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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen staging] x86/mm: introduce l{1, 2}t local variables to map_pages_to_xen
commit 238a8da06d8ea92b3864e9be5aaa2450f77a6d01
Author: Wei Liu <wei.liu2@xxxxxxxxxx>
AuthorDate: Tue Jan 7 12:06:45 2020 +0000
Commit: Wei Liu <wl@xxxxxxx>
CommitDate: Tue Jan 7 13:33:19 2020 +0000
x86/mm: introduce l{1,2}t local variables to map_pages_to_xen
The pl2e and pl1e variables are heavily (ab)used in that function. It
is fine at the moment because all page tables are always mapped so
there is no need to track the life time of each variable.
We will soon have the requirement to map and unmap page tables. We
need to track the life time of each variable to avoid leakage.
Introduce some l{1,2}t variables with limited scope so that we can
track life time of pointers to xen page tables more easily.
No functional change.
Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
xen/arch/x86/mm.c | 72 ++++++++++++++++++++++++++++++-------------------------
1 file changed, 39 insertions(+), 33 deletions(-)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index cc0d71996c..b8bc82953c 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -5177,10 +5177,11 @@ int map_pages_to_xen(
}
else
{
- pl2e = l3e_to_l2e(ol3e);
+ l2_pgentry_t *l2t = l3e_to_l2e(ol3e);
+
for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
{
- ol2e = pl2e[i];
+ ol2e = l2t[i];
if ( !(l2e_get_flags(ol2e) & _PAGE_PRESENT) )
continue;
if ( l2e_get_flags(ol2e) & _PAGE_PSE )
@@ -5188,21 +5189,21 @@ int map_pages_to_xen(
else
{
unsigned int j;
+ const l1_pgentry_t *l1t = l2e_to_l1e(ol2e);
- pl1e = l2e_to_l1e(ol2e);
for ( j = 0; j < L1_PAGETABLE_ENTRIES; j++ )
- flush_flags(l1e_get_flags(pl1e[j]));
+ flush_flags(l1e_get_flags(l1t[j]));
}
}
flush_area(virt, flush_flags);
for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
{
- ol2e = pl2e[i];
+ ol2e = l2t[i];
if ( (l2e_get_flags(ol2e) & _PAGE_PRESENT) &&
!(l2e_get_flags(ol2e) & _PAGE_PSE) )
free_xen_pagetable(l2e_to_l1e(ol2e));
}
- free_xen_pagetable(pl2e);
+ free_xen_pagetable(l2t);
}
}
@@ -5218,6 +5219,7 @@ int map_pages_to_xen(
{
unsigned int flush_flags =
FLUSH_TLB | FLUSH_ORDER(2 * PAGETABLE_ORDER);
+ l2_pgentry_t *l2t;
/* Skip this PTE if there is no change. */
if ( ((l3e_get_pfn(ol3e) & ~(L2_PAGETABLE_ENTRIES *
@@ -5239,12 +5241,12 @@ int map_pages_to_xen(
continue;
}
- pl2e = alloc_xen_pagetable();
- if ( pl2e == NULL )
+ l2t = alloc_xen_pagetable();
+ if ( l2t == NULL )
return -ENOMEM;
for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
- l2e_write(pl2e + i,
+ l2e_write(l2t + i,
l2e_from_pfn(l3e_get_pfn(ol3e) +
(i << PAGETABLE_ORDER),
l3e_get_flags(ol3e)));
@@ -5257,15 +5259,15 @@ int map_pages_to_xen(
if ( (l3e_get_flags(*pl3e) & _PAGE_PRESENT) &&
(l3e_get_flags(*pl3e) & _PAGE_PSE) )
{
- l3e_write_atomic(pl3e, l3e_from_mfn(virt_to_mfn(pl2e),
+ l3e_write_atomic(pl3e, l3e_from_mfn(virt_to_mfn(l2t),
__PAGE_HYPERVISOR));
- pl2e = NULL;
+ l2t = NULL;
}
if ( locking )
spin_unlock(&map_pgdir_lock);
flush_area(virt, flush_flags);
- if ( pl2e )
- free_xen_pagetable(pl2e);
+ if ( l2t )
+ free_xen_pagetable(l2t);
}
