[LTP] [PATCH v2] syscalls/prctl10: Add basic test for PR_SET/GET_TSC

[xuyang2018.jy@fujitsu.com]

Hi Richard


> Hello,
> 
> Yang Xu <xuyang2018.jy@fujitsu.com> writes:
> 
>> Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
>> ---
>>   include/lapi/prctl.h                       |   7 ++
>>   runtest/syscalls                           |   1 +
>>   testcases/kernel/syscalls/prctl/.gitignore |   1 +
>>   testcases/kernel/syscalls/prctl/prctl10.c  | 108 +++++++++++++++++++++
>>   4 files changed, 117 insertions(+)
>>   create mode 100644 testcases/kernel/syscalls/prctl/prctl10.c
>>
>> diff --git a/include/lapi/prctl.h b/include/lapi/prctl.h
>> index fa5922231..8d3ef5c32 100644
>> --- a/include/lapi/prctl.h
>> +++ b/include/lapi/prctl.h
>> @@ -19,6 +19,13 @@
>>   # define PR_SET_SECCOMP  22
>>   #endif
>>   
>> +#ifndef PR_SET_TSC
>> +# define PR_GET_TSC 25
>> +# define PR_SET_TSC 26
>> +# define PR_TSC_ENABLE  1
>> +# define PR_TSC_SIGSEGV 2
>> +#endif
>> +
>>   #ifndef PR_SET_TIMERSLACK
>>   # define PR_SET_TIMERSLACK 29
>>   # define PR_GET_TIMERSLACK 30
>> diff --git a/runtest/syscalls b/runtest/syscalls
>> index 61a7b7677..51de0a614 100644
>> --- a/runtest/syscalls
>> +++ b/runtest/syscalls
>> @@ -1004,6 +1004,7 @@ prctl06 prctl06
>>   prctl07 prctl07
>>   prctl08 prctl08
>>   prctl09 prctl09
>> +prctl10 prctl10
>>   
>>   pread01 pread01
>>   pread01_64 pread01_64
>> diff --git a/testcases/kernel/syscalls/prctl/.gitignore b/testcases/kernel/syscalls/prctl/.gitignore
>> index 0f2c9b194..50ee4bf60 100644
>> --- a/testcases/kernel/syscalls/prctl/.gitignore
>> +++ b/testcases/kernel/syscalls/prctl/.gitignore
>> @@ -8,3 +8,4 @@
>>   /prctl07
>>   /prctl08
>>   /prctl09
>> +/prctl10
>> diff --git a/testcases/kernel/syscalls/prctl/prctl10.c b/testcases/kernel/syscalls/prctl/prctl10.c
>> new file mode 100644
>> index 000000000..01307ecd7
>> --- /dev/null
>> +++ b/testcases/kernel/syscalls/prctl/prctl10.c
>> @@ -0,0 +1,108 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/*
>> + * Copyright (c) 2022 FUJITSU LIMITED. All rights reserved.
>> + * Author: Yang Xu <xuyang2018.jy@fujitsu.com>
>> + */
>> +
>> +/*\
>> + * [Description]
>> + *
>> + * Basic test to test behaviour of PR_GET_TSC and PR_SET_TSC.
>> + *
>> + * Set the state of the flag determining whether the timestamp counter can
>> + * be read by the process.
>> + *
>> + * - Pass PR_TSC_ENABLE to arg2 to allow it to be read.
>> + * - Pass PR_TSC_SIGSEGV to arg2 to generate a SIGSEGV when read.
>> + */
>> +
>> +#include <sys/prctl.h>
>> +#include <string.h>
>> +#include <stdio.h>
>> +#include <stdlib.h>
>> +#include "tst_test.h"
>> +#include "lapi/prctl.h"
>> +
>> +#define TCASE_ENTRY(tsc_read_stat) { .name = #tsc_read_stat, .read_stat = tsc_read_stat}
>> +
>> +static const char * const tsc_read_stat_names[] = {
>> +	[0] = "[not set]",
>> +	[PR_TSC_ENABLE] = "PR_TSC_ENABLE",
>> +	[PR_TSC_SIGSEGV] = "PR_TSC_SIGSEGV",
>> +};
>> +
>> +static struct tcase {
>> +	char *name;
>> +	int read_stat;
>> +} tcases[] = {
>> +	TCASE_ENTRY(PR_TSC_ENABLE),
>> +	TCASE_ENTRY(PR_TSC_SIGSEGV)
>> +};
>> +
>> +static uint64_t rdtsc(void)
>> +{
>> +	uint32_t lo, hi;
>> +	/* We cannot use "=A", since this would use %rax on x86_64 */
>> +	__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
>> +	return (uint64_t)hi << 32 | lo;
>> +}
>> +
>> +
>> +static int expected_status(int status, int exp_status)
>> +{
>> +	if (!exp_status && WIFEXITED(status))
>> +		return 0;
>> +
>> +	if (exp_status && WIFSIGNALED(status) && WTERMSIG(status) == exp_status)
>> +		return 0;
>> +
>> +	return 1;
>> +}
>> +
>> +static void verify_prctl(unsigned int n)
>> +{
>> +	struct tcase *tc = &tcases[n];
>> +	unsigned long long time1, time2;
>> +	int tsc_val = 0, pid, status;
>> +
>> +	pid = SAFE_FORK();
>> +	if (!pid) {
>> +		TST_EXP_PASS_SILENT(prctl(PR_SET_TSC, tc->read_stat));
>> +		TST_EXP_PASS_SILENT(prctl(PR_GET_TSC, &tsc_val));
>> +		if (tsc_val == tc->read_stat)
>> +			tst_res(TPASS, "current state is %s(%d)",
>> +					tc->name, tc->read_stat);
>> +		else
>> +			tst_res(TFAIL, "current state is %s(%d), expect %s(%d)",
>> +					tsc_read_stat_names[tsc_val],
>> +					tsc_val, tc->name, tc->read_stat);
>> +
>> +		time1 = rdtsc();
>> +		time2 = rdtsc();
>> +		if (time2 > time1)
>> +			tst_res(TPASS, "rdtsc works correctly, %lld ->%lld",
>> +				time1, time2);
>> +		else
>> +			tst_res(TFAIL, "rdtsc works incorrectly, %lld ->%lld",
>> +				time1, time2);
>> +		exit(0);
>> +	}
>> +	SAFE_WAITPID(pid, &status, 0);
>> +
>> +	if (expected_status(status, tc->read_stat == PR_TSC_SIGSEGV ? SIGSEGV : 0))
>> +		tst_res(TFAIL, "Test %s failed", tc->name);
>> +	else
>> +		tst_res(TPASS, "Test %s succeeded", tc->name);
>> +}
>> +
>> +static struct tst_test test = {
>> +	.needs_root = 1,
> 
> Why did you add this?

Oh, yes, I should drop this.

So, should I send a v3 or you or other maintainers merge it by deleting it?

Best Regards
Yang Xu
> 
> It doesn't require root, but it could be denied with seccomp or an
> LSM. In some cases having root won't help (e.g. in a container). If
> you want to handle scenarios like these, then it would be better to
> check the return status of prctl.
> 
>> +	.forks_child = 1,
>> +	.test = verify_prctl,
>> +	.tcnt = ARRAY_SIZE(tcases),
>> +	.supported_archs = (const char *const []) {
>> +		"x86",
>> +		"x86_64",
>> +		NULL
>> +	},
>> +};
> 
> Otherwise LGTM.
>