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x86, mm: setup page table in top-down

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Get pgt_buf early from BRK, and use it to map PMD_SIZE from top at first.
Then use mapped pages to map more ranges below, and keep looping until
all pages get mapped.

alloc_low_page will use page from BRK at first, after that buffer is used
up, will use memblock to find and reserve pages for page table usage.

Introduce min_pfn_mapped to make sure find new pages from mapped ranges,
that will be updated when lower pages get mapped.

Also add step_size to make sure that don't try to map too big range with
limited mapped pages initially, and increase the step_size when we have
more mapped pages on hand.

We don't need to call pagetable_reserve anymore, reserve work is done
in alloc_low_page() directly.

At last we can get rid of calculation and find early pgt related code.

-v2: update to after fix_xen change,
     also use MACRO for initial pgt_buf size and add comments with it.
-v3: skip big reserved range in memblock.reserved near end.
-v4: don't need fix_xen change now.
-v5: add changelog about moving about reserving pagetable to alloc_low_page.

Suggested-by: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1353123563-3103-22-git-send-email-yinghai@kernel.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Yinghai Lu 2012-11-16 19:38:58 -08:00 committed by H. Peter Anvin
parent f763ad1d38
commit 8d57470d8f
6 changed files with 94 additions and 155 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/page_types.h
View File

@ -45,6 +45,7 @@ extern int devmem_is_allowed(unsigned long pagenr);
extern unsigned long max_low_pfn_mapped;
extern unsigned long max_pfn_mapped;
extern unsigned long min_pfn_mapped;
static inline phys_addr_t get_max_mapped(void)
{

1
arch/x86/include/asm/pgtable.h
View File

@ -603,6 +603,7 @@ static inline int pgd_none(pgd_t pgd)
extern int direct_gbpages;
void init_mem_mapping(void);
void early_alloc_pgt_buf(void);
/* local pte updates need not use xchg for locking */
static inline pte_t native_local_ptep_get_and_clear(pte_t *ptep)

3
arch/x86/kernel/setup.c
View File

@ -124,6 +124,7 @@
*/
unsigned long max_low_pfn_mapped;
unsigned long max_pfn_mapped;
unsigned long min_pfn_mapped;
#ifdef CONFIG_DMI
RESERVE_BRK(dmi_alloc, 65536);
@ -900,6 +901,8 @@ void __init setup_arch(char **cmdline_p)
reserve_ibft_region();
early_alloc_pgt_buf();
/*
* Need to conclude brk, before memblock_x86_fill()
* it could use memblock_find_in_range, could overlap with

