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

Linus Walleij
2024-02-25T20:08:21Z

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 <linus.walleij@linaro.org>
---
arch/arm/include/asm/page.h | 36 +++++++++++++++++++++++++++++-------
arch/arm/mm/proc-syms.c | 7 +------
2 files changed, 30 insertions(+), 13 deletions(-)

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

--
2.34.1