1 files changed, 39 insertions, 46 deletions

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index b278535b14aa..30326443ab81 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -2,6 +2,7 @@
 #include <linux/initrd.h>
 #include <linux/ioport.h>
 #include <linux/swap.h>
+#include <linux/memblock.h>
 
 #include <asm/cacheflush.h>
 #include <asm/e820.h>
@@ -15,11 +16,9 @@
 #include <asm/tlb.h>
 #include <asm/proto.h>
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
-unsigned long __initdata e820_table_start;
-unsigned long __meminitdata e820_table_end;
-unsigned long __meminitdata e820_table_top;
+unsigned long __initdata pgt_buf_start;
+unsigned long __meminitdata pgt_buf_end;
+unsigned long __meminitdata pgt_buf_top;
 
 int after_bootmem;
 
@@ -32,7 +31,8 @@ int direct_gbpages
 static void __init find_early_table_space(unsigned long end, int use_pse,
                                           int use_gbpages)
 {
-        unsigned long puds, pmds, ptes, tables, start;
+        unsigned long puds, pmds, ptes, tables, start = 0, good_end = end;
+        phys_addr_t base;
 
         puds = (end + PUD_SIZE - 1) >> PUD_SHIFT;
         tables = roundup(puds * sizeof(pud_t), PAGE_SIZE);
@@ -63,29 +63,25 @@ static void __init find_early_table_space(unsigned long end, int use_pse,
 #ifdef CONFIG_X86_32
         /* for fixmap */
         tables += roundup(__end_of_fixed_addresses * sizeof(pte_t), PAGE_SIZE);
-#endif
 
-        /*
-         * RED-PEN putting page tables only on node 0 could
-         * cause a hotspot and fill up ZONE_DMA. The page tables
-         * need roughly 0.5KB per GB.
-         */
-#ifdef CONFIG_X86_32
-        start = 0x7000;
-#else
-        start = 0x8000;
+        good_end = max_pfn_mapped << PAGE_SHIFT;
 #endif
-        e820_table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
-                                        tables, PAGE_SIZE);
-        if (e820_table_start == -1UL)
+
+        base = memblock_find_in_range(start, good_end, tables, PAGE_SIZE);
+        if (base == MEMBLOCK_ERROR)
                 panic("Cannot find space for the kernel page tables");
 
-        e820_table_start >>= PAGE_SHIFT;
-        e820_table_end = e820_table_start;
-        e820_table_top = e820_table_start + (tables >> PAGE_SHIFT);
+        pgt_buf_start = base >> PAGE_SHIFT;
+        pgt_buf_end = pgt_buf_start;
+        pgt_buf_top = pgt_buf_start + (tables >> PAGE_SHIFT);
 
         printk(KERN_DEBUG "kernel direct mapping tables up to %lx @ %lx-%lx\n",
-                end, e820_table_start << PAGE_SHIFT, e820_table_top << PAGE_SHIFT);
+                end, pgt_buf_start << PAGE_SHIFT, pgt_buf_top << PAGE_SHIFT);
+}
+
+void __init native_pagetable_reserve(u64 start, u64 end)
+{
+        memblock_x86_reserve_range(start, end, "PGTABLE");
 }
 
 struct map_range {
@@ -277,30 +273,26 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
         load_cr3(swapper_pg_dir);
 #endif
 
-#ifdef CONFIG_X86_64
-        if (!after_bootmem && !start) {
-                pud_t *pud;
-                pmd_t *pmd;
-
-                mmu_cr4_features = read_cr4();
-
-                /*
-                 * _brk_end cannot change anymore, but it and _end may be
-                 * located on different 2M pages. cleanup_highmap(), however,
-                 * can only consider _end when it runs, so destroy any
-                 * mappings beyond _brk_end here.
-                 */
-                pud = pud_offset(pgd_offset_k(_brk_end), _brk_end);
-                pmd = pmd_offset(pud, _brk_end - 1);
-                while (++pmd <= pmd_offset(pud, (unsigned long)_end - 1))
-                        pmd_clear(pmd);
-        }
-#endif
         __flush_tlb_all();
 
-        if (!after_bootmem && e820_table_end > e820_table_start)
-                reserve_early(e820_table_start << PAGE_SHIFT,
-                                 e820_table_end << PAGE_SHIFT, "PGTABLE");
+        /*
+         * Reserve the kernel pagetable pages we used (pgt_buf_start -
+         * pgt_buf_end) and free the other ones (pgt_buf_end - pgt_buf_top)
+         * so that they can be reused for other purposes.
+         *
+         * On native it just means calling memblock_x86_reserve_range, on Xen it
+         * also means marking RW the pagetable pages that we allocated before
+         * but that haven't been used.
+         *
+         * In fact on xen we mark RO the whole range pgt_buf_start -
+         * pgt_buf_top, because we have to make sure that when
+         * init_memory_mapping reaches the pagetable pages area, it maps
+         * RO all the pagetable pages, including the ones that are beyond
+         * pgt_buf_end at that time.
+         */
+        if (!after_bootmem && pgt_buf_end > pgt_buf_start)
+                x86_init.mapping.pagetable_reserve(PFN_PHYS(pgt_buf_start),
+                                PFN_PHYS(pgt_buf_end));
 
         if (!after_bootmem)
                 early_memtest(start, end);
@@ -362,8 +354,9 @@ void free_init_pages(char *what, unsigned long begin, unsigned long end)
         /*
          * We just marked the kernel text read only above, now that
          * we are going to free part of that, we need to make that
-         * writeable first.
+         * writeable and non-executable first.
          */
+        set_memory_nx(begin, (end - begin) >> PAGE_SHIFT);
         set_memory_rw(begin, (end - begin) >> PAGE_SHIFT);
 
         printk(KERN_INFO "Freeing %s: %luk freed\n", what, (end - begin) >> 10);