[xen staging] x86/mm: Refactor modify_xen_mappings to have one exit path

[patchbot@xxxxxxx]

commit b733f8a8b8db83f2d438cab3adb38b387cecfce0
Author:     Wei Liu <wei.liu2@xxxxxxxxxx>
AuthorDate: Sat Jan 11 21:57:42 2020 +0000
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
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@xxxxxxxxxx>
    Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    Signed-off-by: Hongyan Xia <hongyxia@xxxxxxxxxx>
    Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 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#staging