linux-kernel - Re: [PATCH 15/22] arch: vdso: consolidate gettime prototypes

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Date:   Fri, 10 Nov 2023 10:16:46 +0000
From:   Vincenzo Frascino <vincenzo.frascino@....com>
To:     Arnd Bergmann <arnd@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org,
        Masahiro Yamada <masahiroy@...nel.org>,
        linux-kbuild@...r.kernel.org
Cc:     Arnd Bergmann <arnd@...db.de>, Matt Turner <mattst88@...il.com>,
        Vineet Gupta <vgupta@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Guo Ren <guoren@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Huacai Chen <chenhuacai@...nel.org>,
        Greg Ungerer <gerg@...ux-m68k.org>,
        Michal Simek <monstr@...str.eu>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Dinh Nguyen <dinguyen@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Geoff Levand <geoff@...radead.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        "David S. Miller" <davem@...emloft.net>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        Helge Deller <deller@....de>,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Timur Tabi <timur@...nel.org>,
        Kent Overstreet <kent.overstreet@...ux.dev>,
        David Woodhouse <dwmw2@...radead.org>,
        "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
        Kees Cook <keescook@...omium.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nicolas Schier <nicolas@...sle.eu>,
        Al Viro <viro@...iv.linux.org.uk>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        linux-alpha@...r.kernel.org, linux-snps-arc@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-trace-kernel@...r.kernel.org, linux-csky@...r.kernel.org,
        loongarch@...ts.linux.dev, linux-m68k@...ts.linux-m68k.org,
        linux-mips@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
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Subject: Re: [PATCH 15/22] arch: vdso: consolidate gettime prototypes

Hi Arnd,

On 11/8/23 12:58, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> The VDSO functions are defined as globals in the kernel sources but intended
> to be called from userspace, so there is no need to declare them in a kernel
> side header.
> 
> Without a prototype, this now causes warnings such as
> 
> arch/mips/vdso/vgettimeofday.c:14:5: error: no previous prototype for '__vdso_clock_gettime' [-Werror=missing-prototypes]
> arch/mips/vdso/vgettimeofday.c:28:5: error: no previous prototype for '__vdso_gettimeofday' [-Werror=missing-prototypes]
> arch/mips/vdso/vgettimeofday.c:36:5: error: no previous prototype for '__vdso_clock_getres' [-Werror=missing-prototypes]
> arch/mips/vdso/vgettimeofday.c:42:5: error: no previous prototype for '__vdso_clock_gettime64' [-Werror=missing-prototypes]
> arch/sparc/vdso/vclock_gettime.c:254:1: error: no previous prototype for '__vdso_clock_gettime' [-Werror=missing-prototypes]
> arch/sparc/vdso/vclock_gettime.c:282:1: error: no previous prototype for '__vdso_clock_gettime_stick' [-Werror=missing-prototypes]
> arch/sparc/vdso/vclock_gettime.c:307:1: error: no previous prototype for '__vdso_gettimeofday' [-Werror=missing-prototypes]
> arch/sparc/vdso/vclock_gettime.c:343:1: error: no previous prototype for '__vdso_gettimeofday_stick' [-Werror=missing-prototypes]
> 
> Most architectures have already added workarounds for these by adding
> declarations somewhere, but since these are all compatible, we should
> really just have one copy, with an #ifdef check for the 32-bit vs
> 64-bit variant and use that everywhere.
> 

I agree, it is a good idea to have a single header for this purpose.

> Unfortunately, the sparc version is currently incompatible since
> that never added support for __vdso_clock_gettime64() in 32-bit
> userland. For the moment, I'm leaving this one out, as I can't
> easily test it and it requires a larger rework.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Reviewed-by: Vincenzo Frascino <vincenzo.frascino@....com>

