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Date: Tue, 6 May 2014 20:16:15 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: kvm@...r.kernel.org, bsd@...hat.com
Subject: [RFC PATCH 4/4] KVM: emulate: put pointers in the fetch_cache
This simplifies the code a bit, especially the overflow checks.
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
arch/x86/include/asm/kvm_emulate.h | 4 ++--
arch/x86/kvm/emulate.c | 34 +++++++++++++++-------------------
arch/x86/kvm/trace.h | 6 +++---
3 files changed, 20 insertions(+), 24 deletions(-)
diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 085d68868756..2467e5e1b894 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -269,8 +269,8 @@ struct operand {
struct fetch_cache {
u8 data[15];
- unsigned long start;
- unsigned long end;
+ u8 *ptr;
+ u8 *end;
};
struct read_cache {
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 245a2d0bfe68..3ab9310918a7 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -708,16 +708,15 @@ static int segmented_read_std(struct x86_emulate_ctxt *ctxt,
*/
static int __do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt, int op_size)
{
- struct fetch_cache *fc = &ctxt->fetch;
int rc;
- int size, cur_size;
+ int size;
unsigned long linear;
-
+ int cur_size = ctxt->fetch.end - ctxt->fetch.data;
struct segmented_address addr = { .seg = VCPU_SREG_CS,
- .ea = fc->end };
- cur_size = fc->end - fc->start;
- size = min(15UL - cur_size,
- PAGE_SIZE - offset_in_page(fc->end));
+ .ea = ctxt->eip + cur_size };
+
+ size = min(15UL ^ cur_size,
+ PAGE_SIZE - offset_in_page(addr.ea));
/*
* One instruction can only straddle two pages,
@@ -730,19 +729,18 @@ static int __do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt, int op_size)
rc = __linearize(ctxt, addr, size, false, true, &linear);
if (unlikely(rc != X86EMUL_CONTINUE))
return rc;
- rc = ctxt->ops->fetch(ctxt, linear, fc->data + cur_size,
+ rc = ctxt->ops->fetch(ctxt, linear, ctxt->fetch.end,
size, &ctxt->exception);
if (unlikely(rc != X86EMUL_CONTINUE))
return rc;
- fc->end += size;
+ ctxt->fetch.end += size;
return X86EMUL_CONTINUE;
}
static __always_inline int do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt,
unsigned size)
{
- /* We have to be careful about overflow! */
- if (unlikely(ctxt->_eip > ctxt->fetch.end - size))
+ if (unlikely(ctxt->fetch.end - ctxt->fetch.ptr < size))
return __do_insn_fetch_bytes(ctxt, size);
else
return X86EMUL_CONTINUE;
@@ -751,26 +749,24 @@ static __always_inline int do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt,
/* Fetch next part of the instruction being emulated. */
#define insn_fetch(_type, _ctxt) \
({ _type _x; \
- struct fetch_cache *_fc; \
\
rc = do_insn_fetch_bytes(_ctxt, sizeof(_type)); \
if (rc != X86EMUL_CONTINUE) \
goto done; \
- _fc = &ctxt->fetch; \
- _x = *(_type __aligned(1) *) &_fc->data[ctxt->_eip - _fc->start]; \
ctxt->_eip += sizeof(_type); \
+ _x = *(_type __aligned(1) *) ctxt->fetch.ptr; \
+ ctxt->fetch.ptr += sizeof(_type); \
_x; \
})
#define insn_fetch_arr(_arr, _size, _ctxt) \
({ \
- struct fetch_cache *_fc; \
rc = do_insn_fetch_bytes(_ctxt, _size); \
if (rc != X86EMUL_CONTINUE) \
goto done; \
- _fc = &ctxt->fetch; \
- memcpy(_arr, &_fc->data[ctxt->_eip - _fc->start], _size); \
ctxt->_eip += (_size); \
+ memcpy(_arr, ctxt->fetch.ptr, _size); \
+ ctxt->fetch.ptr += (_size); \
})
/*
@@ -4273,8 +4269,8 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
ctxt->memop.type = OP_NONE;
ctxt->_eip = ctxt->eip;
- ctxt->fetch.start = ctxt->_eip;
- ctxt->fetch.end = ctxt->fetch.start + insn_len;
+ ctxt->fetch.ptr = ctxt->fetch.data;
+ ctxt->fetch.end = ctxt->fetch.data + insn_len;
ctxt->opcode_len = 1;
if (insn_len > 0)
memcpy(ctxt->fetch.data, insn, insn_len);
diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 33574c95220d..e850a7d332be 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -721,10 +721,10 @@ TRACE_EVENT(kvm_emulate_insn,
),
TP_fast_assign(
- __entry->rip = vcpu->arch.emulate_ctxt.fetch.start;
__entry->csbase = kvm_x86_ops->get_segment_base(vcpu, VCPU_SREG_CS);
- __entry->len = vcpu->arch.emulate_ctxt._eip
- - vcpu->arch.emulate_ctxt.fetch.start;
+ __entry->len = vcpu->arch.emulate_ctxt.fetch.ptr
+ - vcpu->arch.emulate_ctxt.fetch.data;
+ __entry->rip = vcpu->arch.emulate_ctxt._eip - __entry->len;
memcpy(__entry->insn,
vcpu->arch.emulate_ctxt.fetch.data,
15);
--
1.8.3.1
--
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