[2/5] powerpc: Fix vDSO clock_getres()
diff mbox series

Message ID 20190401115152.32751-3-vincenzo.frascino@arm.com
State New
Headers show
Series
  • Fix vDSO clock_getres()
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Commit Message

Vincenzo Frascino April 1, 2019, 11:51 a.m. UTC
clock_getres in the vDSO library has to preserve the same behaviour
of posix_get_hrtimer_res().

In particular, posix_get_hrtimer_res() does:
    sec = 0;
    ns = hrtimer_resolution;
and hrtimer_resolution depends on the enablement of the high
resolution timers that can happen either at compile or at run time.

Fix the powerpc vdso implementation of clock_getres keeping a copy of
hrtimer_resolution in vdso data and using that directly.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
 arch/powerpc/include/asm/vdso_datapage.h  |  2 ++
 arch/powerpc/kernel/asm-offsets.c         |  2 +-
 arch/powerpc/kernel/time.c                |  1 +
 arch/powerpc/kernel/vdso32/gettimeofday.S | 22 +++++++++++++++-------
 arch/powerpc/kernel/vdso64/gettimeofday.S | 22 +++++++++++++++-------
 5 files changed, 34 insertions(+), 15 deletions(-)

Comments

Christophe Leroy April 2, 2019, 5:54 a.m. UTC | #1
On 04/01/2019 11:51 AM, Vincenzo Frascino wrote:
> clock_getres in the vDSO library has to preserve the same behaviour
> of posix_get_hrtimer_res().
> 
> In particular, posix_get_hrtimer_res() does:
>      sec = 0;
>      ns = hrtimer_resolution;
> and hrtimer_resolution depends on the enablement of the high
> resolution timers that can happen either at compile or at run time.
> 
> Fix the powerpc vdso implementation of clock_getres keeping a copy of
> hrtimer_resolution in vdso data and using that directly.
> 
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> ---
>   arch/powerpc/include/asm/vdso_datapage.h  |  2 ++

Conflicts with commit b5b4453e7912 ("powerpc/vdso64: Fix CLOCK_MONOTONIC 
inconsistencies across Y2038")

