diff options
| -rw-r--r-- | arch/x86/mm/init.c | 37 |
1 files changed, 17 insertions, 20 deletions
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index a97ee0801475..08a7d313538a 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -438,20 +438,20 @@ static unsigned long __init init_range_memory_mapping( static unsigned long __init get_new_step_size(unsigned long step_size) { /* - * Explain why we shift by 5 and why we don't have to worry about - * 'step_size << 5' overflowing: - * - * initial mapped size is PMD_SIZE (2M). + * Initial mapped size is PMD_SIZE (2M). * We can not set step_size to be PUD_SIZE (1G) yet. * In worse case, when we cross the 1G boundary, and * PG_LEVEL_2M is not set, we will need 1+1+512 pages (2M + 8k) - * to map 1G range with PTE. Use 5 as shift for now. + * to map 1G range with PTE. Hence we use one less than the + * difference of page table level shifts. * - * Don't need to worry about overflow, on 32bit, when step_size - * is 0, round_down() returns 0 for start, and that turns it - * into 0x100000000ULL. + * Don't need to worry about overflow in the top-down case, on 32bit, + * when step_size is 0, round_down() returns 0 for start, and that + * turns it into 0x100000000ULL. + * In the bottom-up case, round_up(x, 0) returns 0 though too, which + * needs to be taken into consideration by the code below. */ - return step_size << 5; + return step_size << (PMD_SHIFT - PAGE_SHIFT - 1); } /** @@ -471,7 +471,6 @@ static void __init memory_map_top_down(unsigned long map_start, unsigned long step_size; unsigned long addr; unsigned long mapped_ram_size = 0; - unsigned long new_mapped_ram_size; /* xen has big range in reserved near end of ram, skip it at first.*/ addr = memblock_find_in_range(map_start, map_end, PMD_SIZE, PMD_SIZE); @@ -496,14 +495,12 @@ static void __init memory_map_top_down(unsigned long map_start, start = map_start; } else start = map_start; - new_mapped_ram_size = init_range_memory_mapping(start, + mapped_ram_size += init_range_memory_mapping(start, last_start); last_start = start; min_pfn_mapped = last_start >> PAGE_SHIFT; - /* only increase step_size after big range get mapped */ - if (new_mapped_ram_size > mapped_ram_size) + if (mapped_ram_size >= step_size) step_size = get_new_step_size(step_size); - mapped_ram_size += new_mapped_ram_size; } if (real_end < map_end) @@ -524,7 +521,7 @@ static void __init memory_map_top_down(unsigned long map_start, static void __init memory_map_bottom_up(unsigned long map_start, unsigned long map_end) { - unsigned long next, new_mapped_ram_size, start; + unsigned long next, start; unsigned long mapped_ram_size = 0; /* step_size need to be small so pgt_buf from BRK could cover it */ unsigned long step_size = PMD_SIZE; @@ -539,19 +536,19 @@ static void __init memory_map_bottom_up(unsigned long map_start, * for page table. */ while (start < map_end) { - if (map_end - start > step_size) { + if (step_size && map_end - start > step_size) { next = round_up(start + 1, step_size); if (next > map_end) next = map_end; - } else + } else { next = map_end; + } - new_mapped_ram_size = init_range_memory_mapping(start, next); + mapped_ram_size += init_range_memory_mapping(start, next); start = next; - if (new_mapped_ram_size > mapped_ram_size) + if (mapped_ram_size >= step_size) step_size = get_new_step_size(step_size); - mapped_ram_size += new_mapped_ram_size; } } |