pl2e = virt_to_xen_l2e(virt);
@@ -5293,11 +5295,12 @@ int map_pages_to_xen(
}
else
{
- pl1e = l2e_to_l1e(ol2e);
+ l1_pgentry_t *l1t = l2e_to_l1e(ol2e);
+
for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
- flush_flags(l1e_get_flags(pl1e[i]));
+ flush_flags(l1e_get_flags(l1t[i]));
flush_area(virt, flush_flags);
- free_xen_pagetable(pl1e);
+ free_xen_pagetable(l1t);
}
}
@@ -5319,6 +5322,7 @@ int map_pages_to_xen(
{
unsigned int flush_flags =
FLUSH_TLB | FLUSH_ORDER(PAGETABLE_ORDER);
+ l1_pgentry_t *l1t;
/* Skip this PTE if there is no change. */
if ( (((l2e_get_pfn(*pl2e) & ~(L1_PAGETABLE_ENTRIES - 1)) +
@@ -5338,12 +5342,12 @@ int map_pages_to_xen(
goto check_l3;
}
- pl1e = alloc_xen_pagetable();
- if ( pl1e == NULL )
+ l1t = alloc_xen_pagetable();
+ if ( l1t == NULL )
return -ENOMEM;
for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
- l1e_write(&pl1e[i],
+ l1e_write(&l1t[i],
l1e_from_pfn(l2e_get_pfn(*pl2e) + i,
lNf_to_l1f(l2e_get_flags(*pl2e))));
@@ -5355,15 +5359,15 @@ int map_pages_to_xen(
if ( (l2e_get_flags(*pl2e) & _PAGE_PRESENT) &&
(l2e_get_flags(*pl2e) & _PAGE_PSE) )
{
- l2e_write_atomic(pl2e, l2e_from_mfn(virt_to_mfn(pl1e),
+ l2e_write_atomic(pl2e, l2e_from_mfn(virt_to_mfn(l1t),
__PAGE_HYPERVISOR));
- pl1e = NULL;
+ l1t = NULL;
}
if ( locking )
spin_unlock(&map_pgdir_lock);
flush_area(virt, flush_flags);
- if ( pl1e )
- free_xen_pagetable(pl1e);
+ if ( l1t )
+ free_xen_pagetable(l1t);
}
pl1e = l2e_to_l1e(*pl2e) + l1_table_offset(virt);
@@ -5388,6 +5392,7 @@ int map_pages_to_xen(
((1u << PAGETABLE_ORDER) - 1)) == 0)) )
{
unsigned long base_mfn;
+ const l1_pgentry_t *l1t;
if ( locking )
spin_lock(&map_pgdir_lock);
@@ -5411,11 +5416,11 @@ int map_pages_to_xen(
goto check_l3;
}
- pl1e = l2e_to_l1e(ol2e);
- base_mfn = l1e_get_pfn(*pl1e) & ~(L1_PAGETABLE_ENTRIES - 1);
- for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++, pl1e++ )
- if ( (l1e_get_pfn(*pl1e) != (base_mfn + i)) ||
- (l1e_get_flags(*pl1e) != flags) )
+ l1t = l2e_to_l1e(ol2e);
+ base_mfn = l1e_get_pfn(l1t[0]) & ~(L1_PAGETABLE_ENTRIES - 1);
+ for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
+ if ( (l1e_get_pfn(l1t[i]) != (base_mfn + i)) ||
+ (l1e_get_flags(l1t[i]) != flags) )
break;
if ( i == L1_PAGETABLE_ENTRIES )
{
@@ -5441,6 +5446,7 @@ int map_pages_to_xen(
((1UL << (L3_PAGETABLE_SHIFT - PAGE_SHIFT)) - 1))) )
{
unsigned long base_mfn;
+ const l2_pgentry_t *l2t;
if ( locking )
spin_lock(&map_pgdir_lock);
@@ -5458,13 +5464,13 @@ int map_pages_to_xen(
continue;
}
- pl2e = l3e_to_l2e(ol3e);
- base_mfn = l2e_get_pfn(*pl2e) & ~(L2_PAGETABLE_ENTRIES *
+ l2t = l3e_to_l2e(ol3e);
+ base_mfn = l2e_get_pfn(l2t[0]) & ~(L2_PAGETABLE_ENTRIES *
L1_PAGETABLE_ENTRIES - 1);
- for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++, pl2e++ )
- if ( (l2e_get_pfn(*pl2e) !=
+ for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
+ if ( (l2e_get_pfn(l2t[i]) !=
(base_mfn + (i << PAGETABLE_ORDER))) ||
- (l2e_get_flags(*pl2e) != l1f_to_lNf(flags)) )
+ (l2e_get_flags(l2t[i]) != l1f_to_lNf(flags)) )
break;
if ( i == L2_PAGETABLE_ENTRIES )
{
--
generated by git-patchbot for /home/xen/git/xen.git#staging
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