> ---
>  arch/arm/include/asm/vdso.h              |  5 -----
>  arch/arm/vdso/vgettimeofday.c            |  1 +
>  arch/arm64/kernel/vdso32/vgettimeofday.c |  1 +
>  arch/csky/kernel/vdso/vgettimeofday.c    | 11 +----------
>  arch/loongarch/vdso/vgettimeofday.c      |  7 +------
>  arch/mips/vdso/vgettimeofday.c           |  1 +
>  arch/riscv/kernel/vdso/vgettimeofday.c   |  7 +------
>  arch/x86/entry/vdso/vclock_gettime.c     | 10 +---------
>  arch/x86/include/asm/vdso/gettimeofday.h |  2 --
>  arch/x86/um/vdso/um_vdso.c               |  1 +
>  include/vdso/gettime.h                   | 23 +++++++++++++++++++++++
>  11 files changed, 31 insertions(+), 38 deletions(-)
>  create mode 100644 include/vdso/gettime.h
> 
> diff --git a/arch/arm/include/asm/vdso.h b/arch/arm/include/asm/vdso.h
> index 422c3afa806a..5b85889f82ee 100644
> --- a/arch/arm/include/asm/vdso.h
> +++ b/arch/arm/include/asm/vdso.h
> @@ -24,11 +24,6 @@ static inline void arm_install_vdso(struct mm_struct *mm, unsigned long addr)
>  
>  #endif /* CONFIG_VDSO */
>  
> -int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts);
> -int __vdso_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts);
> -int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz);
> -int __vdso_clock_getres(clockid_t clock_id, struct old_timespec32 *res);
> -
>  #endif /* __ASSEMBLY__ */
>  
>  #endif /* __KERNEL__ */
> diff --git a/arch/arm/vdso/vgettimeofday.c b/arch/arm/vdso/vgettimeofday.c
> index a003beacac76..3554aa35f1ba 100644
> --- a/arch/arm/vdso/vgettimeofday.c
> +++ b/arch/arm/vdso/vgettimeofday.c
> @@ -8,6 +8,7 @@
>  #include <linux/types.h>
>  #include <asm/vdso.h>
>  #include <asm/unwind.h>
> +#include <vdso/gettime.h>
>  
>  int __vdso_clock_gettime(clockid_t clock,
>  			 struct old_timespec32 *ts)
> diff --git a/arch/arm64/kernel/vdso32/vgettimeofday.c b/arch/arm64/kernel/vdso32/vgettimeofday.c
> index 5acff29c5991..e23c7f4ef26b 100644
> --- a/arch/arm64/kernel/vdso32/vgettimeofday.c
> +++ b/arch/arm64/kernel/vdso32/vgettimeofday.c
> @@ -5,6 +5,7 @@
>   * Copyright (C) 2018 ARM Limited
>   *
>   */
> +#include <vdso/gettime.h>
>  
>  int __vdso_clock_gettime(clockid_t clock,
>  			 struct old_timespec32 *ts)
> diff --git a/arch/csky/kernel/vdso/vgettimeofday.c b/arch/csky/kernel/vdso/vgettimeofday.c
> index c4831145eed5..55af30e83752 100644
> --- a/arch/csky/kernel/vdso/vgettimeofday.c
> +++ b/arch/csky/kernel/vdso/vgettimeofday.c
> @@ -2,36 +2,27 @@
>  
>  #include <linux/time.h>
>  #include <linux/types.h>
> +#include <vdso/gettime.h>
>  
>  extern
> -int __vdso_clock_gettime(clockid_t clock,
> -			 struct old_timespec32 *ts);
>  int __vdso_clock_gettime(clockid_t clock,
>  			 struct old_timespec32 *ts)
>  {
>  	return __cvdso_clock_gettime32(clock, ts);
>  }
>  
> -int __vdso_clock_gettime64(clockid_t clock,
> -			   struct __kernel_timespec *ts);
>  int __vdso_clock_gettime64(clockid_t clock,
>  			   struct __kernel_timespec *ts)
>  {
>  	return __cvdso_clock_gettime(clock, ts);
>  }
>  
> -extern
> -int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
> -			struct timezone *tz);
>  int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
>  			struct timezone *tz)
>  {
>  	return __cvdso_gettimeofday(tv, tz);
>  }
>  
> -extern
> -int __vdso_clock_getres(clockid_t clock_id,
> -			struct old_timespec32 *res);
>  int __vdso_clock_getres(clockid_t clock_id,
>  			struct old_timespec32 *res)
>  {
> diff --git a/arch/loongarch/vdso/vgettimeofday.c b/arch/loongarch/vdso/vgettimeofday.c
> index 8f22863bd7ea..0885c1f3a89d 100644
> --- a/arch/loongarch/vdso/vgettimeofday.c
> +++ b/arch/loongarch/vdso/vgettimeofday.c
> @@ -5,23 +5,18 @@
>   * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
>   */
>  #include <linux/types.h>
> +#include <vdso/gettime.h>
>  
> -extern
> -int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts);
>  int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
>  {
>  	return __cvdso_clock_gettime(clock, ts);
>  }
>  
> -extern
> -int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz);
>  int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
>  {
>  	return __cvdso_gettimeofday(tv, tz);
>  }
>  
> -extern
> -int __vdso_clock_getres(clockid_t clock_id, struct __kernel_timespec *res);
>  int __vdso_clock_getres(clockid_t clock_id, struct __kernel_timespec *res)
>  {
>  	return __cvdso_clock_getres(clock_id, res);
> diff --git a/arch/mips/vdso/vgettimeofday.c b/arch/mips/vdso/vgettimeofday.c
> index 6b83b6376a4b..604afea3f336 100644