210
arch/x86/mm/init.c
View File

@ -21,6 +21,21 @@ unsigned long __initdata pgt_buf_start;
unsigned long __meminitdata pgt_buf_end;
unsigned long __meminitdata pgt_buf_top;
/* need 4 4k for initial PMD_SIZE, 4k for 0-ISA_END_ADDRESS */
#define INIT_PGT_BUF_SIZE (5 * PAGE_SIZE)
RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE);
void __init early_alloc_pgt_buf(void)
{
unsigned long tables = INIT_PGT_BUF_SIZE;
phys_addr_t base;
base = __pa(extend_brk(tables, PAGE_SIZE));
pgt_buf_start = base >> PAGE_SHIFT;
pgt_buf_end = pgt_buf_start;
pgt_buf_top = pgt_buf_start + (tables >> PAGE_SHIFT);
}
int after_bootmem;
int direct_gbpages
@ -228,105 +243,6 @@ static int __meminit split_mem_range(struct map_range *mr, int nr_range,
return nr_range;
}
/*
* First calculate space needed for kernel direct mapping page tables to cover
* mr[0].start to mr[nr_range - 1].end, while accounting for possible 2M and 1GB
* pages. Then find enough contiguous space for those page tables.
*/
static unsigned long __init calculate_table_space_size(unsigned long start, unsigned long end)
{
int i;
unsigned long puds = 0, pmds = 0, ptes = 0, tables;
struct map_range mr[NR_RANGE_MR];
int nr_range;
memset(mr, 0, sizeof(mr));
nr_range = 0;
nr_range = split_mem_range(mr, nr_range, start, end);
for (i = 0; i < nr_range; i++) {
unsigned long range, extra;
range = mr[i].end - mr[i].start;
puds += (range + PUD_SIZE - 1) >> PUD_SHIFT;
if (mr[i].page_size_mask & (1 << PG_LEVEL_1G)) {
extra = range - ((range >> PUD_SHIFT) << PUD_SHIFT);
pmds += (extra + PMD_SIZE - 1) >> PMD_SHIFT;
} else {
pmds += (range + PMD_SIZE - 1) >> PMD_SHIFT;
}
if (mr[i].page_size_mask & (1 << PG_LEVEL_2M)) {
extra = range - ((range >> PMD_SHIFT) << PMD_SHIFT);
#ifdef CONFIG_X86_32
extra += PMD_SIZE;
#endif
ptes += (extra + PAGE_SIZE - 1) >> PAGE_SHIFT;
} else {
ptes += (range + PAGE_SIZE - 1) >> PAGE_SHIFT;
}
}
tables = roundup(puds * sizeof(pud_t), PAGE_SIZE);
tables += roundup(pmds * sizeof(pmd_t), PAGE_SIZE);
tables += roundup(ptes * sizeof(pte_t), PAGE_SIZE);
#ifdef CONFIG_X86_32
/* for fixmap */
tables += roundup(__end_of_fixed_addresses * sizeof(pte_t), PAGE_SIZE);
#endif
return tables;
}
static unsigned long __init calculate_all_table_space_size(void)
{
unsigned long start_pfn, end_pfn;
unsigned long tables;
int i;
/* the ISA range is always mapped regardless of memory holes */
tables = calculate_table_space_size(0, ISA_END_ADDRESS);
for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) {
u64 start = start_pfn << PAGE_SHIFT;
u64 end = end_pfn << PAGE_SHIFT;
if (end <= ISA_END_ADDRESS)
continue;
if (start < ISA_END_ADDRESS)
start = ISA_END_ADDRESS;
#ifdef CONFIG_X86_32
/* on 32 bit, we only map up to max_low_pfn */
if ((start >> PAGE_SHIFT) >= max_low_pfn)
continue;
if ((end >> PAGE_SHIFT) > max_low_pfn)
end = max_low_pfn << PAGE_SHIFT;
#endif
tables += calculate_table_space_size(start, end);
}
return tables;
}
static void __init find_early_table_space(unsigned long start,
unsigned long good_end,
unsigned long tables)
{
phys_addr_t base;
base = memblock_find_in_range(start, good_end, tables, PAGE_SIZE);
if (!base)
panic("Cannot find space for the kernel page tables");
pgt_buf_start = base >> PAGE_SHIFT;
pgt_buf_end = pgt_buf_start;
pgt_buf_top = pgt_buf_start + (tables >> PAGE_SHIFT);
}
static struct range pfn_mapped[E820_X_MAX];
static int nr_pfn_mapped;
@ -391,17 +307,14 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
}
/*
* Iterate through E820 memory map and create direct mappings for only E820_RAM
* regions. We cannot simply create direct mappings for all pfns from
* [0 to max_low_pfn) and [4GB to max_pfn) because of possible memory holes in
* high addresses that cannot be marked as UC by fixed/variable range MTRRs.
* Depending on the alignment of E820 ranges, this may possibly result in using
* smaller size (i.e. 4K instead of 2M or 1G) page tables.
* would have hole in the middle or ends, and only ram parts will be mapped.
*/
static void __init init_range_memory_mapping(unsigned long range_start,
static unsigned long __init init_range_memory_mapping(
unsigned long range_start,
unsigned long range_end)
{
unsigned long start_pfn, end_pfn;
unsigned long mapped_ram_size = 0;
int i;
for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) {
@ -421,71 +334,70 @@ static void __init init_range_memory_mapping(unsigned long range_start,
end = range_end;
init_memory_mapping(start, end);
mapped_ram_size += end - start;
}
return mapped_ram_size;
}
/* (PUD_SHIFT-PMD_SHIFT)/2 */
#define STEP_SIZE_SHIFT 5
void __init init_mem_mapping(void)
{
unsigned long tables, good_end, end;
unsigned long end, 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();
/*
* Find space for the kernel direct mapping tables.
*
* Later we should allocate these tables in the local node of the
* memory mapped. Unfortunately this is done currently before the
* nodes are discovered.
*/
#ifdef CONFIG_X86_64
end = max_pfn << PAGE_SHIFT;
good_end = end;
#else
end = max_low_pfn << PAGE_SHIFT;
good_end = max_pfn_mapped << PAGE_SHIFT;
#endif
tables = calculate_all_table_space_size();
find_early_table_space(0, good_end, tables);
printk(KERN_DEBUG "kernel direct mapping tables up to %#lx @ [mem %#010lx-%#010lx] prealloc\n",
end - 1, pgt_buf_start << PAGE_SHIFT,
(pgt_buf_top << PAGE_SHIFT) - 1);
max_pfn_mapped = 0; /* will get exact value next */
/* the ISA range is always mapped regardless of memory holes */
init_memory_mapping(0, ISA_END_ADDRESS);
init_range_memory_mapping(ISA_END_ADDRESS, end);
/* 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,
PAGE_SIZE);
real_end = addr + PMD_SIZE;
/* step_size need to be small so pgt_buf from BRK could cover it */
step_size = PMD_SIZE;
max_pfn_mapped = 0; /* will get exact value next */
min_pfn_mapped = real_end >> PAGE_SHIFT;
last_start = start = real_end;
while (last_start > ISA_END_ADDRESS) {
if (last_start > step_size) {
start = round_down(last_start - 1, step_size);
if (start < ISA_END_ADDRESS)
start = ISA_END_ADDRESS;
} else
start = ISA_END_ADDRESS;
new_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)
step_size <<= STEP_SIZE_SHIFT;
mapped_ram_size += new_mapped_ram_size;
}
if (real_end < end)
init_range_memory_mapping(real_end, end);
#ifdef CONFIG_X86_64
if (max_pfn > max_low_pfn) {
/* can we preseve max_low_pfn ?*/
max_low_pfn = max_pfn;
}
#endif
/*
* Reserve the kernel pagetable pages we used (pgt_buf_start -
* pgt_buf_end) and free the other ones (pgt_buf_end - pgt_buf_top)
* so that they can be reused for other purposes.
*
* On native it just means calling memblock_reserve, on Xen it also
* means marking RW the pagetable pages that we allocated before
* but that haven't been used.
*
* In fact on xen we mark RO the whole range pgt_buf_start -
* pgt_buf_top, because we have to make sure that when
* init_memory_mapping reaches the pagetable pages area, it maps
* RO all the pagetable pages, including the ones that are beyond
* pgt_buf_end at that time.
*/
if (pgt_buf_end > pgt_buf_start) {
printk(KERN_DEBUG "kernel direct mapping tables up to %#lx @ [mem %#010lx-%#010lx] final\n",
end - 1, pgt_buf_start << PAGE_SHIFT,
(pgt_buf_end << PAGE_SHIFT) - 1);
x86_init.mapping.pagetable_reserve(PFN_PHYS(pgt_buf_start),
PFN_PHYS(pgt_buf_end));
}
/* stop the wrong using */
pgt_buf_top = 0;
early_memtest(0, max_pfn_mapped << PAGE_SHIFT);
}

