[Qemu-devel] [PATCH] hw/s390x/virtio-ccw.c: Don't take address of fields in packed structs

[Peter Maydell <peter.maydell@linaro.org>]

Taking the address of a field in a packed struct is a bad idea, because
it might not be actually aligned enough for that pointer type (and
thus cause a crash on dereference on some host architectures). Newer
versions of clang warn about this. Avoid the bug by not using the
"modify in place" byte swapping functions.

Patch produced with scripts/coccinelle/inplace-byteswaps.cocci
(with a couple of long lines manually wrapped).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
s390 also has some warnings in hw/s390x/css.c which are going to
be harder to fix, relating to taking the address of the 'pmcw' and
'scsw' fields in the SCHUB struct...

 hw/s390x/virtio-ccw.c | 42 ++++++++++++++++++++++--------------------
 1 file changed, 22 insertions(+), 20 deletions(-)

diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index 212b3d3dead..c2b78c8e9b1 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -287,18 +287,18 @@ static int virtio_ccw_handle_set_vq(SubchDev *sch, CCW1 ccw, bool check_len,
     }
     if (is_legacy) {
         ccw_dstream_read(&sch->cds, linfo);
-        be64_to_cpus(&linfo.queue);
-        be32_to_cpus(&linfo.align);
-        be16_to_cpus(&linfo.index);
-        be16_to_cpus(&linfo.num);
+        linfo.queue = be64_to_cpu(linfo.queue);
+        linfo.align = be32_to_cpu(linfo.align);
+        linfo.index = be16_to_cpu(linfo.index);
+        linfo.num = be16_to_cpu(linfo.num);
         ret = virtio_ccw_set_vqs(sch, NULL, &linfo);
     } else {
         ccw_dstream_read(&sch->cds, info);
-        be64_to_cpus(&info.desc);
-        be16_to_cpus(&info.index);
-        be16_to_cpus(&info.num);
-        be64_to_cpus(&info.avail);
-        be64_to_cpus(&info.used);
+        info.desc = be64_to_cpu(info.desc);
+        info.index = be16_to_cpu(info.index);
+        info.num = be16_to_cpu(info.num);
+        info.avail = be64_to_cpu(info.avail);
+        info.used = be64_to_cpu(info.used);
         ret = virtio_ccw_set_vqs(sch, &info, NULL);
     }
     sch->curr_status.scsw.count = 0;
@@ -382,7 +382,7 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
                 features.features = 0;
             }
             ccw_dstream_rewind(&sch->cds);
-            cpu_to_le32s(&features.features);
+            features.features = cpu_to_le32(features.features);
             ccw_dstream_write(&sch->cds, features.features);
             sch->curr_status.scsw.count = ccw.count - sizeof(features);
             ret = 0;
@@ -403,7 +403,7 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
             ret = -EFAULT;
         } else {
             ccw_dstream_read(&sch->cds, features);
-            le32_to_cpus(&features.features);
+            features.features = le32_to_cpu(features.features);
             if (features.index == 0) {
                 virtio_set_features(vdev,
                                     (vdev->guest_features & 0xffffffff00000000ULL) |
@@ -546,7 +546,7 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
             ret = -EFAULT;
         } else {
             ccw_dstream_read(&sch->cds, indicators);
-            be64_to_cpus(&indicators);
+            indicators = be64_to_cpu(indicators);
             dev->indicators = get_indicator(indicators, sizeof(uint64_t));
             sch->curr_status.scsw.count = ccw.count - sizeof(indicators);
             ret = 0;
@@ -567,7 +567,7 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
             ret = -EFAULT;
         } else {
             ccw_dstream_read(&sch->cds, indicators);
-            be64_to_cpus(&indicators);
+            indicators = be64_to_cpu(indicators);
             dev->indicators2 = get_indicator(indicators, sizeof(uint64_t));
             sch->curr_status.scsw.count = ccw.count - sizeof(indicators);
             ret = 0;
@@ -588,14 +588,14 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
             ret = -EFAULT;
         } else {
             ccw_dstream_read(&sch->cds, vq_config.index);
-            be16_to_cpus(&vq_config.index);
+            vq_config.index = be16_to_cpu(vq_config.index);
             if (vq_config.index >= VIRTIO_QUEUE_MAX) {
                 ret = -EINVAL;
                 break;
             }
             vq_config.num_max = virtio_queue_get_num(vdev,
                                                      vq_config.index);
-            cpu_to_be16s(&vq_config.num_max);
+            vq_config.num_max = cpu_to_be16(vq_config.num_max);
             ccw_dstream_write(&sch->cds, vq_config.num_max);
             sch->curr_status.scsw.count = ccw.count - sizeof(vq_config);
             ret = 0;
@@ -621,9 +621,11 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
             if (ccw_dstream_read(&sch->cds, thinint)) {
                 ret = -EFAULT;
             } else {
-                be64_to_cpus(&thinint.ind_bit);
-                be64_to_cpus(&thinint.summary_indicator);
-                be64_to_cpus(&thinint.device_indicator);
+                thinint.ind_bit = be64_to_cpu(thinint.ind_bit);
+                thinint.summary_indicator =
+                    be64_to_cpu(thinint.summary_indicator);
+                thinint.device_indicator =
+                    be64_to_cpu(thinint.device_indicator);
 
                 dev->summary_indicator =
                     get_indicator(thinint.summary_indicator, sizeof(uint8_t));
@@ -654,8 +656,8 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
             break;
         }
         ccw_dstream_read_buf(&sch->cds, &revinfo, 4);
-        be16_to_cpus(&revinfo.revision);
-        be16_to_cpus(&revinfo.length);
+        revinfo.revision = be16_to_cpu(revinfo.revision);
+        revinfo.length = be16_to_cpu(revinfo.length);
         if (ccw.count < len + revinfo.length ||
             (check_len && ccw.count > len + revinfo.length)) {
             ret = -EINVAL;
-- 
2.19.2