linux-kernel - Re: [PATCH 5/5] x86/asm/entry/64: drop exit

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: <CA+55aFxtH-UB-=1o93X5Z0o8-5FYryXKBCag3tbahA+q89Gh4Q@mail.gmail.com>
Date:	Mon, 30 Mar 2015 11:22:56 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Denys Vlasenko <dvlasenk@...hat.com>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andy Lutomirski <luto@...capital.net>,
	Oleg Nesterov <oleg@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Alexei Starovoitov <ast@...mgrid.com>,
	Will Drewry <wad@...omium.org>,
	Kees Cook <keescook@...omium.org>,
	"the arch/x86 maintainers" <x86@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 5/5] x86/asm/entry/64: drop exit_intr label

On Mon, Mar 30, 2015 at 11:09 AM, Denys Vlasenko <dvlasenk@...hat.com> wrote:
> -       cmpl    $0,PER_CPU_VAR(__preempt_count)
> -       jnz     1f
> -       bt      $9,EFLAGS(%rsp) /* interrupts were off? */
> +       bt      $X86_EFLAGS_IF_BIT,EFLAGS(%rsp) /* interrupts were off? */

Since you're changing this anyway, just change it to use "testb" the
way you did the other place.

Yeah, yeah, it might make it less readable, but

        testb $2,EFLAGS+1(%rsp) /* interrupts were off? */

should be smaller and faster than "bt", and the point of this commit
was to make code smaller and faster, no?

                      Linus
--
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/