On Sun, May 13, 2018 at 06:56:14PM +0000, Thomas Gleixner wrote: > On Thu, 10 May 2018, Kirill A. Shutemov wrote: > > > top_pgtable address has to be calculated relative to where the kernel > > image will be relocated for decompression, not relative to position of > > kernel is running at the moment. We do the same for the rest of page > > table we use the stage. It makes them safe from being overwritten during > > decompression. > > > > Calculate the address of top_pgtable in assembly and pass down to > > cleanup_trampoline(). > > > > Move the page table to .pgtable section where the rest of page tables > > are. The section is @nobits so we save 4k in kernel image. > > So this is supposed to be a fix, but the whole changelog talks about WHAT > the patch does and not WHY. Darn, we need proper description of the failure > which is about to be fixed.
"It makes them safe from being overwritten during decompression." > It's not that hard and I'm really tired to tell you that over and over. > > > /* > > * cleanup_trampoline() would restore trampoline memory. > > * > > + * RDI is address of the page table to use instead of page table > > + * in trampoline memory (if required). > > Do you really believe that you understand that comment 6 month from now? Yes, I think I will. -- Kirill A. Shutemov
