Re: [PATCH] vdso: use CONFIG_PAGE_SHIFT in vdso/datapage.h

From: Michael Ellerman
Date: Thu Mar 21 2024 - 08:43:01 EST


Arnd Bergmann <arnd@xxxxxxxxxx> writes:
> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> 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@xxxxxxxxxxxxxx>
> Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
> Cc: Andy Lutomirski <luto@xxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
> Cc: Anna-Maria Behnsen <anna-maria@xxxxxxxxxxxxx>
> See-also: 8b3843ae3634 ("vdso/datapage: Quick fix - use asm/page-def.h for ARM64")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> arch/powerpc/include/asm/vdso/gettimeofday.h | 3 +--
> include/vdso/datapage.h | 8 +-------
> 2 files changed, 2 insertions(+), 9 deletions(-)

Acked-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> (powerpc)

cheers

> 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