Christophe



>   arch/powerpc/kernel/asm-offsets.c         |  2 +-
>   arch/powerpc/kernel/time.c                |  1 +
>   arch/powerpc/kernel/vdso32/gettimeofday.S | 22 +++++++++++++++-------
>   arch/powerpc/kernel/vdso64/gettimeofday.S | 22 +++++++++++++++-------
>   5 files changed, 34 insertions(+), 15 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h
> index 1afe90ade595..4ae43fc77fe9 100644
> --- a/arch/powerpc/include/asm/vdso_datapage.h
> +++ b/arch/powerpc/include/asm/vdso_datapage.h
> @@ -86,6 +86,7 @@ struct vdso_data {
>   	__s32 wtom_clock_nsec;
>   	struct timespec stamp_xtime;	/* xtime as at tb_orig_stamp */
>   	__u32 stamp_sec_fraction;	/* fractional seconds of stamp_xtime */
> +	__u32 hrtimer_res;		/* hrtimer resolution */
>      	__u32 syscall_map_64[SYSCALL_MAP_SIZE]; /* map of syscalls  */
>      	__u32 syscall_map_32[SYSCALL_MAP_SIZE]; /* map of syscalls */
>   };
> @@ -107,6 +108,7 @@ struct vdso_data {
>   	__s32 wtom_clock_nsec;
>   	struct timespec stamp_xtime;	/* xtime as at tb_orig_stamp */
>   	__u32 stamp_sec_fraction;	/* fractional seconds of stamp_xtime */
> +	__u32 hrtimer_res;		/* hrtimer resolution */
>      	__u32 syscall_map_32[SYSCALL_MAP_SIZE]; /* map of syscalls */
>   	__u32 dcache_block_size;	/* L1 d-cache block size     */
>   	__u32 icache_block_size;	/* L1 i-cache block size     */
> diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
> index 86a61e5f8285..52e4b98a8492 100644
> --- a/arch/powerpc/kernel/asm-offsets.c
> +++ b/arch/powerpc/kernel/asm-offsets.c
> @@ -383,6 +383,7 @@ int main(void)
>   	OFFSET(WTOM_CLOCK_NSEC, vdso_data, wtom_clock_nsec);
>   	OFFSET(STAMP_XTIME, vdso_data, stamp_xtime);
>   	OFFSET(STAMP_SEC_FRAC, vdso_data, stamp_sec_fraction);
> +	OFFSET(CLOCK_REALTIME_RES, vdso_data, hrtimer_res);
>   	OFFSET(CFG_ICACHE_BLOCKSZ, vdso_data, icache_block_size);
>   	OFFSET(CFG_DCACHE_BLOCKSZ, vdso_data, dcache_block_size);
>   	OFFSET(CFG_ICACHE_LOGBLOCKSZ, vdso_data, icache_log_block_size);
> @@ -413,7 +414,6 @@ int main(void)
>   	DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE);
>   	DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE);
>   	DEFINE(NSEC_PER_SEC, NSEC_PER_SEC);
> -	DEFINE(CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC);
>   
>   #ifdef CONFIG_BUG
>   	DEFINE(BUG_ENTRY_SIZE, sizeof(struct bug_entry));
> diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
> index bc0503ef9c9c..62c04a6746d8 100644
> --- a/arch/powerpc/kernel/time.c
> +++ b/arch/powerpc/kernel/time.c
> @@ -955,6 +955,7 @@ void update_vsyscall(struct timekeeper *tk)
>   	vdso_data->wtom_clock_nsec = tk->wall_to_monotonic.tv_nsec;
>   	vdso_data->stamp_xtime = xt;
>   	vdso_data->stamp_sec_fraction = frac_sec;
> +	vdso_data->hrtimer_res = hrtimer_resolution;
>   	smp_wmb();
>   	++(vdso_data->tb_update_count);
>   }
> diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
> index 1e0bc5955a40..b21630079496 100644
> --- a/arch/powerpc/kernel/vdso32/gettimeofday.S
> +++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
> @@ -160,14 +160,21 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
>   	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
>   	bne	cr0,99f
>   
> -	li	r3,0
> -	cmpli	cr0,r4,0
> +	mflr	r12
> +  .cfi_register lr,r12
> +	mr	r11,r4
> +	bl	__get_datapage@local
> +	lwz	r5,CLOCK_REALTIME_RES(r3)
> +	li	r4,0
> +	cmplwi	r11,0		/* check if res is NULL */
> +	beq	1f
> +
> +	stw	r4,TSPC32_TV_SEC(r11)
> +	stw	r5,TSPC32_TV_NSEC(r11)
> +
> +1:	mtlr	r12
>   	crclr	cr0*4+so
> -	beqlr
> -	lis	r5,CLOCK_REALTIME_RES@h
> -	ori	r5,r5,CLOCK_REALTIME_RES@l
> -	stw	r3,TSPC32_TV_SEC(r4)
> -	stw	r5,TSPC32_TV_NSEC(r4)
> +	li	r3,0
>   	blr
>   
>   	/*
> @@ -175,6 +182,7 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
>   	 */
>   99:
>   	li	r0,__NR_clock_getres
> +  .cfi_restore lr
>   	sc
>   	blr
>     .cfi_endproc
> diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
> index a4ed9edfd5f0..a7e49bddd475 100644
> --- a/arch/powerpc/kernel/vdso64/gettimeofday.S
> +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
> @@ -190,14 +190,21 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
>   	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
>   	bne	cr0,99f
>   
> -	li	r3,0
> -	cmpldi	cr0,r4,0
> +	mflr	r12
> +  .cfi_register lr,r12
> +	mr	r11, r4
> +	bl	V_LOCAL_FUNC(__get_datapage)
> +	lwz	r5,CLOCK_REALTIME_RES(r3)
> +	li	r4,0
> +	cmpldi	r11,0		/* check if res is NULL */
> +	beq	1f
> +
> +	std	r4,TSPC64_TV_SEC(r11)
> +	std	r5,TSPC64_TV_NSEC(r11)
> +
> +1:	mtlr	r12
>   	crclr	cr0*4+so
> -	beqlr
> -	lis	r5,CLOCK_REALTIME_RES@h
> -	ori	r5,r5,CLOCK_REALTIME_RES@l
> -	std	r3,TSPC64_TV_SEC(r4)
> -	std	r5,TSPC64_TV_NSEC(r4)
> +	li	r3,0
>   	blr
>   
>   	/*
> @@ -205,6 +212,7 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
>   	 */
>   99:
>   	li	r0,__NR_clock_getres
> +  .cfi_restore lr
>   	sc
>   	blr
>     .cfi_endproc
>
Christophe Leroy April 2, 2019, 6:14 a.m. UTC | #2
On 04/01/2019 11:51 AM, Vincenzo Frascino wrote:
> clock_getres in the vDSO library has to preserve the same behaviour
> of posix_get_hrtimer_res().
> 
> In particular, posix_get_hrtimer_res() does:
>      sec = 0;
>      ns = hrtimer_resolution;
> and hrtimer_resolution depends on the enablement of the high
> resolution timers that can happen either at compile or at run time.
> 
> Fix the powerpc vdso implementation of clock_getres keeping a copy of
> hrtimer_resolution in vdso data and using that directly.
> 
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> ---
>   arch/powerpc/include/asm/vdso_datapage.h  |  2 ++
>   arch/powerpc/kernel/asm-offsets.c         |  2 +-
>   arch/powerpc/kernel/time.c                |  1 +
>   arch/powerpc/kernel/vdso32/gettimeofday.S | 22 +++++++++++++++-------
>   arch/powerpc/kernel/vdso64/gettimeofday.S | 22 +++++++++++++++-------
>   5 files changed, 34 insertions(+), 15 deletions(-)
> 

