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Subject[PATCH] tile: add virt_to_kpte() API and clean up and document behavior
We use virt_to_pte(NULL, va) a lot, which isn't very obvious.
I added virt_to_kpte(va) as a more obvious wrapper function,
that also validates the va as being a kernel adddress.

And, I fixed the semantics of virt_to_pte() so that we handle
the pud and pmd the same way, and we now document the fact that
we handle the final pte level differently.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
---
arch/tile/include/asm/mmu_context.h | 2 +-
arch/tile/include/asm/page.h | 1 +
arch/tile/kernel/setup.c | 6 +++---
arch/tile/mm/homecache.c | 6 +++---
arch/tile/mm/init.c | 4 ++--
arch/tile/mm/pgtable.c | 22 ++++++++++++++++++++--
6 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/arch/tile/include/asm/mmu_context.h b/arch/tile/include/asm/mmu_context.h
index 37f0b74..4734215 100644
--- a/arch/tile/include/asm/mmu_context.h
+++ b/arch/tile/include/asm/mmu_context.h
@@ -45,7 +45,7 @@ static inline void __install_page_table(pgd_t *pgdir, int asid, pgprot_t prot)

static inline void install_page_table(pgd_t *pgdir, int asid)
{
- pte_t *ptep = virt_to_pte(NULL, (unsigned long)pgdir);
+ pte_t *ptep = virt_to_kpte((unsigned long)pgdir);
__install_page_table(pgdir, asid, *ptep);
}

diff --git a/arch/tile/include/asm/page.h b/arch/tile/include/asm/page.h
index 65ee752..84441b2 100644
--- a/arch/tile/include/asm/page.h
+++ b/arch/tile/include/asm/page.h
@@ -340,6 +340,7 @@ static inline int pfn_valid(unsigned long pfn)

struct mm_struct;
extern pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr);
+extern pte_t *virt_to_kpte(unsigned long kaddr);

#endif /* !__ASSEMBLY__ */

diff --git a/arch/tile/kernel/setup.c b/arch/tile/kernel/setup.c
index 2352a81..37a5b78 100644
--- a/arch/tile/kernel/setup.c
+++ b/arch/tile/kernel/setup.c
@@ -1613,7 +1613,7 @@ void __init setup_per_cpu_areas(void)

/* Update the vmalloc mapping and page home. */
unsigned long addr = (unsigned long)ptr + i;
- pte_t *ptep = virt_to_pte(NULL, addr);
+ pte_t *ptep = virt_to_kpte(addr);
pte_t pte = *ptep;
BUG_ON(pfn != pte_pfn(pte));
pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_TILE_L3);
@@ -1622,12 +1622,12 @@ void __init setup_per_cpu_areas(void)

/* Update the lowmem mapping for consistency. */
lowmem_va = (unsigned long)pfn_to_kaddr(pfn);
- ptep = virt_to_pte(NULL, lowmem_va);
+ ptep = virt_to_kpte(lowmem_va);
if (pte_huge(*ptep)) {
printk(KERN_DEBUG "early shatter of huge page"
" at %#lx\n", lowmem_va);
shatter_pmd((pmd_t *)ptep);
- ptep = virt_to_pte(NULL, lowmem_va);
+ ptep = virt_to_kpte(lowmem_va);
BUG_ON(pte_huge(*ptep));
}
BUG_ON(pfn != pte_pfn(*ptep));
diff --git a/arch/tile/mm/homecache.c b/arch/tile/mm/homecache.c
index df46a2d..e3ee55b 100644
--- a/arch/tile/mm/homecache.c
+++ b/arch/tile/mm/homecache.c
@@ -200,7 +200,7 @@ void homecache_finv_map_page(struct page *page, int home)
#else
va = __fix_to_virt(FIX_HOMECACHE_BEGIN + smp_processor_id());
#endif
- ptep = virt_to_pte(NULL, (unsigned long)va);
+ ptep = virt_to_kpte(va);
pte = pfn_pte(page_to_pfn(page), PAGE_KERNEL);
__set_pte(ptep, pte_set_home(pte, home));
homecache_finv_page_va((void *)va, home);
@@ -385,7 +385,7 @@ int page_home(struct page *page)
return initial_page_home();
} else {
unsigned long kva = (unsigned long)page_address(page);
- return pte_to_home(*virt_to_pte(NULL, kva));
+ return pte_to_home(*virt_to_kpte(kva));
}
}
EXPORT_SYMBOL(page_home);
@@ -404,7 +404,7 @@ void homecache_change_page_home(struct page *page, int order, int home)
NULL, 0);

