[PATCH v3 3/3] kselftest: Extend vDSO selftest to clock_getres

[Vincenzo Frascino]

Hi Christophe,

thank you for your review.

On 22/05/2019 12:50, Christophe Leroy wrote:
> 
> 
> Le 22/05/2019 à 13:07, Vincenzo Frascino a écrit :
>> The current version of the multiarch vDSO selftest verifies only
>> gettimeofday.
>>
>> Extend the vDSO selftest to clock_getres, to verify that the
>> syscall and the vDSO library function return the same information.
>>
>> The extension has been used to verify the hrtimer_resoltion fix.
>>
>> Cc: Shuah Khan <shuah at kernel.org>
>> Signed-off-by: Vincenzo Frascino <vincenzo.frascino at arm.com>
>> ---
>>
>> Note: This patch is independent from the others in this series, hence it
>> can be merged singularly by the kselftest maintainers.
>>
>>   tools/testing/selftests/vDSO/Makefile         |   2 +
>>   .../selftests/vDSO/vdso_clock_getres.c        | 137 ++++++++++++++++++
>>   2 files changed, 139 insertions(+)
>>   create mode 100644 tools/testing/selftests/vDSO/vdso_clock_getres.c
>>
>> diff --git a/tools/testing/selftests/vDSO/Makefile b/tools/testing/selftests/vDSO/Makefile
>> index 9e03d61f52fd..d5c5bfdf1ac1 100644
>> --- a/tools/testing/selftests/vDSO/Makefile
>> +++ b/tools/testing/selftests/vDSO/Makefile
>> @@ -5,6 +5,7 @@ uname_M := $(shell uname -m 2>/dev/null || echo not)
>>   ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/x86/ -e s/x86_64/x86/)
>>   
>>   TEST_GEN_PROGS := $(OUTPUT)/vdso_test
>> +TEST_GEN_PROGS += $(OUTPUT)/vdso_clock_getres
>>   ifeq ($(ARCH),x86)
>>   TEST_GEN_PROGS += $(OUTPUT)/vdso_standalone_test_x86
>>   endif
>> @@ -18,6 +19,7 @@ endif
>>   
>>   all: $(TEST_GEN_PROGS)
>>   $(OUTPUT)/vdso_test: parse_vdso.c vdso_test.c
>> +$(OUTPUT)/vdso_clock_getres: vdso_clock_getres.c
>>   $(OUTPUT)/vdso_standalone_test_x86: vdso_standalone_test_x86.c parse_vdso.c
>>   	$(CC) $(CFLAGS) $(CFLAGS_vdso_standalone_test_x86) \
>>   		vdso_standalone_test_x86.c parse_vdso.c \
>> diff --git a/tools/testing/selftests/vDSO/vdso_clock_getres.c b/tools/testing/selftests/vDSO/vdso_clock_getres.c
>> new file mode 100644
>> index 000000000000..341a9bc34ffc
>> --- /dev/null
>> +++ b/tools/testing/selftests/vDSO/vdso_clock_getres.c
>> @@ -0,0 +1,137 @@
>> +// SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note
>> +/*
>> + * vdso_clock_getres.c: Sample code to test clock_getres.
>> + * Copyright (c) 2019 Arm Ltd.
>> + *
>> + * Compile with:
>> + * gcc -std=gnu99 vdso_clock_getres.c
>> + *
>> + * Tested on ARM, ARM64, MIPS32, x86 (32-bit and 64-bit),
>> + * Power (32-bit and 64-bit), S390x (32-bit and 64-bit).
>> + * Might work on other architectures.
>> + */
>> +
>> +#define _GNU_SOURCE
>> +#include <elf.h>
>> +#include <err.h>
>> +#include <fcntl.h>
>> +#include <stdint.h>
>> +#include <stdio.h>
>> +#include <stdlib.h>
>> +#include <time.h>
>> +#include <sys/auxv.h>
>> +#include <sys/mman.h>
>> +#include <sys/time.h>
>> +#include <unistd.h>
>> +#include <sys/syscall.h>
>> +
>> +#include "../kselftest.h"
>> +
>> +static long syscall_clock_getres(clockid_t _clkid, struct timespec *_ts)
>> +{
>> +	long ret;
>> +
>> +	ret = syscall(SYS_clock_getres, _clkid, _ts);
>> +
>> +	return ret;
>> +}
>> +
>> +const char *vdso_clock_name[12] = {
>> +	"CLOCK_REALTIME",
>> +	"CLOCK_MONOTONIC",
>> +	"CLOCK_PROCESS_CPUTIME_ID",
>> +	"CLOCK_THREAD_CPUTIME_ID",
>> +	"CLOCK_MONOTONIC_RAW",
>> +	"CLOCK_REALTIME_COARSE",
>> +	"CLOCK_MONOTONIC_COARSE",
>> +	"CLOCK_BOOTTIME",
>> +	"CLOCK_REALTIME_ALARM",
>> +	"CLOCK_BOOTTIME_ALARM",
>> +	"CLOCK_SGI_CYCLE",
>> +	"CLOCK_TAI",
>> +};
>> +
>> +/*
>> + * This function calls clock_getres in vdso and by system call
>> + * with different values for clock_id.
>> + *
>> + * Example of output:
>> + *
>> + * clock_id: CLOCK_REALTIME [PASS]
>> + * clock_id: CLOCK_BOOTTIME [PASS]
>> + * clock_id: CLOCK_TAI [PASS]
>> + * clock_id: CLOCK_REALTIME_COARSE [PASS]
>> + * clock_id: CLOCK_MONOTONIC [PASS]
>> + * clock_id: CLOCK_MONOTONIC_RAW [PASS]
>> + * clock_id: CLOCK_MONOTONIC_COARSE [PASS]
>> + */
>> +static inline int vdso_test_clock(unsigned int clock_id)
>> +{
>> +	struct timespec x, y;
>> +
>> +	printf("clock_id: %s", vdso_clock_name[clock_id]);
>> +	clock_getres(clock_id, &x);
>> +	syscall_clock_getres(clock_id, &y);
>> +
>> +	if ((x.tv_sec != y.tv_sec) || (x.tv_sec != y.tv_sec)) {
>> +		printf(" [FAIL]\n");
>> +		return KSFT_FAIL;
>> +	}
>> +
>> +	printf(" [PASS]\n");
>> +	return 0;
>> +}
>> +
>> +int main(int argc, char **argv)
>> +{
>> +	int ret;
>> +
>> +#if _POSIX_TIMERS > 0
>> +
>> +#ifdef CLOCK_REALTIME
> 
> Why do you need that #ifdef and all the ones below ?
> 
> CLOCK_REALTIME (and others) is defined in include/uapi/linux/time.h, so 
> it should be there when you build the test, shouldn't it ?
> 

