[PATCH v10 1/8] treewide: provide a generic clear_user_page() variant

[Ankur Arora <ankur.a.arora@oracle.com>]

From: David Hildenbrand <david@redhat.com>

Let's drop all variants that effectively map to clear_page() and
provide it in a generic variant instead.

We'll use the macro clear_user_page to indicate whether an architecture
provides it's own variant. Maybe at some point these should be CONFIG_
options.

Also, clear_user_page() is only called from the generic variant of
clear_user_highpage(), so define it only if the architecture does
not provide a clear_user_highpage(). And, for simplicity define it
in linux/highmem.h.

Note that for parisc, clear_page() and clear_user_page() map to
clear_page_asm(), so we can just get rid of the custom clear_user_page()
implementation. There is a clear_user_page_asm() function on parisc,
that seems to be unused. Not sure what's up with that.

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
---

Notes:
  - incorporates Christophe Leroy's suggestion of moving
    clear_user_page() into linux/highmem.h.

    The linkage between clear_user_highpage() and clear_user_page()
    isn't completely obvious but I hope the comment above
    clear_user_page() clarifies it.

    Though I guess if HIGHMEM goes away, we might have to revisit it.

 arch/alpha/include/asm/page.h      |  1 -
 arch/arc/include/asm/page.h        |  2 ++
 arch/arm/include/asm/page-nommu.h  |  1 -
 arch/arm64/include/asm/page.h      |  1 -
 arch/csky/abiv1/inc/abi/page.h     |  1 +
 arch/csky/abiv2/inc/abi/page.h     |  7 -------
 arch/hexagon/include/asm/page.h    |  1 -
 arch/loongarch/include/asm/page.h  |  1 -
 arch/m68k/include/asm/page_no.h    |  1 -
 arch/microblaze/include/asm/page.h |  1 -
 arch/mips/include/asm/page.h       |  1 +
 arch/nios2/include/asm/page.h      |  1 +
 arch/openrisc/include/asm/page.h   |  1 -
 arch/parisc/include/asm/page.h     |  1 -
 arch/powerpc/include/asm/page.h    |  1 +
 arch/riscv/include/asm/page.h      |  1 -
 arch/s390/include/asm/page.h       |  1 -
 arch/sparc/include/asm/page_64.h   |  1 +
 arch/um/include/asm/page.h         |  1 -
 arch/x86/include/asm/page.h        |  6 ------
 arch/xtensa/include/asm/page.h     |  1 -
 include/linux/highmem.h            | 23 +++++++++++++++++++++--
 22 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/arch/alpha/include/asm/page.h b/arch/alpha/include/asm/page.h
index d2c6667d73e9..59d01f9b77f6 100644
--- a/arch/alpha/include/asm/page.h
+++ b/arch/alpha/include/asm/page.h
@@ -11,7 +11,6 @@
 #define STRICT_MM_TYPECHECKS
 
 extern void clear_page(void *page);
-#define clear_user_page(page, vaddr, pg)	clear_page(page)
 
 #define vma_alloc_zeroed_movable_folio(vma, vaddr) \
 	vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, 0, vma, vaddr)
diff --git a/arch/arc/include/asm/page.h b/arch/arc/include/asm/page.h
index 9720fe6b2c24..38214e126c6d 100644
--- a/arch/arc/include/asm/page.h
+++ b/arch/arc/include/asm/page.h
@@ -32,6 +32,8 @@ struct page;
 
 void copy_user_highpage(struct page *to, struct page *from,
 			unsigned long u_vaddr, struct vm_area_struct *vma);
+
+#define clear_user_page clear_user_page
 void clear_user_page(void *to, unsigned long u_vaddr, struct page *page);
 
 typedef struct {
diff --git a/arch/arm/include/asm/page-nommu.h b/arch/arm/include/asm/page-nommu.h
index 7c2c72323d17..e74415c959be 100644
--- a/arch/arm/include/asm/page-nommu.h
+++ b/arch/arm/include/asm/page-nommu.h
@@ -11,7 +11,6 @@
 #define clear_page(page)	memset((page), 0, PAGE_SIZE)
 #define copy_page(to,from)	memcpy((to), (from), PAGE_SIZE)
 
