On Mon, 3 Jun 2019 20:30:49 +0900 Masami Hiramatsu <[email protected]> wrote:
> > > > > > > +#define SHADOW_STACK_SIZE (PAGE_SIZE) > > > > > > Do we really need that big a shadow stack? > > > > Well, this is a sticky point. I allow up to 16 users at a time > > (although I can't imagine more than 5, but you never know), and each > > user adds a long and up to 4 more words (which is probably unlikely > > anyway). And then we can have deep call stacks (we are getting deeper > > each release it seems). > > > > I figured, I start with a page size, and then in the future we can make > > it dynamic, or shrink it if it proves to be too much. > > I'd prefer dynamic allocation, based on the number of users or actual > stack starvation. As stated, it's something we can improve on in the future. I'll probably be pushing out this series for linux-next, and then we can incrementally improve it. First on my list is to add a REGS version of function_graph such that kretprobes can use it ;-) -- Steve