[...]

> diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
> index 1e0bc5955a40..b21630079496 100644
> --- a/arch/powerpc/kernel/vdso32/gettimeofday.S
> +++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
> @@ -160,14 +160,21 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
>   	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
>   	bne	cr0,99f
>   
> -	li	r3,0
> -	cmpli	cr0,r4,0
> +	mflr	r12
> +  .cfi_register lr,r12
> +	mr	r11,r4
> +	bl	__get_datapage@local
> +	lwz	r5,CLOCK_REALTIME_RES(r3)
> +	li	r4,0
> +	cmplwi	r11,0		/* check if res is NULL */
> +	beq	1f
> +
> +	stw	r4,TSPC32_TV_SEC(r11)
> +	stw	r5,TSPC32_TV_NSEC(r11)
> +
> +1:	mtlr	r12
>   	crclr	cr0*4+so
> -	beqlr
> -	lis	r5,CLOCK_REALTIME_RES@h
> -	ori	r5,r5,CLOCK_REALTIME_RES@l
> -	stw	r3,TSPC32_TV_SEC(r4)
> -	stw	r5,TSPC32_TV_NSEC(r4)
> +	li	r3,0
>   	blr

The above can be done simpler, see below

@@ -160,12 +160,15 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
  	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
  	bne	cr0,99f

+	mflr	r12
+  .cfi_register lr,r12
+	bl	__get_datapage@local
+	lwz	r5,CLOCK_REALTIME_RES(r3)
+	mtlr	r12
  	li	r3,0
  	cmpli	cr0,r4,0
  	crclr	cr0*4+so
  	beqlr
-	lis	r5,CLOCK_REALTIME_RES@h
-	ori	r5,r5,CLOCK_REALTIME_RES@l
  	stw	r3,TSPC32_TV_SEC(r4)
  	stw	r5,TSPC32_TV_NSEC(r4)
  	blr

Christophe

>   
>   	/*
> @@ -175,6 +182,7 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
>   	 */
>   99:
>   	li	r0,__NR_clock_getres
> +  .cfi_restore lr
>   	sc
>   	blr
>     .cfi_endproc
> diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
> index a4ed9edfd5f0..a7e49bddd475 100644
> --- a/arch/powerpc/kernel/vdso64/gettimeofday.S
> +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
> @@ -190,14 +190,21 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
>   	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
>   	bne	cr0,99f
>   
> -	li	r3,0
> -	cmpldi	cr0,r4,0
> +	mflr	r12
> +  .cfi_register lr,r12
> +	mr	r11, r4
> +	bl	V_LOCAL_FUNC(__get_datapage)
> +	lwz	r5,CLOCK_REALTIME_RES(r3)
> +	li	r4,0
> +	cmpldi	r11,0		/* check if res is NULL */
> +	beq	1f
> +
> +	std	r4,TSPC64_TV_SEC(r11)
> +	std	r5,TSPC64_TV_NSEC(r11)
> +
> +1:	mtlr	r12
>   	crclr	cr0*4+so
> -	beqlr
> -	lis	r5,CLOCK_REALTIME_RES@h
> -	ori	r5,r5,CLOCK_REALTIME_RES@l
> -	std	r3,TSPC64_TV_SEC(r4)
> -	std	r5,TSPC64_TV_NSEC(r4)
> +	li	r3,0
>   	blr

The same type of simplification applies here too.

