On 12/10/2018 08:58 AM, Peter Maydell wrote:
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 problem by using local copies of the PMCW and SCSW
struct fields in copy_schib_from_guest() and copy_schib_to_guest().
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
---
This seemed like a not totally ugly and reasonably localised fix
that satisfies clang. Oddly, this makes the generated object file
15K smaller (421K vs 406K), so it might even be better code...
hw/s390x/css.c | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index 04ec5cc9705..ef07691e36b 100644
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -1290,9 +1290,15 @@ void copy_scsw_to_guest(SCSW *dest, const SCSW *src)
static void copy_schib_to_guest(SCHIB *dest, const SCHIB *src)
{
int i;
+ PMCW srcpmcw, destpmcw;
+ SCSW srcscsw, destscsw;
- copy_pmcw_to_guest(&dest->pmcw, &src->pmcw);
- copy_scsw_to_guest(&dest->scsw, &src->scsw);
+ srcpmcw = src->pmcw;
+ copy_pmcw_to_guest(&destpmcw, &srcpmcw);
+ dest->pmcw = destpmcw;
+ srcscsw = src->scsw;
+ copy_scsw_to_guest(&destscsw, &srcscsw);
+ dest->scsw = destscsw;
dest->mba = cpu_to_be64(src->mba);
for (i = 0; i < ARRAY_SIZE(dest->mda); i++) {
dest->mda[i] = src->mda[i];
@@ -1339,9 +1345,15 @@ static void copy_scsw_from_guest(SCSW *dest, const SCSW
*src)
static void copy_schib_from_guest(SCHIB *dest, const SCHIB *src)
{
int i;
+ PMCW srcpmcw, destpmcw;
+ SCSW srcscsw, destscsw;
- copy_pmcw_from_guest(&dest->pmcw, &src->pmcw);
- copy_scsw_from_guest(&dest->scsw, &src->scsw);
+ srcpmcw = src->pmcw;
+ copy_pmcw_from_guest(&destpmcw, &srcpmcw);
+ dest->pmcw = destpmcw;
+ srcscsw = src->scsw;
+ copy_scsw_from_guest(&destscsw, &srcscsw);
+ dest->scsw = destscsw;
dest->mba = be64_to_cpu(src->mba);
for (i = 0; i < ARRAY_SIZE(dest->mda); i++) {
dest->mda[i] = src->mda[i];
Reviewed-by: Farhan Ali <al...@linux.ibm.com>
