On Fri, Jan 5, 2018 at 6:55 PM, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > On Fri, Jan 5, 2018 at 5:09 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote: >> +#ifndef nospec_ptr >> +#define nospec_ptr(ptr, lo, hi) \ > > Do we actually want this horrible interface? > > It just causes the compiler - or inline asm - to generate worse code, > because it needs to compare against both high and low limits. > > Basically all users are arrays that are zero-based, and where a > comparison against the high _index_ limit would be sufficient. > > But the way this is all designed, it's literally designed for bad code > generation for the unusual case, and the usual array case is written > in the form of the unusual and wrong non-array case. That really seems > excessively stupid. Yes, it appears we can kill nospec_ptr() and move nospec_array_ptr() to assume 0 based arrays rather than use nospec_ptr.
