linux-kernel - [PATCH] vdso: use CONFIG_PAGE

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Date: Wed, 20 Mar 2024 19:02:15 +0100
From: Arnd Bergmann <arnd@...nel.org>
To: Michael Ellerman <mpe@...erman.id.au>,
	Andy Lutomirski <luto@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Vincenzo Frascino <vincenzo.frascino@....com>
Cc: Arnd Bergmann <arnd@...db.de>,
	linuxppc-dev@...ts.ozlabs.org,
	Anna-Maria Behnsen <anna-maria@...utronix.de>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	"Aneesh Kumar K.V" <aneesh.kumar@...nel.org>,
	"Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
	Kees Cook <keescook@...omium.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] vdso: use CONFIG_PAGE_SHIFT in vdso/datapage.h

From: Arnd Bergmann <arnd@...db.de>

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 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);                              \
      |                                ^

Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: linuxppc-dev@...ts.ozlabs.org
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vincenzo Frascino <vincenzo.frascino@....com>
Cc: Anna-Maria Behnsen <anna-maria@...utronix.de>
See-also: 8b3843ae3634 ("vdso/datapage: Quick fix - use asm/page-def.h for ARM64")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 arch/powerpc/include/asm/vdso/gettimeofday.h | 3 +--
 include/vdso/datapage.h                      | 8 +-------
 2 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h
index f0a4cf01e85c..78302f6c2580 100644
--- a/arch/powerpc/include/asm/vdso/gettimeofday.h
+++ b/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
 
diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h
index 5d5c0b8efff2..c71ddb6d4691 100644
--- a/include/vdso/datapage.h
+++ b/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];
 };
 
 /*
-- 
2.39.2