Date: Thu, 12 Jun 2014 22:30:15 GMT From: op@FreeBSD.org To: svn-soc-all@FreeBSD.org Subject: socsvn commit: r269487 - soc2014/op/freebsd-base/sys/i386/i386 Message-ID: <201406122230.s5CMUFUW021259@socsvn.freebsd.org>
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Author: op Date: Thu Jun 12 22:30:15 2014 New Revision: 269487 URL: http://svnweb.FreeBSD.org/socsvn/?view=rev&rev=269487 Log: SMAP i386: added related trap handler git: https://github.com/opntr/opBSD/tree/op/gsoc2014/smap Signed-off-by: Oliver Pinter <oliver.pntr@gmail.com> Modified: soc2014/op/freebsd-base/sys/i386/i386/trap.c Modified: soc2014/op/freebsd-base/sys/i386/i386/trap.c ============================================================================== --- soc2014/op/freebsd-base/sys/i386/i386/trap.c Thu Jun 12 22:29:50 2014 (r269486) +++ soc2014/op/freebsd-base/sys/i386/i386/trap.c Thu Jun 12 22:30:15 2014 (r269487) @@ -860,6 +860,16 @@ map = &vm->vm_map; /* + * If CPL < 3, SMAP protections are disabled if EFLAGS.AC = 1. + * If CPL = 3, SMAP applies to all supervisor-mode data accesses + * (these are implicit supervisor accesses) regardless of the + * value of EFLAGS.AC." - Intel Ref. # 319433-014 9.3.2 + */ + if (__predict_false(smap_access_violation(frame, usermode))) { + panic("SMAP!"); + } + + /* * When accessing a user-space address, kernel must be * ready to accept the page fault, and provide a * handling routine. Since accessing the address @@ -1020,6 +1030,32 @@ panic("unknown/reserved trap"); } + +/* + * Supervisor Mode Access Prevention violation + * + * If CPL < 3, SMAP protections are disabled if EFLAGS.AC = 1. + * If CPL = 3, SMAP applies to all supervisor-mode data accesses + * (these are implicit supervisor accesses) regardless of the + * value of EFLAGS.AC." - Intel Ref. # 319433-014 9.3.2 + */ +static bool +smap_access_violation(struct trapframe *frame, int usermode) +{ + /* SMAP disabled */ + if ((cpu_stdext_feature & CPUID_STDEXT_SMAP) == 0) + return (false); + + /* CPL == 3 or EFLAGS.AC == 1 */ + if (usermode || (frame->tf_rflags & PSL_AC) != 0) + return (false); + + /* + * CPL < 3 and EFLAGS.AC == 0 + */ + return (true); +} + /* * Double fault handler. Called when a fault occurs while writing * a frame for a trap/exception onto the stack. This usually occurs
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