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, 3 insertions, 35 deletions

diff --git a/arch/powerpc/include/asm/tlb.h b/arch/powerpc/include/asm/tlb.h
index e20ff7541f36..e2b428b0f7ba 100644
--- a/arch/powerpc/include/asm/tlb.h
+++ b/arch/powerpc/include/asm/tlb.h
@@ -25,57 +25,25 @@
 
 #include <linux/pagemap.h>
 
-struct mmu_gather;
-
 #define tlb_start_vma(tlb, vma) do { } while (0)
 #define tlb_end_vma(tlb, vma)   do { } while (0)
 
-#if !defined(CONFIG_PPC_STD_MMU)
-
-#define tlb_flush(tlb)                  flush_tlb_mm((tlb)->mm)
-
-#elif defined(__powerpc64__)
-
-extern void pte_free_finish(void);
-
-static inline void tlb_flush(struct mmu_gather *tlb)
-{
-        struct ppc64_tlb_batch *tlbbatch = &__get_cpu_var(ppc64_tlb_batch);
-
-        /* If there's a TLB batch pending, then we must flush it because the
-         * pages are going to be freed and we really don't want to have a CPU
-         * access a freed page because it has a stale TLB
-         */
-        if (tlbbatch->index)
-                __flush_tlb_pending(tlbbatch);
-
-        pte_free_finish();
-}
-
-#else
-
 extern void tlb_flush(struct mmu_gather *tlb);
 
-#endif
-
 /* Get the generic bits... */
 #include <asm-generic/tlb.h>
 
-#if !defined(CONFIG_PPC_STD_MMU) || defined(__powerpc64__)
-
-#define __tlb_remove_tlb_entry(tlb, pte, address) do { } while (0)
-
-#else
 extern void flush_hash_entry(struct mm_struct *mm, pte_t *ptep,
                              unsigned long address);
 
 static inline void __tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep,
-                                        unsigned long address)
+                                          unsigned long address)
 {
+#ifdef CONFIG_PPC_STD_MMU_32
         if (pte_val(*ptep) & _PAGE_HASHPTE)
                 flush_hash_entry(tlb->mm, ptep, address);
+#endif
 }
 
-#endif
 #endif /* __KERNEL__ */
 #endif /* __ASM_POWERPC_TLB_H */