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    SubjectRe: [PATCH] x86: fix init_memory_mapping over boundary v4
    Yinghai Lu wrote:
    > some end boundary is only page alignment, instead of 2M alignment,
    > so call ker_phycial_mapping_init three times.
    > then don't overmap above the max_low_pfn
    >
    > v2: make init_memory_mapping more solid: start could be any value other than 0
    > v3: fix NON PAE by handling left over in kernel_physical_mapping
    > v4: revert back to v2, and use PMD_SHIFT to calculate boundary
    > also adjust size for pre-allocated table size
    >
    > Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
    >
    > ---
    > arch/x86/mm/init_32.c | 101 +++++++++++++++++++++++++++++++++++++-------------
    > 1 file changed, 75 insertions(+), 26 deletions(-)
    >
    > Index: linux-2.6/arch/x86/mm/init_32.c
    > ===================================================================
    > --- linux-2.6.orig/arch/x86/mm/init_32.c
    > +++ linux-2.6/arch/x86/mm/init_32.c
    > @@ -184,8 +184,9 @@ static inline int is_kernel_text(unsigne
    > * PAGE_OFFSET:
    > */
    > static void __init kernel_physical_mapping_init(pgd_t *pgd_base,
    > - unsigned long start,
    > - unsigned long end)
    > + unsigned long start_pfn,
    > + unsigned long end_pfn,
    > + int use_pse)
    > {
    > int pgd_idx, pmd_idx, pte_ofs;
    > unsigned long pfn;
    > @@ -193,32 +194,33 @@ static void __init kernel_physical_mappi
    > pmd_t *pmd;
    > pte_t *pte;
    > unsigned pages_2m = 0, pages_4k = 0;
    > - unsigned limit_pfn = end >> PAGE_SHIFT;
    >
    > - pgd_idx = pgd_index(PAGE_OFFSET);
    > - pgd = pgd_base + pgd_idx;
    > - pfn = start >> PAGE_SHIFT;
    > + if (!cpu_has_pse)
    > + use_pse = 0;
    >
    > + pfn = start_pfn;
    > + pgd_idx = pgd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
    > + pgd = pgd_base + pgd_idx;
    > for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
    > pmd = one_md_table_init(pgd);
    > - if (pfn >= limit_pfn)
    > - continue;
    >
    > - for (pmd_idx = 0;
    > - pmd_idx < PTRS_PER_PMD && pfn < limit_pfn;
    > + if (pfn >= end_pfn)
    > + continue;
    > +#ifdef CONFIG_X86_PAE
    > + pmd_idx = pmd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
    > + pmd += pmd_idx;
    > +#else
    > + pmd_idx = 0;
    > +#endif
    >

    We should really define X_index() to return 0 for folded pagetable level
    X. I've had to put similar #ifdefs in other code. Also, for the
    purposes of making this code more unifiable, it's probably better to
    test for "#if PAGETABLE_LEVELS >= 3" rather than for PAE specifically.

    > + for (; pmd_idx < PTRS_PER_PMD && pfn < end_pfn;
    > pmd++, pmd_idx++) {
    > unsigned int addr = pfn * PAGE_SIZE + PAGE_OFFSET;
    >
    > /*
    > * Map with big pages if possible, otherwise
    > * create normal page tables:
    > - *
    > - * Don't use a large page for the first 2/4MB of memory
    > - * because there are often fixed size MTRRs in there
    > - * and overlapping MTRRs into large pages can cause
    > - * slowdowns.
    > */
    > - if (cpu_has_pse && !(pgd_idx == 0 && pmd_idx == 0)) {
    > + if (use_pse) {
    > unsigned int addr2;
    > pgprot_t prot = PAGE_KERNEL_LARGE;
    >
    > @@ -233,13 +235,13 @@ static void __init kernel_physical_mappi
    > set_pmd(pmd, pfn_pmd(pfn, prot));
    >
    > pfn += PTRS_PER_PTE;
    > - max_pfn_mapped = pfn;
    > continue;
    > }
    > pte = one_page_table_init(pmd);
    >
    > - for (pte_ofs = 0;
    > - pte_ofs < PTRS_PER_PTE && pfn < max_low_pfn;
    > + pte_ofs = pte_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
    > + pte += pte_ofs;
    > + for (; pte_ofs < PTRS_PER_PTE && pfn < end_pfn;
    > pte++, pfn++, pte_ofs++, addr += PAGE_SIZE) {
    > pgprot_t prot = PAGE_KERNEL;
    >
    > @@ -249,7 +251,6 @@ static void __init kernel_physical_mappi
    > pages_4k++;
    > set_pte(pte, pfn_pte(pfn, prot));
    > }
    > - max_pfn_mapped = pfn;
    > }
    > }
    > update_page_count(PG_LEVEL_2M, pages_2m);
    > @@ -729,7 +730,7 @@ void __init setup_bootmem_allocator(void
    >
    > static void __init find_early_table_space(unsigned long end)
    > {
    > - unsigned long puds, pmds, tables, start;
    > + unsigned long puds, pmds, ptes, tables, start;
    >
    > puds = (end + PUD_SIZE - 1) >> PUD_SHIFT;
    > tables = PAGE_ALIGN(puds * sizeof(pud_t));
    > @@ -737,10 +738,19 @@ static void __init find_early_table_spac
    > pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT;
    > tables += PAGE_ALIGN(pmds * sizeof(pmd_t));
    >
    > - if (!cpu_has_pse) {
    > - int ptes = (end + PAGE_SIZE - 1) >> PAGE_SHIFT;
    > - tables += PAGE_ALIGN(ptes * sizeof(pte_t));
    > - }
    > + if (cpu_has_pse) {
    > + unsigned long extra;
    > +
    > + extra = end - ((end>>PMD_SHIFT) << PMD_SHIFT);
    > + extra += PMD_SIZE;
    >

