rust: mm: add __rust_helper to helpers

This is needed to inline these helpers into Rust code.

Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://patch.msgid.link/20260105-define-rust-helper-v2-11-51da5f454a67@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: Darksonn

rust/helpers/mm.c

@@ -3,48 +3,48 @@
 #include <linux/mm.h>
 #include <linux/sched/mm.h>
 
-void rust_helper_mmgrab(struct mm_struct *mm)
+__rust_helper void rust_helper_mmgrab(struct mm_struct *mm)
 {
 	mmgrab(mm);
 }
 
-void rust_helper_mmdrop(struct mm_struct *mm)
+__rust_helper void rust_helper_mmdrop(struct mm_struct *mm)
 {
 	mmdrop(mm);
 }
 
-void rust_helper_mmget(struct mm_struct *mm)
+__rust_helper void rust_helper_mmget(struct mm_struct *mm)
 {
 	mmget(mm);
 }
 
-bool rust_helper_mmget_not_zero(struct mm_struct *mm)
+__rust_helper bool rust_helper_mmget_not_zero(struct mm_struct *mm)
 {
 	return mmget_not_zero(mm);
 }
 
-void rust_helper_mmap_read_lock(struct mm_struct *mm)
+__rust_helper void rust_helper_mmap_read_lock(struct mm_struct *mm)
 {
 	mmap_read_lock(mm);
 }
 
-bool rust_helper_mmap_read_trylock(struct mm_struct *mm)
+__rust_helper bool rust_helper_mmap_read_trylock(struct mm_struct *mm)
 {
 	return mmap_read_trylock(mm);
 }
 
-void rust_helper_mmap_read_unlock(struct mm_struct *mm)
+__rust_helper void rust_helper_mmap_read_unlock(struct mm_struct *mm)
 {
 	mmap_read_unlock(mm);
 }
 
-struct vm_area_struct *rust_helper_vma_lookup(struct mm_struct *mm,
-					      unsigned long addr)
+__rust_helper struct vm_area_struct *
+rust_helper_vma_lookup(struct mm_struct *mm, unsigned long addr)
 {
 	return vma_lookup(mm, addr);
 }
 
-void rust_helper_vma_end_read(struct vm_area_struct *vma)
+__rust_helper void rust_helper_vma_end_read(struct vm_area_struct *vma)
 {
 	vma_end_read(vma);
 }

rust/helpers/page.c

@@ -4,23 +4,24 @@
 #include <linux/highmem.h>
 #include <linux/mm.h>
 
-struct page *rust_helper_alloc_pages(gfp_t gfp_mask, unsigned int order)
+__rust_helper struct page *rust_helper_alloc_pages(gfp_t gfp_mask,
+						   unsigned int order)
 {
 	return alloc_pages(gfp_mask, order);
 }
 
-void *rust_helper_kmap_local_page(struct page *page)
+__rust_helper void *rust_helper_kmap_local_page(struct page *page)
 {
 	return kmap_local_page(page);
 }
 
-void rust_helper_kunmap_local(const void *addr)
+__rust_helper void rust_helper_kunmap_local(const void *addr)
 {
 	kunmap_local(addr);
 }
 
 #ifndef NODE_NOT_IN_PAGE_FLAGS
-int rust_helper_page_to_nid(const struct page *page)
+__rust_helper int rust_helper_page_to_nid(const struct page *page)
 {
 	return page_to_nid(page);
 }

rust/helpers/vmalloc.c

@@ -2,7 +2,7 @@
 
 #include <linux/vmalloc.h>
 
-void * __must_check __realloc_size(2)
+__rust_helper void *__must_check __realloc_size(2)
 rust_helper_vrealloc_node_align(const void *p, size_t size, unsigned long align,
 				gfp_t flags, int node)
 {