vdso: Use CONFIG_PAGE_SHIFT in vdso/datapage.h

Both the vdso rework and the CONFIG_PAGE_SHIFT changes were merged during
the v6.9 merge window, so it is now possible to use CONFIG_PAGE_SHIFT
instead of including asm/page.h in the vdso.

This avoids the workaround for arm64 - commit 8b3843ae ("vdso/datapage:
Quick fix - use asm/page-def.h for ARM64") and addresses a build warning
for powerpc64:

In file included from <built-in>:4:
In file included from /home/arnd/arm-soc/arm-soc/lib/vdso/gettimeofday.c:5:
In file included from ../include/vdso/datapage.h:25:
arch/powerpc/include/asm/page.h:230:9: error: result of comparison of constant 13835058055282163712 with expression of type 'unsigned long' is always true [-Werror,-Wtautological-constant-out-of-range-compare]
  230 |         return __pa(kaddr) >> PAGE_SHIFT;
      |                ^~~~~~~~~~~
arch/powerpc/include/asm/page.h:217:37: note: expanded from macro '__pa'
  217 |         VIRTUAL_WARN_ON((unsigned long)(x) < PAGE_OFFSET);              \
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
arch/powerpc/include/asm/page.h:202:73: note: expanded from macro 'VIRTUAL_WARN_ON'
  202 | #define VIRTUAL_WARN_ON(x)      WARN_ON(IS_ENABLED(CONFIG_DEBUG_VIRTUAL) && (x))
      |                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
arch/powerpc/include/asm/bug.h:88:25: note: expanded from macro 'WARN_ON'
   88 |         int __ret_warn_on = !!(x);                              \
      |                                ^
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Link: https://lore.kernel.org/r/20240320180228.136371-1-arnd@kernel.org

arch/powerpc/include/asm/vdso/gettimeofday.h

@@ -4,7 +4,6 @@
 
 #ifndef __ASSEMBLY__
 
-#include <asm/page.h>
 #include <asm/vdso/timebase.h>
 #include <asm/barrier.h>
 #include <asm/unistd.h>
@@ -95,7 +94,7 @@ const struct vdso_data *__arch_get_vdso_data(void);
 static __always_inline
 const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd)
 {
-	return (void *)vd + PAGE_SIZE;
+	return (void *)vd + (1U << CONFIG_PAGE_SHIFT);
 }
 #endif
 

include/vdso/datapage.h

@@ -19,12 +19,6 @@
 #include <vdso/time32.h>
 #include <vdso/time64.h>
 
-#ifdef CONFIG_ARM64
-#include <asm/page-def.h>
-#else
-#include <asm/page.h>
-#endif
-
 #ifdef CONFIG_ARCH_HAS_VDSO_DATA
 #include <asm/vdso/data.h>
 #else
@@ -132,7 +126,7 @@ extern struct vdso_data _timens_data[CS_BASES] __attribute__((visibility("hidden
  */
 union vdso_data_store {
 	struct vdso_data	data[CS_BASES];
-	u8			page[PAGE_SIZE];
+	u8			page[1U << CONFIG_PAGE_SHIFT];
 };
 
 /*