Re: xtensa question, was Re: [PATCH V1 00/10] Remove duplicated kmap code

2020-05-01 Thread Max Filippov
On Fri, May 1, 2020 at 2:19 AM Christoph Hellwig 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 wrote: > > > any idea why xtensa uses PAGE_KERNEL_EXEC instead of PAGE_KERNEL > > > for kmap_prot?

Re: xtensa question, was Re: [PATCH V1 00/10] Remove duplicated kmap code

2020-05-01 Thread Christoph Hellwig
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 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. >

Re: xtensa question, was Re: [PATCH V1 00/10] Remove duplicated kmap code

2020-05-01 Thread Max Filippov
Hi Christoph, On Fri, May 1, 2020 at 1:46 AM Christoph Hellwig 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 p

xtensa question, was Re: [PATCH V1 00/10] Remove duplicated kmap code

2020-05-01 Thread Christoph Hellwig
Hi Max, any idea why xtensa uses PAGE_KERNEL_EXEC instead of PAGE_KERNEL for kmap_prot? Mapping all mapped highmem as executable seems rather dangerous.