linux-kernel - Re: [tip:perf/core] tools/perf: Add required memory barriers

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]

Date:	Thu, 7 Nov 2013 09:21:22 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Vince Weaver <vince@...ter.net>, hpa@...or.com, anton@...ba.org,
	mathieu.desnoyers@...ymtl.ca, linux-kernel@...r.kernel.org,
	michael@...erman.id.au, paulmck@...ux.vnet.ibm.com,
	benh@...nel.crashing.org, fweisbec@...il.com, VICTORK@...ibm.com,
	tglx@...utronix.de, oleg@...hat.com, mikey@...ling.org,
	linux-tip-commits@...r.kernel.org,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	David Ahern <dsahern@...il.com>
Subject: Re: [tip:perf/core] tools/perf: Add required memory barriers

* Peter Zijlstra <peterz@...radead.org> wrote:

> > Requiring the user of a kernel interface to have a deep knowledge of 
> > optimizing compilers, barriers, and CPU memory models is just asking 
> > for trouble.
> 
> It shouldn't be all that hard to put this in a (lgpl) library others can 
> link to -- that way you can build it once (using GCC).

I'd suggest to expose it via a new perf syscall, using vsyscall methods to 
not have to enter the kernel for the pure user-space bits. It should also 
have a real usecase in tools/perf/ so that it's constantly tested, with 
matching 'perf test' entries, etc.

I don't want a library that is external and under-tested: for example 
quite a few of the PAPI breakages were found very late, after a new kernel 
has been released - that's the big disadvantage of librarization and 
decentralization. The decentralized library model might work if all you 
want to create is a second-class also-ran GUI, but it just doesn't work 
very well for actively developed kernel code.

Thanks,

	Ingo
--
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/