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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen master] x86/mm: introduce l{1, 2}t local variables to modify_xen_mappings
commit f383de87a2fb077f1fdbd4594493af613b15c233
Author: Wei Liu <wei.liu2@xxxxxxxxxx>
AuthorDate: Tue Jan 7 12:06:46 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 modify_xen_mappings
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 | 68 +++++++++++++++++++++++++++++++------------------------
1 file changed, 38 insertions(+), 30 deletions(-)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index b8bc82953c..9024ab258b 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -5541,6 +5541,8 @@ int modify_xen_mappings(unsigned long s, unsigned long e,
unsigned int nf)
if ( l3e_get_flags(*pl3e) & _PAGE_PSE )
{
+ l2_pgentry_t *l2t;
+
if ( l2_table_offset(v) == 0 &&
l1_table_offset(v) == 0 &&
((e - v) >= (1UL << L3_PAGETABLE_SHIFT)) )
@@ -5556,11 +5558,11 @@ int modify_xen_mappings(unsigned long s, unsigned long
e, unsigned int nf)
}
/* PAGE1GB: shatter the superpage and fall through. */
- pl2e = alloc_xen_pagetable();
- if ( !pl2e )
+ l2t = alloc_xen_pagetable();
+ if ( !l2t )
return -ENOMEM;
for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
- l2e_write(pl2e + i,
+ l2e_write(l2t + i,
l2e_from_pfn(l3e_get_pfn(*pl3e) +
(i << PAGETABLE_ORDER),
l3e_get_flags(*pl3e)));
@@ -5569,14 +5571,14 @@ int modify_xen_mappings(unsigned long s, unsigned long
e, unsigned int nf)
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);
- if ( pl2e )
- free_xen_pagetable(pl2e);
+ if ( l2t )
+ free_xen_pagetable(l2t);
}
/*
@@ -5610,12 +5612,14 @@ int modify_xen_mappings(unsigned long s, unsigned long
e, unsigned int nf)
}
else
{
+ l1_pgentry_t *l1t;
+
/* PSE: shatter the superpage and try again. */
- pl1e = alloc_xen_pagetable();
- if ( !pl1e )
+ l1t = alloc_xen_pagetable();
+ if ( !l1t )
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,
l2e_get_flags(*pl2e) & ~_PAGE_PSE));
if ( locking )
@@ -5623,19 +5627,19 @@ int modify_xen_mappings(unsigned long s, unsigned long
e, unsigned int nf)
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);
- if ( pl1e )
- free_xen_pagetable(pl1e);
+ if ( l1t )
+ free_xen_pagetable(l1t);
}
}
else
{
- l1_pgentry_t nl1e;
+ l1_pgentry_t nl1e, *l1t;
/*
* Ordinary 4kB mapping: The L2 entry has been verified to be
@@ -5682,9 +5686,9 @@ int modify_xen_mappings(unsigned long s, unsigned long e,
unsigned int nf)
continue;
}
- pl1e = l2e_to_l1e(*pl2e);
+ l1t = l2e_to_l1e(*pl2e);
for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
- if ( l1e_get_intpte(pl1e[i]) != 0 )
+ if ( l1e_get_intpte(l1t[i]) != 0 )
break;
if ( i == L1_PAGETABLE_ENTRIES )
{
@@ -5693,7 +5697,7 @@ int modify_xen_mappings(unsigned long s, unsigned long e,
unsigned int nf)
if ( locking )
spin_unlock(&map_pgdir_lock);
flush_area(NULL, FLUSH_TLB_GLOBAL); /* flush before free */
- free_xen_pagetable(pl1e);
+ free_xen_pagetable(l1t);
}
else if ( locking )
spin_unlock(&map_pgdir_lock);
@@ -5722,21 +5726,25 @@ int modify_xen_mappings(unsigned long s, unsigned long
e, unsigned int nf)
continue;
}
- pl2e = l3e_to_l2e(*pl3e);
- for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
- if ( l2e_get_intpte(pl2e[i]) != 0 )
- break;
- if ( i == L2_PAGETABLE_ENTRIES )
{
- /* Empty: zap the L3E and free the L2 page. */
- l3e_write_atomic(pl3e, l3e_empty());
- if ( locking )
+ l2_pgentry_t *l2t;
+
+ l2t = l3e_to_l2e(*pl3e);
+ for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
+ if ( l2e_get_intpte(l2t[i]) != 0 )
+ break;
+ if ( i == L2_PAGETABLE_ENTRIES )
+ {
+ /* Empty: zap the L3E and free the L2 page. */
+ l3e_write_atomic(pl3e, l3e_empty());
+ if ( locking )
+ spin_unlock(&map_pgdir_lock);
+ flush_area(NULL, FLUSH_TLB_GLOBAL); /* flush before free */
+ free_xen_pagetable(l2t);
+ }
+ else if ( locking )
spin_unlock(&map_pgdir_lock);
- flush_area(NULL, FLUSH_TLB_GLOBAL); /* flush before free */
- free_xen_pagetable(pl2e);
}
- else if ( locking )
- spin_unlock(&map_pgdir_lock);
}
flush_area(NULL, FLUSH_TLB_GLOBAL);
--
generated by git-patchbot for /home/xen/git/xen.git#master
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