f132697326
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: Erik Bosman <ejbosman@cs.vu.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
94 lines
2.1 KiB
C
94 lines
2.1 KiB
C
/*
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* Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)
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*
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* Basic test to test behaviour of PR_GET_TSC and PR_SET_TSC
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <signal.h>
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#include <inttypes.h>
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#include <sys/prctl.h>
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#include <linux/prctl.h>
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/* Get/set the process' ability to use the timestamp counter instruction */
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#ifndef PR_GET_TSC
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#define PR_GET_TSC 25
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#define PR_SET_TSC 26
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# define PR_TSC_ENABLE 1 /* allow the use of the timestamp counter */
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# define PR_TSC_SIGSEGV 2 /* throw a SIGSEGV instead of reading the TSC */
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#endif
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const char *tsc_names[] =
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{
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[0] = "[not set]",
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[PR_TSC_ENABLE] = "PR_TSC_ENABLE",
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[PR_TSC_SIGSEGV] = "PR_TSC_SIGSEGV",
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};
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uint64_t rdtsc() {
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uint32_t lo, hi;
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/* We cannot use "=A", since this would use %rax on x86_64 */
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__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
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return (uint64_t)hi << 32 | lo;
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}
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void sigsegv_cb(int sig)
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{
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int tsc_val = 0;
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printf("[ SIG_SEGV ]\n");
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printf("prctl(PR_GET_TSC, &tsc_val); ");
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fflush(stdout);
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if ( prctl(PR_GET_TSC, &tsc_val) == -1)
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perror("prctl");
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printf("tsc_val == %s\n", tsc_names[tsc_val]);
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printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");
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fflush(stdout);
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if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1)
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perror("prctl");
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printf("rdtsc() == ");
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}
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int main(int argc, char **argv)
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{
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int tsc_val = 0;
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signal(SIGSEGV, sigsegv_cb);
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printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
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printf("prctl(PR_GET_TSC, &tsc_val); ");
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fflush(stdout);
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if ( prctl(PR_GET_TSC, &tsc_val) == -1)
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perror("prctl");
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printf("tsc_val == %s\n", tsc_names[tsc_val]);
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printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
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printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");
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fflush(stdout);
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if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1)
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perror("prctl");
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printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
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printf("prctl(PR_SET_TSC, PR_TSC_SIGSEGV)\n");
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fflush(stdout);
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if ( prctl(PR_SET_TSC, PR_TSC_SIGSEGV) == -1)
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perror("prctl");
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printf("rdtsc() == ");
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fflush(stdout);
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printf("%llu\n", (unsigned long long)rdtsc());
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fflush(stdout);
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exit(EXIT_SUCCESS);
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}
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