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KVM: x86 emulator: implement segment permission checks 

Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Avi Kivity 2011-04-03 12:32:09 +03:00
parent 56697687da
commit 618ff15de1
1 changed files with 63 additions and 0 deletions
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63
arch/x86/kvm/emulate.c
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@ -515,6 +515,11 @@ static int emulate_gp(struct x86_emulate_ctxt *ctxt, int err)
return emulate_exception(ctxt, GP_VECTOR, err, true);
}
static int emulate_ss(struct x86_emulate_ctxt *ctxt, int err)
{
return emulate_exception(ctxt, SS_VECTOR, err, true);
}
static int emulate_ud(struct x86_emulate_ctxt *ctxt)
{
return emulate_exception(ctxt, UD_VECTOR, 0, false);
@ -541,13 +546,71 @@ static int linearize(struct x86_emulate_ctxt *ctxt,
ulong *linear)
{
struct decode_cache *c = &ctxt->decode;
struct desc_struct desc;
bool usable;
ulong la;
u32 lim;
unsigned cpl, rpl;
la = seg_base(ctxt, ctxt->ops, addr.seg) + addr.ea;
switch (ctxt->mode) {
case X86EMUL_MODE_REAL:
break;
case X86EMUL_MODE_PROT64:
if (((signed long)la << 16) >> 16 != la)
return emulate_gp(ctxt, 0);
break;
default:
usable = ctxt->ops->get_cached_descriptor(&desc, NULL, addr.seg,
ctxt->vcpu);
if (!usable)
goto bad;
/* code segment or read-only data segment */
if (((desc.type & 8) || !(desc.type & 2)) && write)
goto bad;
/* unreadable code segment */
if ((desc.type & 8) && !(desc.type & 2))
goto bad;
lim = desc_limit_scaled(&desc);
if ((desc.type & 8) || !(desc.type & 4)) {
/* expand-up segment */
if (addr.ea > lim || (u32)(addr.ea + size - 1) > lim)
goto bad;
} else {
/* exapand-down segment */
if (addr.ea <= lim || (u32)(addr.ea + size - 1) <= lim)
goto bad;
lim = desc.d ? 0xffffffff : 0xffff;
if (addr.ea > lim || (u32)(addr.ea + size - 1) > lim)
goto bad;
}
cpl = ctxt->ops->cpl(ctxt->vcpu);
rpl = ctxt->ops->get_segment_selector(addr.seg, ctxt->vcpu) & 3;
cpl = max(cpl, rpl);
if (!(desc.type & 8)) {
/* data segment */
if (cpl > desc.dpl)
goto bad;
} else if ((desc.type & 8) && !(desc.type & 4)) {
/* nonconforming code segment */
if (cpl != desc.dpl)
goto bad;
} else if ((desc.type & 8) && (desc.type & 4)) {
/* conforming code segment */
if (cpl < desc.dpl)
goto bad;
}
break;
}
if (c->ad_bytes != 8)
la &= (u32)-1;
*linear = la;
return X86EMUL_CONTINUE;
bad:
if (addr.seg == VCPU_SREG_SS)
return emulate_ss(ctxt, addr.seg);
else
return emulate_gp(ctxt, addr.seg);
}
static int segmented_read_std(struct x86_emulate_ctxt *ctxt,