On Sun, Dec 09, 2018 at 02:25:23PM -0700, Tycho Andersen wrote: > > Which sparse checks do not trigger? Explain, please - as it is, I had been > > unable to guess what could "specifically looks for a call instruction" refer > > to. > > In sparse.c there's check_call_instruction(), which is triggered when > there's an instruction of OP_CALL type in the basic block. This simply > compares against the name of the call target to determine whether or > not to call check_ctu(). Oh, that Linus' experiment with "look for huge constant size argument to memcpy() et.al."? Frankly, it's not only the wrong place to put the checks, but breaking inlining loses the _real_ "known constant size" checks in there. I don't know if the check_ctu thing has ever caught a bug... What kind of checks do you want to add? Because this place is almost certainly wrong for anything useful... If anything, I would suggest simulating this behaviour with something like if (__builtin_constant_p(size) && size > something) /* something that would trigger a warning */ _inside_ copy_from_user()/copy_to_user() and to hell with name-recognizing magic...
