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authorErik Bosman <ebn310@few.vu.nl>2008-04-11 20:57:22 +0400
committerIngo Molnar <mingo@elte.hu>2008-04-19 21:19:55 +0400
commitf1326973262382150c26bf4dfccd0fce310c4a9c (patch)
tree746cda0780feebf8e97d34f1b8e64f77bb15c3e7 /Documentation/prctl/disable-tsc-test.c
parent529e25f646e08901a6dad5768f681efffd77225e (diff)
downloadlinux-f1326973262382150c26bf4dfccd0fce310c4a9c.tar.xz
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 <ejbosman@cs.vu.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'Documentation/prctl/disable-tsc-test.c')
-rw-r--r--Documentation/prctl/disable-tsc-test.c94
1 files changed, 94 insertions, 0 deletions
diff --git a/Documentation/prctl/disable-tsc-test.c b/Documentation/prctl/disable-tsc-test.c
new file mode 100644
index 000000000000..843c81eac235
--- /dev/null
+++ b/Documentation/prctl/disable-tsc-test.c
@@ -0,0 +1,94 @@
+/*
+ * 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);
+}
+