[PATCH v2 03/11] powerpc32: Use kmem_cache memory for PGDIR

[Christophe Leroy]

When pages are not 4K, PGDIR table is allocated with kmalloc(). In order to
optimise TLB handlers, aligned memory is needed. kmalloc() doesn't provide
aligned memory blocks, so lets use a kmem_cache pool instead.

Signed-off-by: Christophe Leroy <christophe.leroy at c-s.fr>

---
v2: changed to apply cleanly to linux-next (due to patch ab090dc)

 arch/powerpc/include/asm/pgtable-ppc32.h |  4 ++++
 arch/powerpc/mm/pgtable_32.c             | 16 ++++++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/pgtable-ppc32.h b/arch/powerpc/include/asm/pgtable-ppc32.h
index c718bfd..affc703 100644
--- a/arch/powerpc/include/asm/pgtable-ppc32.h
+++ b/arch/powerpc/include/asm/pgtable-ppc32.h
@@ -341,10 +341,14 @@ static inline void __ptep_set_access_flags(pte_t *ptep, pte_t entry)
 #define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val(pte) >> 3 })
 #define __swp_entry_to_pte(x)		((pte_t) { (x).val << 3 })
 
+#ifndef CONFIG_PPC_4K_PAGES
+void pgtable_cache_init(void);
+#else
 /*
  * No page table caches to initialise
  */
 #define pgtable_cache_init()	do { } while (0)
+#endif
 
 extern int get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep,
 		      pmd_t **pmdp);
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 50fad38..c06599f 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -73,13 +73,25 @@ extern unsigned long p_mapped_by_tlbcam(phys_addr_t pa);
 
 #define PGDIR_ORDER	(32 + PGD_T_LOG2 - PGDIR_SHIFT)
 
+#ifndef CONFIG_PPC_4K_PAGES
+static struct kmem_cache *pgtable_cache;
+
+void pgtable_cache_init(void)
+{
+	pgtable_cache = kmem_cache_create("PGDIR cache", 1 << PGDIR_ORDER,
+					  1 << PGDIR_ORDER, 0, NULL);
+	if (pgtable_cache == NULL)
+		panic("Couldn't allocate pgtable caches");
+}
+#endif
+
 pgd_t *pgd_alloc(struct mm_struct *mm)
 {
 	pgd_t *ret;
 
 	/* pgdir take page or two with 4K pages and a page fraction otherwise */
 #ifndef CONFIG_PPC_4K_PAGES
-	ret = kzalloc(1 << PGDIR_ORDER, GFP_KERNEL);
+	ret = kmem_cache_alloc(pgtable_cache, GFP_KERNEL | __GFP_ZERO);
 #else
 	ret = (pgd_t *)__get_free_pages(GFP_KERNEL|__GFP_ZERO,
 			PGDIR_ORDER - PAGE_SHIFT);
@@ -90,7 +102,7 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 {
 #ifndef CONFIG_PPC_4K_PAGES
-	kfree((void *)pgd);
+	kmem_cache_free(pgtable_cache, (void *)pgd);
 #else
 	free_pages((unsigned long)pgd, PGDIR_ORDER - PAGE_SHIFT);
 #endif
-- 
2.1.0