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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2 04/55] x86/mm: introduce l{1, 2}t local variables to map_pages_to_xen
From: Wei Liu <wei.liu2@xxxxxxxxxx>
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>
---
xen/arch/x86/mm.c | 75 ++++++++++++++++++++++++++---------------------
1 file changed, 42 insertions(+), 33 deletions(-)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index e2c8c3f3a1..2ae8a7736f 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -5061,10 +5061,12 @@ int map_pages_to_xen(
}
else
{
- pl2e = l3e_to_l2e(ol3e);
+ l2_pgentry_t *l2t;
+
+ 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 )
@@ -5072,21 +5074,22 @@ int map_pages_to_xen(
else
{
unsigned int j;
+ l1_pgentry_t *l1t;
- pl1e = l2e_to_l1e(ol2e);
+ l1t = 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);
}
}
@@ -5102,6 +5105,7 @@ 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 *
@@ -5123,12 +5127,12 @@ 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)));
@@ -5141,15 +5145,15 @@ 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);
@@ -5177,11 +5181,13 @@ int map_pages_to_xen(
}
else
{
- pl1e = l2e_to_l1e(ol2e);
+ l1_pgentry_t *l1t;
+
+ 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);
}
}
@@ -5203,6 +5209,7 @@ 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)) +
@@ -5222,12 +5229,12 @@ 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))));
@@ -5239,15 +5246,15 @@ 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);
@@ -5272,6 +5279,7 @@ int map_pages_to_xen(
((1u << PAGETABLE_ORDER) - 1)) == 0)) )
{
unsigned long base_mfn;
+ l1_pgentry_t *l1t;
if ( locking )
spin_lock(&map_pgdir_lock);
@@ -5295,11 +5303,11 @@ 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 )
{
@@ -5325,6 +5333,7 @@ int map_pages_to_xen(
((1UL << (L3_PAGETABLE_SHIFT - PAGE_SHIFT)) - 1))) )
{
unsigned long base_mfn;
+ l2_pgentry_t *l2t;
if ( locking )
spin_lock(&map_pgdir_lock);
@@ -5342,13 +5351,13 @@ 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 )
{
--
2.17.1
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