08d00000+b1f000]

   Failing address: 0000000000000000 TEID: 0000000000000800

   Fault in primary space mode while using user ASCE.

   AS:0000000081b381cf R1:0000000081b2c00f R2:0000000081bf400b 
R3:0000000000000024

   CPU: 0 PID: 804 Comm: new_name Tainted: G           OE 
6.8.0-rc1-g690b912d8bb7-dirty #215

   Hardware name: IBM 8561 LT1 400 (KVM/Linux)

   User PSW : 0705000180000000 000002aa0912bbe6

              R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:1 AS:0 CC:0 PM:0 RI:0 EA:3

   User GPRS: 0000000000000000 0000000000000000 0000000000000000 
000002aa0dbcf5c0

              ffffffff00000000 0000000000002710 000003ffb6d00900 
000003ffc7877ad7

              000003ffb6d001e0 000003ffc7877ad6 000003ffc7877ad8 
000003ffb6cffe50

              000003ffb8e26f88 000003ffb6d00900 000002aa0912bb88 
000003ffb6cffe50

   User Code: 000002aa0912bbd6: e310b0b40014	lgf	%r1,180(%r11)
              000002aa0912bbdc: eb110004000d	sllg	%r1,%r1,4
             #000002aa0912bbe2: b9080012		agr	%r1,%r2
             >000002aa0912bbe6: 58101008		l	%r1,8(%r1)
              000002aa0912bbea: 5010b0bc		st	%r1,188(%r11)
              000002aa0912bbee: e310b0a80004	lg	%r1,168(%r11)
              000002aa0912bbf4: e32010080004	lg	%r2,8(%r1)
              000002aa0912bbfa: e310b0bc0016	llgf	%r1,188(%r11)

   Last Breaking-Event-Address:

    [<0000000000000001>] test_progs[2aa08d00000+b1f000]
   ./ci/vmtest/vmtest_selftests.sh: line 69:   116 Segmentation fault 
   ./${selftest} ${args} ${DENYLIST:+-d"$DENYLIST"} 
${ALLOWLIST:+-a"$ALLOWLIST"} --json-summary "${json_file}"
bash: line 5: cd: /tmp/work/bpf/bpf: No such file or directory