powerpc/mm: Extend pte_fragment functionality to PPC32

In order to allow the 8xx to handle pte_fragments, this patch
extends the use of pte_fragments to PPC32 platforms.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/Makefile

@@ -18,6 +18,7 @@ obj-$(CONFIG_PPC_BOOK3E_64)   += pgtable-book3e.o
 obj-$(CONFIG_PPC_BOOK3S_64)	+= pgtable-hash64.o hash_utils_64.o slb.o \
 				   $(hash64-y) mmu_context_book3s64.o \
 				   pgtable-book3s64.o pgtable-frag.o
+obj-$(CONFIG_PPC32)		+= pgtable-frag.o
 obj-$(CONFIG_PPC_RADIX_MMU)	+= pgtable-radix.o tlb-radix.o
 obj-$(CONFIG_PPC_BOOK3S_32)	+= ppc_mmu_32.o hash_low_32.o mmu_context_hash32.o
 obj-$(CONFIG_PPC_BOOK3S)	+= tlb_hash$(BITS).o

arch/powerpc/mm/mmu_context.c

@@ -15,6 +15,7 @@
 #include <linux/sched/mm.h>
 
 #include <asm/mmu_context.h>
+#include <asm/pgalloc.h>
 
 #if defined(CONFIG_PPC32)
 static inline void switch_mm_pgdir(struct task_struct *tsk,
@@ -97,3 +98,12 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
 	switch_mmu_context(prev, next, tsk);
 }
 
+#ifdef CONFIG_PPC32
+void arch_exit_mmap(struct mm_struct *mm)
+{
+	void *frag = pte_frag_get(&mm->context);
+
+	if (frag)
+		pte_frag_destroy(frag);
+}
+#endif

arch/powerpc/mm/mmu_context_nohash.c

@@ -385,6 +385,7 @@ int init_new_context(struct task_struct *t, struct mm_struct *mm)
 #endif
 	mm->context.id = MMU_NO_CONTEXT;
 	mm->context.active = 0;
+	pte_frag_set(&mm->context, NULL);
 	return 0;
 }
 
@@ -487,4 +488,3 @@ void __init mmu_context_init(void)
 	next_context = FIRST_CONTEXT;
 	nr_free_contexts = LAST_CONTEXT - FIRST_CONTEXT + 1;
 }
-

arch/powerpc/mm/pgtable_32.c

@@ -45,32 +45,15 @@ extern char etext[], _stext[], _sinittext[], _einittext[];
 
 __ref pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
 {
-	pte_t *pte;
+	if (!slab_is_available())
+		return memblock_alloc(PTE_FRAG_SIZE, PTE_FRAG_SIZE);
 
-	if (slab_is_available()) {
-		pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
-	} else {
-		pte = __va(memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE));
-		if (pte)
-			clear_page(pte);
-	}
-	return pte;
+	return (pte_t *)pte_fragment_alloc(mm, address, 1);
 }
 
 pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
 {
-	struct page *ptepage;
-
-	gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_ACCOUNT;
-
-	ptepage = alloc_pages(flags, 0);
-	if (!ptepage)
-		return NULL;
-	if (!pgtable_page_ctor(ptepage)) {
-		__free_page(ptepage);
-		return NULL;
-	}
-	return ptepage;
+	return (pgtable_t)pte_fragment_alloc(mm, address, 0);
 }
 
 void __iomem *