Mailing List Archive

[xen master] x86/mm: Refactor modify_xen_mappings to have one exit path
commit b733f8a8b8db83f2d438cab3adb38b387cecfce0
Author: Wei Liu <wei.liu2@citrix.com>
AuthorDate: Sat Jan 11 21:57:42 2020 +0000
Commit: Jan Beulich <jbeulich@suse.com>
CommitDate: Tue Oct 20 14:19:55 2020 +0200

x86/mm: Refactor modify_xen_mappings to have one exit path

We will soon need to perform clean-ups before returning.

No functional change.

This is part of XSA-345.

Reported-by: Hongyan Xia <hongyxia@amazon.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Hongyan Xia <hongyxia@amazon.com>
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
---
xen/arch/x86/mm.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 0495b6891a..1b8202852e 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -5468,6 +5468,7 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
l1_pgentry_t *pl1e;
unsigned int i;
unsigned long v = s;
+ int rc = -ENOMEM;

/* Set of valid PTE bits which may be altered. */
#define FLAGS_MASK (_PAGE_NX|_PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_RW|_PAGE_PRESENT)
@@ -5511,7 +5512,8 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
/* PAGE1GB: shatter the superpage and fall through. */
l2t = alloc_xen_pagetable();
if ( !l2t )
- return -ENOMEM;
+ goto out;
+
for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
l2e_write(l2t + i,
l2e_from_pfn(l3e_get_pfn(*pl3e) +
@@ -5568,7 +5570,8 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
/* PSE: shatter the superpage and try again. */
l1t = alloc_xen_pagetable();
if ( !l1t )
- return -ENOMEM;
+ goto out;
+
for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
l1e_write(&l1t[i],
l1e_from_pfn(l2e_get_pfn(*pl2e) + i,
@@ -5701,7 +5704,10 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
flush_area(NULL, FLUSH_TLB_GLOBAL);

#undef FLAGS_MASK
- return 0;
+ rc = 0;
+
+ out:
+ return rc;
}

#undef flush_area
--
generated by git-patchbot for /home/xen/git/xen.git#master