-#define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 
 /*
diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
index 00f117ff4f7a..b39cc1127e1f 100644
--- a/arch/arm64/include/asm/page.h
+++ b/arch/arm64/include/asm/page.h
@@ -36,7 +36,6 @@ struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma,
 bool tag_clear_highpages(struct page *to, int numpages);
 #define __HAVE_ARCH_TAG_CLEAR_HIGHPAGES
 
-#define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 
 typedef struct page *pgtable_t;
diff --git a/arch/csky/abiv1/inc/abi/page.h b/arch/csky/abiv1/inc/abi/page.h
index 2d2159933b76..58307254e7e5 100644
--- a/arch/csky/abiv1/inc/abi/page.h
+++ b/arch/csky/abiv1/inc/abi/page.h
@@ -10,6 +10,7 @@ static inline unsigned long pages_do_alias(unsigned long addr1,
 	return (addr1 ^ addr2) & (SHMLBA-1);
 }
 
+#define clear_user_page clear_user_page
 static inline void clear_user_page(void *addr, unsigned long vaddr,
 				   struct page *page)
 {
diff --git a/arch/csky/abiv2/inc/abi/page.h b/arch/csky/abiv2/inc/abi/page.h
index cf005f13cd15..a5a255013308 100644
--- a/arch/csky/abiv2/inc/abi/page.h
+++ b/arch/csky/abiv2/inc/abi/page.h
@@ -1,11 +1,4 @@
 /* SPDX-License-Identifier: GPL-2.0 */
-
-static inline void clear_user_page(void *addr, unsigned long vaddr,
-				   struct page *page)
-{
-	clear_page(addr);
-}
-
 static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
 				  struct page *page)
 {
diff --git a/arch/hexagon/include/asm/page.h b/arch/hexagon/include/asm/page.h
index 137ba7c5de48..f0aed3ed812b 100644
--- a/arch/hexagon/include/asm/page.h
+++ b/arch/hexagon/include/asm/page.h
@@ -113,7 +113,6 @@ static inline void clear_page(void *page)
 /*
  * Under assumption that kernel always "sees" user map...
  */
-#define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 
 static inline unsigned long virt_to_pfn(const void *kaddr)
diff --git a/arch/loongarch/include/asm/page.h b/arch/loongarch/include/asm/page.h
index 256d1ff7a1e3..327bf0bc92bf 100644
--- a/arch/loongarch/include/asm/page.h
+++ b/arch/loongarch/include/asm/page.h
@@ -30,7 +30,6 @@
 extern void clear_page(void *page);
 extern void copy_page(void *to, void *from);
 
-#define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 
 extern unsigned long shm_align_mask;
diff --git a/arch/m68k/include/asm/page_no.h b/arch/m68k/include/asm/page_no.h
index 39db2026a4b4..d2532bc407ef 100644
--- a/arch/m68k/include/asm/page_no.h
+++ b/arch/m68k/include/asm/page_no.h
@@ -10,7 +10,6 @@ extern unsigned long memory_end;
 #define clear_page(page)	memset((page), 0, PAGE_SIZE)
 #define copy_page(to,from)	memcpy((to), (from), PAGE_SIZE)
 
-#define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 
 #define vma_alloc_zeroed_movable_folio(vma, vaddr) \
diff --git a/arch/microblaze/include/asm/page.h b/arch/microblaze/include/asm/page.h
index 90ac9f34b4b4..e1e396367ba7 100644
--- a/arch/microblaze/include/asm/page.h
+++ b/arch/microblaze/include/asm/page.h
@@ -45,7 +45,6 @@ typedef unsigned long pte_basic_t;
 # define copy_page(to, from)			memcpy((to), (from), PAGE_SIZE)
 # define clear_page(pgaddr)			memset((pgaddr), 0, PAGE_SIZE)
 