In implementing this test I followed what the man page for clock_gettime(2)
defines in terms of availability of the timers. Since I do not know how old are
the userspace headers, I think it is a good idea checking that the clocks are
defined before trying to use them.

>> +	ret = vdso_test_clock(CLOCK_REALTIME);
>> +	if (ret)
>> +		goto out;
> 
> Why that goto ? Nothing is done at out, so a 'return ret' would be 
> better I think.
>

Agree, thanks for pointing this out. Will fix in v4.


> And do we really want to stop at first failure ? Wouldn't it be better 
> to run all the tests regardless ?
> 

The test is supposed to fail if one of the sub-tests fails, hence once the first
fails doesn't seem convenient running the others, because we already know the
result.

> Christophe
> 
>> +#endif
>> +
>> +#ifdef CLOCK_BOOTTIME
>> +	ret = vdso_test_clock(CLOCK_BOOTTIME);
>> +	if (ret)
>> +		goto out;
>> +#endif
>> +
>> +#ifdef CLOCK_TAI
>> +	ret = vdso_test_clock(CLOCK_TAI);
>> +	if (ret)
>> +		goto out;
>> +#endif
>> +
>> +#ifdef CLOCK_REALTIME_COARSE
>> +	ret = vdso_test_clock(CLOCK_REALTIME_COARSE);
>> +	if (ret)
>> +		goto out;
>> +#endif
>> +
>> +#ifdef CLOCK_MONOTONIC
>> +	ret = vdso_test_clock(CLOCK_MONOTONIC);
>> +	if (ret)
>> +		goto out;
>> +#endif
>> +
>> +#ifdef CLOCK_MONOTONIC_RAW
>> +	ret = vdso_test_clock(CLOCK_MONOTONIC_RAW);
>> +	if (ret)
>> +		goto out;
>> +#endif
>> +
>> +#ifdef CLOCK_MONOTONIC_COARSE
>> +	ret = vdso_test_clock(CLOCK_MONOTONIC_COARSE);
>> +	if (ret)
>> +		goto out;
>> +#endif
>> +
>> +#endif
>> +
>> +out:
>> +	return ret;
>> +}
>>

-- 
Regards,
Vincenzo