On Wed, Oct 19, 2016 at 07:26:02AM -0300, Arnaldo Carvalho de Melo wrote: > Em Wed, Oct 19, 2016 at 12:01:26PM +0200, Peter Zijlstra escreveu: > > On Tue, Oct 18, 2016 at 05:15:01PM -0400, Daniel Micay wrote: > > > It's also worth noting that fine-grained control via a scoped mechanism > > > would likely only be used to implement *more restrictions* on Android, > > > not to make the feature less aggressive. > > > > It's desirable for perf events to be disabled by default for non-root > > > across the board on Android. > > > Right, but this is Android. The knob seems to now also live in Debian > > (and derived) distros. And there it is utter crap. > > > It completely defeats having perf for a fairly large segment of > > corporate developers who do not get to have root on their own machines > > (which is stupid policy but whatever). > > > It similarly defeats development of self profiling JITs and whatnot. > > > A capability would allow people to run perf (or another sanctioned > > binary), even though in general they cannot do sys_perf_event_open(). > > But self profiling JITs would be useful for non-developers, on Android > (anywhere, really), and for that it would require being able to at > least, well, self profile, using sys_perf_event_open() by a normal > process, limited to profiling itself, no? > > This not being possible, self profiling will use some other means, its > like sys_perf_event_open() never existed for them. Right, so with capabilities, we could grant the binary the capability to use sys_perf_event_open(). That would still leave developers of said JIT in a tight spot, because there'd be no way to set the capability on their freshly compiled binary. They'd have to be granted the capability to the user, using pam_cap. Which would involve corp. IT doing something sensible, ergo, this'll never happen :-(. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
