1 files changed, 52 insertions, 10 deletions

diff --git a/drivers/s390/cio/itcw.c b/drivers/s390/cio/itcw.c
index a0ae29564774..358ee16d10a2 100644
--- a/drivers/s390/cio/itcw.c
+++ b/drivers/s390/cio/itcw.c
@@ -93,6 +93,7 @@ EXPORT_SYMBOL(itcw_get_tcw);
 size_t itcw_calc_size(int intrg, int max_tidaws, int intrg_max_tidaws)
 {
         size_t len;
+        int cross_count;
 
         /* Main data. */
         len = sizeof(struct itcw);
@@ -105,12 +106,27 @@ size_t itcw_calc_size(int intrg, int max_tidaws, int intrg_max_tidaws)
                        /* TSB */ sizeof(struct tsb) +
                        /* TIDAL */ intrg_max_tidaws * sizeof(struct tidaw);
         }
+
         /* Maximum required alignment padding. */
         len += /* Initial TCW */ 63 + /* Interrogate TCCB */ 7;
-        /* Maximum padding for structures that may not cross 4k boundary. */
-        if ((max_tidaws > 0) || (intrg_max_tidaws > 0))
-                len += max(max_tidaws, intrg_max_tidaws) *
-                       sizeof(struct tidaw) - 1;
+
+        /* TIDAW lists may not cross a 4k boundary. To cross a
+         * boundary we need to add a TTIC TIDAW. We need to reserve
+         * one additional TIDAW for a TTIC that we may need to add due
+         * to the placement of the data chunk in memory, and a further
+         * TIDAW for each page boundary that the TIDAW list may cross
+         * due to it's own size.
+         */
+        if (max_tidaws) {
+                cross_count = 1 + ((max_tidaws * sizeof(struct tidaw) - 1)
+                                   >> PAGE_SHIFT);
+                len += cross_count * sizeof(struct tidaw);
+        }
+        if (intrg_max_tidaws) {
+                cross_count = 1 + ((intrg_max_tidaws * sizeof(struct tidaw) - 1)
+                                   >> PAGE_SHIFT);
+                len += cross_count * sizeof(struct tidaw);
+        }
         return len;
 }
 EXPORT_SYMBOL(itcw_calc_size);
@@ -165,6 +181,7 @@ struct itcw *itcw_init(void *buffer, size_t size, int op, int intrg,
         void *chunk;
         addr_t start;
         addr_t end;
+        int cross_count;
 
         /* Check for 2G limit. */
         start = (addr_t) buffer;
@@ -177,8 +194,17 @@ struct itcw *itcw_init(void *buffer, size_t size, int op, int intrg,
         if (IS_ERR(chunk))
                 return chunk;
         itcw = chunk;
-        itcw->max_tidaws = max_tidaws;
-        itcw->intrg_max_tidaws = intrg_max_tidaws;
+        /* allow for TTIC tidaws that may be needed to cross a page boundary */
+        cross_count = 0;
+        if (max_tidaws)
+                cross_count = 1 + ((max_tidaws * sizeof(struct tidaw) - 1)
+                                   >> PAGE_SHIFT);
+        itcw->max_tidaws = max_tidaws + cross_count;
+        cross_count = 0;
+        if (intrg_max_tidaws)
+                cross_count = 1 + ((intrg_max_tidaws * sizeof(struct tidaw) - 1)
+                                   >> PAGE_SHIFT);
+        itcw->intrg_max_tidaws = intrg_max_tidaws + cross_count;
         /* Main TCW. */
         chunk = fit_chunk(&start, end, sizeof(struct tcw), 64, 0);
         if (IS_ERR(chunk))
@@ -198,7 +224,7 @@ struct itcw *itcw_init(void *buffer, size_t size, int op, int intrg,
         /* Data TIDAL. */
         if (max_tidaws > 0) {
                 chunk = fit_chunk(&start, end, sizeof(struct tidaw) *
-                                  max_tidaws, 16, 1);
+                                  itcw->max_tidaws, 16, 0);
                 if (IS_ERR(chunk))
                         return chunk;
                 tcw_set_data(itcw->tcw, chunk, 1);
@@ -206,7 +232,7 @@ struct itcw *itcw_init(void *buffer, size_t size, int op, int intrg,
         /* Interrogate data TIDAL. */
         if (intrg && (intrg_max_tidaws > 0)) {
                 chunk = fit_chunk(&start, end, sizeof(struct tidaw) *
-                                  intrg_max_tidaws, 16, 1);
+                                  itcw->intrg_max_tidaws, 16, 0);
                 if (IS_ERR(chunk))
                         return chunk;
                 tcw_set_data(itcw->intrg_tcw, chunk, 1);
@@ -283,13 +309,29 @@ EXPORT_SYMBOL(itcw_add_dcw);
  * the new tidaw on success or -%ENOSPC if the new tidaw would exceed the
  * available space.
  *
- * Note: the tidaw-list is assumed to be contiguous with no ttics. The
- * last-tidaw flag for the last tidaw in the list will be set by itcw_finalize.
+ * Note: TTIC tidaws are automatically added when needed, so explicitly calling
+ * this interface with the TTIC flag is not supported. The last-tidaw flag
+ * for the last tidaw in the list will be set by itcw_finalize.
  */
 struct tidaw *itcw_add_tidaw(struct itcw *itcw, u8 flags, void *addr, u32 count)
 {
+        struct tidaw *following;
+
         if (itcw->num_tidaws >= itcw->max_tidaws)
                 return ERR_PTR(-ENOSPC);
+        /*
+         * Is the tidaw, which follows the one we are about to fill, on the next
+         * page? Then we have to insert a TTIC tidaw first, that points to the
+         * tidaw on the new page.
+         */
+        following = ((struct tidaw *) tcw_get_data(itcw->tcw))
+                + itcw->num_tidaws + 1;
+        if (itcw->num_tidaws && !((unsigned long) following & ~PAGE_MASK)) {
+                tcw_add_tidaw(itcw->tcw, itcw->num_tidaws++,
+                              TIDAW_FLAGS_TTIC, following, 0);
+                if (itcw->num_tidaws >= itcw->max_tidaws)
+                        return ERR_PTR(-ENOSPC);
+        }
         return tcw_add_tidaw(itcw->tcw, itcw->num_tidaws++, flags, addr, count);
 }
 EXPORT_SYMBOL(itcw_add_tidaw);