1 files changed, 59 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 000000000000..b2519e49424f
--- /dev/null
+++ b/tools/perf/arch/x86/util/tsc.c
@@ -0,0 +1,59 @@
+#include <stdbool.h>
+#include <errno.h>
+
+#include <linux/perf_event.h>
+
+#include "../../perf.h"
+#include "../../util/types.h"
+#include "../../util/debug.h"
+#include "tsc.h"
+
+u64 perf_time_to_tsc(u64 ns, struct perf_tsc_conversion *tc)
+{
+        u64 t, quot, rem;
+
+        t = ns - tc->time_zero;
+        quot = t / tc->time_mult;
+        rem  = t % tc->time_mult;
+        return (quot << tc->time_shift) +
+               (rem << tc->time_shift) / tc->time_mult;
+}
+
+u64 tsc_to_perf_time(u64 cyc, struct perf_tsc_conversion *tc)
+{
+        u64 quot, rem;
+
+        quot = cyc >> tc->time_shift;
+        rem  = cyc & ((1 << tc->time_shift) - 1);
+        return tc->time_zero + quot * tc->time_mult +
+               ((rem * tc->time_mult) >> tc->time_shift);
+}
+
+int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
+                             struct perf_tsc_conversion *tc)
+{
+        bool cap_user_time_zero;
+        u32 seq;
+        int i = 0;
+
+        while (1) {
+                seq = pc->lock;
+                rmb();
+                tc->time_mult = pc->time_mult;
+                tc->time_shift = pc->time_shift;
+                tc->time_zero = pc->time_zero;
+                cap_user_time_zero = pc->cap_user_time_zero;
+                rmb();
+                if (pc->lock == seq && !(seq & 1))
+                        break;
+                if (++i > 10000) {
+                        pr_debug("failed to get perf_event_mmap_page lock\n");
+                        return -EINVAL;
+                }
+        }
+
+        if (!cap_user_time_zero)
+                return -EOPNOTSUPP;
+
+        return 0;
+}