Christophe


>   
>   	/*
> @@ -205,6 +212,7 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
>   	 */
>   99:
>   	li	r0,__NR_clock_getres
> +  .cfi_restore lr
>   	sc
>   	blr
>     .cfi_endproc
>
Vincenzo Frascino April 2, 2019, 9 a.m. UTC | #3
Hi Christophe,

thank you for your review.

On 02/04/2019 06:54, Christophe Leroy wrote:
> 
> 
> On 04/01/2019 11:51 AM, Vincenzo Frascino wrote:
>> clock_getres in the vDSO library has to preserve the same behaviour
>> of posix_get_hrtimer_res().
>>
>> In particular, posix_get_hrtimer_res() does:
>>      sec = 0;
>>      ns = hrtimer_resolution;
>> and hrtimer_resolution depends on the enablement of the high
>> resolution timers that can happen either at compile or at run time.
>>
>> Fix the powerpc vdso implementation of clock_getres keeping a copy of
>> hrtimer_resolution in vdso data and using that directly.
>>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Michael Ellerman <mpe@ellerman.id.au>
>> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
>> ---
>>   arch/powerpc/include/asm/vdso_datapage.h  |  2 ++
> 
> Conflicts with commit b5b4453e7912 ("powerpc/vdso64: Fix CLOCK_MONOTONIC 
> inconsistencies across Y2038")
> 

Thanks for pointing this out, I will rebase my code on top of the latest version
before reissuing v2.

...
Vincenzo Frascino April 2, 2019, 9:01 a.m. UTC | #4
On 02/04/2019 07:14, Christophe Leroy wrote:
> 
> 
> On 04/01/2019 11:51 AM, Vincenzo Frascino wrote:
>> clock_getres in the vDSO library has to preserve the same behaviour
>> of posix_get_hrtimer_res().
>>
>> In particular, posix_get_hrtimer_res() does:
>>      sec = 0;
>>      ns = hrtimer_resolution;
>> and hrtimer_resolution depends on the enablement of the high
>> resolution timers that can happen either at compile or at run time.
>>
>> Fix the powerpc vdso implementation of clock_getres keeping a copy of
>> hrtimer_resolution in vdso data and using that directly.
>>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Michael Ellerman <mpe@ellerman.id.au>
>> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
>> ---
>>   arch/powerpc/include/asm/vdso_datapage.h  |  2 ++
>>   arch/powerpc/kernel/asm-offsets.c         |  2 +-
>>   arch/powerpc/kernel/time.c                |  1 +
>>   arch/powerpc/kernel/vdso32/gettimeofday.S | 22 +++++++++++++++-------
>>   arch/powerpc/kernel/vdso64/gettimeofday.S | 22 +++++++++++++++-------
>>   5 files changed, 34 insertions(+), 15 deletions(-)
>>
> 
> [...]
> 
>> diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
>> index 1e0bc5955a40..b21630079496 100644
>> --- a/arch/powerpc/kernel/vdso32/gettimeofday.S
>> +++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
>> @@ -160,14 +160,21 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
>>   	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
>>   	bne	cr0,99f
>>   
>> -	li	r3,0
>> -	cmpli	cr0,r4,0
>> +	mflr	r12
>> +  .cfi_register lr,r12
>> +	mr	r11,r4
>> +	bl	__get_datapage@local
>> +	lwz	r5,CLOCK_REALTIME_RES(r3)
>> +	li	r4,0
>> +	cmplwi	r11,0		/* check if res is NULL */
>> +	beq	1f
>> +
>> +	stw	r4,TSPC32_TV_SEC(r11)
>> +	stw	r5,TSPC32_TV_NSEC(r11)
>> +
>> +1:	mtlr	r12
>>   	crclr	cr0*4+so
>> -	beqlr
>> -	lis	r5,CLOCK_REALTIME_RES@h
>> -	ori	r5,r5,CLOCK_REALTIME_RES@l
>> -	stw	r3,TSPC32_TV_SEC(r4)
>> -	stw	r5,TSPC32_TV_NSEC(r4)
>> +	li	r3,0
>>   	blr
> 
> The above can be done simpler, see below
> 
> @@ -160,12 +160,15 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
>   	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
>   	bne	cr0,99f
> 
> +	mflr	r12
> +  .cfi_register lr,r12
> +	bl	__get_datapage@local
> +	lwz	r5,CLOCK_REALTIME_RES(r3)
> +	mtlr	r12
>   	li	r3,0
>   	cmpli	cr0,r4,0
>   	crclr	cr0*4+so
>   	beqlr
> -	lis	r5,CLOCK_REALTIME_RES@h
> -	ori	r5,r5,CLOCK_REALTIME_RES@l
>   	stw	r3,TSPC32_TV_SEC(r4)
>   	stw	r5,TSPC32_TV_NSEC(r4)
>   	blr
> 

