On 5/18/11, Kostik Belousov <kostik...@gmail.com> wrote: > On Wed, May 18, 2011 at 02:03:07AM +0200, Oliver Pinter wrote: >> ---------- Forwarded message ---------- >> From: Fenghua Yu <fenghua...@intel.com> >> Date: Mon, 16 May 2011 14:34:44 -0700 >> Subject: [PATCH v2 3/4] x86, head_32/64.S: Enable SMEP >> To: Ingo Molnar <mi...@elte.hu>, Thomas Gleixner <t...@linutronix.de>, >> H Peter Anvin <h...@zytor.com>, Asit K Mallick >> <asit.k.mall...@intel.com>, Linus Torvalds >> <torva...@linux-foundation.org>, Avi Kivity <a...@redhat.com>, Arjan >> van de Ven <ar...@infradead.org>, Andrew Morton >> <a...@linux-foundation.org>, Andi Kleen <a...@firstfloor.org> >> Cc: linux-kernel <linux-ker...@vger.kernel.org>, Fenghua Yu >> <fenghua...@intel.com> >> >> From: Fenghua Yu <fenghua...@intel.com> >> >> Enable newly documented SMEP (Supervisor Mode Execution Protection) CPU >> feature in kernel. >> >> SMEP prevents the CPU in kernel-mode to jump to an executable page that >> does >> not have the kernel/system flag set in the pte. This prevents the kernel >> from executing user-space code accidentally or maliciously, so it for >> example >> prevents kernel exploits from jumping to specially prepared user-mode >> shell >> code. The violation will cause page fault #PF and will have error code >> identical to XD violation. >> >> CR4.SMEP (bit 20) is 0 at power-on. If the feature is supported by CPU >> (X86_FEATURE_SMEP), enable SMEP by setting CR4.SMEP. New kernel >> option nosmep disables the feature even if the feature is supported by >> CPU. >> >> Signed-off-by: Fenghua Yu <fenghua...@intel.com> > > So, where is the mentioned documentation for SMEP ? Rev. 38 of the > Intel(R) 64 and IA-32 Architectures Software Developer's Manual does > not contain the description, at least at the places where I looked and > expected to find it.
http://www.intel.com/Assets/PDF/manual/325384.pdf Intel® 64 and IA-32 Architectures Software Developer’s Manual Volume 3 (3A & 3B): System Programming Guide > > Looking forward to hear from you. > > _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
