Adds segment limit checking helper functions. Also added a cs_base() helper while at it.
Signed-off-by: Mohammed Gamal <m.gamal005@xxxxxxxxx>
---
arch/x86/kvm/emulate.c | 33 ++++++++++++++++++++++++++++++++-
1 files changed, 32 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 255473f..07ca28e 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -633,6 +633,15 @@ static unsigned long seg_base(struct x86_emulate_ctxt *ctxt,
return ops->get_cached_segment_base(seg, ctxt->vcpu);
}
+static u64 seg_limit(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops, int seg)
+{
+ if (ctxt->mode == X86EMUL_MODE_PROT64)
+ return -1ULL;
+
+ return ops->get_cached_segment_limit(seg, ctxt->vcpu);
+}
+
static unsigned long seg_override_base(struct x86_emulate_ctxt *ctxt,
struct x86_emulate_ops *ops,
struct decode_cache *c)
@@ -643,6 +652,12 @@ static unsigned long seg_override_base(struct x86_emulate_ctxt *ctxt,
return seg_base(ctxt, ops, c->seg_override);
}
+static unsigned long cs_base(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops)
+{
+ return seg_base(ctxt, ops, VCPU_SREG_CS);
+}
+
static unsigned long es_base(struct x86_emulate_ctxt *ctxt,
struct x86_emulate_ops *ops)
{
@@ -686,6 +701,22 @@ static void emulate_ts(struct x86_emulate_ctxt *ctxt, int err)
emulate_exception(ctxt, TS_VECTOR, err, true);
}
+static int seg_limit_check(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops, int seg,
+ unsigned long addr, unsigned size,
+ int vec, u32 err)
+{
+ unsigned long base = seg_base(ctxt, ops, seg);
+ u64 limit = seg_limit(ctxt, ops, seg);
+
+ if (addr - base + size - 1 > limit) {
+ emulate_exception(ctxt, vec, err, true);
+ return X86EMUL_PROPAGATE_FAULT;
+ }
+
+ return X86EMUL_CONTINUE;
+}
+
static int do_fetch_insn_byte(struct x86_emulate_ctxt *ctxt,
struct x86_emulate_ops *ops,
unsigned long eip, u8 *dest)
@@ -976,7 +1007,7 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
c->eip = ctxt->eip;
c->fetch.start = c->fetch.end = c->eip;
- ctxt->cs_base = seg_base(ctxt, ops, VCPU_SREG_CS);
+ ctxt->cs_base = cs_base(ctxt, ops);
switch (mode) {
case X86EMUL_MODE_REAL:
--
1.7.0.4
--
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