On Fri, May 1, 2020 at 2:19 AM Christoph Hellwig <h...@infradead.org> wrote: > > On Fri, May 01, 2020 at 02:02:19AM -0700, Max Filippov wrote: > > Hi Christoph, > > > > On Fri, May 1, 2020 at 1:46 AM Christoph Hellwig <h...@infradead.org> wrote: > > > any idea why xtensa uses PAGE_KERNEL_EXEC instead of PAGE_KERNEL > > > for kmap_prot? Mapping all mapped highmem as executable seems rather > > > dangerous. > > > > I sure do: to allow instruction cache flushing when writing to high user > > pages temporarily mapped with kmap. Instruction cache management > > opcodes that operate on virtual addresses would raise an exception if > > the address is not executable. > > Seems like this should use kmap_atomic_prot with PAGE_KERNEL_EXEC just > for that case. Which of course didn't exist on xtensa so far, but with > this series will.
Yeah, except it's the __access_remote_vm that does the kmap and then calls copy_to_user_page... -- Thanks. -- Max
