[Xen-devel] [PATCH 03/24] xen: dynamically allocate p2m tables

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

From: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>

Saves about 128k static object size.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
 arch/x86/xen/mmu.c |   38 +++++++++++++++++++++++++++++---------
 1 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index d534986..05280b4 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -159,18 +159,14 @@ DEFINE_PER_CPU(unsigned long, xen_current_cr3);    /* 
actual vcpu cr3 */
 #define TOP_ENTRIES            (MAX_DOMAIN_PAGES / P2M_ENTRIES_PER_PAGE)
 
 /* Placeholder for holes in the address space */
-static unsigned long p2m_missing[P2M_ENTRIES_PER_PAGE] __page_aligned_data =
-               { [ 0 ... P2M_ENTRIES_PER_PAGE-1 ] = ~0UL };
+static unsigned long *p2m_missing;
 
  /* Array of pointers to pages containing p2m entries */
-static unsigned long *p2m_top[TOP_ENTRIES] __page_aligned_data =
-               { [ 0 ... TOP_ENTRIES - 1] = &p2m_missing[0] };
+static unsigned long **p2m_top;
 
 /* Arrays of p2m arrays expressed in mfns used for save/restore */
-static unsigned long p2m_top_mfn[TOP_ENTRIES] __page_aligned_bss;
-
-static unsigned long p2m_top_mfn_list[TOP_ENTRIES / P2M_ENTRIES_PER_PAGE]
-       __page_aligned_bss;
+static unsigned long *p2m_top_mfn;
+static unsigned long *p2m_top_mfn_list;
 
 static inline unsigned p2m_top_index(unsigned long pfn)
 {
@@ -183,18 +179,28 @@ static inline unsigned p2m_index(unsigned long pfn)
        return pfn % P2M_ENTRIES_PER_PAGE;
 }
 
+#define SIZE_TOP_MFN sizeof(*p2m_top_mfn) * TOP_ENTRIES
+#define SIZE_TOP_MFN_LIST sizeof(*p2m_top_mfn_list) *                  \
+       (TOP_ENTRIES / P2M_ENTRIES_PER_PAGE)
+
+RESERVE_BRK(xen_top_mfn, SIZE_TOP_MFN);
+RESERVE_BRK(xen_top_mfn_list, SIZE_TOP_MFN_LIST);
+
 /* Build the parallel p2m_top_mfn structures */
 void xen_setup_mfn_list_list(void)
 {
        unsigned pfn, idx;
 
+       p2m_top_mfn = extend_brk(SIZE_TOP_MFN, PAGE_SIZE);
+       p2m_top_mfn_list = extend_brk(SIZE_TOP_MFN_LIST, PAGE_SIZE);
+
        for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn += P2M_ENTRIES_PER_PAGE) {
                unsigned topidx = p2m_top_index(pfn);
 
                p2m_top_mfn[topidx] = virt_to_mfn(p2m_top[topidx]);
        }
 
-       for (idx = 0; idx < ARRAY_SIZE(p2m_top_mfn_list); idx++) {
+       for (idx = 0; idx < (TOP_ENTRIES / P2M_ENTRIES_PER_PAGE); idx++) {
                unsigned topidx = idx * P2M_ENTRIES_PER_PAGE;
                p2m_top_mfn_list[idx] = virt_to_mfn(&p2m_top_mfn[topidx]);
        }
@@ -206,12 +212,26 @@ void xen_setup_mfn_list_list(void)
        HYPERVISOR_shared_info->arch.max_pfn = xen_start_info->nr_pages;
 }
 
+#define SIZE_P2M_MISSING       sizeof(*p2m_missing) * P2M_ENTRIES_PER_PAGE
+#define SIZE_P2M_TOP           sizeof(*p2m_top) * TOP_ENTRIES
+RESERVE_BRK(xen_p2m_missing, SIZE_P2M_MISSING);
+RESERVE_BRK(xen_p2m_top, SIZE_P2M_TOP);
+
 /* Set up p2m_top to point to the domain-builder provided p2m pages */
 void __init xen_build_dynamic_phys_to_machine(void)
 {
        unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list;
        unsigned long max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages);
        unsigned pfn;
+       unsigned i;
+
+       p2m_missing = extend_brk(SIZE_P2M_MISSING, PAGE_SIZE);
+       for(i = 0; i < P2M_ENTRIES_PER_PAGE; i++)
+               p2m_missing[i] = ~0ul;
+
+       p2m_top = extend_brk(SIZE_P2M_TOP, PAGE_SIZE);
+       for(i = 0; i < TOP_ENTRIES; i++)
+               p2m_top[i] = p2m_missing;
 
        for (pfn = 0; pfn < max_pfn; pfn += P2M_ENTRIES_PER_PAGE) {
                unsigned topidx = p2m_top_index(pfn);
-- 
1.6.0.6


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