asm-generic: pgalloc: provide generic pmd_alloc_one() and pmd_free_one()

For most architectures that support >2 levels of page tables,
pmd_alloc_one() is a wrapper for __get_free_pages(), sometimes with
__GFP_ZERO and sometimes followed by memset(0) instead.

More elaborate versions on arm64 and x86 account memory for the user page
tables and call to pgtable_pmd_page_ctor() as the part of PMD page
initialization.

Move the arm64 version to include/asm-generic/pgalloc.h and use the
generic version on several architectures.

The pgtable_pmd_page_ctor() is a NOP when ARCH_ENABLE_SPLIT_PMD_PTLOCK is
not enabled, so there is no functional change for most architectures
except of the addition of __GFP_ACCOUNT for allocation of user page
tables.

The pmd_free() is a wrapper for free_page() in all the cases, so no
functional change here.

Signed-off-by: Mike Rapoport <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Pekka Enberg <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Abdul Haleem <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Max Filippov <[email protected]>
Cc: Peter Zijlstra (Intel) <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Stafford Horne <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 43 insertions, 0 deletions

diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
index 73f7421413cb..1bc027891a00 100644
--- a/include/asm-generic/pgalloc.h
+++ b/include/asm-generic/pgalloc.h
@@ -102,6 +102,49 @@ static inline void pte_free(struct mm_struct *mm, struct page *pte_page)
 	__free_page(pte_page);
 }
 
+
+#if CONFIG_PGTABLE_LEVELS > 2
+
+#ifndef __HAVE_ARCH_PMD_ALLOC_ONE
+/**
+ * pmd_alloc_one - allocate a page for PMD-level page table
+ * @mm: the mm_struct of the current context
+ *
+ * Allocates a page and runs the pgtable_pmd_page_ctor().
+ * Allocations use %GFP_PGTABLE_USER in user context and
+ * %GFP_PGTABLE_KERNEL in kernel context.
+ *
+ * Return: pointer to the allocated memory or %NULL on error
+ */
+static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
+{
+	struct page *page;
+	gfp_t gfp = GFP_PGTABLE_USER;
+
+	if (mm == &init_mm)
+		gfp = GFP_PGTABLE_KERNEL;
+	page = alloc_pages(gfp, 0);
+	if (!page)
+		return NULL;
+	if (!pgtable_pmd_page_ctor(page)) {
+		__free_pages(page, 0);
+		return NULL;
+	}
+	return (pmd_t *)page_address(page);
+}
+#endif
+
+#ifndef __HAVE_ARCH_PMD_FREE
+static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
+{
+	BUG_ON((unsigned long)pmd & (PAGE_SIZE-1));
+	pgtable_pmd_page_dtor(virt_to_page(pmd));
+	free_page((unsigned long)pmd);
+}
+#endif
+
+#endif /* CONFIG_PGTABLE_LEVELS > 2 */
+
 #endif /* CONFIG_MMU */
 
 #endif /* __ASM_GENERIC_PGALLOC_H */