From: Daniel Borkmann <daniel@iogearbox.net>
To: Ilya Leoshkevich <iii@linux.ibm.com>,
Alexei Starovoitov <ast@kernel.org>
Cc: bpf@vger.kernel.org, Heiko Carstens <heiko.carstens@de.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>
Subject: Re: [PATCH bpf-next] s390/bpf: make sure JIT passes do not increase code size
Date: Fri, 15 Nov 2019 23:28:12 +0100 [thread overview]
Message-ID: <9486776a-a628-dfb4-9d41-726e251bf638@iogearbox.net> (raw)
In-Reply-To: <20191114151820.53222-1-iii@linux.ibm.com>
On 11/14/19 4:18 PM, Ilya Leoshkevich wrote:
> The upcoming s390 branch length extension patches rely on "passes do
> not increase code size" property in order to consistently choose between
> short and long branches. Currently this property does not hold between
> the first and the second passes for register save/restore sequences, as
> well as various code fragments that depend on SEEN_* flags.
>
> Generate the code during the first pass conservatively: assume register
> save/restore sequences have the maximum possible length, and that all
> SEEN_* flags are set.
>
> Also refuse to JIT if this happens anyway (e.g. due to a bug), as this
> might lead to verifier bypass once long branches are introduced.
>
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Applied, thanks!
prev parent reply other threads:[~2019-11-15 22:28 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-14 15:18 [PATCH bpf-next] s390/bpf: make sure JIT passes do not increase code size Ilya Leoshkevich
2019-11-15 22:28 ` Daniel Borkmann [this message]
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=9486776a-a628-dfb4-9d41-726e251bf638@iogearbox.net \
--to=daniel@iogearbox.net \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=gor@linux.ibm.com \
--cc=heiko.carstens@de.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).