Messages in this thread | | | Date | Tue, 29 Sep 2020 15:02:26 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH v3 03/10] arm64, kfence: enable KFENCE for ARM64 |
| |
On Fri, Sep 25, 2020 at 05:25:11PM +0200, Alexander Potapenko wrote: > Will, > > > Given that the pool is relatively small (i.e. when compared with our virtual > > address space), dedicating an area of virtual space sounds like it makes > > the most sense here. How early do you need it to be available? > > How do we assign struct pages to a fixed virtual space area (I'm > currently experimenting with 0xffff7f0000000000-0xffff7f0000200000)?
You don't.
There should be a struct page for each of the /physical/ pages, and these can be found:
* via the physical address, using phyts_to_page() or pfn_to_page() * via the linear/direct map, using virt_to_page() * via the vmalloc page tables using vmalloc_to_page()
If you need virt_to_page() to work, the address has to be part of the linear/direct map.
If you need to find the struct page for something that's part of the kernel image you can use virt_to_page(lm_alias(x)).
> Looks like filling page table entries (similarly to what's being done > in arch/arm64/mm/kasan_init.c) is not enough. > I thought maybe vmemmap_populate() would do the job, but it didn't > (virt_to_pfn() still returns invalid PFNs).
As above, I think lm_alias() will solve the problem here. Please see that and CONFIG_DEBUG_VIRTUAL.
Thanks, Mark.
| |