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  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]
Date:   Thu, 6 Jun 2019 16:34:52 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     "'paulmck@...ux.ibm.com'" <paulmck@...ux.ibm.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>
CC:     Vineet Gupta <Vineet.Gupta1@...opsys.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Will Deacon <Will.Deacon@....com>,
        arcml <linux-snps-arc@...ts.infradead.org>,
        lkml <linux-kernel@...r.kernel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>
Subject: RE: single copy atomicity for double load/stores on 32-bit systems

From: Paul E. McKenney
> Sent: 06 June 2019 10:44
...
> But m68k is !SMP-only, correct?  If so, the only issues would be
> interactions with interrupt handlers and the like, and doesn't current
> m68k hardware use exact interrupts?  Or is it still possible to interrupt
> an m68k in the middle of an instruction like it was in the bad old days?

Hardware interrupts were always on instruction boundaries, the
mid-instruction interrupts would only happen for page faults (etc).

There were SMP m68k systems (but I can't remember one).
It was important to continue from a mid-instruction trap on the
same cpu - unless you could guarantee that all the cpus had
exactly the same version of the microcode.

In any case you could probably use the 'cmp2' instruction
for an atomic 64bit write.
OTOH setting that up was such a PITA it was always easier
to disable interrupts.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

Powered by blists - more mailing lists