From: Erik Bosman Date: Fri, 11 Apr 2008 16:57:22 +0000 (+0200) Subject: generic, x86: add tests for prctl PR_GET_TSC and PR_SET_TSC X-Git-Tag: v2.6.26-rc1~1133^2~60 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f1326973262382150c26bf4dfccd0fce310c4a9c;p=linux-2.6 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: Erik Bosman Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- diff --git a/Documentation/prctl/disable-tsc-ctxt-sw-stress-test.c b/Documentation/prctl/disable-tsc-ctxt-sw-stress-test.c new file mode 100644 index 0000000000..f8e8e95e81 --- /dev/null +++ b/Documentation/prctl/disable-tsc-ctxt-sw-stress-test.c @@ -0,0 +1,96 @@ +/* + * 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 +#include +#include +#include +#include +#include + + +#include +#include + +/* 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 +#include +#include +#include +#include +#include + + +#include +#include + +/* 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 +#include +#include +#include +#include + + +#include +#include + +/* 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); +} +