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authorBjorn Helgaas <bjorn.helgaas@hp.com>2006-01-08 01:04:13 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-08 20:14:02 -0800
commit80851ef2a5a404e6054211ca96ecd5ac4b06d297 (patch)
treedcacd2a475adc28c540b6012b58f1af9783778c1 /drivers/char/sonypi.c
parent44ac8413901167589226abf824d994aa57e4fd28 (diff)
[PATCH] /dev/mem: validate mmap requests
Add a hook so architectures can validate /dev/mem mmap requests. This is analogous to validation we already perform in the read/write paths. The identity mapping scheme used on ia64 requires that each 16MB or 64MB granule be accessed with exactly one attribute (write-back or uncacheable). This avoids "attribute aliasing", which can cause a machine check. Sample problem scenario: - Machine supports VGA, so it has uncacheable (UC) MMIO at 640K-768K - efi_memmap_init() discards any write-back (WB) memory in the first granule - Application (e.g., "hwinfo") mmaps /dev/mem, offset 0 - hwinfo receives UC mapping (the default, since memmap says "no WB here") - Machine check abort (on chipsets that don't support UC access to WB memory, e.g., sx1000) In the scenario above, the only choices are - Use WB for hwinfo mmap. Can't do this because it causes attribute aliasing with the UC mapping for the VGA MMIO space. - Use UC for hwinfo mmap. Can't do this because the chipset may not support UC for that region. - Disallow the hwinfo mmap with -EINVAL. That's what this patch does. Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/char/sonypi.c')
0 files changed, 0 insertions, 0 deletions