lkml.org 
[lkml]   [2017]   [Nov]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Subject[PATCH v2 0/4] kaslr: extend movable_node to movable_node=nn[KMG]@ss[KMG]
    Date
    Here is a problem:
    Here is a machine with several NUMA nodes and some of them are
    hot-pluggable. It's not good for kernel to be extracted in the memory
    region of movable node. But in current code, I print the address chosen by
    kaslr and found it may be placed in movable node sometimes.
    To solve this problem, it's better to limit the memory region chosen by
    kaslr to immovable node in kaslr.c. But the memory information about if
    it's hot-pluggable is stored in ACPI SRAT table, which is parsed after
    kernel is extracted. So we can't get the detail memory information
    before extracting kernel.

    So extend the movable_node to movable_node=nn@ss, in which nn means
    the size of memory in *immovable* node, and ss means the start position of
    this memory region. Then limit kaslr choose memory in these regions.

    There are two policies:
    1. Specify the memory region in *movable* node to avoid:
    Then we can use the existing mem_avoid to handle. But if the memory
    on movable node was separated by memory hole or different movable nodes
    are discontinuous, we don't know how many regions need to avoid.
    OTOH, we must avoid all of the movable memory, otherwise, kaslr may
    choose the wrong place.
    2. Specify the memory region in *immovable* node to select:
    Only support 4 regions in this parameter. Then user can use two nodes
    at least for kaslr to choose, it's enough for the kernel to extract.
    At the same time, because we need only 4 new mem_vector, the usage
    of memory here is not too big. So I think this way is better, and this
    patchset is based on this policy.

    PATCH 1/4 parse the extended movable_node=nn[KMG]@ss[KMG], then
    store the memory regions.
    PATCH 2/4 select the memory region in immovable node when process
    memmap.
    PATCH 3/4 add document.
    PATCH 4/4 cleans up some little problems.

    v1->v2:
    Follow Dou's suggestion:
    - Add the parse for movable_node=nn[KMG] without @ss[KMG]
    - Fix the bug for more than one "movable_node=" specified
    - Drop useless variables and use mem_vector region directely
    - Add more comments.

    Chao Fan (4):
    kaslr: parse the extended movable_node=nn[KMG]@ss[KMG]
    kaslr: select the memory region in immovable node to process
    document: change the document for the extended movable_node
    kaslr: clean up a useless variable and some usless space

    Documentation/admin-guide/kernel-parameters.txt | 9 ++
    arch/x86/boot/compressed/kaslr.c | 141 ++++++++++++++++++++++--
    2 files changed, 138 insertions(+), 12 deletions(-)

    --
    2.13.6



    \
     
     \ /
      Last update: 2017-11-01 12:35    [W:5.240 / U:1.464 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site