linux/arch/i386/mm
Dave Jones f8af095d3a [PATCH] x86: change_page_attr() fix
The 'make rodata read-only' patch in -mm exposes a latent bug in the 32-bit
change_page_attr() function, which causes certain CPUs (Those with NX
basically) to reboot instantly after pages are marked read-only.

The same bug got fixed a while back on x86-64, but never got propagated to
i386.

Stuart Hayes from Dell also picked up on this last June, but it never got
fixed, as the only thing affected by it aparently was the nvidia driver.

Blatantly stealing description from his post..

"It doesn't appear to be fixed (in the i386 arch).  The
 change_page_attr()/split_large_page() code will still still set all the
 4K PTEs to PAGE_KERNEL (setting the _PAGE_NX bit) when a large page
 needs to be split.

 This wouldn't be a problem for the bulk of the kernel memory, but there
 are pages in the lower 4MB of memory that's free, and are part of large
 executable pages that also contain kernel code.  If change_page_attr()
 is called on these, it will set the _PAGE_NX bit on the whole 2MB region
 that was covered by the large page, causing a large chunk of kernel code
 to be non-executable."

Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Dave Jones <davej@redhat.com>
Cc: <Stuart_Hayes@Dell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06 08:33:38 -08:00
..
boot_ioremap.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
discontig.c [PATCH] memory hotplug: i386 addition functions 2005-10-29 21:40:45 -07:00
extable.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
fault.c [PATCH] x86: add an accessor function for getting the per-CPU gdt 2005-10-30 17:37:12 -08:00
highmem.c [PATCH] kdump: Routines for copying dump pages 2005-06-25 16:24:53 -07:00
hugetlbpage.c [PATCH] remove hugetlb_clean_stale_pgtable() and fix huge_pte_alloc() 2005-09-05 00:05:46 -07:00
init.c [PATCH] x86/x86_64: mark rodata section read only: x86 parts 2006-01-06 08:33:36 -08:00
ioremap.c [PATCH] i386,amd64: ioremap.c __iomem annotations 2005-12-15 10:04:30 -08:00
Makefile [PATCH] sparsemem memory model for i386 2005-06-23 09:45:05 -07:00
mmap.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
pageattr.c [PATCH] x86: change_page_attr() fix 2006-01-06 08:33:38 -08:00
pgtable.c [PATCH] memory hotplug locking: node_size_lock 2005-10-29 21:40:44 -07:00