-# define clear_user_page(pgaddr, vaddr, page)	memset((pgaddr), 0, PAGE_SIZE)
 # define copy_user_page(vto, vfrom, vaddr, topg) \
 			memcpy((vto), (vfrom), PAGE_SIZE)
 
diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h
index bc3e3484c1bf..5ec428fcc887 100644
--- a/arch/mips/include/asm/page.h
+++ b/arch/mips/include/asm/page.h
@@ -90,6 +90,7 @@ static inline void clear_user_page(void *addr, unsigned long vaddr,
 	if (pages_do_alias((unsigned long) addr, vaddr & PAGE_MASK))
 		flush_data_cache_page((unsigned long)addr);
 }
+#define clear_user_page clear_user_page
 
 struct vm_area_struct;
 extern void copy_user_highpage(struct page *to, struct page *from,
diff --git a/arch/nios2/include/asm/page.h b/arch/nios2/include/asm/page.h
index 00a51623d38a..722956ac0bf8 100644
--- a/arch/nios2/include/asm/page.h
+++ b/arch/nios2/include/asm/page.h
@@ -45,6 +45,7 @@
 
 struct page;
 
+#define clear_user_page clear_user_page
 extern void clear_user_page(void *addr, unsigned long vaddr, struct page *page);
 extern void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
 				struct page *to);
diff --git a/arch/openrisc/include/asm/page.h b/arch/openrisc/include/asm/page.h
index 85797f94d1d7..d2cdbf3579bb 100644
--- a/arch/openrisc/include/asm/page.h
+++ b/arch/openrisc/include/asm/page.h
@@ -30,7 +30,6 @@
 #define clear_page(page)	memset((page), 0, PAGE_SIZE)
 #define copy_page(to, from)	memcpy((to), (from), PAGE_SIZE)
 
-#define clear_user_page(page, vaddr, pg)        clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)     copy_page(to, from)
 
 /*
diff --git a/arch/parisc/include/asm/page.h b/arch/parisc/include/asm/page.h
index 8f4e51071ea1..3630b36d07da 100644
--- a/arch/parisc/include/asm/page.h
+++ b/arch/parisc/include/asm/page.h
@@ -21,7 +21,6 @@ struct vm_area_struct;
 
 void clear_page_asm(void *page);
 void copy_page_asm(void *to, void *from);
-#define clear_user_page(vto, vaddr, page) clear_page_asm(vto)
 void copy_user_highpage(struct page *to, struct page *from, unsigned long vaddr,
 		struct vm_area_struct *vma);
 #define __HAVE_ARCH_COPY_USER_HIGHPAGE
diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index b28fbb1d57eb..f2bb1f98eebe 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -271,6 +271,7 @@ static inline const void *pfn_to_kaddr(unsigned long pfn)
 
 struct page;
 extern void clear_user_page(void *page, unsigned long vaddr, struct page *pg);
+#define clear_user_page clear_user_page
 extern void copy_user_page(void *to, void *from, unsigned long vaddr,
 		struct page *p);
 extern int devmem_is_allowed(unsigned long pfn);
diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index ffe213ad65a4..061b60b954ec 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -50,7 +50,6 @@ void clear_page(void *page);
 #endif
 #define copy_page(to, from)			memcpy((to), (from), PAGE_SIZE)
 
-#define clear_user_page(pgaddr, vaddr, page)	clear_page(pgaddr)
 #define copy_user_page(vto, vfrom, vaddr, topg) \
 			memcpy((vto), (vfrom), PAGE_SIZE)
 
diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
index c1d63b613bf9..9c8c5283258e 100644
--- a/arch/s390/include/asm/page.h
+++ b/arch/s390/include/asm/page.h
@@ -65,7 +65,6 @@ static inline void copy_page(void *to, void *from)
 		: : "memory", "cc");
 }
 