Thank you for this, I will update my code accordingly before posting v2.

> Christophe
> 
>>   
>>   	/*
>> @@ -175,6 +182,7 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
>>   	 */
>>   99:
>>   	li	r0,__NR_clock_getres
>> +  .cfi_restore lr
>>   	sc
>>   	blr
>>     .cfi_endproc
>> diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
>> index a4ed9edfd5f0..a7e49bddd475 100644
>> --- a/arch/powerpc/kernel/vdso64/gettimeofday.S
>> +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
>> @@ -190,14 +190,21 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
>>   	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
>>   	bne	cr0,99f
>>   
>> -	li	r3,0
>> -	cmpldi	cr0,r4,0
>> +	mflr	r12
>> +  .cfi_register lr,r12
>> +	mr	r11, r4
>> +	bl	V_LOCAL_FUNC(__get_datapage)
>> +	lwz	r5,CLOCK_REALTIME_RES(r3)
>> +	li	r4,0
>> +	cmpldi	r11,0		/* check if res is NULL */
>> +	beq	1f
>> +
>> +	std	r4,TSPC64_TV_SEC(r11)
>> +	std	r5,TSPC64_TV_NSEC(r11)
>> +
>> +1:	mtlr	r12
>>   	crclr	cr0*4+so
>> -	beqlr
>> -	lis	r5,CLOCK_REALTIME_RES@h
>> -	ori	r5,r5,CLOCK_REALTIME_RES@l
>> -	std	r3,TSPC64_TV_SEC(r4)
>> -	std	r5,TSPC64_TV_NSEC(r4)
>> +	li	r3,0
>>   	blr
> 
> The same type of simplification applies here too.
> 
> Christophe
> 
> 
>>   
>>   	/*
>> @@ -205,6 +212,7 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
>>   	 */
>>   99:
>>   	li	r0,__NR_clock_getres
>> +  .cfi_restore lr
>>   	sc
>>   	blr
>>     .cfi_endproc
>>

Patch
diff mbox series

diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h
index 1afe90ade595..4ae43fc77fe9 100644
--- a/arch/powerpc/include/asm/vdso_datapage.h
+++ b/arch/powerpc/include/asm/vdso_datapage.h
@@ -86,6 +86,7 @@  struct vdso_data {
 	__s32 wtom_clock_nsec;
 	struct timespec stamp_xtime;	/* xtime as at tb_orig_stamp */
 	__u32 stamp_sec_fraction;	/* fractional seconds of stamp_xtime */
+	__u32 hrtimer_res;		/* hrtimer resolution */
    	__u32 syscall_map_64[SYSCALL_MAP_SIZE]; /* map of syscalls  */
    	__u32 syscall_map_32[SYSCALL_MAP_SIZE]; /* map of syscalls */
 };
@@ -107,6 +108,7 @@  struct vdso_data {
 	__s32 wtom_clock_nsec;
 	struct timespec stamp_xtime;	/* xtime as at tb_orig_stamp */
 	__u32 stamp_sec_fraction;	/* fractional seconds of stamp_xtime */
+	__u32 hrtimer_res;		/* hrtimer resolution */
    	__u32 syscall_map_32[SYSCALL_MAP_SIZE]; /* map of syscalls */
 	__u32 dcache_block_size;	/* L1 d-cache block size     */
 	__u32 icache_block_size;	/* L1 i-cache block size     */
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 86a61e5f8285..52e4b98a8492 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -383,6 +383,7 @@  int main(void)
 	OFFSET(WTOM_CLOCK_NSEC, vdso_data, wtom_clock_nsec);
 	OFFSET(STAMP_XTIME, vdso_data, stamp_xtime);
 	OFFSET(STAMP_SEC_FRAC, vdso_data, stamp_sec_fraction);
+	OFFSET(CLOCK_REALTIME_RES, vdso_data, hrtimer_res);
 	OFFSET(CFG_ICACHE_BLOCKSZ, vdso_data, icache_block_size);
 	OFFSET(CFG_DCACHE_BLOCKSZ, vdso_data, dcache_block_size);
 	OFFSET(CFG_ICACHE_LOGBLOCKSZ, vdso_data, icache_log_block_size);
@@ -413,7 +414,6 @@  int main(void)
 	DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE);
 	DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE);
 	DEFINE(NSEC_PER_SEC, NSEC_PER_SEC);
-	DEFINE(CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC);
 
