[LTP] [PATCH v2] syscalls/prctl10: Add basic test for PR_SET/GET_TSC
Richard Palethorpe
rpalethorpe@suse.de
Tue Oct 11 09:38:21 CEST 2022
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?
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.
--
Thank you,
Richard.
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