linux-kernel - [PATCH] Use -mskip-rax-setup if supported

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 for Android: free password hash cracker in your pocket

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

Date:	Thu, 16 Apr 2015 14:23:44 -0700
From:	"H.J. Lu" <hjl.tools@...il.com>
To:	LKML <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>, Andi Kleen <andi@...stfloor.org>
Subject: [PATCH] Use -mskip-rax-setup if supported

GCC 5 added a compiler option, -mskip-rax-setup, for x86-64.  It skips
setting up the RAX register when SSE is disabled and there are no
variable arguments passed in vector registers.  Since kernel doesn't
pass vector registers to functions with variable arguments, this option
can be used to optimize the x86-64 kernel.  For kernel 3.17:

    text   data    bss    dec      hex   filename
11455921 2204048 5853184 19513153 129bf41 vmlinux #with -mskip-rax-setup
11480079 2204048 5853184 19537311 12a1d9f vmlinux

-- 
H.J.

View attachment "0001-Use-mskip-rax-setup-if-supported.patch" of type "text/x-patch" (1401 bytes)