On Thu, Jan 21, 2016 at 08:57:17PM +0000, Linux Kernel wrote:
> Web:
> https://git.kernel.org/torvalds/c/c6d308534aef6c99904bf5862066360ae067abc4
> Commit: c6d308534aef6c99904bf5862066360ae067abc4
> Parent: 68920c973254c5b71a684645c5f6f82d6732c5d6
> Refname: refs/heads/master
> Author: Andrey Ryabinin <aryabi...@virtuozzo.com>
> AuthorDate: Wed Jan 20 15:00:55 2016 -0800
> Committer: Linus Torvalds <torva...@linux-foundation.org>
> CommitDate: Wed Jan 20 17:09:18 2016 -0800
>
> UBSAN: run-time undefined behavior sanity checker
>
> UBSAN uses compile-time instrumentation to catch undefined behavior
> (UB). Compiler inserts code that perform certain kinds of checks before
> operations that could cause UB. If check fails (i.e. UB detected)
> __ubsan_handle_* function called to print error message.
>
> So the most of the work is done by compiler. This patch just implements
> ubsan handlers printing errors.
>
> GCC has this capability since 4.9.x [1] (see -fsanitize=undefined
> option and its suboptions).
> However GCC 5.x has more checkers implemented [2].
> Article [3] has a bit more details about UBSAN in the GCC.
If I enable this and CONFIG_UBSAN_ALIGNMENT, the kernel doesn't boot,
and hangs really early (pretty much as soon as I hit return in grub)
far too early for serial console or even tty output.
Compiler is debian unstable's 5.3.1 20160114
I don't know if this is worth chasing down, I chose to just disable it,
but figured I'd post in case other people stumble across the same issue.
That aside though, neat feature. I look forward to breaking kernels with it :)
Dave
