x86, mm: Clean up and simplify NX enablement
The 32- and 64-bit code used very different mechanisms for enabling NX, but even the 32-bit code was enabling NX in head_32.S if it is available. Furthermore, we had a bewildering collection of tests for the available of NX. This patch: a) merges the 32-bit set_nx() and the 64-bit check_efer() function into a single x86_configure_nx() function. EFER control is left to the head code. b) eliminates the nx_enabled variable entirely. Things that need to test for NX enablement can verify __supported_pte_mask directly, and cpu_has_nx gives the supported status of NX. Signed-off-by:H. Peter Anvin <hpa@zytor.com> Cc: Tejun Heo <tj@kernel.org> Cc: Brian Gerst <brgerst@gmail.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Vegard Nossum <vegardno@ifi.uio.no> Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Chris Wright <chrisw@sous-sol.org> LKML-Reference: <1258154897-6770-5-git-send-email-hpa@zytor.com> Acked-by:
Kees Cook <kees.cook@canonical.com>
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