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Commit f1326973 authored by Erik Bosman's avatar Erik Bosman Committed by Ingo Molnar
Browse files

generic, x86: add tests for prctl PR_GET_TSC and PR_SET_TSC 



This patch adds three tests that test whether the PR_GET_TSC and
PR_SET_TSC commands have the desirable effect.

The tests check whether the control register is updated correctly
at context switches and try to discover bugs while enabling/disabling
the timestamp counter.

Signed-off-by: default avatarErik Bosman <ejbosman@cs.vu.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 529e25f6

Documentation/prctl/disable-tsc-ctxt-sw-stress-test.c

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Original line number Diff line number Diff line 
/*

 * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)

 *

 * Tests if the control register is updated correctly

 * at context switches

 *

 * Warning: this test will cause a very high load for a few seconds

 *

 */



#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <signal.h>

#include <inttypes.h>

#include <wait.h>





#include <sys/prctl.h>

#include <linux/prctl.h>



/* Get/set the process' ability to use the timestamp counter instruction */

#ifndef PR_GET_TSC

#define PR_GET_TSC 25

#define PR_SET_TSC 26

# define PR_TSC_ENABLE		1   /* allow the use of the timestamp counter */

# define PR_TSC_SIGSEGV		2   /* throw a SIGSEGV instead of reading the TSC */

#endif



uint64_t rdtsc() {

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;

}



void sigsegv_expect(int sig)

{

	/* */

}



void segvtask(void)

{

	if (prctl(PR_SET_TSC, PR_TSC_SIGSEGV) < 0)

	{

		perror("prctl");

		exit(0);

	}

	signal(SIGSEGV, sigsegv_expect);

	alarm(10);

	rdtsc();

	fprintf(stderr, "FATAL ERROR, rdtsc() succeeded while disabled\n");

	exit(0);

}





void sigsegv_fail(int sig)

{

	fprintf(stderr, "FATAL ERROR, rdtsc() failed while enabled\n");

	exit(0);

}



void rdtsctask(void)

{

	if (prctl(PR_SET_TSC, PR_TSC_ENABLE) < 0)

	{

		perror("prctl");

		exit(0);

	}

	signal(SIGSEGV, sigsegv_fail);

	alarm(10);

	for(;;) rdtsc();

}





int main(int argc, char **argv)

{

	int n_tasks = 100, i;



	fprintf(stderr, "[No further output means we're allright]\n");



	for (i=0; i<n_tasks; i++)

		if (fork() == 0)

		{

			if (i & 1)

				segvtask();

			else

				rdtsctask();

		}



	for (i=0; i<n_tasks; i++)

		wait(NULL);



	exit(0);

}

Documentation/prctl/disable-tsc-on-off-stress-test.c

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Original line number Diff line number Diff line 
/*

 * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)

 *

 * Tests if the control register is updated correctly

 * when set with prctl()

 *

 * Warning: this test will cause a very high load for a few seconds

 *

 */



#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <signal.h>

#include <inttypes.h>

#include <wait.h>





#include <sys/prctl.h>

#include <linux/prctl.h>



/* Get/set the process' ability to use the timestamp counter instruction */

#ifndef PR_GET_TSC

#define PR_GET_TSC 25

#define PR_SET_TSC 26

# define PR_TSC_ENABLE		1   /* allow the use of the timestamp counter */

# define PR_TSC_SIGSEGV		2   /* throw a SIGSEGV instead of reading the TSC */

#endif



/* snippet from wikipedia :-) */



uint64_t rdtsc() {

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;

}



int should_segv = 0;



void sigsegv_cb(int sig)

{

	if (!should_segv)

	{

		fprintf(stderr, "FATAL ERROR, rdtsc() failed while enabled\n");

		exit(0);

	}

	if (prctl(PR_SET_TSC, PR_TSC_ENABLE) < 0)

	{

		perror("prctl");

		exit(0);

	}

	should_segv = 0;



	rdtsc();

}



void task(void)

{

	signal(SIGSEGV, sigsegv_cb);

	alarm(10);

	for(;;)

	{

		rdtsc();

		if (should_segv)

		{

			fprintf(stderr, "FATAL ERROR, rdtsc() succeeded while disabled\n");

			exit(0);

		}

		if (prctl(PR_SET_TSC, PR_TSC_SIGSEGV) < 0)

		{

			perror("prctl");

			exit(0);

		}

		should_segv = 1;

	}

}





int main(int argc, char **argv)

{

	int n_tasks = 100, i;



	fprintf(stderr, "[No further output means we're allright]\n");



	for (i=0; i<n_tasks; i++)

		if (fork() == 0)

			task();



	for (i=0; i<n_tasks; i++)

		wait(NULL);



	exit(0);

}

Documentation/prctl/disable-tsc-test.c

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Original line number Diff line number Diff line 
/*

 * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)

 *

 * Basic test to test behaviour of PR_GET_TSC and PR_SET_TSC

 */



#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <signal.h>

#include <inttypes.h>





#include <sys/prctl.h>

#include <linux/prctl.h>



/* Get/set the process' ability to use the timestamp counter instruction */

#ifndef PR_GET_TSC

#define PR_GET_TSC 25

#define PR_SET_TSC 26

# define PR_TSC_ENABLE		1   /* allow the use of the timestamp counter */

# define PR_TSC_SIGSEGV		2   /* throw a SIGSEGV instead of reading the TSC */

#endif



const char *tsc_names[] =

{

	[0] = "[not set]",

	[PR_TSC_ENABLE] = "PR_TSC_ENABLE",

	[PR_TSC_SIGSEGV] = "PR_TSC_SIGSEGV",

};



uint64_t rdtsc() {

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;

}



void sigsegv_cb(int sig)

{

	int tsc_val = 0;



	printf("[ SIG_SEGV ]\n");

	printf("prctl(PR_GET_TSC, &tsc_val); ");

	fflush(stdout);



	if ( prctl(PR_GET_TSC, &tsc_val) == -1)

		perror("prctl");



	printf("tsc_val == %s\n", tsc_names[tsc_val]);

	printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");

	fflush(stdout);

	if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1)

		perror("prctl");



	printf("rdtsc() == ");

}



int main(int argc, char **argv)

{

	int tsc_val = 0;



	signal(SIGSEGV, sigsegv_cb);



	printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());

	printf("prctl(PR_GET_TSC, &tsc_val); ");

	fflush(stdout);



	if ( prctl(PR_GET_TSC, &tsc_val) == -1)

		perror("prctl");



	printf("tsc_val == %s\n", tsc_names[tsc_val]);

	printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());

	printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");

	fflush(stdout);



	if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1)

		perror("prctl");



	printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());

	printf("prctl(PR_SET_TSC, PR_TSC_SIGSEGV)\n");

	fflush(stdout);



	if ( prctl(PR_SET_TSC, PR_TSC_SIGSEGV) == -1)

		perror("prctl");



	printf("rdtsc() == ");

	fflush(stdout);

	printf("%llu\n", (unsigned long long)rdtsc());

	fflush(stdout);



	exit(EXIT_SUCCESS);

}