> --- a/arch/mips/vdso/vgettimeofday.c
> +++ b/arch/mips/vdso/vgettimeofday.c
> @@ -9,6 +9,7 @@
>   */
>  #include <linux/time.h>
>  #include <linux/types.h>
> +#include <vdso/gettime.h>
>  
>  #if _MIPS_SIM != _MIPS_SIM_ABI64
>  int __vdso_clock_gettime(clockid_t clock,
> diff --git a/arch/riscv/kernel/vdso/vgettimeofday.c b/arch/riscv/kernel/vdso/vgettimeofday.c
> index cc0d80699c31..b35057802584 100644
> --- a/arch/riscv/kernel/vdso/vgettimeofday.c
> +++ b/arch/riscv/kernel/vdso/vgettimeofday.c
> @@ -8,23 +8,18 @@
>  
>  #include <linux/time.h>
>  #include <linux/types.h>
> +#include <vdso/gettime.h>
>  
> -extern
> -int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts);
>  int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
>  {
>  	return __cvdso_clock_gettime(clock, ts);
>  }
>  
> -extern
> -int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz);
>  int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
>  {
>  	return __cvdso_gettimeofday(tv, tz);
>  }
>  
> -extern
> -int __vdso_clock_getres(clockid_t clock_id, struct __kernel_timespec *res);
>  int __vdso_clock_getres(clockid_t clock_id, struct __kernel_timespec *res)
>  {
>  	return __cvdso_clock_getres(clock_id, res);
> diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
> index 7d70935b6758..0debc194bd78 100644
> --- a/arch/x86/entry/vdso/vclock_gettime.c
> +++ b/arch/x86/entry/vdso/vclock_gettime.c
> @@ -11,12 +11,10 @@
>  #include <linux/time.h>
>  #include <linux/kernel.h>
>  #include <linux/types.h>
> +#include <vdso/gettime.h>
>  
>  #include "../../../../lib/vdso/gettimeofday.c"
>  
> -extern int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz);
> -extern __kernel_old_time_t __vdso_time(__kernel_old_time_t *t);
> -
>  int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
>  {
>  	return __cvdso_gettimeofday(tv, tz);
> @@ -35,9 +33,6 @@ __kernel_old_time_t time(__kernel_old_time_t *t)	__attribute__((weak, alias("__v
>  
>  #if defined(CONFIG_X86_64) && !defined(BUILD_VDSO32_64)
>  /* both 64-bit and x32 use these */
> -extern int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts);
> -extern int __vdso_clock_getres(clockid_t clock, struct __kernel_timespec *res);
> -
>  int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
>  {
>  	return __cvdso_clock_gettime(clock, ts);
> @@ -56,9 +51,6 @@ int clock_getres(clockid_t, struct __kernel_timespec *)
>  
>  #else
>  /* i386 only */
> -extern int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts);
> -extern int __vdso_clock_getres(clockid_t clock, struct old_timespec32 *res);
> -
>  int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts)
>  {
>  	return __cvdso_clock_gettime32(clock, ts);
> diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h
> index c81858d903dc..a46edb0e0cf7 100644
> --- a/arch/x86/include/asm/vdso/gettimeofday.h
> +++ b/arch/x86/include/asm/vdso/gettimeofday.h
> @@ -337,8 +337,6 @@ u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
>  }
>  #define vdso_calc_delta vdso_calc_delta
>  
> -int __vdso_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts);
> -
>  #endif /* !__ASSEMBLY__ */
>  
>  #endif /* __ASM_VDSO_GETTIMEOFDAY_H */
> diff --git a/arch/x86/um/vdso/um_vdso.c b/arch/x86/um/vdso/um_vdso.c
> index ff0f3b4b6c45..63768dd347ce 100644
> --- a/arch/x86/um/vdso/um_vdso.c
> +++ b/arch/x86/um/vdso/um_vdso.c
> @@ -12,6 +12,7 @@
>  #include <linux/time.h>
>  #include <linux/getcpu.h>
>  #include <asm/unistd.h>
> +#include <vdso/gettime.h>
>  
>  int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
>  {
> diff --git a/include/vdso/gettime.h b/include/vdso/gettime.h
> new file mode 100644
> index 000000000000..c50d152e7b3e
> --- /dev/null
> +++ b/include/vdso/gettime.h
> @@ -0,0 +1,23 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _VDSO_GETTIME_H
> +#define _VDSO_GETTIME_H
> +
> +#include <linux/types.h>
> +
> +struct __kernel_timespec;
> +struct timezone;
> +
> +#if !defined(CONFIG_64BIT) || defined(BUILD_VDSO32_64)
> +struct old_timespec32;
> +int __vdso_clock_getres(clockid_t clock, struct old_timespec32 *res);
> +int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts);
> +#else
> +int __vdso_clock_getres(clockid_t clock, struct __kernel_timespec *res);
> +int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts);
> +#endif
> +
> +__kernel_old_time_t __vdso_time(__kernel_old_time_t *t);
> +int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz);
> +int __vdso_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts);
> +
> +#endif

-- 
Regards,
Vincenzo