On Wed, Dec 22, 2021 at 10:30 AM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote: > On Wed, 22 Dec 2021 at 03:31, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: > > On Tue, Dec 21, 2021 at 10:16 AM Arnd Bergmann <arnd@xxxxxxxx> wrote: > > > > > I think for CPUs that can use LPAE, we want to eventually move to the 4G:4G > > > memory model, which in turn depends on having the kernel in vmalloc space, as > > > implemented by Linus Walleij in > > > https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-integrator.git/log/?h=kernel-in-vmalloc-v5.14-rc1 > > > > Yeah I'm still working on this series. The 4/4 split works pretty well, Actually it's just kernel-in-vmalloc, 4/4 comes after that. > > but it breaks KASan and I was in the process of fixing that when I left > > for parental leave. > > > > The reason it breaks would be related to KASan not expecting > > executable code in the vmalloc area, and since the shadowing > > algorithm is a simple pointer offset, and since we go to lengths > > to chisel shadow memory out of lowmem at a fixed offset from > > TEXT_OFFSET, we have a problem. > > > > Vmap'ed stacks actually has a similar problem, which is why it is > disabled when KAsan is enabled. But this can be fixed by enabling arch > support for KASAN_VMALLOC, and I suspect it may address the vmap'ed > kernel as well. Yep after seeing the other convo on the topic I realized that this is indeed the same as I'm seeing. I can't disable KASAN just because the kernel is in VMALLOC though, so I suppose when I finally get back to this I have to fix KASAN_VMALLOC too if noone beats me to it. (It'd be great if someone could beat me to it...) Yours, Linus Walleij
