x86: introduce init_memory_mapping for 32bit #1

... so can we use mem below max_low_pfn earlier.

this allows us to move several functions more early instead of waiting
to after paging_init.

That includes moving relocate_initrd() earlier in the bootup, and kva
related early setup done in initmem_init. (in followup patches)

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 118 insertions, 33 deletions

diff --git a/arch/x86/kernel/setup_32.c b/arch/x86/kernel/setup_32.c
index bba8d57bd7d..03007cada0d 100644
--- a/arch/x86/kernel/setup_32.c
+++ b/arch/x86/kernel/setup_32.c
@@ -226,10 +226,8 @@ static void __init reserve_initrd(void)
         }
 
         /* We need to move the initrd down into lowmem */
-        ramdisk_target = max_pfn_mapped<<PAGE_SHIFT;
-        ramdisk_here = find_e820_area(min(ramdisk_target, end_of_lowmem>>1),
-                                 end_of_lowmem, ramdisk_size,
-                                 PAGE_SIZE);
+        ramdisk_here = find_e820_area(0, end_of_lowmem, ramdisk_size,
+                                         PAGE_SIZE);
 
         if (ramdisk_here == -1ULL)
                 panic("Cannot find place for new RAMDISK of size %lld\n",
@@ -433,8 +431,12 @@ void __init setup_arch(char **cmdline_p)
                 max_pfn = e820_end_of_ram();
         }
 
+        /* max_low_pfn get updated here */
         find_low_pfn_range();
 
+        /* max_pfn_mapped is updated here */
+        init_memory_mapping(0, (max_low_pfn << PAGE_SHIFT));
+
         reserve_initrd();
 
         dmi_scan_machine();
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 20ca29591ab..619058e6bff 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -57,6 +57,27 @@ unsigned long highstart_pfn, highend_pfn;
 
 static noinline int do_test_wp_bit(void);
 
+
+static unsigned long __initdata table_start;
+static unsigned long __meminitdata table_end;
+static unsigned long __meminitdata table_top;
+
+static int __initdata after_init_bootmem;
+
+static __init void *alloc_low_page(unsigned long *phys)
+{
+        unsigned long pfn = table_end++;
+        void *adr;
+
+        if (pfn >= table_top)
+                panic("alloc_low_page: ran out of memory");
+
+        adr = __va(pfn * PAGE_SIZE);
+        memset(adr, 0, PAGE_SIZE);
+        *phys  = pfn * PAGE_SIZE;
+        return adr;
+}
+
 /*
  * Creates a middle page table and puts a pointer to it in the
  * given global directory entry. This only returns the gd entry
@@ -68,9 +89,12 @@ static pmd_t * __init one_md_table_init(pgd_t *pgd)
         pmd_t *pmd_table;
 
 #ifdef CONFIG_X86_PAE
+        unsigned long phys;
         if (!(pgd_val(*pgd) & _PAGE_PRESENT)) {
-                pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
-
+                if (after_init_bootmem)
+                        pmd_table = (pmd_t *)alloc_bootmem_low_pages(PAGE_SIZE);
+                else
+                        pmd_table = (pmd_t *)alloc_low_page(&phys);
                 paravirt_alloc_pmd(&init_mm, __pa(pmd_table) >> PAGE_SHIFT);
                 set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
                 pud = pud_offset(pgd, 0);
@@ -92,12 +116,16 @@ static pte_t * __init one_page_table_init(pmd_t *pmd)
         if (!(pmd_val(*pmd) & _PAGE_PRESENT)) {
                 pte_t *page_table = NULL;
 
+                if (after_init_bootmem) {
 #ifdef CONFIG_DEBUG_PAGEALLOC
-                page_table = (pte_t *) alloc_bootmem_pages(PAGE_SIZE);
+                        page_table = (pte_t *) alloc_bootmem_pages(PAGE_SIZE);
 #endif
-                if (!page_table) {
-                        page_table =
+                        if (!page_table)
+                                page_table =
                                 (pte_t *)alloc_bootmem_low_pages(PAGE_SIZE);
+                } else {
+                        unsigned long phys;
+                        page_table = (pte_t *)alloc_low_page(&phys);
                 }
 
                 paravirt_alloc_pte(&init_mm, __pa(page_table) >> PAGE_SHIFT);
@@ -155,7 +183,9 @@ static inline int is_kernel_text(unsigned long addr)
  * of max_low_pfn pages, by creating page tables starting from address
  * PAGE_OFFSET:
  */
-static void __init kernel_physical_mapping_init(pgd_t *pgd_base)
+static void __init kernel_physical_mapping_init(pgd_t *pgd_base,
+                                                unsigned long start,
+                                                unsigned long end)
 {
         int pgd_idx, pmd_idx, pte_ofs;
         unsigned long pfn;
@@ -163,18 +193,19 @@ static void __init kernel_physical_mapping_init(pgd_t *pgd_base)
         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 = 0;
+        pfn = start >> PAGE_SHIFT;
 
         for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
                 pmd = one_md_table_init(pgd);
-                if (pfn >= max_low_pfn)
+                if (pfn >= limit_pfn)
                         continue;
 
                 for (pmd_idx = 0;
-                     pmd_idx < PTRS_PER_PMD && pfn < max_low_pfn;
+                     pmd_idx < PTRS_PER_PMD && pfn < limit_pfn;
                      pmd++, pmd_idx++) {
                         unsigned int addr = pfn * PAGE_SIZE + PAGE_OFFSET;
 
