On May 22, 2017 10:49:06 PM PDT, Ingo Molnar <mingo@xxxxxxxxxx> wrote: > >* H. Peter Anvin <hpa@xxxxxxxxx> wrote: > >> On 05/22/17 04:12, Ingo Molnar wrote: >> \>> >> >> This construct might be useful for other arches, which is why I >called >> >> it "FP" instead of "BP". But then I ruined that with the last 3 >:-) >> > >> > Please call it BP - 'FP' can easily be read as floating-point, >making it all >> > super-confusing. We should use canonical x86 register names and >ordering - even >> > if not all registers are used straight away. >> > >> >> Seriously, I suspect that at the end of the day we will have >reinvented >> DWARF. > >Absolutely - the main difference is: > >- the debug-info implementation is _internal_ to the kernel so it can >be fixed >instead of "oh, wait 2 years for the toolchain to fix this particular >bug, work >it around in the kernel meanwhile" kind of crazy flow and dependencies. >I.e. >the debug-info generation and parsing code is both part of the kernel >Git tree > and can be iterated (and fixed) at once with. > >- the debug-info is auto-generated for assembly as well, leaving >assembly code > maintainable. > >- the debug-info has a sane data structure designed for robustness and > compactness > >So even if it's a subset of the existing complexity of dwarf et al we >are still >literally infinitely better off with this model. > >Thanks, > > Ingo This assumes that it actually ends up being feasible for objtool to do so. It is worth noting that using DWARF for unwinding vs auto-generating the unwind information are independent issues. Another option is to use (or postprocess) the compiler-generated DWARF for C modules and pursue autogeneration only for assembly modules, which ought to be a much easier problem and is less dependent on discovering new compiler-generated patterns. -- Sent from my Android device with K-9 Mail. Please excuse my brevity. -- 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
