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x86: introduce init_memory_mapping for 32bit #1
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... 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>
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Yinghai Lu authored and Ingo Molnar committed Jul 8, 2008
1 parent c3c2fee commit 4e29684
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Showing 3 changed files with 120 additions and 33 deletions.
10 changes: 6 additions & 4 deletions arch/x86/kernel/setup_32.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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",
Expand Down Expand Up @@ -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();
Expand Down
141 changes: 112 additions & 29 deletions arch/x86/mm/init_32.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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);
Expand All @@ -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);
Expand Down Expand Up @@ -155,26 +183,29 @@ 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;
pgd_t *pgd;
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;

Expand Down Expand Up @@ -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():
Expand Down Expand Up @@ -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;
}

/*
Expand All @@ -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.
Expand All @@ -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();
Expand Down
2 changes: 2 additions & 0 deletions include/asm-x86/page_32.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down

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