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x86/mm: introduce l{1,2}t local variables to map_pages_to_xen

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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@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
This commit is contained in:
Wei Liu authored and Wei Liu committed 2020-01-07 13:33:19 +00:00
1 parent 8c4392063f
commit 238a8da06d
1 file changed
+39 -33
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xen/arch/x86/mm.c
+39 -33
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@@ -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 )
{
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