linux-kernel - Re: [PATCH] x86: bpf_jit_comp: Reduce is

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1417734891.22424.2.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Thu, 04 Dec 2014 15:14:51 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Joe Perches <joe@...ches.com>
Cc:	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	Quentin Lambert <lambert.quentin@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: bpf_jit_comp: Reduce is_ereg() code size

On Thu, 2014-12-04 at 15:00 -0800, Joe Perches wrote:
> Use the (1 << reg) & mask trick to reduce code size.
> 
> x86-64 size difference -O2 without profiling for various
> gcc versions:

> 
> Signed-off-by: Joe Perches <joe@...ches.com>
> ---
> 
> compiled, untested by me, but per Alexei Starovoitov this passes
> the test_bpf suite

Really, the root cause of this is the 'inline' abuse in non fast paths
for non trivial functions.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/