lkml.org 
[lkml]   [2017]   [Nov]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 08/30] x86, kaiser: unmap kernel from userspace page tables (core patch)
    From
    Date
    On 11/20/2017 09:21 AM, Thomas Gleixner wrote:
    >> + pgd = native_get_shadow_pgd(pgd_offset_k(0UL));
    >> + for (i = PTRS_PER_PGD / 2; i < PTRS_PER_PGD; i++) {
    >> + unsigned long addr = PAGE_OFFSET + i * PGDIR_SIZE;
    > This looks wrong. The kernel address space gets incremented by PGDIR_SIZE
    > and does not make a jump from PAGE_OFFSET to PAGE_OFFSET + 256 * PGDIR_SIZE
    >
    > int i, j;
    >
    > for (i = PTRS_PER_PGD / 2, j = 0; i < PTRS_PER_PGD; i++, j++) {
    > unsigned long addr = PAGE_OFFSET + j * PGDIR_SIZE;
    >
    > Not that is has any effect right now. Neither p4d_alloc_one() nor
    > pud_alloc_one() are using the 'addr' argument.

    Ahh, you're saying that 'i' is effectively starting *at* PAGE_OFFSET
    since it's halfway up the address space already doing PTRS_PER_PGD/2.
    Adding PAGE_OFFSET to PAGE_OFFSET is nonsense.

    Would it just be simpler to do:

    > for (i = PTRS_PER_PGD / 2; i < PTRS_PER_PGD; i++) {
    > unsigned long addr = i * PGDIR_SIZE;

    ?

    \
     
     \ /
      Last update: 2017-11-22 23:46    [W:3.344 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site