[7/7] ARM: page: Turn highpage accesses into static inlines

Commit Message

Linus Walleij Feb. 25, 2024, 8:08 p.m. UTC

Clearing and copying pages in highmem uses either the cpu_user
vtable or the __glue() assembler stubs to call into per-CPU
versions of these functions.

This is all really confusing for KCFI so wrap these into static
inlines and prefix each inline function with __nocfi.

__cpu_clear_user_highpage() and __cpu_copy_user_highpage() are
exported in arch/arm/mm/proc-syms.c which causes a problem with
using static inlines, but it turns out that these exports are
completely unused, so we can just delete them.

Signed-off-by: Linus Walleij <[e-mail]>
---
 arch/arm/include/asm/page.h | 36 +++++++++++++++++++++++++++++-------
 arch/arm/mm/proc-syms.c     |  7 +------
 2 files changed, 30 insertions(+), 13 deletions(-)

Patch

diff --git a/arch/arm/include/asm/page.h b/arch/arm/include/asm/page.h
index 119aa85d1feb..8bf297228627 100644
--- a/arch/arm/include/asm/page.h
+++ b/arch/arm/include/asm/page.h
@@ -138,17 +138,39 @@  void xscale_mc_clear_user_highpage(struct page *page, unsigned long vaddr);
 #ifdef MULTI_USER
 extern struct cpu_user_fns cpu_user;
 
-#define __cpu_clear_user_highpage	cpu_user.cpu_clear_user_highpage
-#define __cpu_copy_user_highpage	cpu_user.cpu_copy_user_highpage
+static inline void __nocfi __cpu_clear_user_highpage(struct page *page,
+						     unsigned long vaddr)
+{
+	cpu_user.cpu_clear_user_highpage(page, vaddr);
+}
+
+static inline void __nocfi __cpu_copy_user_highpage(struct page *to,
+			struct page *from, unsigned long vaddr,
+			struct vm_area_struct *vma)
+{
+	cpu_user.cpu_copy_user_highpage(to, from, vaddr, vma);
+}
 
 #else
 
-#define __cpu_clear_user_highpage	__glue(_USER,_clear_user_highpage)
-#define __cpu_copy_user_highpage	__glue(_USER,_copy_user_highpage)
+/* These turn into function declarations for each per-CPU glue function */
+void __glue(_USER,_clear_user_highpage)(struct page *page, unsigned long vaddr);
+void __glue(_USER,_copy_user_highpage)(struct page *to, struct page *from,
+		unsigned long vaddr, struct vm_area_struct *vma);
+
+static inline void __nocfi __cpu_clear_user_highpage(struct page *page,
+						     unsigned long vaddr)
+{
+	__glue(_USER,_clear_user_highpage)(page, vaddr);
+}
+
+static inline void __nocfi __cpu_copy_user_highpage(struct page *to,
+			struct page *from, unsigned long vaddr,
+			struct vm_area_struct *vma)
+{
+	__glue(_USER,_copy_user_highpage)(to, from, vaddr, vma);
+}
 
-extern void __cpu_clear_user_highpage(struct page *page, unsigned long vaddr);
-extern void __cpu_copy_user_highpage(struct page *to, struct page *from,
-			unsigned long vaddr, struct vm_area_struct *vma);
 #endif
 
 #define clear_user_highpage(page,vaddr)		\
diff --git a/arch/arm/mm/proc-syms.c b/arch/arm/mm/proc-syms.c
index e21249548e9f..c93fec38d9f4 100644
--- a/arch/arm/mm/proc-syms.c
+++ b/arch/arm/mm/proc-syms.c
@@ -31,14 +31,9 @@  EXPORT_SYMBOL(__cpuc_flush_dcache_area);
 EXPORT_SYMBOL(cpu_cache);
 #endif
 
-#ifdef CONFIG_MMU
-#ifndef MULTI_USER
-EXPORT_SYMBOL(__cpu_clear_user_highpage);
-EXPORT_SYMBOL(__cpu_copy_user_highpage);
-#else
+#if defined(CONFIG_MMU) && defined(MULTI_USER)
 EXPORT_SYMBOL(cpu_user);
 #endif
-#endif
 
 /*
  * No module should need to touch the TLB (and currently