From: Tang Chen <tangchen@xxxxxxxxxxxxxx>
This patch introduces a new function memory_map_top_down to
factor out of the top-down direct memory mapping pagetable
setup. This is also a preparation for the following patch,
which will introduce the bottom-up memory mapping. That said,
we will put the two ways of pagetable setup into separate
functions, and choose to use which way in init_mem_mapping,
which makes the code more clear.
Signed-off-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
Signed-off-by: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
---
arch/x86/mm/init.c | 70 ++++++++++++++++++++++++++++++++-------------------
1 files changed, 44 insertions(+), 26 deletions(-)
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 04664cd..73e79e6 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -401,27 +401,27 @@ static unsigned long __init init_range_memory_mapping(
/* (PUD_SHIFT-PMD_SHIFT)/2 */
#define STEP_SIZE_SHIFT 5
-void __init init_mem_mapping(void)
+
+/**
+ * memory_map_top_down - Map [map_start, map_end) top down
+ * @map_start: start address of the target memory range
+ * @map_end: end address of the target memory range
+ *
+ * This function will setup direct mapping for memory range [map_start, map_end)
+ * in a heuristic way. In the beginning, step_size is small. The more memory we
+ * map memory in the next loop.
+ */
+static void __init memory_map_top_down(unsigned long map_start,
+ unsigned long map_end)
{
- unsigned long end, real_end, start, last_start;
+ unsigned long real_end, start, last_start;
unsigned long step_size;
unsigned long addr;
unsigned long mapped_ram_size = 0;
unsigned long new_mapped_ram_size;
- probe_page_size_mask();
-
-#ifdef CONFIG_X86_64
- end = max_pfn << PAGE_SHIFT;
-#else
- end = max_low_pfn << PAGE_SHIFT;
-#endif
-
- /* the ISA range is always mapped regardless of memory holes */
- init_memory_mapping(0, ISA_END_ADDRESS);
-
/* xen has big range in reserved near end of ram, skip it at first.*/
- addr = memblock_find_in_range(ISA_END_ADDRESS, end, PMD_SIZE, PMD_SIZE);
+ addr = memblock_find_in_range(map_start, map_end, PMD_SIZE, PMD_SIZE);
real_end = addr + PMD_SIZE;
/* step_size need to be small so pgt_buf from BRK could cover it */
@@ -430,19 +430,13 @@ void __init init_mem_mapping(void)
min_pfn_mapped = real_end >> PAGE_SHIFT;
last_start = start = real_end;
- /*
- * We start from the top (end of memory) and go to the bottom.
- * The memblock_find_in_range() gets us a block of RAM from the
- * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages
- * for page table.
- */
- while (last_start > ISA_END_ADDRESS) {
+ while (last_start > map_start) {
if (last_start > step_size) {
start = round_down(last_start - 1, step_size);
- if (start < ISA_END_ADDRESS)
- start = ISA_END_ADDRESS;
+ if (start < map_start)
+ start = map_start;
} else
- start = ISA_END_ADDRESS;
+ start = map_start;
new_mapped_ram_size = init_range_memory_mapping(start,
last_start);
last_start = start;
@@ -453,8 +447,32 @@ void __init init_mem_mapping(void)
mapped_ram_size += new_mapped_ram_size;
}
- if (real_end < end)
- init_range_memory_mapping(real_end, end);
+ if (real_end < map_end)
+ init_range_memory_mapping(real_end, map_end);
+}
+
+void __init init_mem_mapping(void)
+{
+ unsigned long end;
+
+ probe_page_size_mask();
+
+#ifdef CONFIG_X86_64
+ end = max_pfn << PAGE_SHIFT;
+#else
+ end = max_low_pfn << PAGE_SHIFT;
+#endif
+
+ /* the ISA range is always mapped regardless of memory holes */
+ init_memory_mapping(0, ISA_END_ADDRESS);
+
+ /*
+ * We start from the top (end of memory) and go to the bottom.
+ * The memblock_find_in_range() gets us a block of RAM from the
+ * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages
+ * for page table.
+ */
+ memory_map_top_down(ISA_END_ADDRESS, end);
#ifdef CONFIG_X86_64
if (max_pfn > max_low_pfn) {
--
1.7.1
--
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