17
arch/x86/mm/init_32.c
View File

@ -61,11 +61,22 @@ bool __read_mostly __vmalloc_start_set = false;
static __init void *alloc_low_page(void)
{
unsigned long pfn = pgt_buf_end++;
unsigned long pfn;
void *adr;
if (pfn >= pgt_buf_top)
panic("alloc_low_page: ran out of memory");
if ((pgt_buf_end + 1) >= pgt_buf_top) {
unsigned long ret;
if (min_pfn_mapped >= max_pfn_mapped)
panic("alloc_low_page: ran out of memory");
ret = memblock_find_in_range(min_pfn_mapped << PAGE_SHIFT,
max_pfn_mapped << PAGE_SHIFT,
PAGE_SIZE, PAGE_SIZE);
if (!ret)
panic("alloc_low_page: can not alloc memory");
memblock_reserve(ret, PAGE_SIZE);
pfn = ret >> PAGE_SHIFT;
} else
pfn = pgt_buf_end++;
adr = __va(pfn * PAGE_SIZE);
clear_page(adr);

17
arch/x86/mm/init_64.c
View File

@ -316,7 +316,7 @@ void __init cleanup_highmap(void)
static __ref void *alloc_low_page(unsigned long *phys)
{
unsigned long pfn = pgt_buf_end++;
unsigned long pfn;
void *adr;
if (after_bootmem) {
@ -326,8 +326,19 @@ static __ref void *alloc_low_page(unsigned long *phys)
return adr;
}
if (pfn >= pgt_buf_top)
panic("alloc_low_page: ran out of memory");
if ((pgt_buf_end + 1) >= pgt_buf_top) {
unsigned long ret;
if (min_pfn_mapped >= max_pfn_mapped)
panic("alloc_low_page: ran out of memory");
ret = memblock_find_in_range(min_pfn_mapped << PAGE_SHIFT,
max_pfn_mapped << PAGE_SHIFT,
PAGE_SIZE, PAGE_SIZE);
if (!ret)
panic("alloc_low_page: can not alloc memory");
memblock_reserve(ret, PAGE_SIZE);
pfn = ret >> PAGE_SHIFT;
} else
pfn = pgt_buf_end++;
adr = early_memremap(pfn * PAGE_SIZE, PAGE_SIZE);
clear_page(adr);