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kernel: userspace: fix dynamic kernel object alignment

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Previous commit 55350a93e9 fixing
address-of-packed-mem warnings uncovered an issue with
the alignment of dynamic kernel objects. On 64-bit platforms,
the alignment is 16 bytes instead of 4/8 bytes (as in pointer,
void *). This changes the function of mapping between kernel
object types and alignments to use the dynamic object struct
as basis for alignment instead of simply using pointers.

This also uncomments the assertion added in the previous commit
55350a93e9 so that we can keep
an eye on the alignment in the future. Note that the assertion
is moved after checking if the incoming kernel object is
dynamically allocated. Static kernel objects are not subjected
to this alignment requirement.

Fixes #41062

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
This commit is contained in:
Daniel Leung 2021-12-13 14:54:51 -08:00 • committed by Anas Nashif
commit b6dd960be8
1 changed files with 8 additions and 7 deletions
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15
kernel/userspace.c
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@ -190,11 +190,11 @@ static size_t obj_align_get(enum k_objects otype)
#ifdef ARCH_DYMANIC_OBJ_K_THREAD_ALIGNMENT
ret = ARCH_DYMANIC_OBJ_K_THREAD_ALIGNMENT;
#else
ret = sizeof(void *);
ret = __alignof(struct dyn_obj);
#endif
break;
default:
ret = sizeof(void *);
ret = __alignof(struct dyn_obj);
break;
}
@ -466,15 +466,16 @@ static void unref_check(struct z_object *ko, uintptr_t index)
sys_bitfield_clear_bit((mem_addr_t)&ko->perms, index);
#ifdef CONFIG_DYNAMIC_OBJECTS
if ((ko->flags & K_OBJ_FLAG_ALLOC) == 0U) {
/* skip unref check for static kernel object */
goto out;
}
void *vko = ko;
struct dyn_obj *dyn = CONTAINER_OF(vko, struct dyn_obj, kobj);
/* TODO: check why this assert hits */
/*__ASSERT(IS_PTR_ALIGNED(dyn, struct dyn_obj), "unaligned z_object");*/
if ((ko->flags & K_OBJ_FLAG_ALLOC) == 0U) {
goto out;
}
__ASSERT(IS_PTR_ALIGNED(dyn, struct dyn_obj), "unaligned z_object");
for (int i = 0; i < CONFIG_MAX_THREAD_BYTES; i++) {
if (ko->perms[i] != 0U) {