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| author | H. Peter Anvin <hpa@linux.intel.com> | 2014-03-17 02:31:54 +0400 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2014-04-11 21:10:09 +0400 |
| commit | b3b42ac2cbae1f3cecbb6229964a4d48af31d382 (patch) | |
| tree | b611f0f4d789f79ef1b0b9056aae923327a18687 /drivers/gpu/drm/i915/i915_debugfs.c | |
| parent | 3151b942badd059431eff93833cc1e957195b53b (diff) | |
| download | linux-b3b42ac2cbae1f3cecbb6229964a4d48af31d382.tar.xz | |
x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels
The IRET instruction, when returning to a 16-bit segment, only
restores the bottom 16 bits of the user space stack pointer. We have
a software workaround for that ("espfix") for the 32-bit kernel, but
it relies on a nonzero stack segment base which is not available in
32-bit mode.
Since 16-bit support is somewhat crippled anyway on a 64-bit kernel
(no V86 mode), and most (if not quite all) 64-bit processors support
virtualization for the users who really need it, simply reject
attempts at creating a 16-bit segment when running on top of a 64-bit
kernel.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/n/tip-kicdm89kzw9lldryb1br9od0@git.kernel.org
Cc: <stable@vger.kernel.org>
Diffstat (limited to 'drivers/gpu/drm/i915/i915_debugfs.c')
0 files changed, 0 insertions, 0 deletions