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-rw-r--r--tools/perf/arch/x86/util/tsc.c90
1 files changed, 90 insertions, 0 deletions
diff --git a/tools/perf/arch/x86/util/tsc.c b/tools/perf/arch/x86/util/tsc.c
new file mode 100644
index 000000000..eb2b5195b
--- /dev/null
+++ b/tools/perf/arch/x86/util/tsc.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/types.h>
+#include <math.h>
+#include <string.h>
+
+#include "../../../util/debug.h"
+#include "../../../util/tsc.h"
+#include "cpuid.h"
+
+u64 rdtsc(void)
+{
+ unsigned int low, high;
+
+ asm volatile("rdtsc" : "=a" (low), "=d" (high));
+
+ return low | ((u64)high) << 32;
+}
+
+/*
+ * Derive the TSC frequency in Hz from the /proc/cpuinfo, for example:
+ * ...
+ * model name : Intel(R) Xeon(R) Gold 6154 CPU @ 3.00GHz
+ * ...
+ * will return 3000000000.
+ */
+static double cpuinfo_tsc_freq(void)
+{
+ double result = 0;
+ FILE *cpuinfo;
+ char *line = NULL;
+ size_t len = 0;
+
+ cpuinfo = fopen("/proc/cpuinfo", "r");
+ if (!cpuinfo) {
+ pr_err("Failed to read /proc/cpuinfo for TSC frequency");
+ return NAN;
+ }
+ while (getline(&line, &len, cpuinfo) > 0) {
+ if (!strncmp(line, "model name", 10)) {
+ char *pos = strstr(line + 11, " @ ");
+
+ if (pos && sscanf(pos, " @ %lfGHz", &result) == 1) {
+ result *= 1000000000;
+ goto out;
+ }
+ }
+ }
+out:
+ if (fpclassify(result) == FP_ZERO)
+ pr_err("Failed to find TSC frequency in /proc/cpuinfo");
+
+ free(line);
+ fclose(cpuinfo);
+ return result;
+}
+
+double arch_get_tsc_freq(void)
+{
+ unsigned int a, b, c, d, lvl;
+ static bool cached;
+ static double tsc;
+ char vendor[16];
+
+ if (cached)
+ return tsc;
+
+ cached = true;
+ get_cpuid_0(vendor, &lvl);
+ if (!strstr(vendor, "Intel"))
+ return 0;
+
+ /*
+ * Don't support Time Stamp Counter and
+ * Nominal Core Crystal Clock Information Leaf.
+ */
+ if (lvl < 0x15) {
+ tsc = cpuinfo_tsc_freq();
+ return tsc;
+ }
+
+ cpuid(0x15, 0, &a, &b, &c, &d);
+ /* TSC frequency is not enumerated */
+ if (!a || !b || !c) {
+ tsc = cpuinfo_tsc_freq();
+ return tsc;
+ }
+
+ tsc = (double)c * (double)b / (double)a;
+ return tsc;
+}