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Subject[RFC PATCH 04/18] ARM: LPAE: Do not assume Linux PTEs are always at PTRS_PER_PTE offset
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Placing the Linux PTEs at a 2KB offset inside a page is a workaround for
the 2-level page table format where not enough spare bits are available.
With LPAE this is no longer required. This patch changes such assumption
by using a different macro, LINUX_PTE_OFFSET, which is defined to
PTRS_PER_PTE for the 2-level page tables.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm/include/asm/pgalloc.h | 6 +++---
arch/arm/include/asm/pgtable-2level.h | 1 +
arch/arm/include/asm/pgtable.h | 6 +++---
arch/arm/mm/fault.c | 2 +-
arch/arm/mm/mmu.c | 3 ++-
5 files changed, 10 insertions(+), 8 deletions(-)
diff --git a/arch/arm/include/asm/pgalloc.h b/arch/arm/include/asm/pgalloc.h
index b12cc98..c2a1f64 100644
--- a/arch/arm/include/asm/pgalloc.h
+++ b/arch/arm/include/asm/pgalloc.h
@@ -62,7 +62,7 @@ pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr)
pte = (pte_t *)__get_free_page(PGALLOC_GFP);
if (pte) {
clean_dcache_area(pte, sizeof(pte_t) * PTRS_PER_PTE);
- pte += PTRS_PER_PTE;
+ pte += LINUX_PTE_OFFSET;
}

return pte;
@@ -95,7 +95,7 @@ pte_alloc_one(struct mm_struct *mm, unsigned long addr)
static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
{
if (pte) {
- pte -= PTRS_PER_PTE;
+ pte -= LINUX_PTE_OFFSET;
free_page((unsigned long)pte);
}
}
@@ -128,7 +128,7 @@ pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmdp, pte_t *ptep)
* The pmd must be loaded with the physical
* address of the PTE table
*/
- pte_ptr -= PTRS_PER_PTE * sizeof(void *);
+ pte_ptr -= LINUX_PTE_OFFSET * sizeof(void *);
__pmd_populate(pmdp, __pa(pte_ptr) | _PAGE_KERNEL_TABLE);
}

diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h
index d60bda9..36bdef7 100644
--- a/arch/arm/include/asm/pgtable-2level.h
+++ b/arch/arm/include/asm/pgtable-2level.h
@@ -71,6 +71,7 @@
#define PTRS_PER_PTE 512
#define PTRS_PER_PMD 1
#define PTRS_PER_PGD 2048
+#define LINUX_PTE_OFFSET PTRS_PER_PTE

/*
* PMD_SHIFT determines the size of the area a second-level page table can map
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 49dd19e..5b45463 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -137,8 +137,8 @@ extern struct page *empty_zero_page;
#define __pte_map(dir,km) pmd_page_vaddr(*(dir))
#define __pte_unmap(pte,km) do { } while (0)
#else
-#define __pte_map(dir,km) ((pte_t *)kmap_atomic(pmd_page(*(dir)), km) + PTRS_PER_PTE)
-#define __pte_unmap(pte,km) kunmap_atomic((pte - PTRS_PER_PTE), km)
+#define __pte_map(dir,km) ((pte_t *)kmap_atomic(pmd_page(*(dir)), km) + LINUX_PTE_OFFSET)
+#define __pte_unmap(pte,km) kunmap_atomic((pte - LINUX_PTE_OFFSET), km)
#endif

#define set_pte_ext(ptep,pte,ext) cpu_set_pte_ext(ptep,pte,ext)
@@ -234,7 +234,7 @@ static inline pte_t *pmd_page_vaddr(pmd_t pmd)
unsigned long ptr;

ptr = pmd_val(pmd) & ~(PTRS_PER_PTE * sizeof(void *) - 1);
- ptr += PTRS_PER_PTE * sizeof(void *);
+ ptr += LINUX_PTE_OFFSET * sizeof(void *);

return __va(ptr);
}
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 23b0b03..2966897 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -108,7 +108,7 @@ void show_pte(struct mm_struct *mm, unsigned long addr)

pte = pte_offset_map(pmd, addr);
printk(", *pte=%08lx", pte_val(*pte));
- printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE]));
+ printk(", *ppte=%08lx", pte_val(pte[-LINUX_PTE_OFFSET]));
pte_unmap(pte);
} while(0);

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 56df812..3d6b206 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -538,7 +538,8 @@ static void __init *early_alloc(unsigned long sz)
static pte_t * __init early_pte_alloc(pmd_t *pmd, unsigned long addr, unsigned long prot)
{
if (pmd_none(*pmd)) {
- pte_t *pte = early_alloc(2 * PTRS_PER_PTE * sizeof(pte_t));
+ pte_t *pte = early_alloc((LINUX_PTE_OFFSET +
+ PTRS_PER_PTE) * sizeof(pte_t));
__pmd_populate(pmd, __pa(pte) | prot);
}
BUG_ON(pmd_bad(*pmd));


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