From 4c880f363e9e43862230e22a4503e2fc0f092fba Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Tue, 15 Sep 2020 17:46:34 -0700 Subject: 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 Message-Id: <20200916004638.2444147-3-richard.henderson@linaro.org> Signed-off-by: Eduardo Habkost --- qom/object.c | 36 +++++++++++++++++++++++++++++++++--- 1 file changed, 33 insertions(+), 3 deletions(-) (limited to 'qom') diff --git a/qom/object.c b/qom/object.c index cecad35..a91a6a5 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; } -- cgit v1.1