On Tue, Oct 23, 2012 at 03:50:50PM +0200, Peter Zijlstra wrote: > PERF_SAMPLE_RAW has a u32 size header and starts the data after that. > This means you PERF_SAMPLE_RAW output ends up on a u32 aligned end > address -- assuming the data is a u64 multiple, this is not good. > > > It appears to work at least. > > It would on x86, I'm fairly sure it'll break on things like SPARC. We > used to have checks in the userspace code to warn for this on x86 as > well. Not sure if that's still there.
Ok this is x86 specific code. > > Hmm, so in kernel/events/core.c:perf_prepare_sample() there's a > WARN_ON_ONCE() in the PERF_SAMPLE_RAW branch that should trigger with > this. Haven't seen this this warning so far. If I added padding the perf userland would need to learn about it too, I suspect it would need all the ugly macros like NETLINK. I always hated those. -Andi -- a...@linux.intel.com -- Speaking for myself only. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
