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    Subject[PATCH 03/24] xen: dynamically allocate p2m tables
    Date
    From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

    Saves about 128k static object size.

    Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
    ---
    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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