Brainstorming new kernel interfaces for rr
jones.chris.g at gmail.com
Thu Feb 27 12:32:34 PST 2014
I created https://github.com/mozilla/rr/wiki/Kernel-API-wishlist to better
track this list.
On Tue, Feb 25, 2014 at 9:29 PM, Chris Jones <jones.chris.g at gmail.com>wrote:
> I don't want to distract anyone from 1.0, but we've run into enough
> tracing shortcomings that I think we can start putting together a "kernel
> wishlist". This stuff can take awhile to trickle out to where rr users
> will be able to take advantage, so it makes sense to front load. Here's my
> strawman list
> - in-kernel buffering of syscall outparam data. Syscallbuf+vsyscall
> hooking works OK in practice, but the kernel can do so much better, so much
> more easily. Essentially it "just" has to record copy_to_user() within
> syscall handlers, plus a bit of metadata. Perhaps could be exposed through
> - trapping on CPUID, like the RDTSC traps. Modern Intel chips can do
> - expose Branch Trace Store data, probably through perf_event. There was
> a previous attempt to do this, but I think it fizzled out.
> - implement a way for ptrace tracers to efficiently wait on a tracee's
> private futex
> - we hit a pwrite64/pread64 bug that we shouldn't let slip through the
> Anything else to add?
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