powerpc/mm: Rework & cleanup page table freeing code path

That patch used to just add a hook to page table flushing but
pulling that string brought out a whole bunch of issues, so it
now does that and more:

 - We now make the RCU batching of page freeing SMP only, as I
believe it was intended initially. We make a few more things compile
to nothing on !CONFIG_SMP

 - Some macros are turned into functions, though that forced me to
out of line a few stuffs due to unsolvable include depenencies,
however it's probably better that way anyway, it's not -that-
critical code path.

 - 32-bit didn't call pte_free_finish() on tlb_flush() which means
that it wouldn't push out the batch to RCU for delayed freeing when
a bunch of page tables have been freed, they would just stay in there
until the batch gets full.

64-bit BookE will use that hook to maintain the virtually linear
page tables or the indirect entries in the TLB when using the
HW loader.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 28 insertions, 11 deletions

diff --git a/arch/powerpc/include/asm/pgalloc.h b/arch/powerpc/include/asm/pgalloc.h
index 1730e5e..34b0806 100644
--- a/arch/powerpc/include/asm/pgalloc.h
+++ b/arch/powerpc/include/asm/pgalloc.h
@@ -4,6 +4,15 @@
 
 #include <linux/mm.h>
 
+#ifdef CONFIG_PPC_BOOK3E
+extern void tlb_flush_pgtable(struct mmu_gather *tlb, unsigned long address);
+#else /* CONFIG_PPC_BOOK3E */
+static inline void tlb_flush_pgtable(struct mmu_gather *tlb,
+				     unsigned long address)
+{
+}
+#endif /* !CONFIG_PPC_BOOK3E */
+
 static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
 {
 	free_page((unsigned long)pte);
@@ -35,19 +44,27 @@ static inline pgtable_free_t pgtable_free_cache(void *p, int cachenum,
 #include <asm/pgalloc-32.h>
 #endif
 
-extern void pgtable_free_tlb(struct mmu_gather *tlb, pgtable_free_t pgf);
-
 #ifdef CONFIG_SMP
-#define __pte_free_tlb(tlb,ptepage,address)		\
-do { \
-	pgtable_page_dtor(ptepage); \
-	pgtable_free_tlb(tlb, pgtable_free_cache(page_address(ptepage), \
-					PTE_NONCACHE_NUM, PTE_TABLE_SIZE-1)); \
-} while (0)
-#else
-#define __pte_free_tlb(tlb, pte, address)	pte_free((tlb)->mm, (pte))
-#endif
+extern void pgtable_free_tlb(struct mmu_gather *tlb, pgtable_free_t pgf);
+extern void pte_free_finish(void);
+#else /* CONFIG_SMP */
+static inline void pgtable_free_tlb(struct mmu_gather *tlb, pgtable_free_t pgf)
+{
+	pgtable_free(pgf);
+}
+static inline void pte_free_finish(void) { }
+#endif /* !CONFIG_SMP */
 
+static inline void __pte_free_tlb(struct mmu_gather *tlb, struct page *ptepage,
+				  unsigned long address)
+{
+	pgtable_free_t pgf = pgtable_free_cache(page_address(ptepage),
+						PTE_NONCACHE_NUM,
+						PTE_TABLE_SIZE-1);
+	tlb_flush_pgtable(tlb, address);
+	pgtable_page_dtor(ptepage);
+	pgtable_free_tlb(tlb, pgf);
+}
 
 #endif /* __KERNEL__ */
 #endif /* _ASM_POWERPC_PGALLOC_H */