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Subject[PATCH 17/46] x86, mm: Align start address to correct big page size
Date
We are going to use buffer in BRK to map small range just under memory top,
and use those new mapped ram to map ram range under it.

The ram range that will be mapped at first could be only page aligned,
but ranges around it are ram too, we could use bigger page to map it to
avoid small page size.

We will adjust page_size_mask in following patch:
x86, mm: Use big page size for small memory range
to use big page size for small ram range.

Before that patch, this patch will make sure start address to be
aligned down according to bigger page size, otherwise entry in page
page will not have correct value.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
---
arch/x86/mm/init_32.c | 1 +
arch/x86/mm/init_64.c | 5 +++--
2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 11a5800..27f7fc6 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -310,6 +310,7 @@ repeat:
__pgprot(PTE_IDENT_ATTR |
_PAGE_PSE);

+ pfn &= PMD_MASK >> PAGE_SHIFT;
addr2 = (pfn + PTRS_PER_PTE-1) * PAGE_SIZE +
PAGE_OFFSET + PAGE_SIZE-1;

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 32c7e38..869372a 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -464,7 +464,7 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end,
pages++;
spin_lock(&init_mm.page_table_lock);
set_pte((pte_t *)pmd,
- pfn_pte(address >> PAGE_SHIFT,
+ pfn_pte((address & PMD_MASK) >> PAGE_SHIFT,
__pgprot(pgprot_val(prot) | _PAGE_PSE)));
spin_unlock(&init_mm.page_table_lock);
last_map_addr = next;
@@ -541,7 +541,8 @@ phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
pages++;
spin_lock(&init_mm.page_table_lock);
set_pte((pte_t *)pud,
- pfn_pte(addr >> PAGE_SHIFT, PAGE_KERNEL_LARGE));
+ pfn_pte((addr & PUD_MASK) >> PAGE_SHIFT,
+ PAGE_KERNEL_LARGE));
spin_unlock(&init_mm.page_table_lock);
last_map_addr = next;
continue;
--
1.7.7


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