@@ -418,20 +449,7 @@ static void __init pagetable_init(void)
 
         paravirt_pagetable_setup_start(pgd_base);
 
-        /* Enable PSE if available */
-        if (cpu_has_pse)
-                set_in_cr4(X86_CR4_PSE);
-
-        /* Enable PGE if available */
-        if (cpu_has_pge) {
-                set_in_cr4(X86_CR4_PGE);
-                __PAGE_KERNEL |= _PAGE_GLOBAL;
-                __PAGE_KERNEL_EXEC |= _PAGE_GLOBAL;
-        }
-
-        kernel_physical_mapping_init(pgd_base);
         remap_numa_kva();
-
         /*
          * Fixed mappings, only the page table structure has to be
          * created - mappings will be set by set_fixmap():
@@ -703,6 +721,7 @@ void __init setup_bootmem_allocator(void)
                 free_bootmem_with_active_regions(i, max_low_pfn);
         early_res_to_bootmem(0, max_low_pfn<<PAGE_SHIFT);
 
+        after_init_bootmem = 1;
 }
 
 /*
@@ -723,6 +742,77 @@ static void __init remapped_pgdat_init(void)
         }
 }
 
+static void __init find_early_table_space(unsigned long end)
+{
+        unsigned long puds, pmds, tables, start;
+
+        puds = (end + PUD_SIZE - 1) >> PUD_SHIFT;
+        tables = PAGE_ALIGN(puds * sizeof(pud_t));
+
+        pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT;
+        tables += PAGE_ALIGN(pmds * sizeof(pmd_t));
+
+        /*
+         * 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.
+         */
+        start = 0x7000;
+        table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
+                                        tables, PAGE_SIZE);
+        if (table_start == -1UL)
+                panic("Cannot find space for the kernel page tables");
+
+        table_start >>= PAGE_SHIFT;
+        table_end = table_start;
+        table_top = table_start + (tables>>PAGE_SHIFT);
+
+        printk(KERN_DEBUG "kernel direct mapping tables up to %lx @ %lx-%lx\n",
+                end, table_start << PAGE_SHIFT,
+                (table_start << PAGE_SHIFT) + tables);
+}
+
+unsigned long __init_refok init_memory_mapping(unsigned long start,
+                                                unsigned long end)
+{
+        pgd_t *pgd_base = swapper_pg_dir;
+
+        /*
+         * Find space for the kernel direct mapping tables.
+         */
+        if (!after_init_bootmem)
+                find_early_table_space(end);
+
+#ifdef CONFIG_X86_PAE
+        set_nx();
+        if (nx_enabled)
+                printk(KERN_INFO "NX (Execute Disable) protection: active\n");
+#endif
+
+        /* Enable PSE if available */
+        if (cpu_has_pse)
+                set_in_cr4(X86_CR4_PSE);
+
+        /* Enable PGE if available */
+        if (cpu_has_pge) {
+                set_in_cr4(X86_CR4_PGE);
+                __PAGE_KERNEL |= _PAGE_GLOBAL;
+                __PAGE_KERNEL_EXEC |= _PAGE_GLOBAL;
+        }
+
+        kernel_physical_mapping_init(pgd_base, start, end);
+
+        load_cr3(swapper_pg_dir);
+
+        __flush_tlb_all();
+
+        if (!after_init_bootmem)
+                reserve_early(table_start << PAGE_SHIFT,
+                                 table_end << PAGE_SHIFT, "PGTABLE");
+
+        return end >> PAGE_SHIFT;
+}
+
 /*
  * paging_init() sets up the page tables - note that the first 8MB are
  * already mapped by head.S.
@@ -732,15 +822,8 @@ static void __init remapped_pgdat_init(void)
  */
 void __init paging_init(void)
 {
-#ifdef CONFIG_X86_PAE
-        set_nx();
-        if (nx_enabled)
-                printk(KERN_INFO "NX (Execute Disable) protection: active\n");
-#endif
         pagetable_init();
 
-        load_cr3(swapper_pg_dir);
-
         __flush_tlb_all();
 
         kmap_init();