[PATCH 4.4 029/210] s390/pci: enforce fmb page boundary rule

From: Greg Kroah-Hartman
Date: Sun Apr 10 2016 - 16:08:09 EST


4.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Sebastian Ott <sebott@xxxxxxxxxxxxxxxxxx>

commit 80c544ded25ac14d7cc3e555abb8ed2c2da99b84 upstream.

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")
Signed-off-by: Sebastian Ott <sebott@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
arch/s390/include/asm/pci.h | 2 +-
arch/s390/pci/pci.c | 5 ++++-
2 files changed, 5 insertions(+), 2 deletions(-)

--- 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,
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -871,8 +871,11 @@ 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_zdev;