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Subject[PATCH] x86: introduce init_memory_mapping for 32bit #1
Date

so could use mem below max_low_pfn as early.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>

---
arch/x86/kernel/setup_32.c | 10 +--
arch/x86/mm/init_32.c | 141 +++++++++++++++++++++++++++++++++++----------
include/asm-x86/page_32.h | 2
3 files changed, 120 insertions(+), 33 deletions(-)

Index: xy/arch/x86/kernel/setup_32.c
===================================================================
--- xy.orig/arch/x86/kernel/setup_32.c
+++ xy/arch/x86/kernel/setup_32.c
@@ -227,10 +227,8 @@ 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",
@@ -440,8 +438,12 @@ 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();
Index: xy/arch/x86/mm/init_32.c
===================================================================
--- xy.orig/arch/x86/mm/init_32.c
+++ xy/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(
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_ini
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(unsigne
* 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_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 = 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(v
}
}

+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(v
*/
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();
Index: xy/include/asm-x86/page_32.h
===================================================================
--- xy.orig/include/asm-x86/page_32.h
+++ xy/include/asm-x86/page_32.h
@@ -93,6 +93,8 @@ extern int sysctl_legacy_va_layout;
#define MAXMEM (-__PAGE_OFFSET - __VMALLOC_RESERVE)

extern void find_low_pfn_range(void);
+extern unsigned long init_memory_mapping(unsigned long start,
+ unsigned long end);
extern void initmem_init(unsigned long, unsigned long);
extern void zone_sizes_init(void);
extern void setup_bootmem_allocator(void);

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