[PATCH v2] s390/mm: Make virt_to_pfn() a static inline

[Linus Walleij]

Making virt_to_pfn() a static inline taking a strongly typed
(const void *) makes the contract of a passing a pointer of that
type to the function explicit and exposes any misuse of the
macro virt_to_pfn() acting polymorphic and accepting many types
such as (void *), (unitptr_t) or (unsigned long) as arguments
without warnings.

For symmetry do the same with pfn_to_virt() reflecting the
current layout in asm-generic/page.h.

Doing this reveals a number of offenders in the arch code and
the S390-specific drivers, so just bite the bullet and fix up
all of those as well.

Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
Changes in v2:
- Just drop the cast to (unsigned long) in drivers/s390/char/vmcp.c,
  we do not need to cast to (void *) from (char *), a pointer is
  a pointer.
- Link to v1: https://lore.kernel.org/r/20230811-virt-to-phys-s390-v1-1-b661426ca9cd@xxxxxxxxxx
---
 arch/s390/include/asm/kfence.h |  2 +-
 arch/s390/include/asm/page.h   | 12 ++++++++++--
 arch/s390/mm/cmm.c             |  2 +-
 arch/s390/mm/vmem.c            |  2 +-
 drivers/s390/block/scm_blk.c   |  2 +-
 drivers/s390/char/vmcp.c       |  2 +-
 6 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/arch/s390/include/asm/kfence.h b/arch/s390/include/asm/kfence.h
index d55ba878378b..e47fd8cbe701 100644
--- a/arch/s390/include/asm/kfence.h
+++ b/arch/s390/include/asm/kfence.h
@@ -35,7 +35,7 @@ static __always_inline void kfence_split_mapping(void)
 
 static inline bool kfence_protect_page(unsigned long addr, bool protect)
 {
-	__kernel_map_pages(virt_to_page(addr), 1, !protect);
+	__kernel_map_pages(virt_to_page((void *)addr), 1, !protect);
 	return true;
 }
 
diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
index a9c138fcd2ad..cfec0743314e 100644
--- a/arch/s390/include/asm/page.h
+++ b/arch/s390/include/asm/page.h
@@ -191,8 +191,16 @@ int arch_make_page_accessible(struct page *page);
 #define phys_to_page(phys)	pfn_to_page(phys_to_pfn(phys))
 #define page_to_phys(page)	pfn_to_phys(page_to_pfn(page))
 
-#define pfn_to_virt(pfn)	__va(pfn_to_phys(pfn))
-#define virt_to_pfn(kaddr)	(phys_to_pfn(__pa(kaddr)))
+static inline void *pfn_to_virt(unsigned long pfn)
+{
+	return __va(pfn_to_phys(pfn));
+}
+
+static inline unsigned long virt_to_pfn(const void *kaddr)
+{
+	return phys_to_pfn(__pa(kaddr));
+}
+
 #define pfn_to_kaddr(pfn)	pfn_to_virt(pfn)
 
 #define virt_to_page(kaddr)	pfn_to_page(virt_to_pfn(kaddr))
diff --git a/arch/s390/mm/cmm.c b/arch/s390/mm/cmm.c
index 5300c6867d5e..f47515313226 100644
--- a/arch/s390/mm/cmm.c
+++ b/arch/s390/mm/cmm.c
@@ -90,7 +90,7 @@ static long cmm_alloc_pages(long nr, long *counter,
 			} else
 				free_page((unsigned long) npa);
 		}
-		diag10_range(virt_to_pfn(addr), 1);
+		diag10_range(virt_to_pfn((void *)addr), 1);
 		pa->pages[pa->index++] = addr;
 		(*counter)++;
 		spin_unlock(&cmm_lock);
diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
index b26649233d12..30cd6e1be10d 100644
--- a/arch/s390/mm/vmem.c
+++ b/arch/s390/mm/vmem.c
@@ -36,7 +36,7 @@ static void vmem_free_pages(unsigned long addr, int order)
 {
 	/* We don't expect boot memory to be removed ever. */
 	if (!slab_is_available() ||
-	    WARN_ON_ONCE(PageReserved(virt_to_page(addr))))
+	    WARN_ON_ONCE(PageReserved(virt_to_page((void *)addr))))
 		return;
 	free_pages(addr, order);
 }
diff --git a/drivers/s390/block/scm_blk.c b/drivers/s390/block/scm_blk.c
index 0c1df1d5f1ac..3a9cc8a4a230 100644
--- a/drivers/s390/block/scm_blk.c
+++ b/drivers/s390/block/scm_blk.c
@@ -134,7 +134,7 @@ static void scm_request_done(struct scm_request *scmrq)
 
 		if ((msb->flags & MSB_FLAG_IDA) && aidaw &&
 		    IS_ALIGNED(aidaw, PAGE_SIZE))
-			mempool_free(virt_to_page(aidaw), aidaw_pool);
+			mempool_free(virt_to_page((void *)aidaw), aidaw_pool);
 	}
 
 	spin_lock_irqsave(&list_lock, flags);
diff --git a/drivers/s390/char/vmcp.c b/drivers/s390/char/vmcp.c
index 4cebfaaa22b4..eb0520a9d4af 100644
--- a/drivers/s390/char/vmcp.c
+++ b/drivers/s390/char/vmcp.c
@@ -89,7 +89,7 @@ static void vmcp_response_free(struct vmcp_session *session)
 	order = get_order(session->bufsize);
 	nr_pages = ALIGN(session->bufsize, PAGE_SIZE) >> PAGE_SHIFT;
 	if (session->cma_alloc) {
-		page = virt_to_page((unsigned long)session->response);
+		page = virt_to_page(session->response);
 		cma_release(vmcp_cma, page, nr_pages);
 		session->cma_alloc = 0;
 	} else {

---
base-commit: 06c2afb862f9da8dc5efa4b6076a0e48c3fbaaa5
change-id: 20230809-virt-to-phys-s390-2fa3d38b8855

Best regards,
-- 
Linus Walleij <linus.walleij@xxxxxxxxxx>