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authorRichard Henderson <richard.henderson@linaro.org>2020-09-15 17:46:34 -0700
committerEduardo Habkost <ehabkost@redhat.com>2020-09-18 13:59:51 -0400
commit4c880f363e9e43862230e22a4503e2fc0f092fba (patch)
tree64d85085fd5c3696149bdaf049625c7e3928051e /qom
parenta21e6607771a27553814ce3c2c7db532a6a4b576 (diff)
qom: Allow objects to be allocated with increased alignment
It turns out that some hosts have a default malloc alignment less than that required for vectors. We assume that, with compiler annotation on CPUArchState, that we can properly align the vector portion of the guest state. Fix the alignment of the allocation by using qemu_memalloc when required. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <20200916004638.2444147-3-richard.henderson@linaro.org> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Diffstat (limited to 'qom')
-rw-r--r--qom/object.c36
1 files changed, 33 insertions, 3 deletions
diff --git a/qom/object.c b/qom/object.c
index cecad35b99..a91a6a515a 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -50,6 +50,7 @@ struct TypeImpl
size_t class_size;
size_t instance_size;
+ size_t instance_align;
void (*class_init)(ObjectClass *klass, void *data);
void (*class_base_init)(ObjectClass *klass, void *data);
@@ -114,6 +115,7 @@ static TypeImpl *type_new(const TypeInfo *info)
ti->class_size = info->class_size;
ti->instance_size = info->instance_size;
+ ti->instance_align = info->instance_align;
ti->class_init = info->class_init;
ti->class_base_init = info->class_base_init;
@@ -688,16 +690,44 @@ static void object_finalize(void *data)
}
}
+/* Find the minimum alignment guaranteed by the system malloc. */
+#if __STDC_VERSION__ >= 201112L
+typddef max_align_t qemu_max_align_t;
+#else
+typedef union {
+ long l;
+ void *p;
+ double d;
+ long double ld;
+} qemu_max_align_t;
+#endif
+
static Object *object_new_with_type(Type type)
{
Object *obj;
+ size_t size, align;
+ void (*obj_free)(void *);
g_assert(type != NULL);
type_initialize(type);
- obj = g_malloc(type->instance_size);
- object_initialize_with_type(obj, type->instance_size, type);
- obj->free = g_free;
+ size = type->instance_size;
+ align = type->instance_align;
+
+ /*
+ * Do not use qemu_memalign unless required. Depending on the
+ * implementation, extra alignment implies extra overhead.
+ */
+ if (likely(align <= __alignof__(qemu_max_align_t))) {
+ obj = g_malloc(size);
+ obj_free = g_free;
+ } else {
+ obj = qemu_memalign(align, size);
+ obj_free = qemu_vfree;
+ }
+
+ object_initialize_with_type(obj, size, type);
+ obj->free = obj_free;
return obj;
}