linux/arch/x86/xen
Stefan Bader 0b5a50635f 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
2014-09-10 15:23:42 +01:00
..
apic.c xen/apic/xenbus/swiotlb/pcifront/grant/tmem: Make functions or variables static. 2012-08-21 14:50:03 -04:00
debugfs.c debugfs: Add support to print u32 array in debugfs 2012-04-17 00:18:36 -04:00
debugfs.h debugfs: Add support to print u32 array in debugfs 2012-04-17 00:18:36 -04:00
efi.c arch/x86/xen: Silence compiler warnings 2014-07-18 21:24:03 +01:00
enlighten.c - Remove unused V2 grant table support. 2014-08-07 11:33:15 -07:00
grant-table.c x86/xen: use vmap() to map grant table pages in PVH guests 2014-08-11 11:59:35 +01:00
irq.c asmlinkage, x86: Add explicit __visible to arch/x86/* 2014-05-05 16:07:44 -07:00
Kconfig Support PCI devices with multiple MSIs, performance improvement for 2014-04-03 14:01:37 -07:00
Makefile arch/x86/xen: Silence compiler warnings 2014-07-18 21:24:03 +01:00
mmu.c x86/xen: don't copy bogus duplicate entries into kernel page tables 2014-09-10 15:23:42 +01:00
mmu.h xen: make a pile of mmu pvop functions static 2011-05-20 14:25:24 -07:00
multicalls.c xen/multicall: move *idx fields to start of mc_buffer 2011-07-18 15:43:46 -07:00
multicalls.h xen: use this_cpu_xxx replace percpu_xxx funcs 2012-01-24 12:20:24 -05:00
p2m.c xen/setup: Remove Identity Map Debug Message 2014-07-31 18:40:13 +01:00
pci-swiotlb-xen.c pci-swiotlb-xen: call pci_request_acs only ifdef CONFIG_PCI 2013-11-08 15:21:44 -05:00
platform-pci-unplug.c xen/pvhvm: Remove the xen_platform_pci int. 2014-01-03 14:54:53 -05:00
setup.c xen: regression and PVH fixes for 3.16-rc1 2014-06-19 07:53:27 -10:00
smp.c x86/xen: Fix 32-bit PV guests's usage of kernel_stack 2014-04-15 15:00:14 +01:00
smp.h xen: Clean up apic ipi interface 2013-05-29 09:04:21 -04:00
spinlock.c xen/spinlock: Don't enable them unconditionally. 2014-04-15 17:41:28 +01:00
suspend.c xen: refactor suspend pre/post hooks 2014-05-12 17:19:56 +01:00
time.c x86/xen: resume timer irqs early 2014-08-11 11:59:34 +01:00
trace.c xen/trace: Fix compile error when CONFIG_XEN_PRIVILEGED_GUEST is not set 2011-08-05 09:43:02 -04:00
vdso.h
vga.c xen/vga: add the xen EFI video mode support 2012-09-24 09:28:57 -04:00
xen-asm_32.S x86/xen: Fix 32-bit PV guests's usage of kernel_stack 2014-04-15 15:00:14 +01:00
xen-asm_64.S
xen-asm.h
xen-asm.S xen: correctly check for pending events when restoring irq flags 2012-04-27 16:04:21 -04:00
xen-head.S xen/pvh: Support ParaVirtualized Hardware extensions (v3). 2014-01-06 10:44:24 -05:00
xen-ops.h Merge branch 'x86-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-08-04 17:13:50 -07:00