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Date: Wed, 23 Jul 2008 14:21:18 -0700
From: Jeremy Fitzhardinge <jeremy@...p.org>
To: Ingo Molnar <mingo@...e.hu>
CC: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86/paravirt/xen: properly fill out the ldt ops
LTP testing showed that Xen does not properly implement
sys_modify_ldt(). This patch does the final little bits needed to
make the ldt work properly.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
---
arch/x86/kernel/ldt.c | 9 ++++++++-
arch/x86/kernel/paravirt.c | 4 ++++
arch/x86/xen/enlighten.c | 23 +++++++++++++++++++++++
include/asm-x86/desc.h | 10 +++++++++-
include/asm-x86/paravirt.h | 13 +++++++++++++
5 files changed, 57 insertions(+), 2 deletions(-)
===================================================================
--- a/arch/x86/kernel/ldt.c
+++ b/arch/x86/kernel/ldt.c
@@ -52,6 +52,8 @@
memset(newldt + oldsize * LDT_ENTRY_SIZE, 0,
(mincount - oldsize) * LDT_ENTRY_SIZE);
+ paravirt_alloc_ldt(newldt, mincount);
+
#ifdef CONFIG_X86_64
/* CHECKME: Do we really need this ? */
wmb();
@@ -76,6 +78,7 @@
#endif
}
if (oldsize) {
+ paravirt_free_ldt(oldldt, oldsize);
if (oldsize * LDT_ENTRY_SIZE > PAGE_SIZE)
vfree(oldldt);
else
@@ -87,10 +90,13 @@
static inline int copy_ldt(mm_context_t *new, mm_context_t *old)
{
int err = alloc_ldt(new, old->size, 0);
+ int i;
if (err < 0)
return err;
- memcpy(new->ldt, old->ldt, old->size * LDT_ENTRY_SIZE);
+
+ for(i = 0; i < old->size; i++)
+ write_ldt_entry(new->ldt, i, old->ldt + i * LDT_ENTRY_SIZE);
return 0;
}
@@ -127,6 +133,7 @@
if (mm == current->active_mm)
clear_LDT();
#endif
+ paravirt_free_ldt(mm->context.ldt, mm->context.size);
if (mm->context.size * LDT_ENTRY_SIZE > PAGE_SIZE)
vfree(mm->context.ldt);
else
===================================================================
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -350,6 +350,10 @@
.write_ldt_entry = native_write_ldt_entry,
.write_gdt_entry = native_write_gdt_entry,
.write_idt_entry = native_write_idt_entry,
+
+ .alloc_ldt = paravirt_nop,
+ .free_ldt = paravirt_nop,
+
.load_sp0 = native_load_sp0,
#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
===================================================================
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -327,6 +327,26 @@
static unsigned long xen_store_tr(void)
{
return 0;
+}
+
+static void xen_alloc_ldt(struct desc_struct *ldt, unsigned entries)
+{
+ unsigned pages = roundup(entries * LDT_ENTRY_SIZE, PAGE_SIZE);
+ void *v = ldt;
+ int i;
+
+ for(i = 0; i < pages; i += PAGE_SIZE)
+ make_lowmem_page_readonly(v + i);
+}
+
+static void xen_free_ldt(struct desc_struct *ldt, unsigned entries)
+{
+ unsigned pages = roundup(entries * LDT_ENTRY_SIZE, PAGE_SIZE);
+ void *v = ldt;
+ int i;
+
+ for(i = 0; i < pages; i += PAGE_SIZE)
+ make_lowmem_page_readwrite(v + i);
}
static void xen_set_ldt(const void *addr, unsigned entries)
@@ -1269,6 +1289,9 @@
.load_gs_index = xen_load_gs_index,
#endif
+ .alloc_ldt = xen_alloc_ldt,
+ .free_ldt = xen_free_ldt,
+
.store_gdt = native_store_gdt,
.store_idt = native_store_idt,
.store_tr = xen_store_tr,
===================================================================
--- a/include/asm-x86/desc.h
+++ b/include/asm-x86/desc.h
@@ -97,7 +97,15 @@
native_write_gdt_entry(dt, entry, desc, type)
#define write_idt_entry(dt, entry, g) \
native_write_idt_entry(dt, entry, g)
-#endif
+
+static inline void paravirt_alloc_ldt(struct desc_struct *ldt, unsigned entries)
+{
+}
+
+static inline void paravirt_free_ldt(struct desc_struct *ldt, unsigned entries)
+{
+}
+#endif /* CONFIG_PARAVIRT */
static inline void native_write_idt_entry(gate_desc *idt, int entry,
const gate_desc *gate)
===================================================================
--- a/include/asm-x86/paravirt.h
+++ b/include/asm-x86/paravirt.h
@@ -124,6 +124,9 @@
int entrynum, const void *desc, int size);
void (*write_idt_entry)(gate_desc *,
int entrynum, const gate_desc *gate);
+ void (*alloc_ldt)(struct desc_struct *ldt, unsigned entries);
+ void (*free_ldt)(struct desc_struct *ldt, unsigned entries);
+
void (*load_sp0)(struct tss_struct *tss, struct thread_struct *t);
void (*set_iopl_mask)(unsigned mask);
@@ -819,6 +822,16 @@
(aux) = __aux; \
} while (0)
+static inline void paravirt_alloc_ldt(struct desc_struct *ldt, unsigned entries)
+{
+ PVOP_VCALL2(pv_cpu_ops.alloc_ldt, ldt, entries);
+}
+
+static inline void paravirt_free_ldt(struct desc_struct *ldt, unsigned entries)
+{
+ PVOP_VCALL2(pv_cpu_ops.free_ldt, ldt, entries);
+}
+
static inline void load_TR_desc(void)
{
PVOP_VCALL0(pv_cpu_ops.load_tr_desc);
--
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