On 2/20/19 8:35 PM, Arnd Bergmann wrote: > On Wed, Feb 20, 2019 at 6:00 PM Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> wrote: >> On 2/20/19 5:51 PM, Arnd Bergmann wrote: >>> On Wed, Feb 20, 2019 at 3:45 PM Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote: >>> I would have to some more research, but I expect several hundred >>> patches before we get to a clean randconfig build with a broken >>> compiler. >> >> Manually maintaining asan-stack parameter for the sake of one broken compiler isn't a great idea either. >> >> Couple alternative suggestions: >> >> 1) If we can't fix the problem or the cost of fixing is too high, maybe just hide it? Disable -Wframe-larger-then on pre clang-9 compilers. >> >> 2) Fallback cflags. The idea is to try to compile every the file with "-mllvm -asan-stack=1 -Wframe-larger-than=2048 -Werror" at first, >> and fallback to "-mllvm -asan-stack=0" if failed. So it would be something similar to $(call cc-option, -mllvm -asan-stack=1 -Wframe-larger-than=2048 -Werror, -mllvm -asan-stack=0) >> except that "cc-option" tries options only once on some code example while we need to try options on every file that we actually compile. >> Honestly, I'm not sure that it's worthy to hack Kbuild engine for that particular use-case. > > My original plan was to put this under CONFIG_KASAN_EXTRA to allow you > to still enable it in older compilers, but you just removed that option ;-) > > Maybe bringing it back would be a compromise? That way it's hidden from > all the build testing bots (because of the !CONFIG_COMPILE_TEST dependency), > but anyone who really wants it can still have the option, and set > CONFIG_FRAME_WARN > to whichever value they like. > I think there is much simpler solution: --- lib/Kconfig.kasan | 2 ++ 1 file changed, 2 insertions(+) diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index 219cddc913ac..6cd035f06cee 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -105,6 +105,8 @@ endchoice config KASAN_STACK int + range 0 1 + prompt "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && (CLANG_VERSION < 90000) default 0 if CC_IS_CLANG && (CLANG_VERSION < 90000) default 1 help -- AFAIK, randconfig is not able to randomize int config options, so it will be disabled for build robots, but users still will be able to enable it.
