On Wed, 2010-01-27 at 11:55 +0100, Peter Zijlstra wrote: > Right, so there's two aspects: > > 1) concurrency when inserting the probe > 2) concurrency when hitting the probe > > 1) used to be dealt with by using utrace to stop all threads in the > process and then writing the instruction. I suggested to CoW the page, > modify the instruction, set the pagetable and flush tlbs at full speed > -- the very thing you suggest here.
Also, since executable maps are typically MAP_PRIVATE, you have to CoW anyway in order to modify it and I would exclude MAP_SHARED from being probable because then the modification could seep through into whatever was backing that thing.
