| 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
| ||
|
Date: Mon, 22 Jun 2009 12:56:09 +0200 From: Ingo Molnar <mingo@...e.hu> To: Peter Oberparleiter <oberpar@...ux.vnet.ibm.com> Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Andrew Morton <akpm@...ux-foundation.org>, Linus Torvalds <torvalds@...ux-foundation.org> Subject: Re: gcov: enable GCOV_PROFILE_ALL for x86_64 Another thing i was thinking about: the GCOV code cannot be enabled in distros right now, due to the high compiler-generated overhead, and due to the fact that the gcov data structures used are single threaded. (which makes a gcov enabled kernel very slow on SMP, due to the global cacheline bounces) IMO it would be _much_ better to implement hardware-assisted call-graph tracking: - Use the BTS (Branch Trace Store) facilities to hardware-sample all branches+calls (optionally, dynamically enable-able) - Post-process the raw branch trace information (in the kernel BTS-overflow irq handler) to calculate call-coverage information. Unlike the unconditional GCC based GCOV stuff that is currently upstream, BTS tracing is supported by a large range of hardware and it can be enabled _transparently_, so it could be built in and enabled by distros too, to test code coverage. Would you be interested in looking at (and implementing) this? 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/
Powered by blists - more mailing lists