-#define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 
 #define vma_alloc_zeroed_movable_folio(vma, vaddr) \
diff --git a/arch/sparc/include/asm/page_64.h b/arch/sparc/include/asm/page_64.h
index d764d8a8586b..fd4dc85fb38b 100644
--- a/arch/sparc/include/asm/page_64.h
+++ b/arch/sparc/include/asm/page_64.h
@@ -43,6 +43,7 @@ void _clear_page(void *page);
 #define clear_page(X)	_clear_page((void *)(X))
 struct page;
 void clear_user_page(void *addr, unsigned long vaddr, struct page *page);
+#define clear_user_page clear_user_page
 #define copy_page(X,Y)	memcpy((void *)(X), (void *)(Y), PAGE_SIZE)
 void copy_user_page(void *to, void *from, unsigned long vaddr, struct page *topage);
 #define __HAVE_ARCH_COPY_USER_HIGHPAGE
diff --git a/arch/um/include/asm/page.h b/arch/um/include/asm/page.h
index 2d363460d896..e348ff489b89 100644
--- a/arch/um/include/asm/page.h
+++ b/arch/um/include/asm/page.h
@@ -26,7 +26,6 @@ struct page;
 #define clear_page(page)	memset((void *)(page), 0, PAGE_SIZE)
 #define copy_page(to,from)	memcpy((void *)(to), (void *)(from), PAGE_SIZE)
 
-#define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 
 typedef struct { unsigned long pte; } pte_t;
diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
index 9265f2fca99a..416dc88e35c1 100644
--- a/arch/x86/include/asm/page.h
+++ b/arch/x86/include/asm/page.h
@@ -22,12 +22,6 @@ struct page;
 extern struct range pfn_mapped[];
 extern int nr_pfn_mapped;
 
-static inline void clear_user_page(void *page, unsigned long vaddr,
-				   struct page *pg)
-{
-	clear_page(page);
-}
-
 static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
 				  struct page *topage)
 {
diff --git a/arch/xtensa/include/asm/page.h b/arch/xtensa/include/asm/page.h
index 20655174b111..059493256765 100644
--- a/arch/xtensa/include/asm/page.h
+++ b/arch/xtensa/include/asm/page.h
@@ -126,7 +126,6 @@ void clear_user_highpage(struct page *page, unsigned long vaddr);
 void copy_user_highpage(struct page *to, struct page *from,
 			unsigned long vaddr, struct vm_area_struct *vma);
 #else
-# define clear_user_page(page, vaddr, pg)	clear_page(page)
 # define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 #endif
 
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index abc20f9810fd..9a38512b8000 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -197,15 +197,34 @@ static inline void invalidate_kernel_vmap_range(void *vaddr, int size)
 }
 #endif
 
-/* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
 #ifndef clear_user_highpage
+#ifndef clear_user_page
+/**
+ * clear_user_page() - clear a page to be mapped to user space
+ * @addr: the address of the page
+ * @vaddr: the address of the user mapping
+ * @page: the page
+ *
+ * We condition the definition of clear_user_page() on the architecture not
+ * having a custom clear_user_highpage(). That's because if there is some
+ * special flushing needed for clear_user_highpage() then it is likely that
+ * clear_user_page() also needs some magic. And, since our only caller
+ * is the generic clear_user_highpage(), not defining is not much of a loss.
+ */
+static inline void clear_user_page(void *addr, unsigned long vaddr, struct page *page)
+{
+	clear_page(addr);
+}
+#endif
+
+/* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
 static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
 {
 	void *addr = kmap_local_page(page);
 	clear_user_page(addr, vaddr, page);
 	kunmap_local(addr);
 }
-#endif
+#endif /* clear_user_highpage */
 
 #ifndef vma_alloc_zeroed_movable_folio
 /**
-- 
2.31.1