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qom: Allow objects to be allocated with increased alignment

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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>
This commit is contained in:
Richard Henderson 2020-09-15 17:46:34 -07:00 • committed by Eduardo Habkost
parent a21e660777
commit 4c880f363e
2 changed files with 38 additions and 3 deletions
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36
qom/object.c
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@ -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;
}