From 7353b8245193365720cd09147e6dbf15e60380ab Mon Sep 17 00:00:00 2001
From: "kfraser@localhost.localdomain" <kfraser@localhost.localdomain>
Date: Mon, 26 Feb 2007 16:25:17 +0000
Subject: [PATCH] x86: Clean up {alloc,free}_xen_pagetable() interface to avoid
 use of frame_table variable before initialisation. This wasn't a bug, but was
 confusing. Signed-off-by: Keir Fraser <keir@xensource.com>

---
 xen/arch/x86/mm.c          |  6 +++---
 xen/arch/x86/x86_32/mm.c   | 15 ++++++++-------
 xen/arch/x86/x86_64/mm.c   | 23 ++++++++++++++---------
 xen/include/asm-x86/page.h |  4 ++--
 4 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 8e7bdd44a9..1798be5e52 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -3401,7 +3401,7 @@ int map_pages_to_xen(
             {
                 local_flush_tlb_pge();
                 if ( !(l2e_get_flags(ol2e) & _PAGE_PSE) )
-                    free_xen_pagetable(l2e_get_page(ol2e));
+                    free_xen_pagetable(page_to_virt(l2e_get_page(ol2e)));
             }
 
             virt    += 1UL << L2_PAGETABLE_SHIFT;
@@ -3413,14 +3413,14 @@ int map_pages_to_xen(
             /* Normal page mapping. */
             if ( !(l2e_get_flags(*pl2e) & _PAGE_PRESENT) )
             {
-                pl1e = page_to_virt(alloc_xen_pagetable());
+                pl1e = alloc_xen_pagetable();
                 clear_page(pl1e);
                 l2e_write(pl2e, l2e_from_page(virt_to_page(pl1e),
                                               __PAGE_HYPERVISOR));
             }
             else if ( l2e_get_flags(*pl2e) & _PAGE_PSE )
             {
-                pl1e = page_to_virt(alloc_xen_pagetable());
+                pl1e = alloc_xen_pagetable();
                 for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
                     l1e_write(&pl1e[i],
                               l1e_from_pfn(l2e_get_pfn(*pl2e) + i,
diff --git a/xen/arch/x86/x86_32/mm.c b/xen/arch/x86/x86_32/mm.c
index 76303fc275..291a503e4d 100644
--- a/xen/arch/x86/x86_32/mm.c
+++ b/xen/arch/x86/x86_32/mm.c
@@ -35,26 +35,27 @@ unsigned int PAGE_HYPERVISOR_NOCACHE = __PAGE_HYPERVISOR_NOCACHE;
 
 static unsigned long mpt_size;
 
-struct page_info *alloc_xen_pagetable(void)
+void *alloc_xen_pagetable(void)
 {
     extern int early_boot;
     extern unsigned long xenheap_phys_start;
-    struct page_info *pg;
+    unsigned long mfn;
 
     if ( !early_boot )
     {
         void *v = alloc_xenheap_page();
-        return ((v == NULL) ? NULL : virt_to_page(v));
+        BUG_ON(v == NULL);
+        return v;
     }
 
-    pg = maddr_to_page(xenheap_phys_start);
+    mfn = xenheap_phys_start >> PAGE_SHIFT;
     xenheap_phys_start += PAGE_SIZE;
-    return pg;
+    return mfn_to_virt(mfn);
 }
 
-void free_xen_pagetable(struct page_info *pg)
+void free_xen_pagetable(void *v)
 {
-    free_xenheap_page(page_to_virt(pg));
+    free_xenheap_page(v);
 }
 
 l2_pgentry_t *virt_to_xen_l2e(unsigned long v)
diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index 8ff4da2769..a2e38e7e22 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -36,22 +36,27 @@
 unsigned int m2p_compat_vstart = __HYPERVISOR_COMPAT_VIRT_START;
 #endif
 
-struct page_info *alloc_xen_pagetable(void)
+void *alloc_xen_pagetable(void)
 {
     extern int early_boot;
-    unsigned long pfn;
+    unsigned long mfn;
 
     if ( !early_boot )
-        return alloc_domheap_page(NULL);
+    {
+        struct page_info *pg = alloc_domheap_page(NULL);
+        BUG_ON(pg == NULL);
+        return page_to_virt(pg);
+    }
 
     /* Early pagetables must come from low 1GB of memory. */
-    pfn = alloc_boot_low_pages(1, 1); /* 0x0 - 0x40000000 */
-    return ((pfn == 0) ? NULL : mfn_to_page(pfn));
+    mfn = alloc_boot_low_pages(1, 1); /* 0x0 - 0x40000000 */
+    BUG_ON(mfn == 0);
+    return mfn_to_virt(mfn);
 }
 
-void free_xen_pagetable(struct page_info *pg)
+void free_xen_pagetable(void *v)
 {
-    free_domheap_page(pg);
+    free_domheap_page(virt_to_page(v));
 }
 
 l2_pgentry_t *virt_to_xen_l2e(unsigned long v)
@@ -63,7 +68,7 @@ l2_pgentry_t *virt_to_xen_l2e(unsigned long v)
     pl4e = &idle_pg_table[l4_table_offset(v)];
     if ( !(l4e_get_flags(*pl4e) & _PAGE_PRESENT) )
     {
-        pl3e = page_to_virt(alloc_xen_pagetable());
+        pl3e = alloc_xen_pagetable();
         clear_page(pl3e);
         l4e_write(pl4e, l4e_from_paddr(__pa(pl3e), __PAGE_HYPERVISOR));
     }
@@ -71,7 +76,7 @@ l2_pgentry_t *virt_to_xen_l2e(unsigned long v)
     pl3e = l4e_to_l3e(*pl4e) + l3_table_offset(v);
     if ( !(l3e_get_flags(*pl3e) & _PAGE_PRESENT) )
     {
-        pl2e = page_to_virt(alloc_xen_pagetable());
+        pl2e = alloc_xen_pagetable();
         clear_page(pl2e);
         l3e_write(pl3e, l3e_from_paddr(__pa(pl2e), __PAGE_HYPERVISOR));
     }
diff --git a/xen/include/asm-x86/page.h b/xen/include/asm-x86/page.h
index 31ec281920..1fa6d07cdc 100644
--- a/xen/include/asm-x86/page.h
+++ b/xen/include/asm-x86/page.h
@@ -363,8 +363,8 @@ static inline int get_order_from_pages(unsigned long nr_pages)
 }
 
 /* Allocator functions for Xen pagetables. */
-struct page_info *alloc_xen_pagetable(void);
-void free_xen_pagetable(struct page_info *pg);
+void *alloc_xen_pagetable(void);
+void free_xen_pagetable(void *v);
 l2_pgentry_t *virt_to_xen_l2e(unsigned long v);
 
 /* Map machine page range in Xen virtual address space. */
-- 
2.30.2