Remove the distinction between GDT and LDT pages, as was discussed a
while back. Such pages could really be used in both tables. The
purpose, however, is to free up a page type which can subsequently
(by code yet to be written) be used for a generic guest-may-only-map-
readonly page type as would be desirable for e.g. implementing debug
store virtualization (Linux 2.6.25 made a first attempt at adding
support for the debug trace store to the ptrace interface, but due to
issues with that code it got disabled again - nevertheless I would
prefer Xen being able to handle this once it becomes available, so we
don't need to prevent the code from being executed in the kernel).
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
Index: 2008-04-01/xen/arch/x86/mm.c
===================================================================
--- 2008-04-01.orig/xen/arch/x86/mm.c 2008-04-01 14:24:03.000000000 +0200
+++ 2008-04-01/xen/arch/x86/mm.c 2008-04-01 15:12:27.000000000 +0200
@@ -476,7 +476,7 @@ static void invalidate_shadow_ldt(struct
if ( pfn == 0 ) continue;
l1e_write(&v->arch.perdomain_ptes[i], l1e_empty());
page = mfn_to_page(pfn);
- ASSERT_PAGE_IS_TYPE(page, PGT_ldt_page);
+ ASSERT_PAGE_IS_TYPE(page, PGT_descriptor_page);
ASSERT_PAGE_IS_DOMAIN(page, v->domain);
put_page_and_type(page);
}
@@ -530,7 +530,7 @@ int map_ldt_shadow_page(unsigned int off
if ( unlikely(!mfn_valid(mfn)) )
return 0;
- okay = get_page_and_type(mfn_to_page(mfn), d, PGT_ldt_page);
+ okay = get_page_and_type(mfn_to_page(mfn), d, PGT_descriptor_page);
if ( unlikely(!okay) )
return 0;
@@ -924,7 +924,7 @@ void put_page_from_l1e(l1_pgentry_t l1e,
{
/* We expect this is rare so we blow the entire shadow LDT. */
if ( unlikely(((page->u.inuse.type_info & PGT_type_mask) ==
- PGT_ldt_page)) &&
+ PGT_descriptor_page)) &&
unlikely(((page->u.inuse.type_info & PGT_count_mask) != 0)) &&
(d == e) )
{
@@ -1748,8 +1748,7 @@ static int alloc_page_type(struct page_i
return alloc_l3_table(page);
case PGT_l4_page_table:
return alloc_l4_table(page);
- case PGT_gdt_page:
- case PGT_ldt_page:
+ case PGT_descriptor_page:
return alloc_segdesc_page(page);
default:
printk("Bad type in alloc_page_type %lx t=%" PRtype_info " c=%x\n",
@@ -3134,7 +3133,7 @@ long set_gdt(struct vcpu *v,
{
mfn = frames[i] = gmfn_to_mfn(d, frames[i]);
if ( !mfn_valid(mfn) ||
- !get_page_and_type(mfn_to_page(mfn), d, PGT_gdt_page) )
+ !get_page_and_type(mfn_to_page(mfn), d, PGT_descriptor_page) )
goto fail;
}
@@ -3211,12 +3210,8 @@ long do_update_descriptor(u64 pa, u64 de
/* Check if the given frame is in use in an unsafe context. */
switch ( page->u.inuse.type_info & PGT_type_mask )
{
- case PGT_gdt_page:
- if ( unlikely(!get_page_type(page, PGT_gdt_page)) )
- goto out;
- break;
- case PGT_ldt_page:
- if ( unlikely(!get_page_type(page, PGT_ldt_page)) )
+ case PGT_descriptor_page:
+ if ( unlikely(!get_page_type(page, PGT_descriptor_page)) )
goto out;
break;
default:
Index: 2008-04-01/xen/include/asm-x86/mm.h
===================================================================
--- 2008-04-01.orig/xen/include/asm-x86/mm.h 2008-04-01 14:20:25.000000000
+0200
+++ 2008-04-01/xen/include/asm-x86/mm.h 2008-04-01 15:09:44.000000000 +0200
@@ -69,8 +69,7 @@ struct page_info
#define PGT_l2_page_table (2U<<29) /* using this page as an L2 page table? */
#define PGT_l3_page_table (3U<<29) /* using this page as an L3 page table? */
#define PGT_l4_page_table (4U<<29) /* using this page as an L4 page table? */
-#define PGT_gdt_page (5U<<29) /* using this page in a GDT? */
-#define PGT_ldt_page (6U<<29) /* using this page in an LDT? */
+#define PGT_descriptor_page (5U<<29) /* using this page in a GDT/LDT? */
#define PGT_writable_page (7U<<29) /* has writable mappings of this page? */
#define PGT_type_mask (7U<<29) /* Bits 29-31. */
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