From: Seth Forshee <seth.forshee@canonical.com>
To: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
bpf@vger.kernel.org, Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>
Subject: Re: [PATCH 2/5] s390/bpf: fix sign extension in branch_ku
Date: Fri, 17 Jul 2020 17:23:34 -0500 [thread overview]
Message-ID: <20200717222334.GQ3644@ubuntu-x1> (raw)
In-Reply-To: <20200717165326.6786-3-iii@linux.ibm.com>
On Fri, Jul 17, 2020 at 06:53:23PM +0200, Ilya Leoshkevich wrote:
> Both signed and unsigned variants of BPF_JMP | BPF_K require
> sign-extending the immediate. JIT emits cgfi for the signed case,
> which is correct, and clgfi for the unsigned case, which is not
> correct: clgfi zero-extends the immediate.
>
> s390 does not provide an instruction that does sign-extension and
> unsigned comparison at the same time. Therefore, fix by first loading
> the sign-extended immediate into work register REG_1 and proceeding
> as if it's BPF_X.
>
> Fixes: 4e9b4a6883dd ("s390/bpf: Use relative long branches")
> Reported-by: Seth Forshee <seth.forshee@canonical.com>
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
This fixes the failing tests I was seeing. Thanks!
Tested-by: Seth Forshee <seth.forshee@canonical.com>
next prev parent reply other threads:[~2020-07-17 22:23 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-17 16:53 [PATCH 0/5] s390/bpf: fix lib/test_bpf.c failures Ilya Leoshkevich
2020-07-17 16:53 ` [PATCH 1/5] selftests: bpf: test_kmod.sh: fix running out of srctree Ilya Leoshkevich
2020-07-17 16:53 ` [PATCH 2/5] s390/bpf: fix sign extension in branch_ku Ilya Leoshkevich
2020-07-17 22:23 ` Seth Forshee [this message]
2020-07-17 16:53 ` [PATCH 3/5] s390/bpf: use brcl for jumping to exit_ip if necessary Ilya Leoshkevich
2020-07-17 16:53 ` [PATCH 4/5] s390/bpf: tolerate not converging code shrinking Ilya Leoshkevich
2020-07-17 16:53 ` [PATCH 5/5] s390/bpf: use bpf_skip() in bpf_jit_prologue() Ilya Leoshkevich
2020-07-21 18:17 ` [PATCH 0/5] s390/bpf: fix lib/test_bpf.c failures Alexei Starovoitov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200717222334.GQ3644@ubuntu-x1 \
--to=seth.forshee@canonical.com \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=gor@linux.ibm.com \
--cc=hca@linux.ibm.com \
--cc=iii@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.