    Is this the same as "extra = (end + PMD_SIZE + 1) & PMD_MASK"?

    > + ptes = (extra + PAGE_SIZE - 1) >> PAGE_SHIFT;
    > + } else
    > + ptes = (end + PAGE_SIZE - 1) >> PAGE_SHIFT;
    > +
    > + tables += PAGE_ALIGN(ptes * sizeof(pte_t));
    > +
    > + /* for fixmap */
    > + tables += PAGE_SIZE * 2;
    >

    Why not correct for fixmaps by putting "ptes +=
    __end_of_fixed_addresses;" above?

    > /*
    > * RED-PEN putting page tables only on node 0 could
    > @@ -766,6 +776,8 @@ unsigned long __init_refok init_memory_m
    > unsigned long end)
    > {
    > pgd_t *pgd_base = swapper_pg_dir;
    > + unsigned long start_pfn, end_pfn;
    > + unsigned long big_page_start;
    >
    > /*
    > * Find space for the kernel direct mapping tables.
    > @@ -790,7 +802,44 @@ unsigned long __init_refok init_memory_m
    > __PAGE_KERNEL_EXEC |= _PAGE_GLOBAL;
    > }
    >
    > - kernel_physical_mapping_init(pgd_base, start, end);
    > + /*
    > + * Don't use a large page for the first 2/4MB of memory
    > + * because there are often fixed size MTRRs in there
    > + * and overlapping MTRRs into large pages can cause
    > + * slowdowns.
    > + */
    > + big_page_start = PMD_SIZE;
    > +
    > + if (start < big_page_start) {
    > + start_pfn = start >> PAGE_SHIFT;
    > + end_pfn = min(big_page_start>>PAGE_SHIFT, end>>PAGE_SHIFT);
    > + } else {
    > + /* head is not big page alignment ? */
    > + start_pfn = start >> PAGE_SHIFT;
    > + end_pfn = ((start + PMD_SIZE - 1)>>PMD_SHIFT)
    > + << (PMD_SHIFT - PAGE_SHIFT);
    > + }
    > + if (start_pfn < end_pfn)
    > + kernel_physical_mapping_init(pgd_base, start_pfn, end_pfn, 0);
    > +
    > + /* big page range */
    > + start_pfn = ((start + PMD_SIZE - 1)>>PMD_SHIFT)
    > + << (PMD_SHIFT - PAGE_SHIFT);
    > + if (start_pfn < (big_page_start >> PAGE_SHIFT))
    > + start_pfn = big_page_start >> PAGE_SHIFT;
    > + end_pfn = (end>>PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
    > + if (start_pfn < end_pfn)
    > + kernel_physical_mapping_init(pgd_base, start_pfn, end_pfn,
    > + cpu_has_pse);
    > +
    > + /* tail is not big page alignment ? */
    > + start_pfn = end_pfn;
    > + if (start_pfn > (big_page_start>>PAGE_SHIFT)) {
    > + end_pfn = end >> PAGE_SHIFT;
    > + if (start_pfn < end_pfn)
    > + kernel_physical_mapping_init(pgd_base, start_pfn,
    > + end_pfn, 0);
    > + }
    >
    > early_ioremap_page_table_range_init(pgd_base);
    >
    >

    J


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