On 2025-02-22 at 16:06:34 +0100, Andrey Konovalov wrote: >On Fri, Feb 21, 2025 at 3:45 PM Maciej Wieczor-Retman ><maciej.wieczor-retman@xxxxxxxxx> wrote: >> >> >What's the purpose of this config option? I think we can just change >> >the value of the KASAN_SHADOW_SCALE_SHIFT define when KASAN_SW_TAGS is >> >enabled. >> >> Well, I was aiming at later adding the "default 5 if KASAN_SW_TAGS_DENSE", and >> this way it would look much cleaner than the: >> >> if KASAN_SW_TAGS >> if KASAN_SW_TAGS_DENSE >> KASAN_SHADOW_SCALE_SHIFT = 5 >> else >> KASAN_SHADOW_SCALE_SHIFT = 4 >> else >> KASAN_SHADOW_SCALE_SHIFT = 3 > >I think this is fine. It's still better than adding a non-configurable >config option. > >> But now that I think of it, it should be possible to overwrite the >> KASAN_SHADOW_SCALE_SHIFT from non-arch code if dense mode is enabled. > >This should also work. Especially since the dense mode will probably >work for arm64 as well. > >But let's keep this series self-contained. Yes, of course. Anyway I'll just do one preprocessor if else in the same place that the old x86 KASAN_SHADOW_SCALE_SHIFT was. > >> That's a topic for the next series but I'd imagine all architectures would >> normally use the 16 memory bytes / shadow byte and if they'd care for the dense >> mode they'd go for 32 memory bytes / shadow byte. Or do you think that's a >> faulty assumption? > >Probably, but for sure I don't know, not that many architectures that >care about memory tagging yet :) I'll keep this assumption for now then. If some arch will have a different idea about granularity I suppose the relevant code can be moved to arch specific directories. -- Kind regards Maciej Wieczór-Retman
