Date: Sun, 9 Sep 2012 23:29:05 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Michael Fuckner <michael@fuckner.net> Cc: amd64@freebsd.org, current@freebsd.org Subject: Re: Small Ivy features: FSGSBASE and SMEP. Message-ID: <20120909202905.GP33100@deviant.kiev.zoral.com.ua> In-Reply-To: <20120909110255.GM33100@deviant.kiev.zoral.com.ua> References: <20120908181019.GK33100@deviant.kiev.zoral.com.ua> <504C3A5D.4020402@fuckner.net> <20120909110255.GM33100@deviant.kiev.zoral.com.ua>
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--j8h/1PgiTC9rw8+R Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Sep 09, 2012 at 02:02:55PM +0300, Konstantin Belousov wrote: > On Sun, Sep 09, 2012 at 08:42:37AM +0200, Michael Fuckner wrote: > > Hi all, > >=20 > > I changed your patch slightly to apply to specialreh.h on STABLE > >=20 > > root@c64:/root # diff smep.1.patch.bak smep.1.patch > > 80c80 > > < diff --git a/sys/x86/include/specialreg.h b/sys/x86/include/specialre= g.h > > --- > > > diff --git a/sys/amd64/include/specialreg.h=20 > > b/sys/amd64/include/specialreg.h > > 82,83c82,83 > > < --- a/sys/x86/include/specialreg.h > > < +++ b/sys/x86/include/specialreg.h > > --- > > > --- a/sys/amd64/include/specialreg.h > > > +++ b/sys/amd64/include/specialreg.h > >=20 > > I got a new kernel, but it is stuck immediately (kerneltrap 9 with=20 > > interrupts disabled), system doesn't boot on E3-1230 V2 on Supermicro= =20 > > X9SCM-IIF > >=20 > > Anything else I could check? > I need the backtrace and the whole kernel messages. At least, there was a typo in the definition of CR4_FSGSBASE. I still need verbose dmesg and panic messages, if any, with the http://people.freebsd.org/~kib/misc/smep.2.patch=20 version of the patch. >=20 > >=20 > > Regards, > > Michael! > >=20 > >=20 > > On 09/08/2012 08:10 PM, Konstantin Belousov wrote: > > >Please find at > > >http://people.freebsd.org/~kib/misc/smep.1.patch > > >the patch which should enable the FSGSBASE and SMEP features > > >supposedly present in the IvyBridge CPUs. > > > > > >FSGSBASE are four new instructions available in the 64bit mode only. > > >They allow to access bases for %fs and %gs without touching MSRs. > > >This makes it possible to both read and write bases in the user mode, > > >or in ring 0 with lower overhead. > > > > > >At the moment, WRFSBASE/WRGSBASE instructions should work, but are > > >useless since any interrupt or context switch overrides bases with the > > >values set by the arch syscall. Still, RDFSBASE/RDGSBASE might be usef= ul > > >for some code and I see no reason not to enable them. > > > > > >SMEP is the nice feature of the processor which makes it trap if ring > > >0 tries to execute an instruction from usermode-accessible page. It is > > >another mitigation for things like calling user-controllable function > > >pointer in kernel, as well as a protection for NULL function pointer > > >dereference. > > > > > >I am sure that we never execute anything in kernel from user page, but > > >I did not tested the patch since I have no Ivy machine. > > > > > >I need your reports about boot on Ivy with patch applied. Please inclu= de > > >the lines from verbose dmesg with CPU Features. In particular, the > > >'Standard Extended Features' report should appear in output. > > > > > >Thanks. > > > --j8h/1PgiTC9rw8+R Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (FreeBSD) iEYEARECAAYFAlBM/BEACgkQC3+MBN1Mb4juXgCffpEvx7gHV5WSw2zrg5/126e5 5F8AoO9dVtJ1Dpnw1s0BXZ64RsTMMW1h =74/k -----END PGP SIGNATURE----- --j8h/1PgiTC9rw8+R--
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