s390/pci: do not read data after failed load

If a pci load instruction fails the content of the register where the
data is stored is possibly unchanged. Fix the inline assembly wrapper
__pcilg to not return stale data. Additionally fix the callers of this
function who access uninitialized variables.

Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 11 insertions, 5 deletions

diff --git a/arch/s390/include/asm/pci_io.h b/arch/s390/include/asm/pci_io.h
index 0e0bec9a3fb7..83a9caa6ae53 100644
--- a/arch/s390/include/asm/pci_io.h
+++ b/arch/s390/include/asm/pci_io.h
@@ -92,6 +92,9 @@ static inline int zpci_read_single(u64 req, u64 *dst, u64 offset, u8 len)
         int cc;
 
         cc = s390pci_load(&data, req, offset);
+        if (cc)
+                goto out;
+
         switch (len) {
         case 1:
                 *((u8 *) dst) = (u8) data;
@@ -106,6 +109,7 @@ static inline int zpci_read_single(u64 req, u64 *dst, u64 offset, u8 len)
                 *((u64 *) dst) = (u64) data;
                 break;
         }
+out:
         return cc;
 }
 
diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index 2b21749cc2b3..51d16f1fb5ea 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -281,11 +281,11 @@ static int zpci_cfg_load(struct zpci_dev *zdev, int offset, u32 *val, u8 len)
         int rc;
 
         rc = s390pci_load(&data, req, offset);
-        data = data << ((8 - len) * 8);
-        data = le64_to_cpu(data);
-        if (!rc)
+        if (!rc) {
+                data = data << ((8 - len) * 8);
+                data = le64_to_cpu(data);
                 *val = (u32) data;
-        else
+        } else
                 *val = 0xffffffff;
         return rc;
 }
diff --git a/arch/s390/pci/pci_insn.c b/arch/s390/pci/pci_insn.c
index 4bc32f368f7d..22eeb9d7ffeb 100644
--- a/arch/s390/pci/pci_insn.c
+++ b/arch/s390/pci/pci_insn.c
@@ -103,7 +103,9 @@ static inline int __pcilg(u64 *data, u64 req, u64 offset, u8 *status)
                 :  "d" (__offset)
                 : "cc");
         *status = __req >> 24 & 0xff;
-        *data = __data;
+        if (!cc)
+                *data = __data;
+
         return cc;
 }