[PATCH v5sub1 7/8] arm64: move kernel image to base of vmalloc area

Hi Ard,

On Mon, Feb 01, 2016 at 11:54:52AM +0100, Ard Biesheuvel wrote:

This moves the module area to right before the vmalloc area, and
moves the kernel image to the base of the vmalloc area. This is
an intermediate step towards implementing KASLR, which allows the
kernel image to be located anywhere in the vmalloc area.

Signed-off-by: Ard Biesheuvel <redacted>

This patch is causing lots of KASAN warnings on Juno (interestingly, it
doesn't seem to trigger on Seattle, though we only tried for-next/core).
I pushed the branch that I'm currently using here:

git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux for-next/kernmap


A typical error (though its place varies based on the config options,
kernel layout):

BUG: KASAN: stack-out-of-bounds in clockevents_program_event+0x28/0x1b0 at addr ffffffc936257cc8
Read of size 8 by task swapper/2/0
page:ffffffbde6d895c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000000()
page dumped because: kasan: bad access detected
CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.5.0-rc1+ #130
Hardware name: Juno (DT)
Call trace:
[<ffffff900408b590>] dump_backtrace+0x0/0x258
[<ffffff900408b7fc>] show_stack+0x14/0x20
[<ffffff900448789c>] dump_stack+0xac/0x100
[<ffffff9004224f3c>] kasan_report_error+0x544/0x570
[<ffffff9004225328>] kasan_report+0x40/0x48
[<ffffff9004223c58>] __asan_load8+0x60/0x78
[<ffffff90041596f0>] clockevents_program_event+0x28/0x1b0
[<ffffff900415c63c>] tick_program_event+0x74/0xb8
[<ffffff9004148944>] __remove_hrtimer+0xcc/0x100
[<ffffff9004148f0c>] hrtimer_start_range_ns+0x3f4/0x538
[<ffffff900415d450>] __tick_nohz_idle_enter+0x558/0x590
[<ffffff900415d74c>] tick_nohz_idle_enter+0x44/0x78
[<ffffff900411fcc8>] cpu_startup_entry+0x48/0x2c0
[<ffffff9004091f58>] secondary_start_kernel+0x208/0x278
[<0000000080082aac>] 0x80082aac
Memory state around the buggy address:
 ffffffc936257b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffc936257c00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1

ffffffc936257c80: f1 f1 00 00 00 00 f3 f3 f3 f3 00 00 00 00 00 00

                                              ^
 ffffffc936257d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffc936257d80: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1


And some additional info from the kernel boot:

Processing EFI memory map:
  0x000008000000-0x00000bffffff [Memory Mapped I/O  |RUN|  |  |  |  |  |   |  |  |  |UC]
  0x00001c170000-0x00001c170fff [Memory Mapped I/O  |RUN|  |  |  |  |  |   |  |  |  |UC]
  0x000080000000-0x00008000ffff [Loader Data        |   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x000080010000-0x00008007ffff [Conventional Memory|   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x000080080000-0x00008149ffff [Loader Data        |   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0000814a0000-0x00009fdfffff [Conventional Memory|   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x00009fe00000-0x00009fe0ffff [Loader Data        |   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x00009fe10000-0x0000dfffffff [Conventional Memory|   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0000e00f0000-0x0000febd5fff [Conventional Memory|   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0000febd6000-0x0000febd9fff [ACPI Reclaim Memory|   |  |  |  |  |  |   |WB|WT|WC|UC]*
  0x0000febda000-0x0000febdafff [ACPI Memory NVS    |   |  |  |  |  |  |   |WB|WT|WC|UC]*
  0x0000febdb000-0x0000febdcfff [ACPI Reclaim Memory|   |  |  |  |  |  |   |WB|WT|WC|UC]*
  0x0000febdd000-0x0000feffffff [Boot Data          |   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x000880000000-0x0009f8794fff [Conventional Memory|   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0009f8795000-0x0009f8796fff [Loader Data        |   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0009f8797000-0x0009f9bb4fff [Loader Code        |   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0009f9bb5000-0x0009faf6efff [Boot Code          |   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0009faf6f000-0x0009fafa9fff [Runtime Data       |RUN|  |  |  |  |  |   |WB|WT|WC|UC]*
  0x0009fafaa000-0x0009ff2b1fff [Conventional Memory|   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0009ff2b2000-0x0009ffb70fff [Boot Data          |   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0009ffb71000-0x0009ffb89fff [Conventional Memory|   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0009ffb8a000-0x0009ffb8dfff [Boot Data          |   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0009ffb8e000-0x0009ffb8efff [Conventional Memory|   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0009ffb8f000-0x0009ffdddfff [Boot Data          |   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0009ffdde000-0x0009ffe76fff [Conventional Memory|   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0009ffe77000-0x0009fff6dfff [Boot Code          |   |  |  |  |  |  |   |WB|WT|WC|UC]
  0x0009fff6e000-0x0009fffaefff [Runtime Code       |RUN|  |  |  |  |  |   |WB|WT|WC|UC]*
  0x0009fffaf000-0x0009ffffefff [Runtime Data       |RUN|  |  |  |  |  |   |WB|WT|WC|UC]*
  0x0009fffff000-0x0009ffffffff [Boot Data          |   |  |  |  |  |  |   |WB|WT|WC|UC]


Memory: 7068520K/8371264K available (10424K kernel code, 3464K rwdata, 5284K rodata, 1016K init, 380K bss, 1286360K reserved, 16384K cma-reserved)
Virtual kernel memory layout:
    kasan   : 0xffffff8000000000 - 0xffffff9000000000   (    64 GB)
    modules : 0xffffff9000000000 - 0xffffff9004000000   (    64 MB)
    vmalloc : 0xffffff9004000000 - 0xffffffbdbfff0000   (   182 GB)
      .init : 0xffffff9004fd9000 - 0xffffff90050d7000   (  1016 KB)
      .text : 0xffffff9004080000 - 0xffffff9004fd9000   ( 15716 KB)
      .data : 0xffffff90050d7000 - 0xffffff9005439200   (  3465 KB)
    vmemmap : 0xffffffbdc0000000 - 0xffffffbfc0000000   (     8 GB maximum)
              0xffffffbdc2000000 - 0xffffffbde8000000   (   608 MB actual)
    fixed   : 0xffffffbffe7fd000 - 0xffffffbffec00000   (  4108 KB)
    PCI I/O : 0xffffffbffee00000 - 0xffffffbfffe00000   (    16 MB)
    memory  : 0xffffffc000000000 - 0xffffffc980000000   ( 38912 MB)

-- 
Catalin