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Subject: Re: [PATCH RESEND v1 2/4] lib/vdso: Add vdso_data pointer as input to
 __arch_get_timens_vdso_data()
To:     Christophe Leroy <christophe.leroy@csgroup.eu>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        dima@arista.com, avagin@gmail.com, arnd@arndb.de,
        tglx@linutronix.de, luto@kernel.org, linux-arch@vger.kernel.org
References: <cover.1617209141.git.christophe.leroy@csgroup.eu>
 <539c4204b1baa77c55f758904a1ea239abbc7a5c.1617209142.git.christophe.leroy@csgroup.eu>
From:   Vincenzo Frascino <vincenzo.frascino@arm.com>
Message-ID: <d3f27278-b555-ad6b-c3a3-573774ec486e@arm.com>
Date:   Mon, 12 Apr 2021 13:56:23 +0100
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On 3/31/21 5:48 PM, Christophe Leroy wrote:
> For the same reason as commit e876f0b69dc9 ("lib/vdso: Allow
> architectures to provide the vdso data pointer"), powerpc wants to
> avoid calculation of relative position to code.
> 
> As the timens_vdso_data is next page to vdso_data, provide
> vdso_data pointer to __arch_get_timens_vdso_data() in order
> to ease the calculation on powerpc in following patches.
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>

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

> ---
>  arch/arm64/include/asm/vdso/compat_gettimeofday.h |  3 ++-
>  arch/arm64/include/asm/vdso/gettimeofday.h        |  2 +-
>  arch/s390/include/asm/vdso/gettimeofday.h         |  3 ++-
>  arch/x86/include/asm/vdso/gettimeofday.h          |  3 ++-
>  lib/vdso/gettimeofday.c                           | 15 +++++++++------
>  5 files changed, 16 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/vdso/compat_gettimeofday.h b/arch/arm64/include/asm/vdso/compat_gettimeofday.h
> index 7508b0ac1d21..ecb6fd4c3c64 100644
> --- a/arch/arm64/include/asm/vdso/compat_gettimeofday.h
> +++ b/arch/arm64/include/asm/vdso/compat_gettimeofday.h
> @@ -155,7 +155,8 @@ static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
>  }
>  
>  #ifdef CONFIG_TIME_NS
> -static __always_inline const struct vdso_data *__arch_get_timens_vdso_data(void)
> +static __always_inline
> +const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd)
>  {
>  	const struct vdso_data *ret;
>  
> diff --git a/arch/arm64/include/asm/vdso/gettimeofday.h b/arch/arm64/include/asm/vdso/gettimeofday.h
> index 631ab1281633..de86230a9436 100644
> --- a/arch/arm64/include/asm/vdso/gettimeofday.h
> +++ b/arch/arm64/include/asm/vdso/gettimeofday.h
> @@ -100,7 +100,7 @@ const struct vdso_data *__arch_get_vdso_data(void)
>  
>  #ifdef CONFIG_TIME_NS
>  static __always_inline
> -const struct vdso_data *__arch_get_timens_vdso_data(void)
> +const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd)
>  {
>  	return _timens_data;
>  }
> diff --git a/arch/s390/include/asm/vdso/gettimeofday.h b/arch/s390/include/asm/vdso/gettimeofday.h
> index ed89ef742530..383c53c3dddd 100644
> --- a/arch/s390/include/asm/vdso/gettimeofday.h
> +++ b/arch/s390/include/asm/vdso/gettimeofday.h
> @@ -68,7 +68,8 @@ long clock_getres_fallback(clockid_t clkid, struct __kernel_timespec *ts)
>  }
>  
>  #ifdef CONFIG_TIME_NS
> -static __always_inline const struct vdso_data *__arch_get_timens_vdso_data(void)
> +static __always_inline
> +const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd)
>  {
>  	return _timens_data;
>  }
> diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h
> index df01d7349d79..1936f21ed8cd 100644
> --- a/arch/x86/include/asm/vdso/gettimeofday.h
> +++ b/arch/x86/include/asm/vdso/gettimeofday.h
> @@ -58,7 +58,8 @@ extern struct ms_hyperv_tsc_page hvclock_page
>  #endif
>  
>  #ifdef CONFIG_TIME_NS
> -static __always_inline const struct vdso_data *__arch_get_timens_vdso_data(void)
> +static __always_inline
> +const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd)
>  {
>  	return __timens_vdso_data;
>  }
> diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
> index c6f6dee08746..ce2f69552003 100644
> --- a/lib/vdso/gettimeofday.c
> +++ b/lib/vdso/gettimeofday.c
> @@ -49,13 +49,15 @@ static inline bool vdso_cycles_ok(u64 cycles)
>  static __always_inline int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
>  					  struct __kernel_timespec *ts)
>  {
> -	const struct vdso_data *vd = __arch_get_timens_vdso_data();
> +	const struct vdso_data *vd;
>  	const struct timens_offset *offs = &vdns->offset[clk];
>  	const struct vdso_timestamp *vdso_ts;
>  	u64 cycles, last, ns;
>  	u32 seq;
>  	s64 sec;
>  
> +	vd = vdns - (clk == CLOCK_MONOTONIC_RAW ? CS_RAW : CS_HRES_COARSE);
> +	vd = __arch_get_timens_vdso_data(vd);
>  	if (clk != CLOCK_MONOTONIC_RAW)
>  		vd = &vd[CS_HRES_COARSE];
>  	else
> @@ -92,7 +94,8 @@ static __always_inline int do_hres_timens(const struct vdso_data *vdns, clockid_
>  	return 0;
>  }
>  #else
> -static __always_inline const struct vdso_data *__arch_get_timens_vdso_data(void)
> +static __always_inline
> +const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd)
>  {
>  	return NULL;
>  }
> @@ -162,7 +165,7 @@ static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
>  static __always_inline int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
>  					    struct __kernel_timespec *ts)
>  {
> -	const struct vdso_data *vd = __arch_get_timens_vdso_data();
> +	const struct vdso_data *vd = __arch_get_timens_vdso_data(vdns);
>  	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
>  	const struct timens_offset *offs = &vdns->offset[clk];
>  	u64 nsec;
> @@ -310,7 +313,7 @@ __cvdso_gettimeofday_data(const struct vdso_data *vd,
>  	if (unlikely(tz != NULL)) {
>  		if (IS_ENABLED(CONFIG_TIME_NS) &&
>  		    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
> -			vd = __arch_get_timens_vdso_data();
> +			vd = __arch_get_timens_vdso_data(vd);
>  
>  		tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest;
>  		tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime;
> @@ -333,7 +336,7 @@ __cvdso_time_data(const struct vdso_data *vd, __kernel_old_time_t *time)
>  
>  	if (IS_ENABLED(CONFIG_TIME_NS) &&
>  	    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
> -		vd = __arch_get_timens_vdso_data();
> +		vd = __arch_get_timens_vdso_data(vd);
>  
>  	t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
>  
> @@ -363,7 +366,7 @@ int __cvdso_clock_getres_common(const struct vdso_data *vd, clockid_t clock,
>  
>  	if (IS_ENABLED(CONFIG_TIME_NS) &&
>  	    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
> -		vd = __arch_get_timens_vdso_data();
> +		vd = __arch_get_timens_vdso_data(vd);
>  
>  	/*
>  	 * Convert the clockid to a bitmask and use it to check which
> 

-- 
Regards,
Vincenzo