[PATCH v2 01/11] asm-generic/tlb: Fix MMU_GATHER_TABLE_FREE

Peter Zijlstra
2020-07-17T11:10:06Z

The first MMU_GATHER_TABLE_FREE user showed a logic error in the
tlb_needs_table_invalidate() definition. Make sure any TABLE_FREE has
it defined.

Fixes: 0d6e24d430ef ("asm-generic/tlb: provide MMU_GATHER_TABLE_FREE")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
include/asm-generic/tlb.h | 35 +++++++++++++++++++----------------
1 file changed, 19 insertions(+), 16 deletions(-)

--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -172,6 +172,18 @@
* various ptep_get_and_clear() functions.
*/

+#ifndef CONFIG_MMU_GATHER_RCU_TABLE_FREE
+
+/*
+ * Only RCU table free can override this; otherwise the TLBI is needed to
+ * provide existence guarantees for software walkers.
+ */
+#ifdef tlb_needs_table_invalidate
+#error tlb_needs_table_invalidate() requires MMU_GATHER_RCU_TABLE_FREE
+#endif
+
+#endif /* CONFIG_MMU_GATHER_RCU_TABLE_FREE */
+
#ifdef CONFIG_MMU_GATHER_TABLE_FREE

struct mmu_table_batch {
@@ -187,17 +199,6 @@ struct mmu_table_batch {

extern void tlb_remove_table(struct mmu_gather *tlb, void *table);

-#else /* !CONFIG_MMU_GATHER_HAVE_TABLE_FREE */
-
-/*
- * Without MMU_GATHER_TABLE_FREE the architecture is assumed to have page based
- * page directories and we can use the normal page batching to free them.
- */
-#define tlb_remove_table(tlb, page) tlb_remove_page((tlb), (page))
-
-#endif /* CONFIG_MMU_GATHER_TABLE_FREE */
-
-#ifdef CONFIG_MMU_GATHER_RCU_TABLE_FREE
/*
* This allows an architecture that does not use the linux page-tables for
* hardware to skip the TLBI when freeing page tables.
@@ -206,13 +207,15 @@ extern void tlb_remove_table(struct mmu_
#define tlb_needs_table_invalidate() (true)
#endif

-#else
+#else /* !CONFIG_MMU_GATHER_HAVE_TABLE_FREE */

-#ifdef tlb_needs_table_invalidate
-#error tlb_needs_table_invalidate() requires MMU_GATHER_RCU_TABLE_FREE
-#endif
+/*
+ * Without MMU_GATHER_TABLE_FREE the architecture is assumed to have page based
+ * page directories and we can use the normal page batching to free them.
+ */
+#define tlb_remove_table(tlb, page) tlb_remove_page((tlb), (page))

-#endif /* CONFIG_MMU_GATHER_RCU_TABLE_FREE */
+#endif /* CONFIG_MMU_GATHER_TABLE_FREE */

#ifndef CONFIG_MMU_GATHER_NO_GATHER