for (i = 0; i < pages; ++i, kva += PAGE_SIZE) {
- pte_t *ptep = virt_to_pte(NULL, kva);
+ pte_t *ptep = virt_to_kpte(kva);
pte_t pteval = *ptep;
BUG_ON(!pte_present(pteval) || pte_huge(pteval));
__set_pte(ptep, pte_set_home(pteval, home));
diff --git a/arch/tile/mm/init.c b/arch/tile/mm/init.c
index c6d2160..c8f58c1 100644
--- a/arch/tile/mm/init.c
+++ b/arch/tile/mm/init.c
@@ -951,7 +951,7 @@ static void mark_w1data_ro(void)
BUG_ON((addr & (PAGE_SIZE-1)) != 0);
for (; addr <= (unsigned long)__w1data_end - 1; addr += PAGE_SIZE) {
unsigned long pfn = kaddr_to_pfn((void *)addr);
- pte_t *ptep = virt_to_pte(NULL, addr);
+ pte_t *ptep = virt_to_kpte(addr);
BUG_ON(pte_huge(*ptep)); /* not relevant for kdata_huge */
set_pte_at(&init_mm, addr, ptep, pfn_pte(pfn, PAGE_KERNEL_RO));
}
@@ -997,7 +997,7 @@ static void free_init_pages(char *what, unsigned long begin, unsigned long end)
*/
int pfn = kaddr_to_pfn((void *)addr);
struct page *page = pfn_to_page(pfn);
- pte_t *ptep = virt_to_pte(NULL, addr);
+ pte_t *ptep = virt_to_kpte(addr);
if (!initfree) {
/*
* If debugging page accesses then do not free
diff --git a/arch/tile/mm/pgtable.c b/arch/tile/mm/pgtable.c
index d6948d4..33b006a 100644
--- a/arch/tile/mm/pgtable.c
+++ b/arch/tile/mm/pgtable.c
@@ -325,6 +325,17 @@ void ptep_set_wrprotect(struct mm_struct *mm,

#endif

+/*
+ * Return a pointer to the PTE that corresponds to the given
+ * address in the given page table. A NULL page table just uses
+ * the standard kernel page table; the preferred API in this case
+ * is virt_to_kpte().
+ *
+ * The returned pointer can point to a huge page in other levels
+ * of the page table than the bottom, if the huge page is present
+ * in the page table. For bottom-level PTEs, the returned pointer
+ * can point to a PTE that is either present or not.
+ */
pte_t *virt_to_pte(struct mm_struct* mm, unsigned long addr)
{
pgd_t *pgd;
@@ -341,14 +352,21 @@ pte_t *virt_to_pte(struct mm_struct* mm, unsigned long addr)
if (pud_huge_page(*pud))
return (pte_t *)pud;
pmd = pmd_offset(pud, addr);
- if (pmd_huge_page(*pmd))
- return (pte_t *)pmd;
if (!pmd_present(*pmd))
return NULL;
+ if (pmd_huge_page(*pmd))
+ return (pte_t *)pmd;
return pte_offset_kernel(pmd, addr);
}
EXPORT_SYMBOL(virt_to_pte);

+pte_t *virt_to_kpte(unsigned long kaddr)
+{
+ BUG_ON(kaddr < PAGE_OFFSET);
+ return virt_to_pte(NULL, kaddr);
+}
+EXPORT_SYMBOL(virt_to_kpte);
+
pgprot_t set_remote_cache_cpu(pgprot_t prot, int cpu)
{
unsigned int width = smp_width;
--
1.8.3.1


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