diff options
author | Stefan Bader <stefan.bader@canonical.com> | 2014-09-02 14:16:01 +0400 |
---|---|---|
committer | David Vrabel <david.vrabel@citrix.com> | 2014-09-10 18:23:42 +0400 |
commit | 0b5a50635fc916cf46e3de0b819a61fc3f17e7ee (patch) | |
tree | 18c086fa571218617a62fa38210af63e1a0eb9f5 /include | |
parent | 5903c6bd1a48d90b99e207ec2a6a7673cbbb732d (diff) | |
download | linux-0b5a50635fc916cf46e3de0b819a61fc3f17e7ee.tar.xz |
x86/xen: don't copy bogus duplicate entries into kernel page tables
When RANDOMIZE_BASE (KASLR) is enabled; or the sum of all loaded
modules exceeds 512 MiB, then loading modules fails with a warning
(and hence a vmalloc allocation failure) because the PTEs for the
newly-allocated vmalloc address space are not zero.
WARNING: CPU: 0 PID: 494 at linux/mm/vmalloc.c:128
vmap_page_range_noflush+0x2a1/0x360()
This is caused by xen_setup_kernel_pagetables() copying
level2_kernel_pgt into level2_fixmap_pgt, overwriting many non-present
entries.
Without KASLR, the normal kernel image size only covers the first half
of level2_kernel_pgt and module space starts after that.
L4[511]->level3_kernel_pgt[510]->level2_kernel_pgt[ 0..255]->kernel
[256..511]->module
[511]->level2_fixmap_pgt[ 0..505]->module
This allows 512 MiB of of module vmalloc space to be used before
having to use the corrupted level2_fixmap_pgt entries.
With KASLR enabled, the kernel image uses the full PUD range of 1G and
module space starts in the level2_fixmap_pgt. So basically:
L4[511]->level3_kernel_pgt[510]->level2_kernel_pgt[0..511]->kernel
[511]->level2_fixmap_pgt[0..505]->module
And now no module vmalloc space can be used without using the corrupt
level2_fixmap_pgt entries.
Fix this by properly converting the level2_fixmap_pgt entries to MFNs,
and setting level1_fixmap_pgt as read-only.
A number of comments were also using the the wrong L3 offset for
level2_kernel_pgt. These have been corrected.
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: stable@vger.kernel.org
Diffstat (limited to 'include')
0 files changed, 0 insertions, 0 deletions