Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 19964fec authored by Chuck Ebbert's avatar Chuck Ebbert Committed by Linus Torvalds
Browse files

[PATCH] i386: fix get_segment_eip() with vm86 segments 



We need to check for vm86 mode first before looking at selector privilege
bits.

Segment limit is always base + 64k and only the low 16 bits of EIP are
significant in vm86 mode.

Signed-off-by: default avatarChuck Ebbert <76306.1226@compuserve.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Rohit Seth <rohitseth@google.com>
Acked-by: default avatarAnanth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 110cb1d2

arch/i386/mm/fault.c

+7 −4
Original line number Diff line number Diff line
@@ -77,13 +77,16 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs, 
	unsigned seg = regs->xcs & 0xffff;

	u32 seg_ar, seg_limit, base, *desc;



	/* Unlikely, but must come before segment checks. */

	if (unlikely(regs->eflags & VM_MASK)) {

		base = seg << 4;

		*eip_limit = base + 0xffff;

		return base + (eip & 0xffff);

	}



	/* The standard kernel/user address space limit. */

	*eip_limit = (seg & 3) ? USER_DS.seg : KERNEL_DS.seg;

	

	/* Unlikely, but must come before segment checks. */

	if (unlikely((regs->eflags & VM_MASK) != 0))

		return eip + (seg << 4);

	

	/* By far the most common cases. */

	if (likely(seg == __USER_CS || seg == __KERNEL_CS))

		return eip;