s390/pci: enforce fmb page boundary rule

The function measurement block must not cross a page boundary. Ensure
that by raising the alignment requirement to the smallest power of 2
larger than the size of the fmb.

Fixes: d0b088531 ("s390/pci: performance statistics and debug infrastructure")
Cc: stable@vger.kernel.org # v3.8+
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 5 insertions, 2 deletions

diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
index dc763eae7c49..f833082d9167 100644
--- a/arch/s390/include/asm/pci.h
+++ b/arch/s390/include/asm/pci.h
@@ -45,7 +45,7 @@ struct zpci_fmb {
         u64 rpcit_ops;
         u64 dma_rbytes;
         u64 dma_wbytes;
-} __packed __aligned(16);
+} __packed __aligned(64);
 
 enum zpci_state {
         ZPCI_FN_STATE_RESERVED,
diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index f76d01e69fb8..9fd59a7cfcd3 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -860,8 +860,11 @@ static inline int barsize(u8 size)
 
 static int zpci_mem_init(void)
 {
+        BUILD_BUG_ON(!is_power_of_2(__alignof__(struct zpci_fmb)) ||
+                     __alignof__(struct zpci_fmb) < sizeof(struct zpci_fmb));
+
         zdev_fmb_cache = kmem_cache_create("PCI_FMB_cache", sizeof(struct zpci_fmb),
-                                16, 0, NULL);
+                                           __alignof__(struct zpci_fmb), 0, NULL);
         if (!zdev_fmb_cache)
                 goto error_fmb;