 #ifdef CONFIG_BUG
 	DEFINE(BUG_ENTRY_SIZE, sizeof(struct bug_entry));
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index bc0503ef9c9c..62c04a6746d8 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -955,6 +955,7 @@  void update_vsyscall(struct timekeeper *tk)
 	vdso_data->wtom_clock_nsec = tk->wall_to_monotonic.tv_nsec;
 	vdso_data->stamp_xtime = xt;
 	vdso_data->stamp_sec_fraction = frac_sec;
+	vdso_data->hrtimer_res = hrtimer_resolution;
 	smp_wmb();
 	++(vdso_data->tb_update_count);
 }
diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
index 1e0bc5955a40..b21630079496 100644
--- a/arch/powerpc/kernel/vdso32/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
@@ -160,14 +160,21 @@  V_FUNCTION_BEGIN(__kernel_clock_getres)
 	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
 	bne	cr0,99f
 
-	li	r3,0
-	cmpli	cr0,r4,0
+	mflr	r12
+  .cfi_register lr,r12
+	mr	r11,r4
+	bl	__get_datapage@local
+	lwz	r5,CLOCK_REALTIME_RES(r3)
+	li	r4,0
+	cmplwi	r11,0		/* check if res is NULL */
+	beq	1f
+
+	stw	r4,TSPC32_TV_SEC(r11)
+	stw	r5,TSPC32_TV_NSEC(r11)
+
+1:	mtlr	r12
 	crclr	cr0*4+so
-	beqlr
-	lis	r5,CLOCK_REALTIME_RES@h
-	ori	r5,r5,CLOCK_REALTIME_RES@l
-	stw	r3,TSPC32_TV_SEC(r4)
-	stw	r5,TSPC32_TV_NSEC(r4)
+	li	r3,0
 	blr
 
 	/*
@@ -175,6 +182,7 @@  V_FUNCTION_BEGIN(__kernel_clock_getres)
 	 */
 99:
 	li	r0,__NR_clock_getres
+  .cfi_restore lr
 	sc
 	blr
   .cfi_endproc
diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
index a4ed9edfd5f0..a7e49bddd475 100644
--- a/arch/powerpc/kernel/vdso64/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
@@ -190,14 +190,21 @@  V_FUNCTION_BEGIN(__kernel_clock_getres)
 	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
 	bne	cr0,99f
 
-	li	r3,0
-	cmpldi	cr0,r4,0
+	mflr	r12
+  .cfi_register lr,r12
+	mr	r11, r4
+	bl	V_LOCAL_FUNC(__get_datapage)
+	lwz	r5,CLOCK_REALTIME_RES(r3)
+	li	r4,0
+	cmpldi	r11,0		/* check if res is NULL */
+	beq	1f
+
+	std	r4,TSPC64_TV_SEC(r11)
+	std	r5,TSPC64_TV_NSEC(r11)
+
+1:	mtlr	r12
 	crclr	cr0*4+so
-	beqlr
-	lis	r5,CLOCK_REALTIME_RES@h
-	ori	r5,r5,CLOCK_REALTIME_RES@l
-	std	r3,TSPC64_TV_SEC(r4)
-	std	r5,TSPC64_TV_NSEC(r4)
+	li	r3,0
 	blr
 
 	/*
@@ -205,6 +212,7 @@  V_FUNCTION_BEGIN(__kernel_clock_getres)
 	 */
 99:
 	li	r0,__NR_clock_getres
+  .cfi_restore lr
 	sc
 	blr
   .cfi_endproc