On Thu, Jun 11, 2015 at 08:10:50AM +0200, Ingo Molnar wrote: > * Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > > > I imagine that an automatic CFI annotation adder would walk through functions > > > one instruction at a time and keep track of the frame state. If so, then it > > > could verify that common jump targets had identical state and continue walking > > > through them and annotating. I think this would get this case right, and it > > > might be necessary anyway to handle jumps within functions. > > > > This would definitely add complexity to both asmvalidate and the CFI generator. > > In fact it sounds like it would push the CFI generator out of its current awk > > script territory and more into complex C code territory. > > I'd count that as a plus: awk isn't a common skillset while C is, and properly > written it doesn't have to be _that_ complex. The thing is, C is quite painful for text processing. And I think we'd have to do the analysis at the source text level in order to generate the .cfi_* instructions to pass to the gnu assembler. C would definitely make more sense when analyzing object code. In fact, asmvalidate is written in C. But then I guess we'd have to re-implement the .cfi stuff and populate the DWARF sections manually instead of letting the assembler do it. -- Josh -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
