On 28/04/2026 18:23, Ard Biesheuvel wrote: > Hi Kevin, > > On Tue, 28 Apr 2026, at 16:16, Kevin Brodsky wrote: >> On 27/04/2026 17:34, Ard Biesheuvel wrote: >>> From: Ard Biesheuvel <[email protected]> >>> >>> Before moving the empty_zero_page into the __ro_after_init section, make >>> sure it has the memory-tagged type. This is needed to ensure that >>> cpu_enable_mte() will be able to initialize the tags correctly. >> mark_linear_text_alias_ro() is called after all features have been >> detected and enabled, so do we actually need this? >> >> AFAICT the lines that matter for cpu_enable_mte() are those, in map_mem(): >> >> __map_memblock(pgdp, kernel_start, kernel_end, >> PAGE_KERNEL, NO_CONT_MAPPINGS); >> >> It is probably this call that needs to be changed to use >> pgprot_tagged(PAGE_KERNEL). >> > I see. I guess we should probably update both, no?
We could, but would we ever access the tags in data mapped read-only? cpu_enable_mte() needs tag access to zero them, but AFAIU it's really a special case that is only relevant to the situation where the data is RW. - Kevin
