linux-kernel - Re: [PATCH] selftests: vdso

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Message-ID: <d12193bb-fa2c-ad9c-82d9-5db85279ba91@kernel.org>
Date:   Wed, 1 Nov 2017 15:24:28 -0600
From:   Shuah Khan <shuah@...nel.org>
To:     Greg Hackmann <ghackmann@...gle.com>
Cc:     Steve Muckle <smuckle@...gle.com>, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org, Shuah Khan <shuahkh@....samsung.com>,
        Shuah Khan <shuah@...nel.org>
Subject: Re: [PATCH] selftests: vdso_test: support ARM64 targets

Hi Greg,

On 10/31/2017 03:28 PM, Greg Hackmann wrote:
> ARM64's vDSO exports its gettimeofday() implementation with a different
> name (__kernel_gettimeofday) and version (LINUX_2.6.39) from other
> architectures.  Add a corresponding special-case to vdso_test.
> 
> Signed-off-by: Greg Hackmann <ghackmann@...gle.com>

Thanks for the patch.

> ---
>  tools/testing/selftests/vDSO/vdso_test.c | 17 ++++++++++++++---
>  1 file changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/vDSO/vdso_test.c b/tools/testing/selftests/vDSO/vdso_test.c
> index 8daeb7d7032c..f0f8cc59c195 100644
> --- a/tools/testing/selftests/vDSO/vdso_test.c
> +++ b/tools/testing/selftests/vDSO/vdso_test.c
> @@ -21,6 +21,17 @@ extern void vdso_init_from_auxv(void *auxv);
>  
>  int main(int argc, char **argv)
>  {
> +	const char *version;
> +	const char *name;
> +
> +#if defined(__aarch64__)
> +	version = "LINUX_2.6.39";
> +	name = "__kernel_gettimeofday";
> +#else
> +	version = "LINUX_2.6";
> +	name = "__vdso_gettimeofday";
> +#endif
> +

Could you move these defines up and add them before the main.
It will be easier to follow the code that way.

Please capture the change log description as a comment block
for these defines.

thanks,
-- Shuah


>  	unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR);
>  	if (!sysinfo_ehdr) {
>  		printf("AT_SYSINFO_EHDR is not present!\n");
> @@ -31,10 +42,10 @@ int main(int argc, char **argv)
>  
>  	/* Find gettimeofday. */
>  	typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
> -	gtod_t gtod = (gtod_t)vdso_sym("LINUX_2.6", "__vdso_gettimeofday");
> +	gtod_t gtod = (gtod_t)vdso_sym(version, name);
>  
>  	if (!gtod) {
> -		printf("Could not find __vdso_gettimeofday\n");
> +		printf("Could not find %s\n", name);
>  		return 1;
>  	}
>  
> @@ -45,7 +56,7 @@ int main(int argc, char **argv)
>  		printf("The time is %lld.%06lld\n",
>  		       (long long)tv.tv_sec, (long long)tv.tv_usec);
>  	} else {
> -		printf("__vdso_gettimeofday failed\n");
> +		printf("%s failed\n", name);
>  	}
>  
>  	return 0;
>