Merge branch 'slab/for-6.1/kmalloc_size_roundup' into slab/for-next

The first two patches from a series by Kees Cook [1] that introduce
kmalloc_size_roundup(). This will allow merging of per-subsystem patches using
the new function and ultimately stop (ab)using ksize() in a way that causes
ongoing trouble for debugging functionality and static checkers.

[1] https://lore.kernel.org/all/20220923202822.2667581-1-keescook@chromium.org/

--
Resolved a conflict of modifying mm/slab.c __ksize() comment with a commit that
unifies __ksize() implementation into mm/slab_common.c

1 files changed, 14 insertions, 0 deletions

diff --git a/mm/slob.c b/mm/slob.c
index 45a061b8ba38..fe567fcfa3a3 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -564,6 +564,20 @@ void kfree(const void *block)
 }
 EXPORT_SYMBOL(kfree);
 
+size_t kmalloc_size_roundup(size_t size)
+{
+	/* Short-circuit the 0 size case. */
+	if (unlikely(size == 0))
+		return 0;
+	/* Short-circuit saturated "too-large" case. */
+	if (unlikely(size == SIZE_MAX))
+		return SIZE_MAX;
+
+	return ALIGN(size, ARCH_KMALLOC_MINALIGN);
+}
+
+EXPORT_SYMBOL(kmalloc_size_roundup);
+
 /* can't use ksize for kmem_cache_alloc memory, only kmalloc */
 size_t __ksize(const void *block)
 {