Rather than opencoding it in two places. While only used in the PV emulation
code, this helper is in principle usable anywhere in the hypervisor.
No functional change.
Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
---
CC: Jan Beulich <jbeul...@suse.com>
CC: Wei Liu <wei.l...@citrix.com>
---
xen/arch/x86/pv/emul-gate-op.c | 5 +----
xen/arch/x86/pv/emulate.c | 6 +-----
xen/arch/x86/pv/emulate.h | 11 +++++++++++
3 files changed, 13 insertions(+), 9 deletions(-)
diff --git a/xen/arch/x86/pv/emul-gate-op.c b/xen/arch/x86/pv/emul-gate-op.c
index 0f89c91..14ce95e 100644
--- a/xen/arch/x86/pv/emul-gate-op.c
+++ b/xen/arch/x86/pv/emul-gate-op.c
@@ -54,11 +54,8 @@ static int read_gate_descriptor(unsigned int gate_sel,
unsigned int *ar)
{
struct desc_struct desc;
- const struct desc_struct *pdesc;
+ const struct desc_struct *pdesc = gdt_ldt_desc_ptr(gate_sel);
- pdesc = (const struct desc_struct *)
- (!(gate_sel & 4) ? GDT_VIRT_START(v) : LDT_VIRT_START(v))
- + (gate_sel >> 3);
if ( (gate_sel < 4) ||
((gate_sel >= FIRST_RESERVED_GDT_BYTE) && !(gate_sel & 4)) ||
__get_user(desc, pdesc) )
diff --git a/xen/arch/x86/pv/emulate.c b/xen/arch/x86/pv/emulate.c
index 5750c76..1b60911 100644
--- a/xen/arch/x86/pv/emulate.c
+++ b/xen/arch/x86/pv/emulate.c
@@ -33,11 +33,7 @@ int pv_emul_read_descriptor(unsigned int sel, const struct
vcpu *v,
if ( sel < 4)
desc.b = desc.a = 0;
- else if ( __get_user(desc,
- (const struct desc_struct *)(!(sel & 4)
- ? GDT_VIRT_START(v)
- : LDT_VIRT_START(v))
- + (sel >> 3)) )
+ else if ( __get_user(desc, gdt_ldt_desc_ptr(sel)) )
return 0;
if ( !insn_fetch )
desc.b &= ~_SEGMENT_L;
diff --git a/xen/arch/x86/pv/emulate.h b/xen/arch/x86/pv/emulate.h
index 656c12f..9d58794 100644
--- a/xen/arch/x86/pv/emulate.h
+++ b/xen/arch/x86/pv/emulate.h
@@ -1,6 +1,7 @@
#ifndef __PV_EMULATE_H__
#define __PV_EMULATE_H__
+#include <asm/processor.h>
#include <asm/x86_emulate.h>
int pv_emul_read_descriptor(unsigned int sel, const struct vcpu *v,
@@ -16,4 +17,14 @@ static inline int pv_emul_is_mem_write(const struct
x86_emulate_state *state,
: X86EMUL_UNHANDLEABLE;
}
+/* Return a pointer to the GDT/LDT descriptor referenced by sel. */
+static inline const struct desc_struct *gdt_ldt_desc_ptr(unsigned int sel)
+{
+ const struct vcpu *curr = current;
+ const struct desc_struct *tbl = (void *)
+ ((sel & X86_XEC_TI) ? LDT_VIRT_START(curr) : GDT_VIRT_START(curr));
+
+ return &tbl[sel >> 3];
+}
+
#endif /* __PV_EMULATE_H__ */
--
2.1.4
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